[clang] [X86_32][C++] fix 0 sized struct case in vaarg. (PR #86388)
https://github.com/CoTinker edited https://github.com/llvm/llvm-project/pull/86388 ___ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[clang] [X86_32][C++] fix 0 sized struct case in vaarg. (PR #86388)
efriedma-quic wrote: If you implement #86075 like I suggested, the inconsistency here also goes away, I think: if va_arg queries classifyArgumentType, you get the same result as argument lowering, so clang becomes self-consistent. (Whether that's gcc-compatible is a different question...) https://github.com/llvm/llvm-project/pull/86388 ___ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[clang] [X86_32][C++] fix 0 sized struct case in vaarg. (PR #86388)
CoTinker wrote:
Inconsistency here is inevitable.
Such struct `SuperEmpty { struct{ int a[0];} b;}` in c++ mode can not be
ignored in i386 for that c++ fields are never empty, and its TypeInfo.Width =
TypeInfo.Align = 0.
https://github.com/llvm/llvm-project/blob/594989918bf9e178f3b7c5e200d700d0574f15ec/clang/lib/CodeGen/Targets/X86.cpp#L1070-L1091
And Indirect is false, so that DirectSize = DirectAlign = 0, which leads to
error.
https://github.com/llvm/llvm-project/blob/594989918bf9e178f3b7c5e200d700d0574f15ec/clang/lib/CodeGen/ABIInfoImpl.cpp#L205-L230
How do I fix this? Change the classifyArgumentType or the EmiVAArg?
@efriedma-quic
https://github.com/llvm/llvm-project/pull/86388
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[clang] [X86_32][C++] fix 0 sized struct case in vaarg. (PR #86388)
efriedma-quic wrote: There are two ways we could analyze, this, I think: - EmitVAArg is doing something which disagrees with the classification done by classifyArgumentType, so that's a bug in EmitVAArg. - classifyArgumentType is returning a malformed value; EmitVAArg should assert that it never sees such a value, and classifyArgumentType should be changed to return something else in that case. What exactly is classifyArgumentType returning here? https://github.com/llvm/llvm-project/pull/86388 ___ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[clang] [X86_32][C++] fix 0 sized struct case in vaarg. (PR #86388)
https://github.com/CoTinker updated
https://github.com/llvm/llvm-project/pull/86388
>From 54f75d7068d0acf336d6d1e61bcf800ff52cc310 Mon Sep 17 00:00:00 2001
From: Longsheng Mou
Date: Sat, 23 Mar 2024 17:53:58 +0800
Subject: [PATCH] [X86_32] fix 0 sized struct case in vaarg.
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 ignore this kind of
arguments.
---
clang/lib/CodeGen/Targets/X86.cpp | 4
clang/test/CodeGenCXX/regparm.cpp | 2 +-
clang/test/CodeGenCXX/x86_32-vaarg.cpp | 22 ++
3 files changed, 27 insertions(+), 1 deletion(-)
diff --git a/clang/lib/CodeGen/Targets/X86.cpp
b/clang/lib/CodeGen/Targets/X86.cpp
index 16d52bee3490b..26ff4e4ac0a3b 100644
--- a/clang/lib/CodeGen/Targets/X86.cpp
+++ b/clang/lib/CodeGen/Targets/X86.cpp
@@ -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;
diff --git a/clang/test/CodeGenCXX/regparm.cpp
b/clang/test/CodeGenCXX/regparm.cpp
index 1fd471c2d0727..b9735485db8de 100644
--- a/clang/test/CodeGenCXX/regparm.cpp
+++ b/clang/test/CodeGenCXX/regparm.cpp
@@ -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);
}
diff --git a/clang/test/CodeGenCXX/x86_32-vaarg.cpp
b/clang/test/CodeGenCXX/x86_32-vaarg.cpp
index a3f2791484362..90665652a0286 100644
--- a/clang/test/CodeGenCXX/x86_32-vaarg.cpp
+++ b/clang/test/CodeGenCXX/x86_32-vaarg.cpp
@@ -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);
+}
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[clang] [X86_32][C++] fix 0 sized struct case in vaarg. (PR #86388)
https://github.com/CoTinker edited https://github.com/llvm/llvm-project/pull/86388 ___ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[clang] [X86_32][C++] fix 0 sized struct case in vaarg. (PR #86388)
CoTinker wrote: Could you please take time to review it, thank you. @efriedma-quic https://github.com/llvm/llvm-project/pull/86388 ___ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[clang] [X86_32][C++] fix 0 sized struct case in vaarg. (PR #86388)
https://github.com/efriedma-quic approved this pull request. LGTM https://github.com/llvm/llvm-project/pull/86388 ___ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[clang] [X86_32][C++] fix 0 sized struct case in vaarg. (PR #86388)
https://github.com/CoTinker closed https://github.com/llvm/llvm-project/pull/86388 ___ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[clang] [X86_32][C++] fix 0 sized struct case in vaarg. (PR #86388)
RSilicon wrote: Should this be backported to 19.x? https://github.com/llvm/llvm-project/pull/86388 ___ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[clang] [X86_32][C++] fix 0 sized struct case in vaarg. (PR #86388)
CoTinker wrote: I don't know, but maybe Eli can give you an answer. https://github.com/llvm/llvm-project/pull/86388 ___ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
