[clang] [clang] Fix crashes when passing VLA to va_arg (PR #119563)

2025-01-07 Thread via cfe-commits 

github-actions[bot] wrote:



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https://github.com/llvm/llvm-project/pull/119563
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[clang] [clang] Fix crashes when passing VLA to va_arg (PR #119563)

2025-01-07 Thread Aaron Ballman via cfe-commits 

https://github.com/AaronBallman closed 
https://github.com/llvm/llvm-project/pull/119563
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[clang] [clang] Fix crashes when passing VLA to va_arg (PR #119563)

2025-01-06 Thread via cfe-commits 

https://github.com/amane-ame updated 
https://github.com/llvm/llvm-project/pull/119563

From 659eda3ec76b63418f8b621b004728d9d7bf26ad Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Wed, 11 Dec 2024 22:17:51 +0800
Subject: [PATCH 01/11] [clang] Fix crashes when passing VLA to va_arg

---
 clang/lib/CodeGen/CGExprAgg.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index 2ad6587089f101..a4111cb65c8b1c 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -2201,6 +2201,8 @@ void CodeGenFunction::EmitAggregateCopy(LValue Dest, 
LValue Src, QualType Ty,
 // But note that getTypeInfo returns 0 for a VLA.
 if (auto *VAT = dyn_cast_or_null(
 getContext().getAsArrayType(Ty))) {
+  assert(Ty->isVariableArrayType());
+  EmitVariablyModifiedType(Ty);
   QualType BaseEltTy;
   SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr);
   TypeInfo = getContext().getTypeInfoInChars(BaseEltTy);

From 5937db790ff0a59ea5bf18cb008d38a4524dc7dc Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 13:50:13 +0800
Subject: [PATCH 02/11] [clang] Add a testcase for passing VLA to va_arg

---
 clang/test/CodeGen/varargs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/clang/test/CodeGen/varargs.c b/clang/test/CodeGen/varargs.c
index 625399b87f7ad7..b7b1b52156be37 100644
--- a/clang/test/CodeGen/varargs.c
+++ b/clang/test/CodeGen/varargs.c
@@ -20,4 +20,7 @@ void vla(int n, ...)
   __builtin_va_list ap;
   void *p;
   p = __builtin_va_arg(ap, typeof (int (*)[++n])); // CHECK: add nsw i32 
{{.*}}, 1
+  // Don't crash on some undefined behaviors.
+  p = __builtin_va_arg(ap, typeof (int [++n]));
+  p = __builtin_va_arg(ap, typeof (int [n][n]));
 }

From df9f8f61ee21b81c9cfd300d113afea9298b8067 Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 13:52:59 +0800
Subject: [PATCH 03/11] [clang] Move the parsing of VLA in va_arg to EmitVAArg

---
 clang/lib/CodeGen/CGCall.cpp| 2 ++
 clang/lib/CodeGen/CGExprAgg.cpp | 2 --
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index 3cefc9da66ddb8..4e2812c62f4357 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -6121,6 +6121,8 @@ RValue CodeGenFunction::EmitVAArg(VAArgExpr *VE, Address 
&VAListAddr,
   VAListAddr = VE->isMicrosoftABI() ? EmitMSVAListRef(VE->getSubExpr())
 : EmitVAListRef(VE->getSubExpr());
   QualType Ty = VE->getType();
+  if (Ty->isVariableArrayType())
+EmitVariablyModifiedType(Ty);
   if (VE->isMicrosoftABI())
 return CGM.getABIInfo().EmitMSVAArg(*this, VAListAddr, Ty, Slot);
   return CGM.getABIInfo().EmitVAArg(*this, VAListAddr, Ty, Slot);
diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index a4111cb65c8b1c..2ad6587089f101 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -2201,8 +2201,6 @@ void CodeGenFunction::EmitAggregateCopy(LValue Dest, 
LValue Src, QualType Ty,
 // But note that getTypeInfo returns 0 for a VLA.
 if (auto *VAT = dyn_cast_or_null(
 getContext().getAsArrayType(Ty))) {
-  assert(Ty->isVariableArrayType());
-  EmitVariablyModifiedType(Ty);
   QualType BaseEltTy;
   SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr);
   TypeInfo = getContext().getTypeInfoInChars(BaseEltTy);

From b38c1d1ee20d3308a4120c3b95a167a936314a6b Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 15:43:35 +0800
Subject: [PATCH 04/11] [clang] Emit an undefined-behavior warning for passing
 VLA to va_arg

---
 clang/include/clang/Basic/DiagnosticSemaKinds.td | 4 
 clang/lib/Sema/SemaExpr.cpp  | 7 +++
 clang/test/CodeGen/varargs.c | 6 +++---
 3 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td 
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 0a245e2077f68f..3a352f23faa353 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -10497,6 +10497,10 @@ def 
warn_second_parameter_to_va_arg_ownership_qualified : Warning<
 def warn_second_parameter_to_va_arg_never_compatible : Warning<
   "second argument to 'va_arg' is of promotable type %0; this va_arg has "
   "undefined behavior because arguments will be promoted to %1">, 
InGroup;
+def warn_second_parameter_to_va_arg_vla : Warning<
+  "second argument to 'va_arg' is of variable length array type %0; "
+  "this va_arg has undefined behavior because arguments will never "
+  "be compatible with variable length array type">, InGroup;
 
 def warn_return_missing_expr : Warning<
   "non-void %select{function|method}1 %0 should return a value">, DefaultError,
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp

[clang] [clang] Fix crashes when passing VLA to va_arg (PR #119563)

2025-01-06 Thread via cfe-commits 

https://github.com/amane-ame updated 
https://github.com/llvm/llvm-project/pull/119563

From 659eda3ec76b63418f8b621b004728d9d7bf26ad Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Wed, 11 Dec 2024 22:17:51 +0800
Subject: [PATCH 01/11] [clang] Fix crashes when passing VLA to va_arg

---
 clang/lib/CodeGen/CGExprAgg.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index 2ad6587089f101..a4111cb65c8b1c 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -2201,6 +2201,8 @@ void CodeGenFunction::EmitAggregateCopy(LValue Dest, 
LValue Src, QualType Ty,
 // But note that getTypeInfo returns 0 for a VLA.
 if (auto *VAT = dyn_cast_or_null(
 getContext().getAsArrayType(Ty))) {
+  assert(Ty->isVariableArrayType());
+  EmitVariablyModifiedType(Ty);
   QualType BaseEltTy;
   SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr);
   TypeInfo = getContext().getTypeInfoInChars(BaseEltTy);

From 5937db790ff0a59ea5bf18cb008d38a4524dc7dc Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 13:50:13 +0800
Subject: [PATCH 02/11] [clang] Add a testcase for passing VLA to va_arg

---
 clang/test/CodeGen/varargs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/clang/test/CodeGen/varargs.c b/clang/test/CodeGen/varargs.c
index 625399b87f7ad7..b7b1b52156be37 100644
--- a/clang/test/CodeGen/varargs.c
+++ b/clang/test/CodeGen/varargs.c
@@ -20,4 +20,7 @@ void vla(int n, ...)
   __builtin_va_list ap;
   void *p;
   p = __builtin_va_arg(ap, typeof (int (*)[++n])); // CHECK: add nsw i32 
{{.*}}, 1
+  // Don't crash on some undefined behaviors.
+  p = __builtin_va_arg(ap, typeof (int [++n]));
+  p = __builtin_va_arg(ap, typeof (int [n][n]));
 }

From df9f8f61ee21b81c9cfd300d113afea9298b8067 Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 13:52:59 +0800
Subject: [PATCH 03/11] [clang] Move the parsing of VLA in va_arg to EmitVAArg

