[PATCH] D144870: [Clang][DebugInfo] Emit zero size bitfields in the debug info to delimit bitfields in different allocation units.

[Juan Manuel Martinez Caamaño via Phabricator via cfe-commits]

jmmartinez added a comment.

In D144870#4225437 , @probinson wrote:

> One entirely optional suggestion on the test. LGTM.

Thanks! I used `SECONDDUP` and `FIRSTDUP`.

And thanks a lot for the reviews!


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[PATCH] D144870: [Clang][DebugInfo] Emit zero size bitfields in the debug info to delimit bitfields in different allocation units.

[Juan Manuel Martinez Caamaño via Phabricator via cfe-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rG488185cca387: [Clang][DebugInfo][AMDGPU] Emit zero size 
bitfields in the debug info to… (authored by jmmartinez).

Changed prior to commit:
  https://reviews.llvm.org/D144870?vs=508538=508926#toc

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Files:
  clang/lib/CodeGen/CGDebugInfo.cpp
  clang/lib/CodeGen/CGDebugInfo.h
  clang/lib/CodeGen/TargetInfo.cpp
  clang/lib/CodeGen/TargetInfo.h
  clang/test/CodeGen/debug-info-bitfield-0-struct.c

Index: clang/test/CodeGen/debug-info-bitfield-0-struct.c
===
--- /dev/null
+++ clang/test/CodeGen/debug-info-bitfield-0-struct.c
@@ -0,0 +1,119 @@
+// RUN: %clang_cc1 -triple x86_64-unk-unk -o - -emit-llvm -debug-info-kind=limited %s | FileCheck --check-prefixes NOSEPARATOR,BOTH %s
+// RUN: %clang_cc1 -triple amdgcn-unk-unk -o - -emit-llvm -debug-info-kind=limited %s | FileCheck --check-prefixes SEPARATOR,BOTH %s
+
+struct First {
+  // BOTH-DAG: ![[FIRST:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "First", file: !{{[0-9]+}}, line: {{[0-9]+}}, size: 32, elements: ![[FIRST_ELEMENTS:[0-9]+]])
+  // BOTH-DAG: ![[FIRST_ELEMENTS]] = !{![[FIRST_X:[0-9]+]], ![[FIRST_Y:[0-9]+]]}
+  // BOTH-DAG: ![[FIRST_X]] = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: ![[FIRST]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, flags: DIFlagBitField, extraData: i64 0)
+  // BOTH-DAG: ![[FIRST_Y]] = !DIDerivedType(tag: DW_TAG_member, name: "y", scope: ![[FIRST]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, offset: 4, flags: DIFlagBitField, extraData: i64 0)
+  int : 0;
+  int x : 4;
+  int y : 4;
+};
+
+struct FirstDuplicate {
+  // BOTH-DAG: ![[FIRSTDUP:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "FirstDuplicate", file: !{{[0-9]+}}, line: {{[0-9]+}}, size: 32, elements: ![[FIRSTDUP_ELEMENTS:[0-9]+]])
+  // BOTH-DAG: ![[FIRSTDUP_ELEMENTS]] = !{![[FIRSTDUP_X:[0-9]+]], ![[FIRSTDUP_Y:[0-9]+]]}
+  // BOTH-DAG: ![[FIRSTDUP_X]] = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: ![[FIRSTDUP]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, flags: DIFlagBitField, extraData: i64 0)
+  // BOTH-DAG: ![[FIRSTDUP_Y]] = !DIDerivedType(tag: DW_TAG_member, name: "y", scope: ![[FIRSTDUP]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, offset: 4, flags: DIFlagBitField, extraData: i64 0)
+  int : 0;
+  int : 0;
+  int x : 4;
+  int y : 4;
+};
+
+struct Second {
+  // BOTH-DAG: ![[SECOND:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "Second", file: !{{[0-9]+}}, line: {{[0-9]+}}, size: 64, elements: ![[SECOND_ELEMENTS:[0-9]+]])
+
+  // NOSEPARATOR-DAG: ![[SECOND_ELEMENTS]] = !{![[SECOND_X:[0-9]+]], ![[SECOND_Y:[0-9]+]]}
+  // SEPARATOR-DAG: ![[SECOND_ELEMENTS]] = !{![[SECOND_X:[0-9]+]], ![[SECOND_ZERO:[0-9]+]], ![[SECOND_Y:[0-9]+]]}
+
+  // BOTH-DAG: ![[SECOND_X]] = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: ![[SECOND]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, flags: DIFlagBitField, extraData: i64 0)
+  // SEPARATOR-DAG: ![[SECOND_ZERO]] = !DIDerivedType(tag: DW_TAG_member, scope: ![[SECOND]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, offset: 32, flags: DIFlagBitField, extraData: i64 32)
+  // BOTH-DAG: ![[SECOND_Y]] = !DIDerivedType(tag: DW_TAG_member, name: "y", scope: ![[SECOND]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, offset: 32, flags: DIFlagBitField, extraData: i64 32)
+  int x : 4;
+  int : 0;
+  int y : 4;
+};
+
+struct SecondDuplicate {
+  // BOTH-DAG: ![[SECONDDUP:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "SecondDuplicate", file: !{{[0-9]+}}, line: {{[0-9]+}}, size: 64, elements: ![[SECONDDUP_ELEMENTS:[0-9]+]])
+
+  // NOSEPARATOR-DAG: ![[SECONDDUP_ELEMENTS]] = !{![[SECONDDUP_X:[0-9]+]], ![[SECONDDUP_Y:[0-9]+]]}
+  // SEPARATOR-DAG: ![[SECONDDUP_ELEMENTS]] = !{![[SECONDDUP_X:[0-9]+]], ![[SECONDDUP_ZERO:[0-9]+]], ![[SECONDDUP_Y:[0-9]+]]}
+
+  // BOTH-DAG: ![[SECONDDUP_X]] = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: ![[SECONDDUP]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, flags: DIFlagBitField, extraData: i64 0)
+  // SEPARATOR-DAG: ![[SECONDDUP_ZERO]] = !DIDerivedType(tag: DW_TAG_member, scope: ![[SECONDDUP]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, offset: 32, flags: DIFlagBitField, extraData: i64 32)
+  // BOTH-DAG: ![[SECONDDUP_Y]] = !DIDerivedType(tag: DW_TAG_member, name: "y", scope: ![[SECONDDUP]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, offset: 32, flags: DIFlagBitField, extraData: i64 32)
+  int x : 4;
+  int : 0;
+  int : 0;
+  int y : 4;
+};
+
+struct Last {
+  // BOTH-DAG: 

