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[X86_32][C++] fix 0 sized struct case in vaarg. (#86388)

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struct SuperEmpty { struct{ int a[0];} b;};
Such 0 sized structs in c++ mode can not be ignored in i386 for that c++
fields are never empty.But when EmitVAArg, its size is 0, so that
va_list not increase.Maybe we can just Ignore this kind of arguments,
like X86_64 did. Fix #86385.
This commit is contained in:
Longsheng Mou 2024-08-02 09:20:49 +08:00 committed by GitHub
parent c5f1395f2f
commit 4461b69022
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3 changed files with 27 additions and 1 deletions
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4
clang/lib/CodeGen/Targets/X86.cpp
View File

@ -795,6 +795,10 @@ ABIArgInfo X86_32ABIInfo::classifyArgumentType(QualType Ty, CCState &State,
if (!IsWin32StructABI && isEmptyRecord(getContext(), Ty, true))
return ABIArgInfo::getIgnore();
// Ignore 0 sized structs.
if (TI.Width == 0)
return ABIArgInfo::getIgnore();
llvm::LLVMContext &LLVMContext = getVMContext();
llvm::IntegerType *Int32 = llvm::Type::getInt32Ty(LLVMContext);
bool NeedsPadding = false;

2
clang/test/CodeGenCXX/regparm.cpp
View File

@ -32,7 +32,7 @@ struct S3 {
} a;
};
__attribute((regparm(2))) void foo4(S3 a, int b);
// CHECK: declare void @_Z4foo42S3i(ptr noundef byval(%struct.S3) align 4, i32 inreg noundef)
// CHECK: declare void @_Z4foo42S3i(i32 inreg noundef)
void bar3(S3 a, int b) {
foo4(a, b);
}

22
clang/test/CodeGenCXX/x86_32-vaarg.cpp
View File

@ -18,3 +18,25 @@ empty empty_record_test(int z, ...) {
__builtin_va_start(list, z);
return __builtin_va_arg(list, empty);
}
typedef struct {
struct {
int a[0];
} b;
} SortOfEmpty;
// CHECK-LABEL: @_Z18test_sort_of_emptyiz(
// CHECK-NEXT: entry:
// CHECK-NEXT: [[RESULT_PTR:%.*]] = alloca ptr, align 4
// CHECK-NEXT: [[Z_ADDR:%.*]] = alloca i32, align 4
// CHECK-NEXT: [[LIST:%.*]] = alloca ptr, align 4
// CHECK-NEXT: store ptr [[AGG_RESULT:%.*]], ptr [[RESULT_PTR]], align 4
// CHECK-NEXT: store i32 [[Z:%.*]], ptr [[Z_ADDR]], align 4
// CHECK-NEXT: call void @llvm.va_start.p0(ptr [[LIST]])
// CHECK-NEXT: ret void
//
SortOfEmpty test_sort_of_empty(int z, ...) {
__builtin_va_list list;
__builtin_va_start(list, z);
return __builtin_va_arg(list, SortOfEmpty);
}