[Arm64EC] Improve alignment mangling in arm64ec thunks. #90115
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In some cases, MSVC's mangling for arm64ec thunks includes the alignment of a struct. I added some code to try to match... but it never really worked right. The issues: - Alignment is only mangled if it's 16 or more (I guess the default is supposed to be 8). - Alignment isn't mangled on return values (since the memory is allocated by the caller). The current patch leaves hooks to make alignment mangling work... but doesn't actually ever mangle alignment: clang never actually encodes a relevant alignment into the IR. Once we get clang to emit the real size/alignment of structs, we can start emitting it.
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@llvm/pr-subscribers-backend-aarch64 Author: Eli Friedman (efriedma-quic) ChangesIn some cases, MSVC's mangling for arm64ec thunks includes the alignment of a struct. I added some code to try to match... but it never really worked right. The issues:
The current patch leaves hooks to make alignment mangling work... but doesn't actually ever mangle alignment: clang never actually encodes a relevant alignment into the IR. Once we get clang to emit the real size/alignment of structs, we can start emitting it. Full diff: https://github.com/llvm/llvm-project/pull/90115.diff 3 Files Affected:
diff --git a/llvm/lib/Target/AArch64/AArch64Arm64ECCallLowering.cpp b/llvm/lib/Target/AArch64/AArch64Arm64ECCallLowering.cpp
index 3bf6283b79e9b8..dddc181b031444 100644
--- a/llvm/lib/Target/AArch64/AArch64Arm64ECCallLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64Arm64ECCallLowering.cpp
@@ -178,13 +178,14 @@ void AArch64Arm64ECCallLowering::getThunkArgTypes(
}
for (unsigned E = FT->getNumParams(); I != E; ++I) {
- Align ParamAlign = AttrList.getParamAlignment(I).valueOrOne();
#if 0
// FIXME: Need more information about argument size; see
// https://reviews.llvm.org/D132926
uint64_t ArgSizeBytes = AttrList.getParamArm64ECArgSizeBytes(I);
+ Align ParamAlign = AttrList.getParamAlignment(I).valueOrOne();
#else
uint64_t ArgSizeBytes = 0;
+ Align ParamAlign = Align();
#endif
Type *Arm64Ty, *X64Ty;
canonicalizeThunkType(FT->getParamType(I), ParamAlign,
@@ -294,7 +295,7 @@ void AArch64Arm64ECCallLowering::canonicalizeThunkType(
uint64_t TotalSizeBytes = ElementCnt * ElementSizePerBytes;
if (ElementTy->isFloatTy() || ElementTy->isDoubleTy()) {
Out << (ElementTy->isFloatTy() ? "F" : "D") << TotalSizeBytes;
- if (Alignment.value() >= 8 && !T->isPointerTy())
+ if (Alignment.value() >= 16 && !Ret)
Out << "a" << Alignment.value();
Arm64Ty = T;
if (TotalSizeBytes <= 8) {
@@ -325,7 +326,7 @@ void AArch64Arm64ECCallLowering::canonicalizeThunkType(
Out << "m";
if (TypeSize != 4)
Out << TypeSize;
- if (Alignment.value() >= 8 && !T->isPointerTy())
+ if (Alignment.value() >= 16 && !Ret)
Out << "a" << Alignment.value();
// FIXME: Try to canonicalize Arm64Ty more thoroughly?
Arm64Ty = T;
diff --git a/llvm/test/CodeGen/AArch64/arm64ec-entry-thunks.ll b/llvm/test/CodeGen/AArch64/arm64ec-entry-thunks.ll
index bb9ba05f7a2724..c00c9bfe127e8a 100644
--- a/llvm/test/CodeGen/AArch64/arm64ec-entry-thunks.ll
+++ b/llvm/test/CodeGen/AArch64/arm64ec-entry-thunks.ll
@@ -223,8 +223,8 @@ define i8 @matches_has_sret() nounwind {
%TSRet = type { i64, i64 }
define void @has_aligned_sret(ptr align 32 sret(%TSRet)) nounwind {
-; CHECK-LABEL: .def $ientry_thunk$cdecl$m16a32$v;
-; CHECK: .section .wowthk$aa,"xr",discard,$ientry_thunk$cdecl$m16a32$v
+; CHECK-LABEL: .def $ientry_thunk$cdecl$m16$v;
+; CHECK: .section .wowthk$aa,"xr",discard,$ientry_thunk$cdecl$m16$v
; CHECK: // %bb.0:
; CHECK-NEXT: stp q6, q7, [sp, #-176]! // 32-byte Folded Spill
; CHECK-NEXT: .seh_save_any_reg_px q6, 176
@@ -457,7 +457,7 @@ define %T2 @simple_struct(%T1 %0, %T2 %1, %T3, %T4) nounwind {
; CHECK-NEXT: .symidx $ientry_thunk$cdecl$i8$v
; CHECK-NEXT: .word 1
; CHECK-NEXT: .symidx "#has_aligned_sret"