[PATCH] D144870: [Clang][DebugInfo] Emit zero size bitfields in the debug info to delimit bitfields in different allocation units.

[Paul Robinson via Phabricator via cfe-commits]

probinson accepted this revision.
probinson added a comment.
This revision is now accepted and ready to land.

One entirely optional suggestion on the test. LGTM.




Comment at: clang/lib/CodeGen/CGDebugInfo.cpp:1563
+
+  assert(PreviousBitfield->isBitField());
+

jmmartinez wrote:
> probinson wrote:
> > Is this true for cases like
> > ```
> > struct nonadjacent {
> >   char a : 8;
> >   char : 0;
> >   int b;
> >   char d : 8;
> > };
> > ```
> > where the field `d` has a predecessor that is not a bitfield? (This might 
> > be my ignorance of how Decls are put together, but asserting that `advance` 
> > is guaranteed to get you a bitfield just seems a little odd.)
> In that case the assert is never reached.
> 
> When emiting the debug-info for `d`, when looking at the metadata generated 
> for the previous field the function should exit early on this condition:
> ```
>   if (!PreviousMDField || !PreviousMDField->isBitField() ||
>   PreviousMDField->getSizeInBits() == 0)
> return nullptr;
> ```
Ah, you are right. Thanks!



Comment at: clang/test/CodeGen/debug-info-bitfield-0-struct.c:40
+struct SecondDuplicate {
+  // BOTH-DAG: ![[SECONDD:[0-9]+]] = distinct !DICompositeType(tag: 
DW_TAG_structure_type, name: "SecondDuplicate", file: !{{[0-9]+}}, line: 
{{[0-9]+}}, size: 64, elements: ![[SECONDD_ELEMENTS:[0-9]+]])
+

Maybe use something like `SECONDDUP` instead of `SECONDD` which can look like a 
typo.


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[PATCH] D144870: [Clang][DebugInfo] Emit zero size bitfields in the debug info to delimit bitfields in different allocation units.

[Juan Manuel Martinez Caamaño via Phabricator via cfe-commits]

jmmartinez added inline comments.



Comment at: clang/lib/CodeGen/CGDebugInfo.cpp:1563
+
+  assert(PreviousBitfield->isBitField());
+

probinson wrote:
> Is this true for cases like
> ```
> struct nonadjacent {
>   char a : 8;
>   char : 0;
>   int b;
>   char d : 8;
> };
> ```
> where the field `d` has a predecessor that is not a bitfield? (This might be 
> my ignorance of how Decls are put together, but asserting that `advance` is 
> guaranteed to get you a bitfield just seems a little odd.)
In that case the assert is never reached.

When emiting the debug-info for `d`, when looking at the metadata generated for 
the previous field the function should exit early on this condition:
```
  if (!PreviousMDField || !PreviousMDField->isBitField() ||
  PreviousMDField->getSizeInBits() == 0)
return nullptr;
```


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[PATCH] D144870: [Clang][DebugInfo] Emit zero size bitfields in the debug info to delimit bitfields in different allocation units.

[Juan Manuel Martinez Caamaño via Phabricator via cfe-commits]

jmmartinez updated this revision to Diff 508538.
jmmartinez marked 3 inline comments as done.
jmmartinez added a comment.

- Took remarks into account


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Files:
  clang/lib/CodeGen/CGDebugInfo.cpp
  clang/lib/CodeGen/CGDebugInfo.h
  clang/lib/CodeGen/TargetInfo.cpp
  clang/lib/CodeGen/TargetInfo.h
  clang/test/CodeGen/debug-info-bitfield-0-struct.c

