Supports option 1 of ARM-software/acle#403

Author: labrinea

clang/lib/CodeGen/Targets/AArch64.cpp

@@ -1336,10 +1336,13 @@ void AArch64ABIInfo::appendAttributeMangling(StringRef AttrStr,
   });
 
   llvm::SmallDenseSet<StringRef, 8> UniqueFeats;
-  for (auto &Feat : Features)
+  for (auto &Feat : Features) {
+    if (!getTarget().doesFeatureAffectCodeGen(Feat))
+      continue;
     if (auto Ext = llvm::AArch64::parseFMVExtension(Feat))
       if (UniqueFeats.insert(Ext->Name).second)
         Out << 'M' << Ext->Name;
+  }
 }
 
 std::unique_ptr<TargetCodeGenInfo>

clang/test/CodeGen/AArch64/fmv-duplicate-mangled-name.c

@@ -1,5 +1,7 @@
 // RUN: %clang_cc1 -triple aarch64-linux-gnu -verify -emit-llvm-only %s -DCHECK_IMPLICIT_DEFAULT
 // RUN: %clang_cc1 -triple aarch64-linux-gnu -verify -emit-llvm-only %s -DCHECK_EXPLICIT_DEFAULT
+// RUN: %clang_cc1 -triple aarch64-linux-gnu -verify -emit-llvm-only %s -DCHECK_EXPLICIT_VERSION_PRIORITY
+// RUN: %clang_cc1 -triple aarch64-linux-gnu -verify -emit-llvm-only %s -DCHECK_EXPLICIT_CLONES_PRIORITY
 
 #if defined(CHECK_IMPLICIT_DEFAULT)
 
@@ -21,4 +23,18 @@ __attribute__((target_version("default"))) int explicit_default_bad(void) { retu
 // expected-note@-2 {{previous definition is here}}
 __attribute__((target_clones("aes", "lse", "default"))) int explicit_default_bad(void) { return 1; }
 
+#elif defined(CHECK_EXPLICIT_VERSION_PRIORITY)
+
+__attribute__((target_version("aes"))) int explicit_version_priority(void) { return 0; }
+// expected-error@+2 {{definition with same mangled name 'explicit_version_priority._Maes' as another definition}}
+// expected-note@-2 {{previous definition is here}}
+__attribute__((target_version("priority1+aes"))) int explicit_version_priority(void) { return 1; }
+
+#elif defined(CHECK_EXPLICIT_CLONES_PRIORITY)
+
+__attribute__((target_version("aes+priority2"))) int explicit_clones_priority(void) { return 0; }
+// expected-error@+2 {{definition with same mangled name 'explicit_clones_priority._Maes' as another definition}}
+// expected-note@-2 {{previous definition is here}}
+__attribute__((target_clones("priority1+aes", "lse"))) int explicit_clones_priority(void) { return 1; }
+
 #endif

llvm/include/llvm/TargetParser/AArch64FeatPriorities.inc

@@ -59,7 +59,12 @@ enum FeatPriorities {
   PRIOR_SME_I64,
   PRIOR_SME2,
   PRIOR_MOPS,
-  PRIOR_CSSC
+  PRIOR_CSSC,
+  PRIOR_5,
+  PRIOR_4,
+  PRIOR_3,
+  PRIOR_2,
+  PRIOR_1
 };
 
 #endif

llvm/lib/Target/AArch64/AArch64FMV.td

@@ -83,3 +83,8 @@ def : FMVExtension<"sve2-sha3", "SVE_SHA3">;
 def : FMVExtension<"sve2-sm4", "SVE_SM4">;
 def : FMVExtension<"wfxt", "WFXT">;
 def : FMVExtension<"cssc", "CSSC">;
+let FeatureBit = "FEAT_MAX" in def : FMVExtension<"priority1", "1">;
+let FeatureBit = "FEAT_MAX" in def : FMVExtension<"priority2", "2">;
+let FeatureBit = "FEAT_MAX" in def : FMVExtension<"priority3", "3">;
+let FeatureBit = "FEAT_MAX" in def : FMVExtension<"priority4", "4">;
+let FeatureBit = "FEAT_MAX" in def : FMVExtension<"priority5", "5">;

llvm/lib/TargetParser/AArch64TargetParser.cpp

@@ -58,18 +58,23 @@ std::optional<AArch64::FMVInfo> lookupFMVByID(AArch64::ArchExtKind ExtID) {
 uint64_t AArch64::getFMVPriority(ArrayRef<StringRef> Features) {
   // Transitively enable the Arch Extensions which correspond to each feature.
   ExtensionSet FeatureBits;
+  uint64_t PriorityMask = 0;
   for (const StringRef Feature : Features) {
     std::optional<FMVInfo> FMV = parseFMVExtension(Feature);
     if (!FMV && Feature.starts_with('+')) {
       if (std::optional<ExtensionInfo> Info = targetFeatureToExtension(Feature))
         FMV = lookupFMVByID(Info->ID);
     }
-    if (FMV && FMV->ID)
-      FeatureBits.enable(*FMV->ID);
+    if (FMV) {
+      // FMV feature without a corresponding Arch Extension may affect priority
+      if (FMV->ID)
+        FeatureBits.enable(*FMV->ID);
+      else
+        PriorityMask |= (1ULL << FMV->PriorityBit);
+    }
   }
 
   // Construct a bitmask for all the transitively enabled Arch Extensions.
-  uint64_t PriorityMask = 0;
   for (const FMVInfo &Info : getFMVInfo())
     if (Info.ID && FeatureBits.Enabled.test(*Info.ID))
       PriorityMask |= (1ULL << Info.PriorityBit);