-; CHECK-NEXT: .symidx $ientry_thunk$cdecl$m16a32$v
+; CHECK-NEXT: .symidx $ientry_thunk$cdecl$m16$v
; CHECK-NEXT: .word 1
; CHECK-NEXT: .symidx "#small_array"
; CHECK-NEXT: .symidx $ientry_thunk$cdecl$m2$m2F8
diff --git a/llvm/test/CodeGen/AArch64/arm64ec-exit-thunks.ll b/llvm/test/CodeGen/AArch64/arm64ec-exit-thunks.ll
index 3b911e78aff2a4..7a40fcd85ac585 100644
--- a/llvm/test/CodeGen/AArch64/arm64ec-exit-thunks.ll
+++ b/llvm/test/CodeGen/AArch64/arm64ec-exit-thunks.ll
@@ -236,8 +236,8 @@ declare void @has_sret(ptr sret([100 x i8])) nounwind;
%TSRet = type { i64, i64 }
declare void @has_aligned_sret(ptr align 32 sret(%TSRet)) nounwind;
-; CHECK-LABEL: .def $iexit_thunk$cdecl$m16a32$v;
-; CHECK: .section .wowthk$aa,"xr",discard,$iexit_thunk$cdecl$m16a32$v
+; CHECK-LABEL: .def $iexit_thunk$cdecl$m16$v;
+; CHECK: .section .wowthk$aa,"xr",discard,$iexit_thunk$cdecl$m16$v
; CHECK: // %bb.0:
; CHECK-NEXT: sub sp, sp, #48
; CHECK-NEXT: .seh_stackalloc 48
@@ -271,8 +271,8 @@ declare void @has_aligned_sret(ptr align 32 sret(%TSRet)) nounwind;
; CHECK: adrp x11, has_aligned_sret
; CHECK: add x11, x11, :lo12:has_aligned_sret
; CHECK: ldr x9, [x9, :lo12:__os_arm64x_check_icall]
-; CHECK: adrp x10, ($iexit_thunk$cdecl$m16a32$v)
-; CHECK: add x10, x10, :lo12:($iexit_thunk$cdecl$m16a32$v)
+; CHECK: adrp x10, ($iexit_thunk$cdecl$m16$v)
+; CHECK: add x10, x10, :lo12:($iexit_thunk$cdecl$m16$v)
; CHECK: blr x9
; CHECK: .seh_startepilogue
; CHECK: ldr x30, [sp], #16 // 8-byte Folded Reload
@@ -492,7 +492,7 @@ declare %T2 @simple_struct(%T1, %T2, %T3, %T4) nounwind;
; CHECK-NEXT: .symidx has_sret
; CHECK-NEXT: .word 0
; CHECK-NEXT: .symidx has_aligned_sret
-; CHECK-NEXT: .symidx $iexit_thunk$cdecl$m16a32$v
+; CHECK-NEXT: .symidx $iexit_thunk$cdecl$m16$v
; CHECK-NEXT: .word 4
; CHECK-NEXT: .symidx "#has_aligned_sret$exit_thunk"
; CHECK-NEXT: .symidx has_aligned_sret
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dpaoliello
approved these changes
Apr 25, 2024
cjacek
approved these changes
Apr 26, 2024
This was referenced Apr 29, 2024
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In some cases, MSVC's mangling for arm64ec thunks includes the alignment of a struct. I added some code to try to match... but it never really worked right. The issues: - Alignment is only mangled if it's 16 or more (I guess the default is supposed to be 8). - Alignment isn't mangled on return values (since the memory is allocated by the caller). The current patch leaves hooks to make alignment mangling work... but doesn't actually ever mangle alignment: clang never actually encodes a relevant alignment into the IR. Once we get clang to emit the real size/alignment of structs, we can start emitting it.
tstellar
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to dpaoliello/llvm-project
that referenced
this pull request
May 17, 2024
In some cases, MSVC's mangling for arm64ec thunks includes the alignment of a struct. I added some code to try to match... but it never really worked right. The issues: - Alignment is only mangled if it's 16 or more (I guess the default is supposed to be 8). - Alignment isn't mangled on return values (since the memory is allocated by the caller). The current patch leaves hooks to make alignment mangling work... but doesn't actually ever mangle alignment: clang never actually encodes a relevant alignment into the IR. Once we get clang to emit the real size/alignment of structs, we can start emitting it.
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In some cases, MSVC's mangling for arm64ec thunks includes the alignment of a struct. I added some code to try to match... but it never really worked right. The issues:
The current patch leaves hooks to make alignment mangling work... but doesn't actually ever mangle alignment: clang never actually encodes a relevant alignment into the IR. Once we get clang to emit the real size/alignment of structs, we can start emitting it.