Index: clang/test/CodeGen/debug-info-bitfield-0-struct.c
===
--- /dev/null
+++ clang/test/CodeGen/debug-info-bitfield-0-struct.c
@@ -0,0 +1,119 @@
+// RUN: %clang_cc1 -triple x86_64-unk-unk -o - -emit-llvm -debug-info-kind=limited %s | FileCheck --check-prefixes NOSEPARATOR,BOTH %s
+// RUN: %clang_cc1 -triple amdgcn-unk-unk -o - -emit-llvm -debug-info-kind=limited %s | FileCheck --check-prefixes SEPARATOR,BOTH %s
+
+struct First {
+  // BOTH-DAG: ![[FIRST:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "First", file: !{{[0-9]+}}, line: {{[0-9]+}}, size: 32, elements: ![[FIRST_ELEMENTS:[0-9]+]])
+  // BOTH-DAG: ![[FIRST_ELEMENTS]] = !{![[FIRST_X:[0-9]+]], ![[FIRST_Y:[0-9]+]]}
+  // BOTH-DAG: ![[FIRST_X]] = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: ![[FIRST]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, flags: DIFlagBitField, extraData: i64 0)
+  // BOTH-DAG: ![[FIRST_Y]] = !DIDerivedType(tag: DW_TAG_member, name: "y", scope: ![[FIRST]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, offset: 4, flags: DIFlagBitField, extraData: i64 0)
+  int : 0;
+  int x : 4;
+  int y : 4;
+};
+
+struct FirstDuplicate {
+  // BOTH-DAG: ![[FIRSTD:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "FirstDuplicate", file: !{{[0-9]+}}, line: {{[0-9]+}}, size: 32, elements: ![[FIRSTD_ELEMENTS:[0-9]+]])
+  // BOTH-DAG: ![[FIRSTD_ELEMENTS]] = !{![[FIRSTD_X:[0-9]+]], ![[FIRSTD_Y:[0-9]+]]}
+  // BOTH-DAG: ![[FIRSTD_X]] = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: ![[FIRSTD]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, flags: DIFlagBitField, extraData: i64 0)
+  // BOTH-DAG: ![[FIRSTD_Y]] = !DIDerivedType(tag: DW_TAG_member, name: "y", scope: ![[FIRSTD]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, offset: 4, flags: DIFlagBitField, extraData: i64 0)
+  int : 0;
+  int : 0;
+  int x : 4;
+  int y : 4;
+};
+
+struct Second {
+  // BOTH-DAG: ![[SECOND:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "Second", file: !{{[0-9]+}}, line: {{[0-9]+}}, size: 64, elements: ![[SECOND_ELEMENTS:[0-9]+]])
+
+  // NOSEPARATOR-DAG: ![[SECOND_ELEMENTS]] = !{![[SECOND_X:[0-9]+]], ![[SECOND_Y:[0-9]+]]}
+  // SEPARATOR-DAG: ![[SECOND_ELEMENTS]] = !{![[SECOND_X:[0-9]+]], ![[SECOND_ZERO:[0-9]+]], ![[SECOND_Y:[0-9]+]]}
+
+  // BOTH-DAG: ![[SECOND_X]] = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: ![[SECOND]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, flags: DIFlagBitField, extraData: i64 0)
+  // SEPARATOR-DAG: ![[SECOND_ZERO]] = !DIDerivedType(tag: DW_TAG_member, scope: ![[SECOND]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, offset: 32, flags: DIFlagBitField, extraData: i64 32)
+  // BOTH-DAG: ![[SECOND_Y]] = !DIDerivedType(tag: DW_TAG_member, name: "y", scope: ![[SECOND]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, offset: 32, flags: DIFlagBitField, extraData: i64 32)
+  int x : 4;
+  int : 0;
+  int y : 4;
+};
+
+struct SecondDuplicate {
+  // BOTH-DAG: ![[SECONDD:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "SecondDuplicate", file: !{{[0-9]+}}, line: {{[0-9]+}}, size: 64, elements: ![[SECONDD_ELEMENTS:[0-9]+]])
+
+  // NOSEPARATOR-DAG: ![[SECONDD_ELEMENTS]] = !{![[SECONDD_X:[0-9]+]], ![[SECONDD_Y:[0-9]+]]}
+  // SEPARATOR-DAG: ![[SECONDD_ELEMENTS]] = !{![[SECONDD_X:[0-9]+]], ![[SECONDD_ZERO:[0-9]+]], ![[SECONDD_Y:[0-9]+]]}
+
+  // BOTH-DAG: ![[SECONDD_X]] = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: ![[SECONDD]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, flags: DIFlagBitField, extraData: i64 0)
+  // SEPARATOR-DAG: ![[SECONDD_ZERO]] = !DIDerivedType(tag: DW_TAG_member, scope: ![[SECONDD]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, offset: 32, flags: DIFlagBitField, extraData: i64 32)
+  // BOTH-DAG: ![[SECONDD_Y]] = !DIDerivedType(tag: DW_TAG_member, name: "y", scope: ![[SECONDD]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, offset: 32, flags: DIFlagBitField, extraData: i64 32)
+  int x : 4;
+  int : 0;
+  int : 0;
+  int y : 4;
+};
+
+struct Last {
+  // BOTH-DAG: ![[LAST:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "Last", file: !{{[0-9]+}}, line: {{[0-9]+}}, size: 32, elements: ![[LAST_ELEMENTS:[0-9]+]])
+  // 

[PATCH] D144870: [Clang][DebugInfo] Emit zero size bitfields in the debug info to delimit bitfields in different allocation units.

[Paul Robinson via Phabricator via cfe-commits]

probinson added a comment.

Still one question, and haven't dug into the test in detail yet.




Comment at: clang/lib/CodeGen/CGDebugInfo.cpp:1552
+
+  auto *PreviousMDEntry =
+  PreviousFieldsDI.empty() ? nullptr : PreviousFieldsDI.back();

Maybe a comment here,
`// If we already emitted metadata for a 0-length bitfield, nothing to do here.`
(I was briefly confused by "if the previous field is a 0-length bitfield, do 
nothing" until I realized this is looking at the metadata not the decl.



Comment at: clang/lib/CodeGen/CGDebugInfo.cpp:1563
+
+  assert(PreviousBitfield->isBitField());
+

Is this true for cases like
```
struct nonadjacent {
  char a : 8;
  char : 0;
  int b;
  char d : 8;
};
```
where the field `d` has a predecessor that is not a bitfield? (This might be my 
ignorance of how Decls are put together, but asserting that `advance` is 
guaranteed to get you a bitfield just seems a little odd.)



Comment at: clang/lib/CodeGen/CGDebugInfo.h:324
 
-  /// Create new bit field member.
-  llvm::DIType *createBitFieldType(const FieldDecl *BitFieldDecl,
-   llvm::DIScope *RecordTy,
-   const RecordDecl *RD);
+  /// Create new bit field member
+  llvm::DIDerivedType *createBitFieldType(const FieldDecl *BitFieldDecl,

Please keep that final `.`



Comment at: clang/lib/CodeGen/CGDebugInfo.h:330
+  /// Create an anonnymous zero-size separator for bit-field-decl if needed on
+  /// the target
+  llvm::DIDerivedType *createBitFieldSeparatorIfNeeded(




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[PATCH] D144870: [Clang][DebugInfo] Emit zero size bitfields in the debug info to delimit bitfields in different allocation units.

