Author: pengfei
Date: Wed May 29 01:42:35 2019
New Revision: 361934
URL: http://llvm.org/viewvc/llvm-project?rev=361934&view=rev
Log:
[X86] Fix i386 struct and union parameter alignment
According to i386 System V ABI 2.1: Structures and unions assume the
alignment of their most strictly aligned component. But current
implementation always takes them as 4-byte aligned which will result
in incorrect code, e.g:
1 #include <immintrin.h>
2 typedef union {
3 int d[4];
4 __m128 m;
5 } M128;
6 extern void foo(int, ...);
7 void test(void)
8 {
9 M128 a;
10 foo(1, a);
11 foo(1, a.m);
12 }
The first call (line 10) takes the second arg as 4-byte aligned while
the second call (line 11) takes the second arg as 16-byte aligned.
There is oxymoron for the alignment of the 2 calls because they should
be the same.
This patch fixes the bug by 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.
Patch by Wei Xiao (wxiao3)
Differential Revision: https://reviews.llvm.org/D60748
Added:
cfe/trunk/test/CodeGen/x86_32-align-linux.c
Modified:
cfe/trunk/lib/CodeGen/TargetInfo.cpp
cfe/trunk/test/CodeGen/x86_32-arguments-linux.c
Modified: cfe/trunk/lib/CodeGen/TargetInfo.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/TargetInfo.cpp?rev=361934&r1=361933&r2=361934&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/TargetInfo.cpp (original)
+++ cfe/trunk/lib/CodeGen/TargetInfo.cpp Wed May 29 01:42:35 2019
@@ -1010,6 +1010,7 @@ class X86_32ABIInfo : public SwiftABIInf
bool IsWin32StructABI;
bool IsSoftFloatABI;
bool IsMCUABI;
+ bool IsLinuxABI;
unsigned DefaultNumRegisterParameters;
static bool isRegisterSize(unsigned Size) {
@@ -1076,6 +1077,7 @@ public:
IsWin32StructABI(Win32StructABI),
IsSoftFloatABI(SoftFloatABI),
IsMCUABI(CGT.getTarget().getTriple().isOSIAMCU()),
+ IsLinuxABI(CGT.getTarget().getTriple().isOSLinux()),
DefaultNumRegisterParameters(NumRegisterParameters) {}
bool shouldPassIndirectlyForSwift(ArrayRef<llvm::Type*> scalars,
@@ -1492,8 +1494,15 @@ unsigned X86_32ABIInfo::getTypeStackAlig
if (Align <= MinABIStackAlignInBytes)
return 0; // Use default alignment.
- // On non-Darwin, the stack type alignment is always 4.
- if (!IsDarwinVectorABI) {
+ if (IsLinuxABI) {
+ // i386 System V ABI 2.1: Structures and unions assume the alignment of
their
+ // most strictly aligned component.
+ //
+ // 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.
+ return Align;
+ } else if (!IsDarwinVectorABI) {
+ // On non-Darwin and non-Linux, the stack type alignment is always 4.
// Set explicit alignment, since we may need to realign the top.
return MinABIStackAlignInBytes;
}
Added: cfe/trunk/test/CodeGen/x86_32-align-linux.c
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/x86_32-align-linux.c?rev=361934&view=auto
==============================================================================
--- cfe/trunk/test/CodeGen/x86_32-align-linux.c (added)
+++ cfe/trunk/test/CodeGen/x86_32-align-linux.c Wed May 29 01:42:35 2019
@@ -0,0 +1,25 @@
+// RUN: %clang_cc1 -w -fblocks -ffreestanding -triple i386-pc-linux-gnu
-emit-llvm -o %t %s
+// RUN: FileCheck < %t %s
+
+#include <immintrin.h>
+
+typedef union {
+ int d[4];
+ __m128 m;
+} M128;
+
+extern void foo(int, ...);
+
+M128 a;
+
+// CHECK-LABEL: define void @test
+// CHECK: entry:
+// CHECK: call void (i32, ...) @foo(i32 1, %union.M128* byval align 16
+// CHECK: call void (i32, ...) @foo(i32 1, <4 x float>
+
+void test(void)
+{
+ foo(1, a);
+ foo(1, a.m);
+}
+
Modified: cfe/trunk/test/CodeGen/x86_32-arguments-linux.c
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/x86_32-arguments-linux.c?rev=361934&r1=361933&r2=361934&view=diff
==============================================================================
--- cfe/trunk/test/CodeGen/x86_32-arguments-linux.c (original)
+++ cfe/trunk/test/CodeGen/x86_32-arguments-linux.c Wed May 29 01:42:35 2019
@@ -3,21 +3,21 @@
// CHECK-LABEL: define void @f56(
// CHECK: i8 signext %a0, %struct.s56_0* byval align 4 %a1,
-// CHECK: i64 %a2.coerce, %struct.s56_1* byval align 4,
-// CHECK: <1 x double> %a4, %struct.s56_2* byval align 4,
-// CHECK: <4 x i32> %a6, %struct.s56_3* byval align 4,
-// CHECK: <2 x double> %a8, %struct.s56_4* byval align 4,
-// CHECK: <8 x i32> %a10, %struct.s56_5* byval align 4,
-// CHECK: <4 x double> %a12, %struct.s56_6* byval align 4)
+// CHECK: i64 %a2.coerce, %struct.s56_1* byval align 8 %a3,
+// CHECK: <1 x double> %a4, %struct.s56_2* byval align 8 %a5,
+// CHECK: <4 x i32> %a6, %struct.s56_3* byval align 16 %a7,
+// CHECK: <2 x double> %a8, %struct.s56_4* byval align 16 %a9,
+// CHECK: <8 x i32> %a10, %struct.s56_5* byval align 32 %a11,
+// CHECK: <4 x double> %a12, %struct.s56_6* byval align 32 %a13)
// CHECK: call void (i32, ...) @f56_0(i32 1,
// CHECK: i32 %{{.*}}, %struct.s56_0* byval align 4 %{{[^ ]*}},
-// CHECK: i64 %{{[^ ]*}}, %struct.s56_1* byval align 4 %{{[^ ]*}},
-// CHECK: <1 x double> %{{[^ ]*}}, %struct.s56_2* byval align 4 %{{[^ ]*}},
-// CHECK: <4 x i32> %{{[^ ]*}}, %struct.s56_3* byval align 4 %{{[^ ]*}},
-// CHECK: <2 x double> %{{[^ ]*}}, %struct.s56_4* byval align 4 %{{[^ ]*}},
-// CHECK: <8 x i32> %{{[^ ]*}}, %struct.s56_5* byval align 4 %{{[^ ]*}},
-// CHECK: <4 x double> %{{[^ ]*}}, %struct.s56_6* byval align 4 %{{[^ ]*}})
+// CHECK: i64 %{{[^ ]*}}, %struct.s56_1* byval align 8 %{{[^ ]*}},
+// CHECK: <1 x double> %{{[^ ]*}}, %struct.s56_2* byval align 8 %{{[^ ]*}},
+// CHECK: <4 x i32> %{{[^ ]*}}, %struct.s56_3* byval align 16 %{{[^ ]*}},
+// CHECK: <2 x double> %{{[^ ]*}}, %struct.s56_4* byval align 16 %{{[^ ]*}},
+// CHECK: <8 x i32> %{{[^ ]*}}, %struct.s56_5* byval align 32 %{{[^ ]*}},
+// CHECK: <4 x double> %{{[^ ]*}}, %struct.s56_6* byval align 32 %{{[^ ]*}})
// CHECK: }
//
// <rdar://problem/7964854> [i386] clang misaligns long double in structures
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