---
 clang/lib/CodeGen/CGCall.cpp| 2 ++
 clang/lib/CodeGen/CGExprAgg.cpp | 2 --
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index 3cefc9da66ddb8..4e2812c62f4357 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -6121,6 +6121,8 @@ RValue CodeGenFunction::EmitVAArg(VAArgExpr *VE, Address 
&VAListAddr,
   VAListAddr = VE->isMicrosoftABI() ? EmitMSVAListRef(VE->getSubExpr())
 : EmitVAListRef(VE->getSubExpr());
   QualType Ty = VE->getType();
+  if (Ty->isVariableArrayType())
+EmitVariablyModifiedType(Ty);
   if (VE->isMicrosoftABI())
 return CGM.getABIInfo().EmitMSVAArg(*this, VAListAddr, Ty, Slot);
   return CGM.getABIInfo().EmitVAArg(*this, VAListAddr, Ty, Slot);
diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index a4111cb65c8b1c..2ad6587089f101 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -2201,8 +2201,6 @@ void CodeGenFunction::EmitAggregateCopy(LValue Dest, 
LValue Src, QualType Ty,
 // But note that getTypeInfo returns 0 for a VLA.
 if (auto *VAT = dyn_cast_or_null(
 getContext().getAsArrayType(Ty))) {
-  assert(Ty->isVariableArrayType());
-  EmitVariablyModifiedType(Ty);
   QualType BaseEltTy;
   SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr);
   TypeInfo = getContext().getTypeInfoInChars(BaseEltTy);

From b38c1d1ee20d3308a4120c3b95a167a936314a6b Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 15:43:35 +0800
Subject: [PATCH 04/11] [clang] Emit an undefined-behavior warning for passing
 VLA to va_arg

---
 clang/include/clang/Basic/DiagnosticSemaKinds.td | 4 
 clang/lib/Sema/SemaExpr.cpp  | 7 +++
 clang/test/CodeGen/varargs.c | 6 +++---
 3 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td 
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 0a245e2077f68f..3a352f23faa353 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -10497,6 +10497,10 @@ def 
warn_second_parameter_to_va_arg_ownership_qualified : Warning<
 def warn_second_parameter_to_va_arg_never_compatible : Warning<
   "second argument to 'va_arg' is of promotable type %0; this va_arg has "
   "undefined behavior because arguments will be promoted to %1">, 
InGroup;
+def warn_second_parameter_to_va_arg_vla : Warning<
+  "second argument to 'va_arg' is of variable length array type %0; "
+  "this va_arg has undefined behavior because arguments will never "
+  "be compatible with variable length array type">, InGroup;
 
 def warn_return_missing_expr : Warning<
   "non-void %select{function|method}1 %0 should return a value">, DefaultError,
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp

[clang] [clang] Fix crashes when passing VLA to va_arg (PR #119563)

2025-01-06 Thread Eli Friedman via cfe-commits 

https://github.com/efriedma-quic approved this pull request.

LGTM

https://github.com/llvm/llvm-project/pull/119563
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[clang] [clang] Fix crashes when passing VLA to va_arg (PR #119563)

2024-12-31 Thread via cfe-commits 

amane-ame wrote:

cc @efriedma-quic @tbaederr.
Could anyone please review this?

https://github.com/llvm/llvm-project/pull/119563
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[clang] [clang] Fix crashes when passing VLA to va_arg (PR #119563)

2024-12-24 Thread via cfe-commits 

amane-ame wrote:

Ping.

https://github.com/llvm/llvm-project/pull/119563
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[clang] [clang] Fix crashes when passing VLA to va_arg (PR #119563)

2024-12-20 Thread via cfe-commits 

https://github.com/amane-ame updated 
https://github.com/llvm/llvm-project/pull/119563

From 659eda3ec76b63418f8b621b004728d9d7bf26ad Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Wed, 11 Dec 2024 22:17:51 +0800
Subject: [PATCH 01/10] [clang] Fix crashes when passing VLA to va_arg

---
 clang/lib/CodeGen/CGExprAgg.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index 2ad6587089f101..a4111cb65c8b1c 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -2201,6 +2201,8 @@ void CodeGenFunction::EmitAggregateCopy(LValue Dest, 
LValue Src, QualType Ty,
 // But note that getTypeInfo returns 0 for a VLA.
 if (auto *VAT = dyn_cast_or_null(
 getContext().getAsArrayType(Ty))) {
+  assert(Ty->isVariableArrayType());
+  EmitVariablyModifiedType(Ty);
   QualType BaseEltTy;
   SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr);
   TypeInfo = getContext().getTypeInfoInChars(BaseEltTy);

From 5937db790ff0a59ea5bf18cb008d38a4524dc7dc Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 13:50:13 +0800
Subject: [PATCH 02/10] [clang] Add a testcase for passing VLA to va_arg

---
 clang/test/CodeGen/varargs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/clang/test/CodeGen/varargs.c b/clang/test/CodeGen/varargs.c
index 625399b87f7ad7..b7b1b52156be37 100644
--- a/clang/test/CodeGen/varargs.c
+++ b/clang/test/CodeGen/varargs.c
@@ -20,4 +20,7 @@ void vla(int n, ...)
   __builtin_va_list ap;
   void *p;
   p = __builtin_va_arg(ap, typeof (int (*)[++n])); // CHECK: add nsw i32 
{{.*}}, 1
+  // Don't crash on some undefined behaviors.
+  p = __builtin_va_arg(ap, typeof (int [++n]));
+  p = __builtin_va_arg(ap, typeof (int [n][n]));
 }

From df9f8f61ee21b81c9cfd300d113afea9298b8067 Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 13:52:59 +0800
Subject: [PATCH 03/10] [clang] Move the parsing of VLA in va_arg to EmitVAArg

---
 clang/lib/CodeGen/CGCall.cpp| 2 ++
 clang/lib/CodeGen/CGExprAgg.cpp | 2 --
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index 3cefc9da66ddb8..4e2812c62f4357 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -6121,6 +6121,8 @@ RValue CodeGenFunction::EmitVAArg(VAArgExpr *VE, Address 
&VAListAddr,
   VAListAddr = VE->isMicrosoftABI() ? EmitMSVAListRef(VE->getSubExpr())
 : EmitVAListRef(VE->getSubExpr());
   QualType Ty = VE->getType();
+  if (Ty->isVariableArrayType())
+EmitVariablyModifiedType(Ty);
   if (VE->isMicrosoftABI())
 return CGM.getABIInfo().EmitMSVAArg(*this, VAListAddr, Ty, Slot);
   return CGM.getABIInfo().EmitVAArg(*this, VAListAddr, Ty, Slot);
diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index a4111cb65c8b1c..2ad6587089f101 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -2201,8 +2201,6 @@ void CodeGenFunction::EmitAggregateCopy(LValue Dest, 
LValue Src, QualType Ty,
 // But note that getTypeInfo returns 0 for a VLA.
 if (auto *VAT = dyn_cast_or_null(
 getContext().getAsArrayType(Ty))) {
-  assert(Ty->isVariableArrayType());
-  EmitVariablyModifiedType(Ty);
   QualType BaseEltTy;
   SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr);
   TypeInfo = getContext().getTypeInfoInChars(BaseEltTy);

From b38c1d1ee20d3308a4120c3b95a167a936314a6b Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 15:43:35 +0800
Subject: [PATCH 04/10] [clang] Emit an undefined-behavior warning for passing
 VLA to va_arg

---
 clang/include/clang/Basic/DiagnosticSemaKinds.td | 4 
 clang/lib/Sema/SemaExpr.cpp  | 7 +++
 clang/test/CodeGen/varargs.c | 6 +++---
 3 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td 
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 0a245e2077f68f..3a352f23faa353 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -10497,6 +10497,10 @@ def 
warn_second_parameter_to_va_arg_ownership_qualified : Warning<
 def warn_second_parameter_to_va_arg_never_compatible : Warning<
   "second argument to 'va_arg' is of promotable type %0; this va_arg has "
   "undefined behavior because arguments will be promoted to %1">, 
InGroup;
+def warn_second_parameter_to_va_arg_vla : Warning<
+  "second argument to 'va_arg' is of variable length array type %0; "
+  "this va_arg has undefined behavior because arguments will never "
+  "be compatible with variable length array type">, InGroup;
 
 def warn_return_missing_expr : Warning<
   "non-void %select{function|method}1 %0 should return a value">, DefaultError,
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp

[clang] [clang] Fix crashes when passing VLA to va_arg (PR #119563)

2024-12-17 Thread via cfe-commits 

https://github.com/amane-ame edited 
https://github.com/llvm/llvm-project/pull/119563
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[clang] [clang] Fix crashes when passing VLA to va_arg (PR #119563)

2024-12-17 Thread via cfe-commits 

https://github.com/amane-ame updated 
https://github.com/llvm/llvm-project/pull/119563

From 659eda3ec76b63418f8b621b004728d9d7bf26ad Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Wed, 11 Dec 2024 22:17:51 +0800
Subject: [PATCH 01/10] [clang] Fix crashes when passing VLA to va_arg

---
 clang/lib/CodeGen/CGExprAgg.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index 2ad6587089f101..a4111cb65c8b1c 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -2201,6 +2201,8 @@ void CodeGenFunction::EmitAggregateCopy(LValue Dest, 
LValue Src, QualType Ty,
 // But note that getTypeInfo returns 0 for a VLA.
 if (auto *VAT = dyn_cast_or_null(
 getContext().getAsArrayType(Ty))) {
+  assert(Ty->isVariableArrayType());
+  EmitVariablyModifiedType(Ty);
   QualType BaseEltTy;
   SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr);
   TypeInfo = getContext().getTypeInfoInChars(BaseEltTy);

From 5937db790ff0a59ea5bf18cb008d38a4524dc7dc Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 13:50:13 +0800
Subject: [PATCH 02/10] [clang] Add a testcase for passing VLA to va_arg

---
 clang/test/CodeGen/varargs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/clang/test/CodeGen/varargs.c b/clang/test/CodeGen/varargs.c
index 625399b87f7ad7..b7b1b52156be37 100644
--- a/clang/test/CodeGen/varargs.c
+++ b/clang/test/CodeGen/varargs.c
@@ -20,4 +20,7 @@ void vla(int n, ...)
   __builtin_va_list ap;
   void *p;
   p = __builtin_va_arg(ap, typeof (int (*)[++n])); // CHECK: add nsw i32 
{{.*}}, 1
+  // Don't crash on some undefined behaviors.
+  p = __builtin_va_arg(ap, typeof (int [++n]));
+  p = __builtin_va_arg(ap, typeof (int [n][n]));
 }

From df9f8f61ee21b81c9cfd300d113afea9298b8067 Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 13:52:59 +0800
Subject: [PATCH 03/10] [clang] Move the parsing of VLA in va_arg to EmitVAArg

---
 clang/lib/CodeGen/CGCall.cpp| 2 ++
 clang/lib/CodeGen/CGExprAgg.cpp | 2 --
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index 3cefc9da66ddb8..4e2812c62f4357 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -6121,6 +6121,8 @@ RValue CodeGenFunction::EmitVAArg(VAArgExpr *VE, Address 
&VAListAddr,
   VAListAddr = VE->isMicrosoftABI() ? EmitMSVAListRef(VE->getSubExpr())
 : EmitVAListRef(VE->getSubExpr());
   QualType Ty = VE->getType();
+  if (Ty->isVariableArrayType())
+EmitVariablyModifiedType(Ty);
   if (VE->isMicrosoftABI())
 return CGM.getABIInfo().EmitMSVAArg(*this, VAListAddr, Ty, Slot);
   return CGM.getABIInfo().EmitVAArg(*this, VAListAddr, Ty, Slot);
diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index a4111cb65c8b1c..2ad6587089f101 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -2201,8 +2201,6 @@ void CodeGenFunction::EmitAggregateCopy(LValue Dest, 
LValue Src, QualType Ty,
 // But note that getTypeInfo returns 0 for a VLA.
 if (auto *VAT = dyn_cast_or_null(
 getContext().getAsArrayType(Ty))) {
-  assert(Ty->isVariableArrayType());
-  EmitVariablyModifiedType(Ty);
   QualType BaseEltTy;
   SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr);
   TypeInfo = getContext().getTypeInfoInChars(BaseEltTy);

From b38c1d1ee20d3308a4120c3b95a167a936314a6b Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 15:43:35 +0800
Subject: [PATCH 04/10] [clang] Emit an undefined-behavior warning for passing
 VLA to va_arg

---
 clang/include/clang/Basic/DiagnosticSemaKinds.td | 4 
 clang/lib/Sema/SemaExpr.cpp  | 7 +++
 clang/test/CodeGen/varargs.c | 6 +++---
 3 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td 
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 0a245e2077f68f..3a352f23faa353 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -10497,6 +10497,10 @@ def 
warn_second_parameter_to_va_arg_ownership_qualified : Warning<
 def warn_second_parameter_to_va_arg_never_compatible : Warning<
   "second argument to 'va_arg' is of promotable type %0; this va_arg has "
   "undefined behavior because arguments will be promoted to %1">, 
InGroup;
+def warn_second_parameter_to_va_arg_vla : Warning<
+  "second argument to 'va_arg' is of variable length array type %0; "
+  "this va_arg has undefined behavior because arguments will never "
+  "be compatible with variable length array type">, InGroup;
 
 def warn_return_missing_expr : Warning<
   "non-void %select{function|method}1 %0 should return a value">, DefaultError,
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp

[clang] [clang] Fix crashes when passing VLA to va_arg (PR #119563)

2024-12-17 Thread via cfe-commits 

https://github.com/amane-ame updated 
https://github.com/llvm/llvm-project/pull/119563

From 3e2e04fbf1978d657bb6968c16f68ef7c4adfbdb Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Wed, 11 Dec 2024 22:17:51 +0800
Subject: [PATCH 01/10] [clang] Fix crashes when passing VLA to va_arg

---
 clang/lib/CodeGen/CGExprAgg.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index 2ad6587089f101..a4111cb65c8b1c 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -2201,6 +2201,8 @@ void CodeGenFunction::EmitAggregateCopy(LValue Dest, 
LValue Src, QualType Ty,
 // But note that getTypeInfo returns 0 for a VLA.
 if (auto *VAT = dyn_cast_or_null(
 getContext().getAsArrayType(Ty))) {
+  assert(Ty->isVariableArrayType());
+  EmitVariablyModifiedType(Ty);
   QualType BaseEltTy;
   SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr);
   TypeInfo = getContext().getTypeInfoInChars(BaseEltTy);

From 9cda4ee46cdcaa6e5353fa97482640ab7f8f6368 Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 13:50:13 +0800
Subject: [PATCH 02/10] [clang] Add a testcase for passing VLA to va_arg

---
 clang/test/CodeGen/varargs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/clang/test/CodeGen/varargs.c b/clang/test/CodeGen/varargs.c
index 625399b87f7ad7..b7b1b52156be37 100644
--- a/clang/test/CodeGen/varargs.c
+++ b/clang/test/CodeGen/varargs.c
@@ -20,4 +20,7 @@ void vla(int n, ...)
   __builtin_va_list ap;
   void *p;
   p = __builtin_va_arg(ap, typeof (int (*)[++n])); // CHECK: add nsw i32 
{{.*}}, 1
+  // Don't crash on some undefined behaviors.
+  p = __builtin_va_arg(ap, typeof (int [++n]));
+  p = __builtin_va_arg(ap, typeof (int [n][n]));
 }

From 62e0069330d03191151df8f5709160c543bb82d0 Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 13:52:59 +0800
Subject: [PATCH 03/10] [clang] Move the parsing of VLA in va_arg to EmitVAArg

