Author: Matthew Nagy
Date: 2025-11-03T17:24:55Z
New Revision: 6a275de13f6cdf927cf3cd6125ea858ddc0c4b1d

URL: 
https://github.com/llvm/llvm-project/commit/6a275de13f6cdf927cf3cd6125ea858ddc0c4b1d
DIFF: 
https://github.com/llvm/llvm-project/commit/6a275de13f6cdf927cf3cd6125ea858ddc0c4b1d.diff

LOG: Revert "[UBSan] Improve error message when a misalignment is due to t… 
(#166197)

…arget de…"

This reverts commit 47c54d55c9fac5ea7c87881e00f96e8c12b18174.

Added: 
    

Modified: 
    clang/lib/CodeGen/CGExprCXX.cpp
    clang/lib/CodeGen/CodeGenFunction.h
    compiler-rt/lib/ubsan/ubsan_checks.inc
    compiler-rt/lib/ubsan/ubsan_handlers.cpp
    compiler-rt/test/ubsan/TestCases/TypeCheck/misaligned.cpp

Removed: 
    compiler-rt/test/ubsan/TestCases/TypeCheck/minimum-alignment.cpp


################################################################################
diff  --git a/clang/lib/CodeGen/CGExprCXX.cpp b/clang/lib/CodeGen/CGExprCXX.cpp
index f2dd22e9bed3b..14d8db32bafc6 100644
--- a/clang/lib/CodeGen/CGExprCXX.cpp
+++ b/clang/lib/CodeGen/CGExprCXX.cpp
@@ -18,9 +18,6 @@
 #include "ConstantEmitter.h"
 #include "TargetInfo.h"
 #include "clang/Basic/CodeGenOptions.h"
-#include "clang/Basic/Sanitizers.h"
-#include "clang/Basic/SourceLocation.h"
-#include "clang/Basic/SourceManager.h"
 #include "clang/CodeGen/CGFunctionInfo.h"
 #include "llvm/IR/Intrinsics.h"
 
@@ -1752,17 +1749,6 @@ llvm::Value *CodeGenFunction::EmitCXXNewExpr(const 
CXXNewExpr *E) {
       allocator->isReservedGlobalPlacementOperator())
     result = Builder.CreateLaunderInvariantGroup(result);
 
-  // Check the default alignment of the type and why. Users may incorrectly
-  // return misaligned memory from a replaced operator new without knowing
-  // about default alignment.
-  TypeCheckKind checkKind = CodeGenFunction::TCK_ConstructorCall;
-  const TargetInfo &TI = getContext().getTargetInfo();
-  unsigned DefaultTargetAlignment = TI.getNewAlign() / TI.getCharWidth();
-  if (SanOpts.has(SanitizerKind::Alignment) &&
-      (DefaultTargetAlignment >
-       CGM.getContext().getTypeAlignInChars(allocType).getQuantity()))
-    checkKind = CodeGenFunction::TCK_ConstructorCallMinimumAlign;
-
   // Emit sanitizer checks for pointer value now, so that in the case of an
   // array it was checked only once and not at each constructor call. We may
   // have already checked that the pointer is non-null.
@@ -1770,9 +1756,10 @@ llvm::Value *CodeGenFunction::EmitCXXNewExpr(const 
CXXNewExpr *E) {
   // we'll null check the wrong pointer here.
   SanitizerSet SkippedChecks;
   SkippedChecks.set(SanitizerKind::Null, nullCheck);
-  EmitTypeCheck(
-      checkKind, E->getAllocatedTypeSourceInfo()->getTypeLoc().getBeginLoc(),
-      result, allocType, result.getAlignment(), SkippedChecks, numElements);
+  EmitTypeCheck(CodeGenFunction::TCK_ConstructorCall,
+                E->getAllocatedTypeSourceInfo()->getTypeLoc().getBeginLoc(),
+                result, allocType, result.getAlignment(), SkippedChecks,
+                numElements);
 
