[clang] [X86_64] fix arg pass error in struct. (PR #86902)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang-codegen

Author: Longsheng Mou (CoTinker)

<details>
<summary>Changes</summary>

```
typedef long long t67 __attribute__((aligned (4)));
struct s67 {
  int a;
  t67 b;
};
void f67(struct s67 x) {
}
```
When classify:
a: Lo = Integer, Hi = NoClass
b: Lo = Integer, Hi = NoClass
struct S: Lo = Integer, Hi = NoClass

```
define dso_local void @<!-- -->f67(i64 %x.coerce) {
```
In this case, only one i64 register is used when the structure parameter is transferred, which is obviously incorrect.So we need to treat the split case specially. fix https://github.com/llvm/llvm-project/issues/85387.

---
Full diff: https://github.com/llvm/llvm-project/pull/86902.diff


2 Files Affected:

- (modified) clang/lib/CodeGen/Targets/X86.cpp (+5-1) 
- (modified) clang/test/CodeGen/X86/x86_64-arguments.c (+18) 


``````````diff
diff --git a/clang/lib/CodeGen/Targets/X86.cpp b/clang/lib/CodeGen/Targets/X86.cpp
index 2291c991fb1107..de0dfe32a54d3a 100644
--- a/clang/lib/CodeGen/Targets/X86.cpp
+++ b/clang/lib/CodeGen/Targets/X86.cpp
@@ -2100,8 +2100,12 @@ void X86_64ABIInfo::classify(QualType Ty, uint64_t OffsetBase, Class &Lo,
         postMerge(Size, Lo, Hi);
         return;
       }
+
+      bool InMemory = Offset % getContext().getTypeAlign(i->getType()) ||
+                      (i->getType()->getAs<BuiltinType>() &&
+                       Offset % getContext().getTypeSize(i->getType()));
       // Note, skip this test for bit-fields, see below.
-      if (!BitField && Offset % getContext().getTypeAlign(i->getType())) {
+      if (!BitField && InMemory) {
         Lo = Memory;
         postMerge(Size, Lo, Hi);
         return;
diff --git a/clang/test/CodeGen/X86/x86_64-arguments.c b/clang/test/CodeGen/X86/x86_64-arguments.c
index cf5636cfd518b6..82845f0a2b31fd 100644
--- a/clang/test/CodeGen/X86/x86_64-arguments.c
+++ b/clang/test/CodeGen/X86/x86_64-arguments.c
@@ -533,6 +533,24 @@ typedef float t66 __attribute__((__vector_size__(128), __aligned__(128)));
 void f66(t66 a0) {
 }
 
+typedef long long t67 __attribute__((aligned (4)));
+struct s67 {
+  int a;
+  t67 b;
+};
+// CHECK-LABEL: define{{.*}} void @f67(ptr noundef byval(%struct.s67) align 8 %x)
+void f67(struct s67 x) {
+}
+
+typedef double t68 __attribute__((aligned (4)));
+struct s68 {
+  int a;
+  t68 b;
+};
+// CHECK-LABEL: define{{.*}} void @f68(ptr noundef byval(%struct.s68) align 8 %x)
+void f68(struct s68 x) {
+}
+
 /// The synthesized __va_list_tag does not have file/line fields.
 // CHECK:      = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "__va_list_tag",
 // CHECK-NOT:  file:

``````````

</details>


https://github.com/llvm/llvm-project/pull/86902