---
 clang/lib/CodeGen/CGCall.cpp| 2 ++
 clang/lib/CodeGen/CGExprAgg.cpp | 2 --
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index 50b9dfbbab083a..a278d7c5ecfa36 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -6121,6 +6121,8 @@ RValue CodeGenFunction::EmitVAArg(VAArgExpr *VE, Address 
&VAListAddr,
   VAListAddr = VE->isMicrosoftABI() ? EmitMSVAListRef(VE->getSubExpr())
 : EmitVAListRef(VE->getSubExpr());
   QualType Ty = VE->getType();
+  if (Ty->isVariableArrayType())
+EmitVariablyModifiedType(Ty);
   if (VE->isMicrosoftABI())
 return CGM.getABIInfo().EmitMSVAArg(*this, VAListAddr, Ty, Slot);
   return CGM.getABIInfo().EmitVAArg(*this, VAListAddr, Ty, Slot);
diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index a4111cb65c8b1c..2ad6587089f101 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -2201,8 +2201,6 @@ void CodeGenFunction::EmitAggregateCopy(LValue Dest, 
LValue Src, QualType Ty,
 // But note that getTypeInfo returns 0 for a VLA.
 if (auto *VAT = dyn_cast_or_null(
 getContext().getAsArrayType(Ty))) {
-  assert(Ty->isVariableArrayType());
-  EmitVariablyModifiedType(Ty);
   QualType BaseEltTy;
   SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr);
   TypeInfo = getContext().getTypeInfoInChars(BaseEltTy);

From edef80bc2a81858dd4b9ade94659e4aeb69d2e2d Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 15:43:35 +0800
Subject: [PATCH 04/10] [clang] Emit an undefined-behavior warning for passing
 VLA to va_arg

---
 clang/include/clang/Basic/DiagnosticSemaKinds.td | 4 
 clang/lib/Sema/SemaExpr.cpp  | 7 +++
 clang/test/CodeGen/varargs.c | 6 +++---
 3 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td 
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index d67a81f8564a8e..18e350d5e41192 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -10497,6 +10497,10 @@ def 
warn_second_parameter_to_va_arg_ownership_qualified : Warning<
 def warn_second_parameter_to_va_arg_never_compatible : Warning<
   "second argument to 'va_arg' is of promotable type %0; this va_arg has "
   "undefined behavior because arguments will be promoted to %1">, 
InGroup;
+def warn_second_parameter_to_va_arg_vla : Warning<
+  "second argument to 'va_arg' is of variable length array type %0; "
+  "this va_arg has undefined behavior because arguments will never "
+  "be compatible with variable length array type">, InGroup;
 
 def warn_return_missing_expr : Warning<
   "non-void %select{function|method}1 %0 should return a value">, DefaultError,
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp

[clang] [clang] Fix crashes when passing VLA to va_arg (PR #119563)

2024-12-16 Thread via cfe-commits 

https://github.com/amane-ame updated 
https://github.com/llvm/llvm-project/pull/119563

From 659eda3ec76b63418f8b621b004728d9d7bf26ad Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Wed, 11 Dec 2024 22:17:51 +0800
Subject: [PATCH 1/9] [clang] Fix crashes when passing VLA to va_arg

---
 clang/lib/CodeGen/CGExprAgg.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index 2ad6587089f101..a4111cb65c8b1c 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -2201,6 +2201,8 @@ void CodeGenFunction::EmitAggregateCopy(LValue Dest, 
LValue Src, QualType Ty,
 // But note that getTypeInfo returns 0 for a VLA.
 if (auto *VAT = dyn_cast_or_null(
 getContext().getAsArrayType(Ty))) {
+  assert(Ty->isVariableArrayType());
+  EmitVariablyModifiedType(Ty);
   QualType BaseEltTy;
   SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr);
   TypeInfo = getContext().getTypeInfoInChars(BaseEltTy);

From 5937db790ff0a59ea5bf18cb008d38a4524dc7dc Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 13:50:13 +0800
Subject: [PATCH 2/9] [clang] Add a testcase for passing VLA to va_arg

---
 clang/test/CodeGen/varargs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/clang/test/CodeGen/varargs.c b/clang/test/CodeGen/varargs.c
index 625399b87f7ad7..b7b1b52156be37 100644
--- a/clang/test/CodeGen/varargs.c
+++ b/clang/test/CodeGen/varargs.c
@@ -20,4 +20,7 @@ void vla(int n, ...)
   __builtin_va_list ap;
   void *p;
   p = __builtin_va_arg(ap, typeof (int (*)[++n])); // CHECK: add nsw i32 
{{.*}}, 1
+  // Don't crash on some undefined behaviors.
+  p = __builtin_va_arg(ap, typeof (int [++n]));
+  p = __builtin_va_arg(ap, typeof (int [n][n]));
 }

From df9f8f61ee21b81c9cfd300d113afea9298b8067 Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 13:52:59 +0800
Subject: [PATCH 3/9] [clang] Move the parsing of VLA in va_arg to EmitVAArg

---
 clang/lib/CodeGen/CGCall.cpp| 2 ++
 clang/lib/CodeGen/CGExprAgg.cpp | 2 --
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index 3cefc9da66ddb8..4e2812c62f4357 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -6121,6 +6121,8 @@ RValue CodeGenFunction::EmitVAArg(VAArgExpr *VE, Address 
&VAListAddr,
   VAListAddr = VE->isMicrosoftABI() ? EmitMSVAListRef(VE->getSubExpr())
 : EmitVAListRef(VE->getSubExpr());
   QualType Ty = VE->getType();
+  if (Ty->isVariableArrayType())
+EmitVariablyModifiedType(Ty);
   if (VE->isMicrosoftABI())
 return CGM.getABIInfo().EmitMSVAArg(*this, VAListAddr, Ty, Slot);
   return CGM.getABIInfo().EmitVAArg(*this, VAListAddr, Ty, Slot);
diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index a4111cb65c8b1c..2ad6587089f101 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -2201,8 +2201,6 @@ void CodeGenFunction::EmitAggregateCopy(LValue Dest, 
LValue Src, QualType Ty,
 // But note that getTypeInfo returns 0 for a VLA.
 if (auto *VAT = dyn_cast_or_null(
 getContext().getAsArrayType(Ty))) {
-  assert(Ty->isVariableArrayType());
-  EmitVariablyModifiedType(Ty);
   QualType BaseEltTy;
   SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr);
   TypeInfo = getContext().getTypeInfoInChars(BaseEltTy);

From b38c1d1ee20d3308a4120c3b95a167a936314a6b Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 15:43:35 +0800
Subject: [PATCH 4/9] [clang] Emit an undefined-behavior warning for passing
 VLA to va_arg

---
 clang/include/clang/Basic/DiagnosticSemaKinds.td | 4 
 clang/lib/Sema/SemaExpr.cpp  | 7 +++
 clang/test/CodeGen/varargs.c | 6 +++---
 3 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td 
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 0a245e2077f68f..3a352f23faa353 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -10497,6 +10497,10 @@ def 
warn_second_parameter_to_va_arg_ownership_qualified : Warning<
 def warn_second_parameter_to_va_arg_never_compatible : Warning<
   "second argument to 'va_arg' is of promotable type %0; this va_arg has "
   "undefined behavior because arguments will be promoted to %1">, 
InGroup;
+def warn_second_parameter_to_va_arg_vla : Warning<
+  "second argument to 'va_arg' is of variable length array type %0; "
+  "this va_arg has undefined behavior because arguments will never "
+  "be compatible with variable length array type">, InGroup;
 
 def warn_return_missing_expr : Warning<
   "non-void %select{function|method}1 %0 should return a value">, DefaultError,
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 15

[clang] [clang] Fix crashes when passing VLA to va_arg (PR #119563)

2024-12-16 Thread via cfe-commits 

github-actions[bot] wrote:




:warning: C/C++ code formatter, clang-format found issues in your code. 
:warning:



You can test this locally with the following command:


``bash
git-clang-format --diff f4081711f0884ec7afe93577e118ecc89cb7b1cf 
7dcd400df3670d749902ab04485974ba843415f2 --extensions c,cpp -- 
clang/lib/CodeGen/CGCall.cpp clang/lib/CodeGen/CGExprScalar.cpp 
clang/lib/Sema/SemaExpr.cpp clang/test/CodeGen/xcore-abi.c 
clang/test/Sema/varargs.c
``





View the diff from clang-format here.


