https://github.com/hstk30-hw updated
https://github.com/llvm/llvm-project/pull/77907
>From 63ed15b49cfb87b85c858fe826c6a401a1f052eb Mon Sep 17 00:00:00 2001
From: Longsheng Mou <moulongsh...@huawei.com>
Date: Fri, 12 Jan 2024 18:24:08 +0800
Subject: [PATCH] [X86_64] fix empty structure vaarg in c++
SizeInBytes of empty structure is 0 in C, while 1 in C++.
And empty structure argument of the function is ignored
in X86_64 backend.As a result, the value of variable
arguments in C++ is incorrect.
---
clang/lib/CodeGen/Targets/X86.cpp | 5 +++++
clang/test/CodeGen/X86/x86_64-vaarg.c | 15 +++++++++++++++
2 files changed, 20 insertions(+)
create mode 100644 clang/test/CodeGen/X86/x86_64-vaarg.c
diff --git a/clang/lib/CodeGen/Targets/X86.cpp
b/clang/lib/CodeGen/Targets/X86.cpp
index d053f41ab168f5..4f9e903b8f0e98 100644
--- a/clang/lib/CodeGen/Targets/X86.cpp
+++ b/clang/lib/CodeGen/Targets/X86.cpp
@@ -2989,6 +2989,11 @@ static Address EmitX86_64VAArgFromMemory(CodeGenFunction
&CGF,
// an 8 byte boundary.
uint64_t SizeInBytes = (CGF.getContext().getTypeSize(Ty) + 7) / 8;
+
+ if (isEmptyRecord(CGF.getContext(), Ty, true)) {
+ SizeInBytes = 0;
+ }
+
llvm::Value *Offset =
llvm::ConstantInt::get(CGF.Int32Ty, (SizeInBytes + 7) & ~7);
overflow_arg_area = CGF.Builder.CreateGEP(CGF.Int8Ty, overflow_arg_area,
diff --git a/clang/test/CodeGen/X86/x86_64-vaarg.c
b/clang/test/CodeGen/X86/x86_64-vaarg.c
new file mode 100644
index 00000000000000..ae201a2d3f3017
--- /dev/null
+++ b/clang/test/CodeGen/X86/x86_64-vaarg.c
@@ -0,0 +1,15 @@
+// RUN: %clang -xc++ -target x86_64-linux-gnu -emit-llvm -S -o - %s |
FileCheck %s
+
+struct Empty {};
+
+struct Empty emptyvar;
+
+void take_args(int a, ...) {
+ // CHECK: %overflow_arg_area = load ptr, ptr %overflow_arg_area_p,
align 8
+ // CHECK-NEXT: %overflow_arg_area.next = getelementptr i8, ptr
%overflow_arg_area, i32 0
+ // CHECK-NEXT: store ptr %overflow_arg_area.next, ptr
%overflow_arg_area_p, align 8
+ __builtin_va_list l;
+ __builtin_va_start(l, a);
+ emptyvar = __builtin_va_arg(l, struct Empty);
+ __builtin_va_end(l);
+}
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