https://github.com/bwendling created
https://github.com/llvm/llvm-project/pull/125298
If the __bdos argument isn't an array (e.g. a pointer), due to
'-Wno-int-conversion' or some other shenanigans, default to using the
llvm.objectsize intrinsic.
Fixes: cff0a460ae86 ("[Clang][counted_by] Refactor
__builtin_dynamic_object_size on FAMs (#122198)")
Signed-off-by: Bill Wendling <mo...@google.com>
>From df6b80c82f1a9ce4f1eef580f008c86fd691ba71 Mon Sep 17 00:00:00 2001
From: Bill Wendling <mo...@google.com>
Date: Fri, 31 Jan 2025 12:48:36 -0800
Subject: [PATCH] [Clang][counted_by] Don't treat a pointer as an array
If the __bdos field isn't an array, don't process it. We'll default to
using the llvm.objectsize intrinsic.
---
clang/lib/CodeGen/CGBuiltin.cpp | 30 ++++++++++++++++++++++++------
1 file changed, 24 insertions(+), 6 deletions(-)
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index 11fa295dad9524c..21faf85a16e2d25 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -1319,12 +1319,36 @@ CodeGenFunction::emitCountedByMemberSize(const Expr *E,
llvm::Value *EmittedE,
// size_t field_offset = offsetof (struct s, field);
Value *FieldOffset = nullptr;
+ llvm::ConstantInt *FieldBaseSize = nullptr;
if (FlexibleArrayMemberFD != FD) {
std::optional<int64_t> Offset = GetFieldOffset(Ctx, RD, FD);
if (!Offset)
return nullptr;
FieldOffset =
llvm::ConstantInt::get(ResType, *Offset / CharWidth, IsSigned);
+
+ if (Idx) {
+ // From option (4):
+ // size_t field_base_size = sizeof (*ptr->field_array);
+ if (!FieldTy->isArrayType())
+ // The field isn't an array. For example:
+ //
+ // struct {
+ // int count;
+ // char *string;
+ // int array[] __counted_by(count);
+ // } x;
+ //
+ // __builtin_dynamic_object_size(x.string[42], 0);
+ //
+ // If built with '-Wno-int-conversion', FieldTy won't be an array here.
+ return nullptr;
+
+ const ArrayType *ArrayTy = Ctx.getAsArrayType(FieldTy);
+ CharUnits BaseSize = Ctx.getTypeSizeInChars(ArrayTy->getElementType());
+ FieldBaseSize =
+ llvm::ConstantInt::get(ResType, BaseSize.getQuantity(), IsSigned);
+ }
}
// size_t count = (size_t) ptr->count;
@@ -1376,12 +1400,6 @@ CodeGenFunction::emitCountedByMemberSize(const Expr *E,
llvm::Value *EmittedE,
llvm::ConstantInt::get(ResType, Size.getKnownMinValue() / CharWidth);
if (Idx) { // Option (4) '&ptr->field_array[idx]'
- // size_t field_base_size = sizeof (*ptr->field_array);
- const ArrayType *ArrayTy = Ctx.getAsArrayType(FieldTy);
- CharUnits BaseSize = Ctx.getTypeSizeInChars(ArrayTy->getElementType());
- auto *FieldBaseSize =
- llvm::ConstantInt::get(ResType, BaseSize.getQuantity(), IsSigned);
-
// field_offset += index * field_base_size;
Value *Mul = Builder.CreateMul(Index, FieldBaseSize, "field_offset",
!IsSigned, IsSigned);
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