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[clang] [AArch64] Fix Windows va_arg handling for larger structs 

Aggregate types over 16 bytes are passed by reference.

Contrary to the x86_64 ABI, smaller structs with an odd (non power
of two) are padded and passed in registers.

Differential Revision: https://reviews.llvm.org/D100374
This commit is contained in:
Martin Storsjö 2021-04-11 12:38:40 +03:00
parent 6cdc2239db
commit 3637c5c8ec
2 changed files with 37 additions and 3 deletions
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8
clang/lib/CodeGen/TargetInfo.cpp
View File

@ -6121,7 +6121,13 @@ Address AArch64ABIInfo::EmitDarwinVAArg(Address VAListAddr, QualType Ty,
Address AArch64ABIInfo::EmitMSVAArg(CodeGenFunction &CGF, Address VAListAddr,
QualType Ty) const {
return emitVoidPtrVAArg(CGF, VAListAddr, Ty, /*indirect*/ false,
bool IsIndirect = false;
// Composites larger than 16 bytes are passed by reference.
if (isAggregateTypeForABI(Ty) && getContext().getTypeSize(Ty) > 128)
IsIndirect = true;
return emitVoidPtrVAArg(CGF, VAListAddr, Ty, IsIndirect,
CGF.getContext().getTypeInfoInChars(Ty),
CharUnits::fromQuantity(8),
/*allowHigherAlign*/ false);

32
clang/test/CodeGen/ms_abi_aarch64.c
View File

@ -1,5 +1,13 @@
// RUN: %clang_cc1 -triple aarch64-linux-gnu -emit-llvm < %s | FileCheck -check-prefix=LINUX %s
// RUN: %clang_cc1 -triple aarch64-pc-win32 -emit-llvm < %s | FileCheck -check-prefix=WIN64 %s
// RUN: %clang_cc1 -triple aarch64-linux-gnu -emit-llvm < %s | FileCheck -check-prefixes=LINUX,COMMON %s
// RUN: %clang_cc1 -triple aarch64-pc-win32 -emit-llvm < %s | FileCheck -check-prefixes=WIN64,COMMON %s
struct small_odd {
char a, b, c;
};
struct larger {
int a, b, c, d, e;
};
void __attribute__((ms_abi)) f1(void);
void f2(void);
@ -48,6 +56,26 @@ void __attribute__((ms_abi)) f4(int a, ...) {
// WIN64: call void @llvm.va_end
}
void __attribute__((ms_abi)) f4_2(int a, ...) {
// LINUX-LABEL: define{{.*}} win64cc void @f4_2
// WIN64-LABEL: define dso_local void @f4_2
__builtin_ms_va_list ap;
__builtin_ms_va_start(ap, a);
// COMMON: %[[AP:.*]] = alloca i8*
// COMMON: call void @llvm.va_start
struct small_odd s1 = __builtin_va_arg(ap, struct small_odd);
// COMMON: %[[AP_CUR:.*]] = load i8*, i8** %[[AP]]
// COMMON-NEXT: %[[AP_NEXT:.*]] = getelementptr inbounds i8, i8* %[[AP_CUR]], i64 8
// COMMON-NEXT: store i8* %[[AP_NEXT]], i8** %[[AP]]
// COMMON-NEXT: bitcast i8* %[[AP_CUR]] to %struct.small_odd*
struct larger s2 = __builtin_va_arg(ap, struct larger);
// COMMON: %[[AP_CUR2:.*]] = load i8*, i8** %[[AP]]
// COMMON-NEXT: %[[AP_NEXT3:.*]] = getelementptr inbounds i8, i8* %[[AP_CUR2]], i64 8
// COMMON-NEXT: store i8* %[[AP_NEXT3]], i8** %[[AP]]
// COMMON-NEXT: bitcast i8* %[[AP_CUR2]] to %struct.larger**
__builtin_ms_va_end(ap);
}
// Let's verify that normal va_lists work right on Win64, too.
void f5(int a, ...) {
// WIN64-LABEL: define dso_local void @f5