[Juan Manuel Martinez Caamaño via Phabricator via cfe-commits]

jmmartinez updated this revision to Diff 506611.
jmmartinez added a comment.

- Updated to use `elements` array to avoid the complicated loop.


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Files:
  clang/lib/CodeGen/CGDebugInfo.cpp
  clang/lib/CodeGen/CGDebugInfo.h
  clang/lib/CodeGen/TargetInfo.cpp
  clang/lib/CodeGen/TargetInfo.h
  clang/test/CodeGen/debug-info-bitfield-0-struct.c

Index: clang/test/CodeGen/debug-info-bitfield-0-struct.c
===
--- /dev/null
+++ clang/test/CodeGen/debug-info-bitfield-0-struct.c
@@ -0,0 +1,119 @@
+// RUN: %clang_cc1 -triple x86_64-unk-unk -o - -emit-llvm -debug-info-kind=limited %s | FileCheck --check-prefixes NOSEPARATOR,BOTH %s
+// RUN: %clang_cc1 -triple amdgcn-unk-unk -o - -emit-llvm -debug-info-kind=limited %s | FileCheck --check-prefixes SEPARATOR,BOTH %s
+
+struct First {
+  // BOTH-DAG: ![[FIRST:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "First", file: !{{[0-9]+}}, line: {{[0-9]+}}, size: 32, elements: ![[FIRST_ELEMENTS:[0-9]+]])
+  // BOTH-DAG: ![[FIRST_ELEMENTS]] = !{![[FIRST_X:[0-9]+]], ![[FIRST_Y:[0-9]+]]}
+  // BOTH-DAG: ![[FIRST_X]] = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: ![[FIRST]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, flags: DIFlagBitField, extraData: i64 0)
+  // BOTH-DAG: ![[FIRST_Y]] = !DIDerivedType(tag: DW_TAG_member, name: "y", scope: ![[FIRST]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, offset: 4, flags: DIFlagBitField, extraData: i64 0)
+  int : 0;
+  int x : 4;
+  int y : 4;
+};
+
+struct FirstDuplicate {
+  // BOTH-DAG: ![[FIRSTD:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "FirstDuplicate", file: !{{[0-9]+}}, line: {{[0-9]+}}, size: 32, elements: ![[FIRSTD_ELEMENTS:[0-9]+]])
+  // BOTH-DAG: ![[FIRSTD_ELEMENTS]] = !{![[FIRSTD_X:[0-9]+]], ![[FIRSTD_Y:[0-9]+]]}
+  // BOTH-DAG: ![[FIRSTD_X]] = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: ![[FIRSTD]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, flags: DIFlagBitField, extraData: i64 0)
+  // BOTH-DAG: ![[FIRSTD_Y]] = !DIDerivedType(tag: DW_TAG_member, name: "y", scope: ![[FIRSTD]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, offset: 4, flags: DIFlagBitField, extraData: i64 0)
+  int : 0;
+  int : 0;
+  int x : 4;
+  int y : 4;
+};
+
+struct Second {
+  // BOTH-DAG: ![[SECOND:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "Second", file: !{{[0-9]+}}, line: {{[0-9]+}}, size: 64, elements: ![[SECOND_ELEMENTS:[0-9]+]])
+
+  // NOSEPARATOR-DAG: ![[SECOND_ELEMENTS]] = !{![[SECOND_X:[0-9]+]], ![[SECOND_Y:[0-9]+]]}
+  // SEPARATOR-DAG: ![[SECOND_ELEMENTS]] = !{![[SECOND_X:[0-9]+]], ![[SECOND_ZERO:[0-9]+]], ![[SECOND_Y:[0-9]+]]}
+
+  // BOTH-DAG: ![[SECOND_X]] = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: ![[SECOND]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, flags: DIFlagBitField, extraData: i64 0)
+  // SEPARATOR-DAG: ![[SECOND_ZERO]] = !DIDerivedType(tag: DW_TAG_member, scope: ![[SECOND]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, offset: 32, flags: DIFlagBitField, extraData: i64 32)
+  // BOTH-DAG: ![[SECOND_Y]] = !DIDerivedType(tag: DW_TAG_member, name: "y", scope: ![[SECOND]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, offset: 32, flags: DIFlagBitField, extraData: i64 32)
+  int x : 4;
+  int : 0;
+  int y : 4;
+};
+
+struct SecondDuplicate {
+  // BOTH-DAG: ![[SECONDD:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "SecondDuplicate", file: !{{[0-9]+}}, line: {{[0-9]+}}, size: 64, elements: ![[SECONDD_ELEMENTS:[0-9]+]])
+
+  // NOSEPARATOR-DAG: ![[SECONDD_ELEMENTS]] = !{![[SECONDD_X:[0-9]+]], ![[SECONDD_Y:[0-9]+]]}
+  // SEPARATOR-DAG: ![[SECONDD_ELEMENTS]] = !{![[SECONDD_X:[0-9]+]], ![[SECONDD_ZERO:[0-9]+]], ![[SECONDD_Y:[0-9]+]]}
+
+  // BOTH-DAG: ![[SECONDD_X]] = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: ![[SECONDD]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, flags: DIFlagBitField, extraData: i64 0)
+  // SEPARATOR-DAG: ![[SECONDD_ZERO]] = !DIDerivedType(tag: DW_TAG_member, scope: ![[SECONDD]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, offset: 32, flags: DIFlagBitField, extraData: i64 32)
+  // BOTH-DAG: ![[SECONDD_Y]] = !DIDerivedType(tag: DW_TAG_member, name: "y", scope: ![[SECONDD]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, offset: 32, flags: DIFlagBitField, extraData: i64 32)
+  int x : 4;
+  int : 0;
+  int : 0;
+  int y : 4;
+};
+
+struct Last {
+  // BOTH-DAG: ![[LAST:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "Last", file: !{{[0-9]+}}, line: {{[0-9]+}}, size: 32, elements: ![[LAST_ELEMENTS:[0-9]+]])
+  // BOTH-DAG: 

[PATCH] D144870: [Clang][DebugInfo] Emit zero size bitfields in the debug info to delimit bitfields in different allocation units.