``diff
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index fca678e024..4c1cb82219 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -16540,9 +16540,9 @@ ExprResult Sema::BuildVAArgExpr(SourceLocation 
BuiltinLoc,
 
 if (TInfo->getType()->isArrayType()) {
   DiagRuntimeBehavior(TInfo->getTypeLoc().getBeginLoc(), E,
-  PDiag(diag::warn_second_parameter_to_va_arg_array)
-  << TInfo->getType()
-  << TInfo->getTypeLoc().getSourceRange());
+  PDiag(diag::warn_second_parameter_to_va_arg_array)
+  << TInfo->getType()
+  << TInfo->getTypeLoc().getSourceRange());
 }
 
 // Check for va_arg where arguments of the given type will be promoted

``




https://github.com/llvm/llvm-project/pull/119563
___
cfe-commits mailing list
cfe-commits@lists.llvm.org
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[clang] [clang] Fix crashes when passing VLA to va_arg (PR #119563)

2024-12-14 Thread via cfe-commits 

https://github.com/amane-ame updated 
https://github.com/llvm/llvm-project/pull/119563

From 659eda3ec76b63418f8b621b004728d9d7bf26ad Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Wed, 11 Dec 2024 22:17:51 +0800
Subject: [PATCH 1/8] [clang] Fix crashes when passing VLA to va_arg

---
 clang/lib/CodeGen/CGExprAgg.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index 2ad6587089f101..a4111cb65c8b1c 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -2201,6 +2201,8 @@ void CodeGenFunction::EmitAggregateCopy(LValue Dest, 
LValue Src, QualType Ty,
 // But note that getTypeInfo returns 0 for a VLA.
 if (auto *VAT = dyn_cast_or_null(
 getContext().getAsArrayType(Ty))) {
+  assert(Ty->isVariableArrayType());
+  EmitVariablyModifiedType(Ty);
   QualType BaseEltTy;
   SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr);
   TypeInfo = getContext().getTypeInfoInChars(BaseEltTy);

From 5937db790ff0a59ea5bf18cb008d38a4524dc7dc Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 13:50:13 +0800
Subject: [PATCH 2/8] [clang] Add a testcase for passing VLA to va_arg

---
 clang/test/CodeGen/varargs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/clang/test/CodeGen/varargs.c b/clang/test/CodeGen/varargs.c
index 625399b87f7ad7..b7b1b52156be37 100644
--- a/clang/test/CodeGen/varargs.c
+++ b/clang/test/CodeGen/varargs.c
@@ -20,4 +20,7 @@ void vla(int n, ...)
   __builtin_va_list ap;
   void *p;
   p = __builtin_va_arg(ap, typeof (int (*)[++n])); // CHECK: add nsw i32 
{{.*}}, 1
+  // Don't crash on some undefined behaviors.
+  p = __builtin_va_arg(ap, typeof (int [++n]));
+  p = __builtin_va_arg(ap, typeof (int [n][n]));
 }

From df9f8f61ee21b81c9cfd300d113afea9298b8067 Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 13:52:59 +0800
Subject: [PATCH 3/8] [clang] Move the parsing of VLA in va_arg to EmitVAArg

---
 clang/lib/CodeGen/CGCall.cpp| 2 ++
 clang/lib/CodeGen/CGExprAgg.cpp | 2 --
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index 3cefc9da66ddb8..4e2812c62f4357 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -6121,6 +6121,8 @@ RValue CodeGenFunction::EmitVAArg(VAArgExpr *VE, Address 
&VAListAddr,
   VAListAddr = VE->isMicrosoftABI() ? EmitMSVAListRef(VE->getSubExpr())
 : EmitVAListRef(VE->getSubExpr());
   QualType Ty = VE->getType();
+  if (Ty->isVariableArrayType())
+EmitVariablyModifiedType(Ty);
   if (VE->isMicrosoftABI())
 return CGM.getABIInfo().EmitMSVAArg(*this, VAListAddr, Ty, Slot);
   return CGM.getABIInfo().EmitVAArg(*this, VAListAddr, Ty, Slot);
diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index a4111cb65c8b1c..2ad6587089f101 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -2201,8 +2201,6 @@ void CodeGenFunction::EmitAggregateCopy(LValue Dest, 
LValue Src, QualType Ty,
 // But note that getTypeInfo returns 0 for a VLA.
 if (auto *VAT = dyn_cast_or_null(
 getContext().getAsArrayType(Ty))) {
-  assert(Ty->isVariableArrayType());
-  EmitVariablyModifiedType(Ty);
   QualType BaseEltTy;
   SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr);
   TypeInfo = getContext().getTypeInfoInChars(BaseEltTy);

From b38c1d1ee20d3308a4120c3b95a167a936314a6b Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 15:43:35 +0800
Subject: [PATCH 4/8] [clang] Emit an undefined-behavior warning for passing
 VLA to va_arg

---
 clang/include/clang/Basic/DiagnosticSemaKinds.td | 4 
 clang/lib/Sema/SemaExpr.cpp  | 7 +++
 clang/test/CodeGen/varargs.c | 6 +++---
 3 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td 
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 0a245e2077f68f..3a352f23faa353 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -10497,6 +10497,10 @@ def 
warn_second_parameter_to_va_arg_ownership_qualified : Warning<
 def warn_second_parameter_to_va_arg_never_compatible : Warning<
   "second argument to 'va_arg' is of promotable type %0; this va_arg has "
   "undefined behavior because arguments will be promoted to %1">, 
InGroup;
+def warn_second_parameter_to_va_arg_vla : Warning<
+  "second argument to 'va_arg' is of variable length array type %0; "
+  "this va_arg has undefined behavior because arguments will never "
+  "be compatible with variable length array type">, InGroup;
 
 def warn_return_missing_expr : Warning<
   "non-void %select{function|method}1 %0 should return a value">, DefaultError,
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 15

[clang] [clang] Fix crashes when passing VLA to va_arg (PR #119563)

2024-12-13 Thread via cfe-commits 

https://github.com/amane-ame updated 
https://github.com/llvm/llvm-project/pull/119563

From 659eda3ec76b63418f8b621b004728d9d7bf26ad Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Wed, 11 Dec 2024 22:17:51 +0800
Subject: [PATCH 1/7] [clang] Fix crashes when passing VLA to va_arg

---
 clang/lib/CodeGen/CGExprAgg.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index 2ad6587089f101..a4111cb65c8b1c 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -2201,6 +2201,8 @@ void CodeGenFunction::EmitAggregateCopy(LValue Dest, 
LValue Src, QualType Ty,
 // But note that getTypeInfo returns 0 for a VLA.
 if (auto *VAT = dyn_cast_or_null(
 getContext().getAsArrayType(Ty))) {
+  assert(Ty->isVariableArrayType());
+  EmitVariablyModifiedType(Ty);
   QualType BaseEltTy;
   SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr);
   TypeInfo = getContext().getTypeInfoInChars(BaseEltTy);

From 5937db790ff0a59ea5bf18cb008d38a4524dc7dc Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 13:50:13 +0800
Subject: [PATCH 2/7] [clang] Add a testcase for passing VLA to va_arg

---
 clang/test/CodeGen/varargs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/clang/test/CodeGen/varargs.c b/clang/test/CodeGen/varargs.c
index 625399b87f7ad7..b7b1b52156be37 100644
--- a/clang/test/CodeGen/varargs.c
+++ b/clang/test/CodeGen/varargs.c
@@ -20,4 +20,7 @@ void vla(int n, ...)
   __builtin_va_list ap;
   void *p;
   p = __builtin_va_arg(ap, typeof (int (*)[++n])); // CHECK: add nsw i32 
{{.*}}, 1
+  // Don't crash on some undefined behaviors.
+  p = __builtin_va_arg(ap, typeof (int [++n]));
+  p = __builtin_va_arg(ap, typeof (int [n][n]));
 }