   EmitNewInitializer(*this, E, allocType, elementTy, result, numElements,
                      allocSizeWithoutCookie);

diff  --git a/clang/lib/CodeGen/CodeGenFunction.h 
b/clang/lib/CodeGen/CodeGenFunction.h
index 047ca844c79de..8c4c1c8c2dc95 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -3296,10 +3296,7 @@ class CodeGenFunction : public CodeGenTypeCache {
     TCK_NonnullAssign,
     /// Checking the operand of a dynamic_cast or a typeid expression.  Must be
     /// null or an object within its lifetime.
-    TCK_DynamicOperation,
-    /// Checking the 'this' poiner for a constructor call, including that the
-    /// alignment is greater or equal to the targets minimum alignment
-    TCK_ConstructorCallMinimumAlign
+    TCK_DynamicOperation
   };
 
   /// Determine whether the pointer type check \p TCK permits null pointers.

diff  --git a/compiler-rt/lib/ubsan/ubsan_checks.inc 
b/compiler-rt/lib/ubsan/ubsan_checks.inc
index f8757d781afb8..b1d09a9024e7e 100644
--- a/compiler-rt/lib/ubsan/ubsan_checks.inc
+++ b/compiler-rt/lib/ubsan/ubsan_checks.inc
@@ -28,7 +28,6 @@ UBSAN_CHECK(NullptrAfterNonZeroOffset, 
"nullptr-after-nonzero-offset",
 UBSAN_CHECK(PointerOverflow, "pointer-overflow", "pointer-overflow")
 UBSAN_CHECK(MisalignedPointerUse, "misaligned-pointer-use", "alignment")
 UBSAN_CHECK(AlignmentAssumption, "alignment-assumption", "alignment")
-UBSAN_CHECK(MinumumAssumedAlignment, "minimum-assumed-alignment", "alignment")
 UBSAN_CHECK(InsufficientObjectSize, "insufficient-object-size", "object-size")
 UBSAN_CHECK(SignedIntegerOverflow, "signed-integer-overflow",
             "signed-integer-overflow")

diff  --git a/compiler-rt/lib/ubsan/ubsan_handlers.cpp 
b/compiler-rt/lib/ubsan/ubsan_handlers.cpp
index fc6063af4562b..63319f46734a4 100644
--- a/compiler-rt/lib/ubsan/ubsan_handlers.cpp
+++ b/compiler-rt/lib/ubsan/ubsan_handlers.cpp
@@ -73,26 +73,14 @@ enum TypeCheckKind {
   TCK_NonnullAssign,
   /// Checking the operand of a dynamic_cast or a typeid expression.  Must be
   /// null or an object within its lifetime.
-  TCK_DynamicOperation,
-  /// Checking the 'this' poiner for a constructor call, including that the
-  /// alignment is greater or equal to the targets minimum alignment
-  TCK_ConstructorCallMinimumAlign
+  TCK_DynamicOperation
 };
 
 extern const char *const TypeCheckKinds[] = {
-    "load of",
-    "store to",
-    "reference binding to",
-    "member access within",
-    "member call on",
-    "constructor call on",
-    "downcast of",
-    "downcast of",
-    "upcast of",
-    "cast to virtual base of",
-    "_Nonnull binding to",
-    "dynamic operation on",
-    "constructor call with pointer from operator new on"};
+    "load of", "store to", "reference binding to", "member access within",
+    "member call on", "constructor call on", "downcast of", "downcast of",
+    "upcast of", "cast to virtual base of", "_Nonnull binding to",
+    "dynamic operation on"};
 }
 
 static void handleTypeMismatchImpl(TypeMismatchData *Data, ValueHandle Pointer,
@@ -106,9 +94,7 @@ static void handleTypeMismatchImpl(TypeMismatchData *Data, 
ValueHandle Pointer,
              ? ErrorType::NullPointerUseWithNullability
              : ErrorType::NullPointerUse;
   else if (Pointer & (Alignment - 1))
-    ET = (Data->TypeCheckKind == TCK_ConstructorCallMinimumAlign)
-             ? ErrorType::MinumumAssumedAlignment
-             : ErrorType::MisalignedPointerUse;
+    ET = ErrorType::MisalignedPointerUse;
   else
     ET = ErrorType::InsufficientObjectSize;
 
@@ -131,13 +117,6 @@ static void handleTypeMismatchImpl(TypeMismatchData *Data, 
ValueHandle Pointer,
     Diag(Loc, DL_Error, ET, "%0 null pointer of type %1")
         << TypeCheckKinds[Data->TypeCheckKind] << Data->Type;
     break;
-  case ErrorType::MinumumAssumedAlignment:
-    Diag(Loc, DL_Error, ET,
-         "%0 misaligned address %1 for type %2, "
-         "which requires target minimum assumed %3 byte alignment")
-        << TypeCheckKinds[Data->TypeCheckKind] << (void *)Pointer << Data->Type
-        << Alignment;
-    break;
   case ErrorType::MisalignedPointerUse:
     Diag(Loc, DL_Error, ET, "%0 misaligned address %1 for type %3, "
                         "which requires %2 byte alignment")

diff  --git a/compiler-rt/test/ubsan/TestCases/TypeCheck/minimum-alignment.cpp 
b/compiler-rt/test/ubsan/TestCases/TypeCheck/minimum-alignment.cpp
deleted file mode 100644
index 4642126ab74c4..0000000000000
--- a/compiler-rt/test/ubsan/TestCases/TypeCheck/minimum-alignment.cpp
+++ /dev/null
@@ -1,36 +0,0 @@
-// RUN: %clangxx %gmlt -fsanitize=alignment %s -o %t
-// RUN: %run %t 2>&1 | FileCheck %s
-
-// UNSUPPORTED: i386
-// UNSUPPORTED: armv7l
-
-// These sanitizers already overload the new operator so won't compile this 
test
-// UNSUPPORTED: ubsan-msan
-// UNSUPPORTED: ubsan-tsan
-
-#include <cassert>
-#include <cstdlib>
-
-void *operator new(std::size_t count) {
-  constexpr const size_t offset = 8;
-
-  // allocate a bit more so we can safely offset it
-  void *ptr = std::malloc(count + offset);
-
-  // verify malloc returned 16 bytes aligned mem
-  static_assert(__STDCPP_DEFAULT_NEW_ALIGNMENT__ == 16);
-  assert(((std::ptr
diff _t)ptr & (__STDCPP_DEFAULT_NEW_ALIGNMENT__ - 1)) == 0);
-
-  return (char *)ptr + offset;
-}
-
-struct Foo {
-  void *_cookie1, *_cookie2;
-};
-
-static_assert(alignof(Foo) == 8);
-int main() {
-  // CHECK: runtime error: constructor call with pointer from operator new on 
misaligned address 0x{{.*}} for type 'Foo', which requires target minimum 
assumed 16 byte alignment
-  Foo *f = new Foo;
-  return 0;
-}

diff  --git a/compiler-rt/test/ubsan/TestCases/TypeCheck/misaligned.cpp 
b/compiler-rt/test/ubsan/TestCases/TypeCheck/misaligned.cpp
index 4b0b2b5923c6f..e39a0ab4e6589 100644
--- a/compiler-rt/test/ubsan/TestCases/TypeCheck/misaligned.cpp
+++ b/compiler-rt/test/ubsan/TestCases/TypeCheck/misaligned.cpp
@@ -101,7 +101,7 @@ int main(int, char **argv) {
     return s->f() && 0;
 
   case 'n':
-    // CHECK-NEW: misaligned.cpp:[[@LINE+4]]{{(:21)?}}: runtime error: 
constructor call with pointer from operator new on misaligned address 
[[PTR:0x[0-9a-f]*]] for type 'S', which requires target minimum assumed 4 byte 
alignment
+    // CHECK-NEW: misaligned.cpp:[[@LINE+4]]{{(:21)?}}: runtime error: 
constructor call on misaligned address [[PTR:0x[0-9a-f]*]] for type 'S', which 
requires 4 byte alignment
     // CHECK-NEW-NEXT: [[PTR]]: note: pointer points here
     // CHECK-NEW-NEXT: {{^ 00 00 00 01 02 03 04  05}}
     // CHECK-NEW-NEXT: {{^             \^}}


        
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