[Juan Manuel Martinez Caamaño via Phabricator via cfe-commits]

jmmartinez added a comment.

In D144870#4202121 , @probinson wrote:

> (Of course it's possible that finding the preceding field can be done only by 
> iterating, but I'd hope that isn't necessary.)

Sadly, this is the case. `field_iterator` and the underlying `decl_iterator` 
used to implement it are forward iterators.

However, your comment made me realize that we could forward the `elements` 
array from `CGDebugInfoCollectRecordNormalFields`  which contains the already 
created debug-info for the previous fields. By using this array I could get 
pretty much the same effect. What do you think?

In D144870#4202121 , @probinson wrote:

>   struct non_adjacent_bitfields {
> char d;
> char : 0;
> char e;
> char f : 8;
>   };
>
> (1) Is `e` affected by the presence of the zero-length bitfield? (2) is `f` 
> affected? (3) If the answers are "no" and "yes" then you do need to iterate 
> looking for the zero-length bitfield, but otherwise I think it's sufficient 
> to look only at the preceding field.

(1) and (2): They do not get affected by the precense of the annonymous 
bitfield. Only sequences of bitfields get "squashed" in the same integer.


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[PATCH] D144870: [Clang][DebugInfo] Emit zero size bitfields in the debug info to delimit bitfields in different allocation units.

[Paul Robinson via Phabricator via cfe-commits]

probinson added a comment.

Is it possible you need to look only at the immediately preceding field, and 
not iterate? For example,

  struct zero_bitfield {
char a : 8;
char : 0;
char b : 8;
char c : 8;
  };

If processing `b` sees the zero-length bitfield and does the needful, then when 
processing `c` it's sufficient to see that `b` is a preceding bitfield and know 
that the needful has been done.

I'm now also curious whether this ABI aspect affects non-bitfields. For example:

  struct non_adjacent_bitfields {
char d;
char : 0;
char e;
char f : 8;
  };

(1) Is `e` affected by the presence of the zero-length bitfield? (2) is `f` 
affected? (3) If the answers are "no" and "yes" then you do need to iterate 
looking for the zero-length bitfield, but otherwise I think it's sufficient to 
look only at the preceding field.

(Of course it's possible that finding the preceding field can be done only by 
iterating, but I'd hope that isn't necessary.)


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[PATCH] D144870: [Clang][DebugInfo] Emit zero size bitfields in the debug info to delimit bitfields in different allocation units.

[Juan Manuel Martinez Caamaño via Phabricator via cfe-commits]

jmmartinez added inline comments.



Comment at: clang/lib/CodeGen/CGDebugInfo.cpp:1558
+  EmitSeparator = FieldIt->isBitField();
+  }
+

probinson wrote:
> I might not be following this correctly, but it feels like EmitSeparator will 
> end up true if the last field is a bitfield, even if there are no zero-length 
> bitfields in front of it. The test does not cover this case (to show that the 
> no-zero-bitfields case is handled properly).
Ouch! I feel ashamed about that loop I originally wrote.

I've added a case covering the non-zero-bitfields case and fixed the code.


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[PATCH] D144870: [Clang][DebugInfo] Emit zero size bitfields in the debug info to delimit bitfields in different allocation units.

[Juan Manuel Martinez Caamaño via Phabricator via cfe-commits]

jmmartinez updated this revision to Diff 505507.
jmmartinez added a comment.

- Fixed the loop and added test case


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Files:
  clang/lib/CodeGen/CGDebugInfo.cpp
  clang/lib/CodeGen/CGDebugInfo.h
  clang/lib/CodeGen/TargetInfo.cpp
  clang/lib/CodeGen/TargetInfo.h
  clang/test/CodeGen/debug-info-bitfield-0-struct.c