From df9f8f61ee21b81c9cfd300d113afea9298b8067 Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 13:52:59 +0800
Subject: [PATCH 3/7] [clang] Move the parsing of VLA in va_arg to EmitVAArg

---
 clang/lib/CodeGen/CGCall.cpp| 2 ++
 clang/lib/CodeGen/CGExprAgg.cpp | 2 --
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index 3cefc9da66ddb8..4e2812c62f4357 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -6121,6 +6121,8 @@ RValue CodeGenFunction::EmitVAArg(VAArgExpr *VE, Address 
&VAListAddr,
   VAListAddr = VE->isMicrosoftABI() ? EmitMSVAListRef(VE->getSubExpr())
 : EmitVAListRef(VE->getSubExpr());
   QualType Ty = VE->getType();
+  if (Ty->isVariableArrayType())
+EmitVariablyModifiedType(Ty);
   if (VE->isMicrosoftABI())
 return CGM.getABIInfo().EmitMSVAArg(*this, VAListAddr, Ty, Slot);
   return CGM.getABIInfo().EmitVAArg(*this, VAListAddr, Ty, Slot);
diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index a4111cb65c8b1c..2ad6587089f101 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -2201,8 +2201,6 @@ void CodeGenFunction::EmitAggregateCopy(LValue Dest, 
LValue Src, QualType Ty,
 // But note that getTypeInfo returns 0 for a VLA.
 if (auto *VAT = dyn_cast_or_null(
 getContext().getAsArrayType(Ty))) {
-  assert(Ty->isVariableArrayType());
-  EmitVariablyModifiedType(Ty);
   QualType BaseEltTy;
   SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr);
   TypeInfo = getContext().getTypeInfoInChars(BaseEltTy);

From b38c1d1ee20d3308a4120c3b95a167a936314a6b Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 15:43:35 +0800
Subject: [PATCH 4/7] [clang] Emit an undefined-behavior warning for passing
 VLA to va_arg

---
 clang/include/clang/Basic/DiagnosticSemaKinds.td | 4 
 clang/lib/Sema/SemaExpr.cpp  | 7 +++
 clang/test/CodeGen/varargs.c | 6 +++---
 3 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td 
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 0a245e2077f68f..3a352f23faa353 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -10497,6 +10497,10 @@ def 
warn_second_parameter_to_va_arg_ownership_qualified : Warning<
 def warn_second_parameter_to_va_arg_never_compatible : Warning<
   "second argument to 'va_arg' is of promotable type %0; this va_arg has "
   "undefined behavior because arguments will be promoted to %1">, 
InGroup;
+def warn_second_parameter_to_va_arg_vla : Warning<
+  "second argument to 'va_arg' is of variable length array type %0; "
+  "this va_arg has undefined behavior because arguments will never "
+  "be compatible with variable length array type">, InGroup;
 
 def warn_return_missing_expr : Warning<
   "non-void %select{function|method}1 %0 should return a value">, DefaultError,
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 15

[clang] [clang] Fix crashes when passing VLA to va_arg (PR #119563)

2024-12-13 Thread via cfe-commits 

https://github.com/amane-ame updated 
https://github.com/llvm/llvm-project/pull/119563

From 659eda3ec76b63418f8b621b004728d9d7bf26ad Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Wed, 11 Dec 2024 22:17:51 +0800
Subject: [PATCH 1/7] [clang] Fix crashes when passing VLA to va_arg

---
 clang/lib/CodeGen/CGExprAgg.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index 2ad6587089f101..a4111cb65c8b1c 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -2201,6 +2201,8 @@ void CodeGenFunction::EmitAggregateCopy(LValue Dest, 
LValue Src, QualType Ty,
 // But note that getTypeInfo returns 0 for a VLA.
 if (auto *VAT = dyn_cast_or_null(
 getContext().getAsArrayType(Ty))) {
+  assert(Ty->isVariableArrayType());
+  EmitVariablyModifiedType(Ty);
   QualType BaseEltTy;
   SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr);
   TypeInfo = getContext().getTypeInfoInChars(BaseEltTy);

From 5937db790ff0a59ea5bf18cb008d38a4524dc7dc Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 13:50:13 +0800
Subject: [PATCH 2/7] [clang] Add a testcase for passing VLA to va_arg

---
 clang/test/CodeGen/varargs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/clang/test/CodeGen/varargs.c b/clang/test/CodeGen/varargs.c
index 625399b87f7ad7..b7b1b52156be37 100644
--- a/clang/test/CodeGen/varargs.c
+++ b/clang/test/CodeGen/varargs.c
@@ -20,4 +20,7 @@ void vla(int n, ...)
   __builtin_va_list ap;
   void *p;
   p = __builtin_va_arg(ap, typeof (int (*)[++n])); // CHECK: add nsw i32 
{{.*}}, 1
+  // Don't crash on some undefined behaviors.
+  p = __builtin_va_arg(ap, typeof (int [++n]));
+  p = __builtin_va_arg(ap, typeof (int [n][n]));
 }

From df9f8f61ee21b81c9cfd300d113afea9298b8067 Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 13:52:59 +0800
Subject: [PATCH 3/7] [clang] Move the parsing of VLA in va_arg to EmitVAArg

---
 clang/lib/CodeGen/CGCall.cpp| 2 ++
 clang/lib/CodeGen/CGExprAgg.cpp | 2 --
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index 3cefc9da66ddb8..4e2812c62f4357 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -6121,6 +6121,8 @@ RValue CodeGenFunction::EmitVAArg(VAArgExpr *VE, Address 
&VAListAddr,
   VAListAddr = VE->isMicrosoftABI() ? EmitMSVAListRef(VE->getSubExpr())
 : EmitVAListRef(VE->getSubExpr());
   QualType Ty = VE->getType();
+  if (Ty->isVariableArrayType())
+EmitVariablyModifiedType(Ty);
   if (VE->isMicrosoftABI())
 return CGM.getABIInfo().EmitMSVAArg(*this, VAListAddr, Ty, Slot);
   return CGM.getABIInfo().EmitVAArg(*this, VAListAddr, Ty, Slot);
diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index a4111cb65c8b1c..2ad6587089f101 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -2201,8 +2201,6 @@ void CodeGenFunction::EmitAggregateCopy(LValue Dest, 
LValue Src, QualType Ty,
 // But note that getTypeInfo returns 0 for a VLA.
 if (auto *VAT = dyn_cast_or_null(
 getContext().getAsArrayType(Ty))) {
-  assert(Ty->isVariableArrayType());
-  EmitVariablyModifiedType(Ty);
   QualType BaseEltTy;
   SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr);
   TypeInfo = getContext().getTypeInfoInChars(BaseEltTy);

From b38c1d1ee20d3308a4120c3b95a167a936314a6b Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 15:43:35 +0800
Subject: [PATCH 4/7] [clang] Emit an undefined-behavior warning for passing
 VLA to va_arg

---
 clang/include/clang/Basic/DiagnosticSemaKinds.td | 4 
 clang/lib/Sema/SemaExpr.cpp  | 7 +++
 clang/test/CodeGen/varargs.c | 6 +++---
 3 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td 
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 0a245e2077f68f..3a352f23faa353 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -10497,6 +10497,10 @@ def 
warn_second_parameter_to_va_arg_ownership_qualified : Warning<
 def warn_second_parameter_to_va_arg_never_compatible : Warning<
   "second argument to 'va_arg' is of promotable type %0; this va_arg has "
   "undefined behavior because arguments will be promoted to %1">, 
InGroup;
+def warn_second_parameter_to_va_arg_vla : Warning<
+  "second argument to 'va_arg' is of variable length array type %0; "
+  "this va_arg has undefined behavior because arguments will never "
+  "be compatible with variable length array type">, InGroup;
 
 def warn_return_missing_expr : Warning<
   "non-void %select{function|method}1 %0 should return a value">, DefaultError,
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 15

