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

[Alexandros Lamprineas via cfe-commits]

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

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.

>From 1c10c683bc73fd928e7f3dfb58bc8de2b6776a88 Mon Sep 17 00:00:00 2001
From: Alexandros Lamprineas <alexandros.lamprineas at arm.com>
Date: Wed, 6 Mar 2024 12:30:30 +0000
Subject: [PATCH] [FMV] Remove duplicate features from mangled name.

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.
---
 clang/lib/CodeGen/Targets/AArch64.cpp    | 4 +++-
 clang/test/CodeGen/attr-target-version.c | 4 ++--
 2 files changed, 5 insertions(+), 3 deletions(-)

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