Index: clang/test/CodeGen/debug-info-bitfield-0-struct.c
===
--- /dev/null
+++ clang/test/CodeGen/debug-info-bitfield-0-struct.c
@@ -0,0 +1,119 @@
+// RUN: %clang_cc1 -triple x86_64-unk-unk -o - -emit-llvm -debug-info-kind=limited %s | FileCheck --check-prefixes NOSEPARATOR,BOTH %s
+// RUN: %clang_cc1 -triple amdgcn-unk-unk -o - -emit-llvm -debug-info-kind=limited %s | FileCheck --check-prefixes SEPARATOR,BOTH %s
+
+struct First {
+  // BOTH-DAG: ![[FIRST:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "First", file: !{{[0-9]+}}, line: {{[0-9]+}}, size: 32, elements: ![[FIRST_ELEMENTS:[0-9]+]])
+  // BOTH-DAG: ![[FIRST_ELEMENTS]] = !{![[FIRST_X:[0-9]+]], ![[FIRST_Y:[0-9]+]]}
+  // BOTH-DAG: ![[FIRST_X]] = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: ![[FIRST]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, flags: DIFlagBitField, extraData: i64 0)
+  // BOTH-DAG: ![[FIRST_Y]] = !DIDerivedType(tag: DW_TAG_member, name: "y", scope: ![[FIRST]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, offset: 4, flags: DIFlagBitField, extraData: i64 0)
+  int : 0;
+  int x : 4;
+  int y : 4;
+};
+
+struct FirstDuplicate {
+  // BOTH-DAG: ![[FIRSTD:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "FirstDuplicate", file: !{{[0-9]+}}, line: {{[0-9]+}}, size: 32, elements: ![[FIRSTD_ELEMENTS:[0-9]+]])
+  // BOTH-DAG: ![[FIRSTD_ELEMENTS]] = !{![[FIRSTD_X:[0-9]+]], ![[FIRSTD_Y:[0-9]+]]}
+  // BOTH-DAG: ![[FIRSTD_X]] = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: ![[FIRSTD]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, flags: DIFlagBitField, extraData: i64 0)
+  // BOTH-DAG: ![[FIRSTD_Y]] = !DIDerivedType(tag: DW_TAG_member, name: "y", scope: ![[FIRSTD]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, offset: 4, flags: DIFlagBitField, extraData: i64 0)
+  int : 0;
+  int : 0;
+  int x : 4;
+  int y : 4;
+};
+
+struct Second {
+  // BOTH-DAG: ![[SECOND:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "Second", file: !{{[0-9]+}}, line: {{[0-9]+}}, size: 64, elements: ![[SECOND_ELEMENTS:[0-9]+]])
+
+  // NOSEPARATOR-DAG: ![[SECOND_ELEMENTS]] = !{![[SECOND_X:[0-9]+]], ![[SECOND_Y:[0-9]+]]}
+  // SEPARATOR-DAG: ![[SECOND_ELEMENTS]] = !{![[SECOND_X:[0-9]+]], ![[SECOND_ZERO:[0-9]+]], ![[SECOND_Y:[0-9]+]]}
+
+  // BOTH-DAG: ![[SECOND_X]] = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: ![[SECOND]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, flags: DIFlagBitField, extraData: i64 0)
+  // SEPARATOR-DAG: ![[SECOND_ZERO]] = !DIDerivedType(tag: DW_TAG_member, scope: ![[SECOND]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, offset: 32, flags: DIFlagBitField, extraData: i64 32)
+  // BOTH-DAG: ![[SECOND_Y]] = !DIDerivedType(tag: DW_TAG_member, name: "y", scope: ![[SECOND]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, offset: 32, flags: DIFlagBitField, extraData: i64 32)
+  int x : 4;
+  int : 0;
+  int y : 4;
+};
+
+struct SecondDuplicate {
+  // BOTH-DAG: ![[SECONDD:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "SecondDuplicate", file: !{{[0-9]+}}, line: {{[0-9]+}}, size: 64, elements: ![[SECONDD_ELEMENTS:[0-9]+]])
+
+  // NOSEPARATOR-DAG: ![[SECONDD_ELEMENTS]] = !{![[SECONDD_X:[0-9]+]], ![[SECONDD_Y:[0-9]+]]}
+  // SEPARATOR-DAG: ![[SECONDD_ELEMENTS]] = !{![[SECONDD_X:[0-9]+]], ![[SECONDD_ZERO:[0-9]+]], ![[SECONDD_Y:[0-9]+]]}
+
+  // BOTH-DAG: ![[SECONDD_X]] = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: ![[SECONDD]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, flags: DIFlagBitField, extraData: i64 0)
+  // SEPARATOR-DAG: ![[SECONDD_ZERO]] = !DIDerivedType(tag: DW_TAG_member, scope: ![[SECONDD]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, offset: 32, flags: DIFlagBitField, extraData: i64 32)
+  // BOTH-DAG: ![[SECONDD_Y]] = !DIDerivedType(tag: DW_TAG_member, name: "y", scope: ![[SECONDD]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, offset: 32, flags: DIFlagBitField, extraData: i64 32)
+  int x : 4;
+  int : 0;
+  int : 0;
+  int y : 4;
+};
+
+struct Last {
+  // BOTH-DAG: ![[LAST:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "Last", file: !{{[0-9]+}}, line: {{[0-9]+}}, size: 32, elements: ![[LAST_ELEMENTS:[0-9]+]])
+  // BOTH-DAG: ![[LAST_ELEMENTS]] = 

[PATCH] D144870: [Clang][DebugInfo] Emit zero size bitfields in the debug info to delimit bitfields in different allocation units.

[Paul Robinson via Phabricator via cfe-commits]

probinson added inline comments.



Comment at: clang/lib/CodeGen/CGDebugInfo.cpp:1558
+  EmitSeparator = FieldIt->isBitField();
+  }
+

I might not be following this correctly, but it feels like EmitSeparator will 
end up true if the last field is a bitfield, even if there are no zero-length 
bitfields in front of it. The test does not cover this case (to show that the 
no-zero-bitfields case is handled properly).


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[PATCH] D144870: [Clang][DebugInfo] Emit zero size bitfields in the debug info to delimit bitfields in different allocation units.

[Juan Manuel Martinez Caamaño via Phabricator via cfe-commits]

jmmartinez updated this revision to Diff 505148.
jmmartinez added a comment.

Update:

- Took into account remarks and got my ideas straight.


