[clang] [FMV] Remove duplicate features from mangled name. (PR #84165)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-aarch64

Author: Alexandros Lamprineas (labrinea)

<details>
<summary>Changes</summary>

ACLE suggests: https://github.com/ARM-software/acle/pull/308 GCC emits diagnostics for attribute strings which contain duplicate features, but for now let's follow the SPEC in regards to mangling rules and we can change the semantic behavior of the compiler later if there's value to it.

---
Full diff: https://github.com/llvm/llvm-project/pull/84165.diff


2 Files Affected:

- (modified) clang/lib/CodeGen/Targets/AArch64.cpp (+3-1) 
- (modified) clang/test/CodeGen/attr-target-version.c (+2-2) 


``````````diff
diff --git a/clang/lib/CodeGen/Targets/AArch64.cpp b/clang/lib/CodeGen/Targets/AArch64.cpp
index 725e8a70fddfe6..85117366de0ee8 100644
--- a/clang/lib/CodeGen/Targets/AArch64.cpp
+++ b/clang/lib/CodeGen/Targets/AArch64.cpp
@@ -886,9 +886,11 @@ void AArch64ABIInfo::appendAttributeMangling(StringRef AttrStr,
     return LHS.compare(RHS) < 0;
   });
 
+  llvm::SmallDenseSet<StringRef, 8> UniqueFeats;
   for (auto &Feat : Features)
     if (auto Ext = llvm::AArch64::parseArchExtension(Feat))
-      Out << 'M' << Ext->Name;
+      if (UniqueFeats.insert(Ext->Name).second)
+        Out << 'M' << Ext->Name;
 }
 
 std::unique_ptr<TargetCodeGenInfo>
diff --git a/clang/test/CodeGen/attr-target-version.c b/clang/test/CodeGen/attr-target-version.c
index ae1a8772f6cc07..b7112c783da913 100644
--- a/clang/test/CodeGen/attr-target-version.c
+++ b/clang/test/CodeGen/attr-target-version.c
@@ -273,7 +273,7 @@ int hoo(void) {
 // CHECK-NEXT:    [[TMP3:%.*]] = and i1 true, [[TMP2]]
 // CHECK-NEXT:    br i1 [[TMP3]], label [[RESOLVER_RETURN:%.*]], label [[RESOLVER_ELSE:%.*]]
 // CHECK:       resolver_return:
-// CHECK-NEXT:    ret ptr @fmv_inline._MfcmaMfp16Mfp16MrdmMsme
+// CHECK-NEXT:    ret ptr @fmv_inline._MfcmaMfp16MrdmMsme
 // CHECK:       resolver_else:
 // CHECK-NEXT:    [[TMP4:%.*]] = load i64, ptr @__aarch64_cpu_features, align 8
 // CHECK-NEXT:    [[TMP5:%.*]] = and i64 [[TMP4]], 864726312827224064
@@ -582,7 +582,7 @@ int hoo(void) {
 //
 //
 // CHECK: Function Attrs: noinline nounwind optnone
-// CHECK-LABEL: define {{[^@]+}}@fmv_inline._MfcmaMfp16Mfp16MrdmMsme
+// CHECK-LABEL: define {{[^@]+}}@fmv_inline._MfcmaMfp16MrdmMsme
 // CHECK-SAME: () #[[ATTR13:[0-9]+]] {
 // CHECK-NEXT:  entry:
 // CHECK-NEXT:    ret i32 2

``````````

</details>


https://github.com/llvm/llvm-project/pull/84165