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[i386] Modify the alignment of __m128/__m256/__m512 vector type according i386 abi. 

According to i386 System V ABI:

1. when __m256 are required to be passed on the stack, the stack pointer must be aligned on a 0 mod 32 byte boundary at the time of the call.
2. when __m512 are required to be passed on the stack, the stack pointer must be aligned on a 0 mod 64 byte boundary at the time of the call.

The current method of clang passing __m512 parameter are as follow:

1. when target supports avx512, passing it with 64 byte alignment;
2. when target supports avx, passing it with 32 byte alignment;
3. Otherwise, passing it with 16 byte alignment.

Passing __m256 parameter are as follow:

1. when target supports avx or avx512, passing it with 32 byte alignment;
2. Otherwise, passing it with 16 byte alignment.

This pach will passing __m128/__m256/__m512 following i386 System V ABI and
apply it to Linux only since other System V OS (e.g Darwin, PS4 and FreeBSD) don't
want to spend any effort dealing with the ramifications of ABI breaks at present.

Differential Revision: https://reviews.llvm.org/D78564
This commit is contained in:
Liu, Chen3 2021-04-02 08:45:26 +08:00
parent bda20282cb
commit 1c4108ab66
2 changed files with 71 additions and 2 deletions
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13
clang/lib/CodeGen/TargetInfo.cpp
View File

@ -1105,6 +1105,7 @@ class X86_32ABIInfo : public SwiftABIInfo {
bool IsWin32StructABI;
bool IsSoftFloatABI;
bool IsMCUABI;
bool IsLinuxABI;
unsigned DefaultNumRegisterParameters;
static bool isRegisterSize(unsigned Size) {
@ -1167,9 +1168,9 @@ public:
unsigned NumRegisterParameters, bool SoftFloatABI)
: SwiftABIInfo(CGT), IsDarwinVectorABI(DarwinVectorABI),
IsRetSmallStructInRegABI(RetSmallStructInRegABI),
IsWin32StructABI(Win32StructABI),
IsSoftFloatABI(SoftFloatABI),
IsWin32StructABI(Win32StructABI), IsSoftFloatABI(SoftFloatABI),
IsMCUABI(CGT.getTarget().getTriple().isOSIAMCU()),
IsLinuxABI(CGT.getTarget().getTriple().isOSLinux()),
DefaultNumRegisterParameters(NumRegisterParameters) {}
bool shouldPassIndirectlyForSwift(ArrayRef<llvm::Type*> scalars,
@ -1594,6 +1595,14 @@ unsigned X86_32ABIInfo::getTypeStackAlignInBytes(QualType Ty,
if (Align <= MinABIStackAlignInBytes)
return 0; // Use default alignment.
if (IsLinuxABI) {
// Exclude other System V OS (e.g Darwin, PS4 and FreeBSD) since we don't
// want to spend any effort dealing with the ramifications of ABI breaks.
//
// If the vector type is __m128/__m256/__m512, return the default alignment.
if (Ty->isVectorType() && (Align == 16 || Align == 32 || Align == 64))
return Align;
}
// On non-Darwin, the stack type alignment is always 4.
if (!IsDarwinVectorABI) {
// Set explicit alignment, since we may need to realign the top.

60
clang/test/CodeGen/x86_32-align-linux.c Normal file
View File

@ -0,0 +1,60 @@
// RUN: %clang_cc1 -w -fblocks -ffreestanding -triple i386-pc-linux-gnu -emit-llvm -o - %s | FileCheck %s
// RUN: %clang_cc1 -w -fblocks -ffreestanding -triple i386-pc-linux-gnu -target-feature +avx -emit-llvm -o - %s | FileCheck %s
// RUN: %clang_cc1 -w -fblocks -ffreestanding -triple i386-pc-linux-gnu -target-feature +avx512f -emit-llvm -o - %s | FileCheck %s
#include <immintrin.h>
// CHECK-LABEL: define dso_local void @testm128
// CHECK-LABEL: %argp.cur = load i8*, i8** %args, align 4
// CHECK-NEXT: %0 = ptrtoint i8* %argp.cur to i32
// CHECK-NEXT: %1 = add i32 %0, 15
// CHECK-NEXT: %2 = and i32 %1, -16
// CHECK-NEXT: %argp.cur.aligned = inttoptr i32 %2 to i8*
void testm128(int argCount, ...) {
__m128 res;
__builtin_va_list args;
__builtin_va_start(args, argCount);
res = __builtin_va_arg(args, __m128);
__builtin_va_end(args);
}
// CHECK-LABEL: define dso_local void @testm256
// CHECK-LABEL: %argp.cur = load i8*, i8** %args, align 4
// CHECK-NEXT: %0 = ptrtoint i8* %argp.cur to i32
// CHECK-NEXT: %1 = add i32 %0, 31
// CHECK-NEXT: %2 = and i32 %1, -32
// CHECK-NEXT: %argp.cur.aligned = inttoptr i32 %2 to i8*
void testm256(int argCount, ...) {
__m256 res;
__builtin_va_list args;
__builtin_va_start(args, argCount);
res = __builtin_va_arg(args, __m256);
__builtin_va_end(args);
}
// CHECK-LABEL: define dso_local void @testm512
// CHECK-LABEL: %argp.cur = load i8*, i8** %args, align 4
// CHECK-NEXT: %0 = ptrtoint i8* %argp.cur to i32
// CHECK-NEXT: %1 = add i32 %0, 63
// CHECK-NEXT: %2 = and i32 %1, -64
// CHECK-NEXT: %argp.cur.aligned = inttoptr i32 %2 to i8*
void testm512(int argCount, ...) {
__m512 res;
__builtin_va_list args;
__builtin_va_start(args, argCount);
res = __builtin_va_arg(args, __m512);
__builtin_va_end(args);
}
// CHECK-LABEL: define dso_local void @testPastArguments
// CHECK: call void (i32, ...) @testm128(i32 1, <4 x float> %0)
// CHECK: call void (i32, ...) @testm256(i32 1, <8 x float> %1)
// CHECK: call void (i32, ...) @testm512(i32 1, <16 x float> %2)
void testPastArguments(void) {
__m128 a;
__m256 b;
__m512 c;
testm128(1, a);
testm256(1, b);
testm512(1, c);
}