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Files:
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  clang/lib/CodeGen/CGDebugInfo.h
  clang/lib/CodeGen/TargetInfo.cpp
  clang/lib/CodeGen/TargetInfo.h
  clang/test/CodeGen/debug-info-bitfield-0-struct.c

Index: clang/test/CodeGen/debug-info-bitfield-0-struct.c
===
--- /dev/null
+++ clang/test/CodeGen/debug-info-bitfield-0-struct.c
@@ -0,0 +1,106 @@
+// RUN: %clang_cc1 -triple x86_64-unk-unk -o - -emit-llvm -debug-info-kind=limited %s | FileCheck --check-prefixes NOSEPARATOR,BOTH %s
+// RUN: %clang_cc1 -triple amdgcn-unk-unk -o - -emit-llvm -debug-info-kind=limited %s | FileCheck --check-prefixes SEPARATOR,BOTH %s
+
+struct First {
+  // BOTH-DAG: ![[FIRST:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "First", file: !{{[0-9]+}}, line: {{[0-9]+}}, size: 32, elements: ![[FIRST_ELEMENTS:[0-9]+]])
+  // BOTH-DAG: ![[FIRST_ELEMENTS]] = !{![[FIRST_X:[0-9]+]], ![[FIRST_Y:[0-9]+]]}
+  // BOTH-DAG: ![[FIRST_X]] = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: ![[FIRST]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, flags: DIFlagBitField, extraData: i64 0)
+  // BOTH-DAG: ![[FIRST_Y]] = !DIDerivedType(tag: DW_TAG_member, name: "y", scope: ![[FIRST]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, offset: 4, flags: DIFlagBitField, extraData: i64 0)
+  int : 0;
+  int x : 4;
+  int y : 4;
+};
+
+struct FirstDuplicate {
+  // BOTH-DAG: ![[FIRSTD:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "FirstDuplicate", file: !{{[0-9]+}}, line: {{[0-9]+}}, size: 32, elements: ![[FIRSTD_ELEMENTS:[0-9]+]])
+  // BOTH-DAG: ![[FIRSTD_ELEMENTS]] = !{![[FIRSTD_X:[0-9]+]], ![[FIRSTD_Y:[0-9]+]]}
+  // BOTH-DAG: ![[FIRSTD_X]] = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: ![[FIRSTD]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, flags: DIFlagBitField, extraData: i64 0)
+  // BOTH-DAG: ![[FIRSTD_Y]] = !DIDerivedType(tag: DW_TAG_member, name: "y", scope: ![[FIRSTD]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, offset: 4, flags: DIFlagBitField, extraData: i64 0)
+  int : 0;
+  int : 0;
+  int x : 4;
+  int y : 4;
+};
+
+struct Second {
+  // BOTH-DAG: ![[SECOND:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "Second", file: !{{[0-9]+}}, line: {{[0-9]+}}, size: 64, elements: ![[SECOND_ELEMENTS:[0-9]+]])
+
+  // NOSEPARATOR-DAG: ![[SECOND_ELEMENTS]] = !{![[SECOND_X:[0-9]+]], ![[SECOND_Y:[0-9]+]]}
+  // SEPARATOR-DAG: ![[SECOND_ELEMENTS]] = !{![[SECOND_X:[0-9]+]], ![[SECOND_ZERO:[0-9]+]], ![[SECOND_Y:[0-9]+]]}
+
+  // BOTH-DAG: ![[SECOND_X]] = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: ![[SECOND]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, flags: DIFlagBitField, extraData: i64 0)
+  // SEPARATOR-DAG: ![[SECOND_ZERO]] = !DIDerivedType(tag: DW_TAG_member, scope: ![[SECOND]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, offset: 32, flags: DIFlagBitField, extraData: i64 32)
+  // BOTH-DAG: ![[SECOND_Y]] = !DIDerivedType(tag: DW_TAG_member, name: "y", scope: ![[SECOND]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, offset: 32, flags: DIFlagBitField, extraData: i64 32)
+  int x : 4;
+  int : 0;
+  int y : 4;
+};
+
+struct SecondDuplicate {
+  // BOTH-DAG: ![[SECONDD:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "SecondDuplicate", file: !{{[0-9]+}}, line: {{[0-9]+}}, size: 64, elements: ![[SECONDD_ELEMENTS:[0-9]+]])
+
+  // NOSEPARATOR-DAG: ![[SECONDD_ELEMENTS]] = !{![[SECONDD_X:[0-9]+]], ![[SECONDD_Y:[0-9]+]]}
+  // SEPARATOR-DAG: ![[SECONDD_ELEMENTS]] = !{![[SECONDD_X:[0-9]+]], ![[SECONDD_ZERO:[0-9]+]], ![[SECONDD_Y:[0-9]+]]}
+
+  // BOTH-DAG: ![[SECONDD_X]] = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: ![[SECONDD]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, flags: DIFlagBitField, extraData: i64 0)
+  // SEPARATOR-DAG: ![[SECONDD_ZERO]] = !DIDerivedType(tag: DW_TAG_member, scope: ![[SECONDD]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, offset: 32, flags: DIFlagBitField, extraData: i64 32)
+  // BOTH-DAG: ![[SECONDD_Y]] = !DIDerivedType(tag: DW_TAG_member, name: "y", scope: ![[SECONDD]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, offset: 32, flags: DIFlagBitField, extraData: i64 32)
+  int x : 4;
+  int : 0;
+  int : 0;
+  int y : 4;
+};
+
+struct Last {
+  // BOTH-DAG: ![[LAST:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "Last", file: !{{[0-9]+}}, line: {{[0-9]+}}, size: 32, elements: ![[LAST_ELEMENTS:[0-9]+]])
+  // BOTH-DAG: 

[PATCH] D144870: [Clang][DebugInfo] Emit zero size bitfields in the debug info to delimit bitfields in different allocation units.

[David Blaikie via Phabricator via cfe-commits]

dblaikie added a comment.

Haven't followed the patch in detail - but why does this require changes to the 
RecordLayout code? (I'd expect this to only require charnges to the debug info 
code - maybe with a shared helper utility function that both the AMDGPU ABI 
implementation, and the debug info can use to observe this property, if it's 
non-trivial code to duplicate in both places? (but doesn't look like it's 
sharing code with the ABI implementation, or moving the logic out of the ABI 
implementation into the record layout code for reuse there))


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[PATCH] D144870: [Clang][DebugInfo] Emit zero size bitfields in the debug info to delimit bitfields in different allocation units.