[clang] [clang] Fix crashes when passing VLA to va_arg (PR #119563)

2024-12-13 Thread Eli Friedman via cfe-commits 


@@ -20,4 +20,7 @@ void vla(int n, ...)
   __builtin_va_list ap;
   void *p;
   p = __builtin_va_arg(ap, typeof (int (*)[++n])); // CHECK: add nsw i32 
{{.*}}, 1
+  // Don't crash on some undefined behaviors.
+  p = __builtin_va_arg(ap, typeof (int [++n])); // expected-warning{{second 
argument to 'va_arg' is of variable length array type 'typeof(int[++n])'}}

efriedma-quic wrote:

Maybe put the warning checks into some test in clang/test/Sema.

https://github.com/llvm/llvm-project/pull/119563
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[clang] [clang] Fix crashes when passing VLA to va_arg (PR #119563)

2024-12-13 Thread Eli Friedman via cfe-commits 


@@ -16538,6 +16538,13 @@ ExprResult Sema::BuildVAArgExpr(SourceLocation 
BuiltinLoc,
 << TInfo->getTypeLoc().getSourceRange();
 }
 
+if (TInfo->getType()->isVariableArrayType()) {

efriedma-quic wrote:

This should check for any array type; the issue with compatibility isn't 
specific to variadic arrays.

https://github.com/llvm/llvm-project/pull/119563
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[clang] [clang] Fix crashes when passing VLA to va_arg (PR #119563)

2024-12-13 Thread Eli Friedman via cfe-commits 


@@ -6121,6 +6121,8 @@ RValue CodeGenFunction::EmitVAArg(VAArgExpr *VE, Address 
&VAListAddr,
   VAListAddr = VE->isMicrosoftABI() ? EmitMSVAListRef(VE->getSubExpr())
 : EmitVAListRef(VE->getSubExpr());
   QualType Ty = VE->getType();
+  if (Ty->isVariableArrayType())
+EmitVariablyModifiedType(Ty);

efriedma-quic wrote:

You can drop the call to EmitVariablyModifiedType in 
ScalarExprEmitter::VisitVAArgExpr, since it's now redundant.

https://github.com/llvm/llvm-project/pull/119563
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[clang] [clang] Fix crashes when passing VLA to va_arg (PR #119563)

2024-12-11 Thread via cfe-commits 

https://github.com/amane-ame updated 
https://github.com/llvm/llvm-project/pull/119563

From 659eda3ec76b63418f8b621b004728d9d7bf26ad Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Wed, 11 Dec 2024 22:17:51 +0800
Subject: [PATCH 1/4] [clang] Fix crashes when passing VLA to va_arg

---
 clang/lib/CodeGen/CGExprAgg.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index 2ad6587089f101..a4111cb65c8b1c 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -2201,6 +2201,8 @@ void CodeGenFunction::EmitAggregateCopy(LValue Dest, 
LValue Src, QualType Ty,
 // But note that getTypeInfo returns 0 for a VLA.
 if (auto *VAT = dyn_cast_or_null(
 getContext().getAsArrayType(Ty))) {
+  assert(Ty->isVariableArrayType());
+  EmitVariablyModifiedType(Ty);
   QualType BaseEltTy;
   SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr);
   TypeInfo = getContext().getTypeInfoInChars(BaseEltTy);

From 5937db790ff0a59ea5bf18cb008d38a4524dc7dc Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 13:50:13 +0800
Subject: [PATCH 2/4] [clang] Add a testcase for passing VLA to va_arg

---
 clang/test/CodeGen/varargs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/clang/test/CodeGen/varargs.c b/clang/test/CodeGen/varargs.c
index 625399b87f7ad7..b7b1b52156be37 100644
--- a/clang/test/CodeGen/varargs.c
+++ b/clang/test/CodeGen/varargs.c
@@ -20,4 +20,7 @@ void vla(int n, ...)
   __builtin_va_list ap;
   void *p;
   p = __builtin_va_arg(ap, typeof (int (*)[++n])); // CHECK: add nsw i32 
{{.*}}, 1
+  // Don't crash on some undefined behaviors.
+  p = __builtin_va_arg(ap, typeof (int [++n]));
+  p = __builtin_va_arg(ap, typeof (int [n][n]));
 }

From df9f8f61ee21b81c9cfd300d113afea9298b8067 Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 13:52:59 +0800
Subject: [PATCH 3/4] [clang] Move the parsing of VLA in va_arg to EmitVAArg

---
 clang/lib/CodeGen/CGCall.cpp| 2 ++
 clang/lib/CodeGen/CGExprAgg.cpp | 2 --
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index 3cefc9da66ddb8..4e2812c62f4357 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -6121,6 +6121,8 @@ RValue CodeGenFunction::EmitVAArg(VAArgExpr *VE, Address 
&VAListAddr,
   VAListAddr = VE->isMicrosoftABI() ? EmitMSVAListRef(VE->getSubExpr())
 : EmitVAListRef(VE->getSubExpr());
   QualType Ty = VE->getType();
+  if (Ty->isVariableArrayType())
+EmitVariablyModifiedType(Ty);
   if (VE->isMicrosoftABI())
 return CGM.getABIInfo().EmitMSVAArg(*this, VAListAddr, Ty, Slot);
   return CGM.getABIInfo().EmitVAArg(*this, VAListAddr, Ty, Slot);
diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index a4111cb65c8b1c..2ad6587089f101 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -2201,8 +2201,6 @@ void CodeGenFunction::EmitAggregateCopy(LValue Dest, 
LValue Src, QualType Ty,
 // But note that getTypeInfo returns 0 for a VLA.
 if (auto *VAT = dyn_cast_or_null(
 getContext().getAsArrayType(Ty))) {
-  assert(Ty->isVariableArrayType());
-  EmitVariablyModifiedType(Ty);
   QualType BaseEltTy;
   SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr);
   TypeInfo = getContext().getTypeInfoInChars(BaseEltTy);

From b38c1d1ee20d3308a4120c3b95a167a936314a6b Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 15:43:35 +0800
Subject: [PATCH 4/4] [clang] Emit an undefined-behavior warning for passing
 VLA to va_arg

---
 clang/include/clang/Basic/DiagnosticSemaKinds.td | 4 
 clang/lib/Sema/SemaExpr.cpp  | 7 +++
 clang/test/CodeGen/varargs.c | 6 +++---
 3 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td 
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 0a245e2077f68f..3a352f23faa353 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -10497,6 +10497,10 @@ def 
warn_second_parameter_to_va_arg_ownership_qualified : Warning<
 def warn_second_parameter_to_va_arg_never_compatible : Warning<
   "second argument to 'va_arg' is of promotable type %0; this va_arg has "
   "undefined behavior because arguments will be promoted to %1">, 
InGroup;
+def warn_second_parameter_to_va_arg_vla : Warning<
+  "second argument to 'va_arg' is of variable length array type %0; "
+  "this va_arg has undefined behavior because arguments will never "
+  "be compatible with variable length array type">, InGroup;
 
 def warn_return_missing_expr : Warning<
   "non-void %select{function|method}1 %0 should return a value">, DefaultError,
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 15

[clang] [clang] Fix crashes when passing VLA to va_arg (PR #119563)

2024-12-11 Thread via cfe-commits 

https://github.com/amane-ame updated 
https://github.com/llvm/llvm-project/pull/119563

From 659eda3ec76b63418f8b621b004728d9d7bf26ad Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Wed, 11 Dec 2024 22:17:51 +0800
Subject: [PATCH 1/3] [clang] Fix crashes when passing VLA to va_arg

---
 clang/lib/CodeGen/CGExprAgg.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index 2ad6587089f101..a4111cb65c8b1c 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -2201,6 +2201,8 @@ void CodeGenFunction::EmitAggregateCopy(LValue Dest, 
LValue Src, QualType Ty,
 // But note that getTypeInfo returns 0 for a VLA.
 if (auto *VAT = dyn_cast_or_null(
 getContext().getAsArrayType(Ty))) {
+  assert(Ty->isVariableArrayType());
+  EmitVariablyModifiedType(Ty);
   QualType BaseEltTy;
   SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr);
   TypeInfo = getContext().getTypeInfoInChars(BaseEltTy);

From 5937db790ff0a59ea5bf18cb008d38a4524dc7dc Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 13:50:13 +0800
Subject: [PATCH 2/3] [clang] Add a testcase for passing VLA to va_arg

---
 clang/test/CodeGen/varargs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/clang/test/CodeGen/varargs.c b/clang/test/CodeGen/varargs.c
index 625399b87f7ad7..b7b1b52156be37 100644
--- a/clang/test/CodeGen/varargs.c
+++ b/clang/test/CodeGen/varargs.c
@@ -20,4 +20,7 @@ void vla(int n, ...)
   __builtin_va_list ap;
   void *p;
   p = __builtin_va_arg(ap, typeof (int (*)[++n])); // CHECK: add nsw i32 
{{.*}}, 1
+  // Don't crash on some undefined behaviors.
+  p = __builtin_va_arg(ap, typeof (int [++n]));
+  p = __builtin_va_arg(ap, typeof (int [n][n]));
 }

From df9f8f61ee21b81c9cfd300d113afea9298b8067 Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Thu, 12 Dec 2024 13:52:59 +0800
Subject: [PATCH 3/3] [clang] Move the parsing of VLA in va_arg to EmitVAArg

---
 clang/lib/CodeGen/CGCall.cpp| 2 ++
 clang/lib/CodeGen/CGExprAgg.cpp | 2 --
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index 3cefc9da66ddb8..4e2812c62f4357 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -6121,6 +6121,8 @@ RValue CodeGenFunction::EmitVAArg(VAArgExpr *VE, Address 
&VAListAddr,
   VAListAddr = VE->isMicrosoftABI() ? EmitMSVAListRef(VE->getSubExpr())
 : EmitVAListRef(VE->getSubExpr());
   QualType Ty = VE->getType();
+  if (Ty->isVariableArrayType())
+EmitVariablyModifiedType(Ty);
   if (VE->isMicrosoftABI())
 return CGM.getABIInfo().EmitMSVAArg(*this, VAListAddr, Ty, Slot);
   return CGM.getABIInfo().EmitVAArg(*this, VAListAddr, Ty, Slot);
diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index a4111cb65c8b1c..2ad6587089f101 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -2201,8 +2201,6 @@ void CodeGenFunction::EmitAggregateCopy(LValue Dest, 
LValue Src, QualType Ty,
 // But note that getTypeInfo returns 0 for a VLA.
 if (auto *VAT = dyn_cast_or_null(
 getContext().getAsArrayType(Ty))) {
-  assert(Ty->isVariableArrayType());
-  EmitVariablyModifiedType(Ty);
   QualType BaseEltTy;
   SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr);
   TypeInfo = getContext().getTypeInfoInChars(BaseEltTy);

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[clang] [clang] Fix crashes when passing VLA to va_arg (PR #119563)

2024-12-11 Thread Eli Friedman via cfe-commits 

efriedma-quic wrote:

C standard rules for va_arg: "[...] if *type* is not compatible with the type 
of the actual next argument [...], the behavior is undefined [...]".  A struct 
is never compatible with an array, so yes , it's undefined.  (See 6.2.7 for 
what constitutes a "compatible type".)

As a practical matter, breaking the "compatible type" rule can cause crashes or 
data corruption.  Modern ABIs don't just pass everything on the stack.

https://github.com/llvm/llvm-project/pull/119563
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[clang] [clang] Fix crashes when passing VLA to va_arg (PR #119563)

2024-12-11 Thread Robear Selwans via cfe-commits 

mo7sen wrote:

> While you're here, maybe look at emitting an undefined-behavior warning for 
> this construct? A VLA is never compatible with a function argument: if you 
> try to write an array in an function type, it gets promoted to a pointer. So 
> this construct is guaranteed to produce broken results (which is why nobody 
> has tripped over this before).

Assuming the actual argument is a struct and the `va_arg(args, 
uint8_t[sizeof(struct)])` is just to get the struct bytes, would that still be 
considered undefined behaviour?

https://github.com/llvm/llvm-project/pull/119563
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[clang] [clang] Fix crashes when passing VLA to va_arg (PR #119563)

2024-12-11 Thread Eli Friedman via cfe-commits 

efriedma-quic wrote:

Please add a testcase to clang/test/CodeGen/ .  Put it in an existing file if 
there's already some related test.  (See also 
https://llvm.org/docs/Contributing.html#how-to-submit-a-patch )

I don't think EmitAggregateCopy is the right place to call 
EmitVariablyModifiedType: we want to call EmitVariablyModifiedType exactly once 
for every VLA written in the source code.  So the call should be located 
somewhere that's tightly related to the expression itself: 
CodeGenFunction::EmitVAArg, or something like that.

While you're here, maybe look at emitting an undefined-behavior warning for 
this construct?  A VLA is never compatible with a function argument: if you try 
to write an array in an function type, it gets promoted to a pointer.  So this 
construct is guaranteed to produce broken results (which is why nobody has 
tripped over this before).

https://github.com/llvm/llvm-project/pull/119563
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[clang] [clang] Fix crashes when passing VLA to va_arg (PR #119563)

2024-12-11 Thread via cfe-commits 

llvmbot wrote:



@llvm/pr-subscribers-clang

@llvm/pr-subscribers-clang-codegen

Author: 天音あめ (amane-ame)


Changes

Closes #119360.

---
Full diff: https://github.com/llvm/llvm-project/pull/119563.diff


1 Files Affected:

- (modified) clang/lib/CodeGen/CGExprAgg.cpp (+2) 


``diff
diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index 2ad6587089f101..a4111cb65c8b1c 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -2201,6 +2201,8 @@ void CodeGenFunction::EmitAggregateCopy(LValue Dest, 
LValue Src, QualType Ty,
 // But note that getTypeInfo returns 0 for a VLA.
 if (auto *VAT = dyn_cast_or_null(
 getContext().getAsArrayType(Ty))) {
+  assert(Ty->isVariableArrayType());
+  EmitVariablyModifiedType(Ty);
   QualType BaseEltTy;
   SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr);
   TypeInfo = getContext().getTypeInfoInChars(BaseEltTy);

``




https://github.com/llvm/llvm-project/pull/119563
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[clang] [clang] Fix crashes when passing VLA to va_arg (PR #119563)

2024-12-11 Thread via cfe-commits 

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https://github.com/llvm/llvm-project/pull/119563
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[clang] [clang] Fix crashes when passing VLA to va_arg (PR #119563)

2024-12-11 Thread via cfe-commits 

https://github.com/amane-ame created 
https://github.com/llvm/llvm-project/pull/119563

Closes #119360.

From 659eda3ec76b63418f8b621b004728d9d7bf26ad Mon Sep 17 00:00:00 2001
From: amane-ame 
Date: Wed, 11 Dec 2024 22:17:51 +0800
Subject: [PATCH] [clang] Fix crashes when passing VLA to va_arg

---
 clang/lib/CodeGen/CGExprAgg.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index 2ad6587089f101..a4111cb65c8b1c 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -2201,6 +2201,8 @@ void CodeGenFunction::EmitAggregateCopy(LValue Dest, 
LValue Src, QualType Ty,
 // But note that getTypeInfo returns 0 for a VLA.
 if (auto *VAT = dyn_cast_or_null(
 getContext().getAsArrayType(Ty))) {
+  assert(Ty->isVariableArrayType());
+  EmitVariablyModifiedType(Ty);
   QualType BaseEltTy;
   SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr);
   TypeInfo = getContext().getTypeInfoInChars(BaseEltTy);

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