[Juan Manuel Martinez Caamaño via Phabricator via cfe-commits]

jmmartinez created this revision.
jmmartinez added reviewers: dblaikie, probinson.
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I'm looking for some feedback, this is definitively not the final solution.
I was wondering if there was an alternative to pass this information in the 
dwarf debug-info.

Consider the following sturctures when targetting:

  struct foo {
int space[4];
char a : 8;
char b : 8;
char x : 8;
char y : 8;
  };
  
  struct bar {
int space[4];
char a : 8;
char b : 8;
char : 0;
char x : 8;
char y : 8;
  };

Even if both structs have the same layout in memory, they are handled
differenlty by the AMDGPU ABI.

With the following code:

// clang --target=amdgcn-amd-amdhsa -g -O1 example.c -S
char use_foo(struct foo f) { return f.y; }
char use_bar(struct bar b) { return b.y; }

For use_foo, the 'y' field is passed in v4
; v_ashrrev_i32_e32 v0, 24, v4
; s_setpc_b64 s[30:31]

For use_bar, the 'y' field is passed in v5
; v_bfe_i32 v0, v5, 8, 8
; s_setpc_b64 s[30:31]

To make this distinction, we record a single 0-size bitfield for every member 
that is preceded
by it.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D144870

Files:
  clang/lib/CodeGen/CGDebugInfo.cpp
  clang/lib/CodeGen/CGDebugInfo.h
  clang/lib/CodeGen/CGRecordLayout.h
  clang/lib/CodeGen/CGRecordLayoutBuilder.cpp
  clang/test/CodeGen/debug-info-bitfield-0-struct.c

Index: clang/test/CodeGen/debug-info-bitfield-0-struct.c
===
--- /dev/null
+++ clang/test/CodeGen/debug-info-bitfield-0-struct.c
@@ -0,0 +1,97 @@
+// RUN: %clang_cc1 -triple x86_64-unk-unk -o - -emit-llvm -debug-info-kind=limited %s | FileCheck %s
+
+struct First {
+  // CHECK-DAG: ![[FIRST:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "First", file: !{{[0-9]+}}, line: {{[0-9]+}}, size: 32, elements: ![[FIRST_ELEMENTS:[0-9]+]])
+  // CHECK-DAG: ![[FIRST_ELEMENTS]] = !{![[FIRST_X:[0-9]+]], ![[FIRST_Y:[0-9]+]]}
+  // CHECK-DAG: ![[FIRST_X]] = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: ![[FIRST]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, flags: DIFlagBitField, extraData: i64 0)
+  // CHECK-DAG: ![[FIRST_Y]] = !DIDerivedType(tag: DW_TAG_member, name: "y", scope: ![[FIRST]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, offset: 4, flags: DIFlagBitField, extraData: i64 0)
+  int : 0;
+  int x : 4;
+  int y : 4;
+};
+
+struct FirstDuplicate {
+  // CHECK-DAG: ![[FIRSTD:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "FirstDuplicate", file: !{{[0-9]+}}, line: {{[0-9]+}}, size: 32, elements: ![[FIRSTD_ELEMENTS:[0-9]+]])
+  // CHECK-DAG: ![[FIRSTD_ELEMENTS]] = !{![[FIRSTD_X:[0-9]+]], ![[FIRSTD_Y:[0-9]+]]}
+  // CHECK-DAG: ![[FIRSTD_X]] = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: ![[FIRSTD]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, flags: DIFlagBitField, extraData: i64 0)
+  // CHECK-DAG: ![[FIRSTD_Y]] = !DIDerivedType(tag: DW_TAG_member, name: "y", scope: ![[FIRSTD]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, offset: 4, flags: DIFlagBitField, extraData: i64 0)
+  int : 0;
+  int : 0;
+  int x : 4;
+  int y : 4;
+};
+
+struct Second {
+  // CHECK-DAG: ![[SECOND:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "Second", file: !{{[0-9]+}}, line: {{[0-9]+}}, size: 64, elements: ![[SECOND_ELEMENTS:[0-9]+]])
+  // CHECK-DAG: ![[SECOND_ELEMENTS]] = !{![[SECOND_X:[0-9]+]], ![[SECOND_ZERO:[0-9]+]], ![[SECOND_Y:[0-9]+]]}
+  // CHECK-DAG: ![[SECOND_X]] = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: ![[SECOND]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, flags: DIFlagBitField, extraData: i64 0)
+  // CHECK-DAG: ![[SECOND_ZERO]] = !DIDerivedType(tag: DW_TAG_member, scope: ![[SECOND]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, offset: 32, flags: DIFlagBitField, extraData: i64 32)
+  // CHECK-DAG: ![[SECOND_Y]] = !DIDerivedType(tag: DW_TAG_member, name: "y", scope: ![[SECOND]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, offset: 32, flags: DIFlagBitField, extraData: i64 32)
+  int x : 4;
+  int : 0;
+  int y : 4;
+};
+
+struct SecondDuplicate {
+  // CHECK-DAG: ![[SECONDD:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "SecondDuplicate", file: !{{[0-9]+}}, line: {{[0-9]+}}, size: 64, elements: ![[SECONDD_ELEMENTS:[0-9]+]])
+  // CHECK-DAG: ![[SECONDD_ELEMENTS]] = !{![[SECONDD_X:[0-9]+]], ![[SECONDD_ZERO:[0-9]+]], ![[SECONDD_Y:[0-9]+]]}
+  // CHECK-DAG: ![[SECONDD_X]] = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: ![[SECONDD]], file: !{{[0-9]+}}, line: {{[0-9]+}}, baseType: !{{[0-9]+}}, size: 4, flags: DIFlagBitField, extraData: