Revert "Reland "[AArch64] Decouple feature dependency expansion. (#94279)" (#95231)"

This reverts commit 7051073.

The following code is now incorrectly rejected.

```
% cat neon.c
#include <arm_neon.h>
__attribute__((target("arch=armv8-a")))
uint64x2_t foo(uint64x2_t a, uint64x2_t b) {
  return veorq_u64(a, b);
}
% newclang --target=aarch64-linux-gnu -c neon.c
neon.c:5:10: error: always_inline function 'veorq_u64' requires target feature 'outline-atomics', but would be inlined into function 'foo' that is compiled without support for 'outline-atomics'
    5 |   return veorq_u64(a, b);
      |          ^
1 error generated.
```

"+outline-atomics" seems misleading here.

Author: MaskRay

clang/include/clang/AST/ASTContext.h

@@ -3210,6 +3210,9 @@ class ASTContext : public RefCountedBase<ASTContext> {
   /// valid feature names.
   ParsedTargetAttr filterFunctionTargetAttrs(const TargetAttr *TD) const;
 
+  std::vector<std::string>
+  filterFunctionTargetVersionAttrs(const TargetVersionAttr *TV) const;
+
   void getFunctionFeatureMap(llvm::StringMap<bool> &FeatureMap,
                              const FunctionDecl *) const;
   void getFunctionFeatureMap(llvm::StringMap<bool> &FeatureMap,

clang/lib/AST/ASTContext.cpp

@@ -87,7 +87,6 @@
 #include "llvm/Support/MD5.h"
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/raw_ostream.h"
-#include "llvm/TargetParser/AArch64TargetParser.h"
 #include "llvm/TargetParser/Triple.h"
 #include <algorithm>
 #include <cassert>
@@ -13677,20 +13676,17 @@ QualType ASTContext::getCorrespondingSignedFixedPointType(QualType Ty) const {
   }
 }
 
-// Given a list of FMV features, return a concatenated list of the
-// corresponding backend features (which may contain duplicates).
-static std::vector<std::string> getFMVBackendFeaturesFor(
-    const llvm::SmallVectorImpl<StringRef> &FMVFeatStrings) {
-  std::vector<std::string> BackendFeats;
-  for (StringRef F : FMVFeatStrings) {
-    if (auto FMVExt = llvm::AArch64::parseArchExtension(F)) {
-      SmallVector<StringRef, 8> Feats;
-      FMVExt->DependentFeatures.split(Feats, ',', -1, false);
-      for (StringRef F : Feats)
-        BackendFeats.push_back(F.str());
-    }
-  }
-  return BackendFeats;
+std::vector<std::string> ASTContext::filterFunctionTargetVersionAttrs(
+    const TargetVersionAttr *TV) const {
+  assert(TV != nullptr);
+  llvm::SmallVector<StringRef, 8> Feats;
+  std::vector<std::string> ResFeats;
+  TV->getFeatures(Feats);
+  for (auto &Feature : Feats)
+    if (Target->validateCpuSupports(Feature.str()))
+      // Use '?' to mark features that came from TargetVersion.
+      ResFeats.push_back("?" + Feature.str());
+  return ResFeats;
 }
 
 ParsedTargetAttr
@@ -13725,12 +13721,10 @@ void ASTContext::getFunctionFeatureMap(llvm::StringMap<bool> &FeatureMap,
 
     // Make a copy of the features as passed on the command line into the
     // beginning of the additional features from the function to override.
-    // AArch64 handles command line option features in parseTargetAttr().
-    if (!Target->getTriple().isAArch64())
-      ParsedAttr.Features.insert(
-          ParsedAttr.Features.begin(),
-          Target->getTargetOpts().FeaturesAsWritten.begin(),
-          Target->getTargetOpts().FeaturesAsWritten.end());
+    ParsedAttr.Features.insert(
+        ParsedAttr.Features.begin(),
+        Target->getTargetOpts().FeaturesAsWritten.begin(),
+        Target->getTargetOpts().FeaturesAsWritten.end());
 
     if (ParsedAttr.CPU != "" && Target->isValidCPUName(ParsedAttr.CPU))
       TargetCPU = ParsedAttr.CPU;
@@ -13751,31 +13745,32 @@ void ASTContext::getFunctionFeatureMap(llvm::StringMap<bool> &FeatureMap,
                     Target->getTargetOpts().FeaturesAsWritten.end());
     Target->initFeatureMap(FeatureMap, getDiagnostics(), TargetCPU, Features);
   } else if (const auto *TC = FD->getAttr<TargetClonesAttr>()) {
+    std::vector<std::string> Features;
     if (Target->getTriple().isAArch64()) {
+      // TargetClones for AArch64
       llvm::SmallVector<StringRef, 8> Feats;
       TC->getFeatures(Feats, GD.getMultiVersionIndex());
-      std::vector<std::string> Features = getFMVBackendFeaturesFor(Feats);
+      for (StringRef Feat : Feats)
+        if (Target->validateCpuSupports(Feat.str()))
+          // Use '?' to mark features that came from AArch64 TargetClones.
+          Features.push_back("?" + Feat.str());
       Features.insert(Features.begin(),
                       Target->getTargetOpts().FeaturesAsWritten.begin(),
                       Target->getTargetOpts().FeaturesAsWritten.end());
-      Target->initFeatureMap(FeatureMap, getDiagnostics(), TargetCPU, Features);
     } else {
-      std::vector<std::string> Features;
       StringRef VersionStr = TC->getFeatureStr(GD.getMultiVersionIndex());
       if (VersionStr.starts_with("arch="))
         TargetCPU = VersionStr.drop_front(sizeof("arch=") - 1);
       else if (VersionStr != "default")
         Features.push_back((StringRef{"+"} + VersionStr).str());
-      Target->initFeatureMap(FeatureMap, getDiagnostics(), TargetCPU, Features);
     }
-  } else if (const auto *TV = FD->getAttr<TargetVersionAttr>()) {
-    llvm::SmallVector<StringRef, 8> Feats;
-    TV->getFeatures(Feats);
-    std::vector<std::string> Features = getFMVBackendFeaturesFor(Feats);
-    Features.insert(Features.begin(),
-                    Target->getTargetOpts().FeaturesAsWritten.begin(),
-                    Target->getTargetOpts().FeaturesAsWritten.end());
     Target->initFeatureMap(FeatureMap, getDiagnostics(), TargetCPU, Features);
+  } else if (const auto *TV = FD->getAttr<TargetVersionAttr>()) {
+    std::vector<std::string> Feats = filterFunctionTargetVersionAttrs(TV);
+    Feats.insert(Feats.begin(),
+                 Target->getTargetOpts().FeaturesAsWritten.begin(),
+                 Target->getTargetOpts().FeaturesAsWritten.end());
+    Target->initFeatureMap(FeatureMap, getDiagnostics(), TargetCPU, Feats);
   } else {
     FeatureMap = Target->getTargetOpts().FeatureMap;
   }

clang/lib/AST/CMakeLists.txt

@@ -139,6 +139,4 @@ add_clang_library(clangAST
   omp_gen
   ClangDriverOptions
   intrinsics_gen
-  # These generated headers are included transitively.
-  AArch64TargetParserTableGen
   )

clang/lib/Basic/Targets/AArch64.cpp

@@ -1052,18 +1052,57 @@ bool AArch64TargetInfo::handleTargetFeatures(std::vector<std::string> &Features,
   return true;
 }
 
+bool AArch64TargetInfo::initFeatureMap(
+    llvm::StringMap<bool> &Features, DiagnosticsEngine &Diags, StringRef CPU,
+    const std::vector<std::string> &FeaturesVec) const {
+  std::vector<std::string> UpdatedFeaturesVec;
+  // Parse the CPU and add any implied features.
+  std::optional<llvm::AArch64::CpuInfo> CpuInfo = llvm::AArch64::parseCpu(CPU);
+  if (CpuInfo) {
+    auto Exts = CpuInfo->getImpliedExtensions();
+    std::vector<StringRef> CPUFeats;
+    llvm::AArch64::getExtensionFeatures(Exts, CPUFeats);
+    for (auto F : CPUFeats) {
+      assert((F[0] == '+' || F[0] == '-') && "Expected +/- in target feature!");
+      UpdatedFeaturesVec.push_back(F.str());
+    }
+  }
+
+  // Process target and dependent features. This is done in two loops collecting
+  // them into UpdatedFeaturesVec: first to add dependent '+'features, second to
+  // add target '+/-'features that can later disable some of features added on
+  // the first loop. Function Multi Versioning features begin with '?'.
+  for (const auto &Feature : FeaturesVec)
+    if (((Feature[0] == '?' || Feature[0] == '+')) &&
+        AArch64TargetInfo::doesFeatureAffectCodeGen(Feature.substr(1))) {
+      StringRef DepFeatures =
+          AArch64TargetInfo::getFeatureDependencies(Feature.substr(1));
+      SmallVector<StringRef, 1> AttrFeatures;
+      DepFeatures.split(AttrFeatures, ",");
+      for (auto F : AttrFeatures)
+        UpdatedFeaturesVec.push_back(F.str());
+    }
+  for (const auto &Feature : FeaturesVec)
+    if (Feature[0] != '?') {
+      std::string UpdatedFeature = Feature;
+      if (Feature[0] == '+') {
+        std::optional<llvm::AArch64::ExtensionInfo> Extension =
+            llvm::AArch64::parseArchExtension(Feature.substr(1));
+        if (Extension)
+          UpdatedFeature = Extension->Feature.str();
+      }
+      UpdatedFeaturesVec.push_back(UpdatedFeature);
+    }
+
+  return TargetInfo::initFeatureMap(Features, Diags, CPU, UpdatedFeaturesVec);
+}
+
 // Parse AArch64 Target attributes, which are a comma separated list of:
 //  "arch=<arch>" - parsed to features as per -march=..
 //  "cpu=<cpu>" - parsed to features as per -mcpu=.., with CPU set to <cpu>
 //  "tune=<cpu>" - TuneCPU set to <cpu>
 //  "feature", "no-feature" - Add (or remove) feature.
 //  "+feature", "+nofeature" - Add (or remove) feature.
-//
-// A feature may correspond to an Extension (anything with a corresponding
-// AEK_), in which case an ExtensionSet is used to parse it and expand its
-// dependencies. Otherwise the feature is passed through (e.g. +v8.1a,
-// +outline-atomics, -fmv, etc). Features coming from the command line are
-// already parsed, therefore their dependencies do not need expansion.
 ParsedTargetAttr AArch64TargetInfo::parseTargetAttr(StringRef Features) const {
   ParsedTargetAttr Ret;
   if (Features == "default")
@@ -1073,26 +1112,23 @@ ParsedTargetAttr AArch64TargetInfo::parseTargetAttr(StringRef Features) const {
   bool FoundArch = false;
 
   auto SplitAndAddFeatures = [](StringRef FeatString,
-                                std::vector<std::string> &Features,
-                                llvm::AArch64::ExtensionSet &FeatureBits) {
+                                std::vector<std::string> &Features) {
     SmallVector<StringRef, 8> SplitFeatures;
     FeatString.split(SplitFeatures, StringRef("+"), -1, false);
     for (StringRef Feature : SplitFeatures) {
-      if (FeatureBits.parseModifier(Feature, /* AllowNoDashForm = */ true))
-        continue;
-      // Pass through features that are not extensions, e.g. +v8.1a,
-      // +outline-atomics, -fmv, etc.
-      if (Feature.starts_with("no"))
-        Features.push_back("-" + Feature.drop_front(2).str());
+      StringRef FeatureName = llvm::AArch64::getArchExtFeature(Feature);
+      if (!FeatureName.empty())
+        Features.push_back(FeatureName.str());
       else
-        Features.push_back("+" + Feature.str());
+        // Pushing the original feature string to give a sema error later on
+        // when they get checked.
+        if (Feature.starts_with("no"))
+          Features.push_back("-" + Feature.drop_front(2).str());
+        else
+          Features.push_back("+" + Feature.str());
     }
   };
 
-  llvm::AArch64::ExtensionSet FeatureBits;
-  // Reconstruct the bitset from the command line option features.
-  FeatureBits.reconstructFromParsedFeatures(getTargetOpts().FeaturesAsWritten);
-
   for (auto &Feature : AttrFeatures) {
     Feature = Feature.trim();
     if (Feature.starts_with("fpmath="))
@@ -1115,9 +1151,9 @@ ParsedTargetAttr AArch64TargetInfo::parseTargetAttr(StringRef Features) const {
       // Ret.Features.
       if (!AI)
         continue;
-      FeatureBits.addArchDefaults(*AI);
+      Ret.Features.push_back(AI->ArchFeature.str());
       // Add any extra features, after the +
-      SplitAndAddFeatures(Split.second, Ret.Features, FeatureBits);
+      SplitAndAddFeatures(Split.second, Ret.Features);
     } else if (Feature.starts_with("cpu=")) {
       if (!Ret.CPU.empty())
         Ret.Duplicate = "cpu=";
@@ -1127,30 +1163,33 @@ ParsedTargetAttr AArch64TargetInfo::parseTargetAttr(StringRef Features) const {
         std::pair<StringRef, StringRef> Split =
             Feature.split("=").second.trim().split("+");
         Ret.CPU = Split.first;
-        if (auto CpuInfo = llvm::AArch64::parseCpu(Ret.CPU)) {
-          FeatureBits.addCPUDefaults(*CpuInfo);
-          SplitAndAddFeatures(Split.second, Ret.Features, FeatureBits);
-        }
+        SplitAndAddFeatures(Split.second, Ret.Features);
       }
     } else if (Feature.starts_with("tune=")) {
       if (!Ret.Tune.empty())
         Ret.Duplicate = "tune=";
       else
         Ret.Tune = Feature.split("=").second.trim();
     } else if (Feature.starts_with("+")) {
-      SplitAndAddFeatures(Feature, Ret.Features, FeatureBits);
+      SplitAndAddFeatures(Feature, Ret.Features);
+    } else if (Feature.starts_with("no-")) {
+      StringRef FeatureName =
+          llvm::AArch64::getArchExtFeature(Feature.split("-").second);
+      if (!FeatureName.empty())
+        Ret.Features.push_back("-" + FeatureName.drop_front(1).str());
+      else
+        Ret.Features.push_back("-" + Feature.split("-").second.str());
     } else {
-      if (FeatureBits.parseModifier(Feature, /* AllowNoDashForm = */ true))
-        continue;
-      // Pass through features that are not extensions, e.g. +v8.1a,
-      // +outline-atomics, -fmv, etc.
-      if (Feature.starts_with("no-"))
-        Ret.Features.push_back("-" + Feature.drop_front(3).str());
+      // Try parsing the string to the internal target feature name. If it is
+      // invalid, add the original string (which could already be an internal
+      // name). These should be checked later by isValidFeatureName.
+      StringRef FeatureName = llvm::AArch64::getArchExtFeature(Feature);
+      if (!FeatureName.empty())
+        Ret.Features.push_back(FeatureName.str());
       else
         Ret.Features.push_back("+" + Feature.str());
     }
   }
-  FeatureBits.toLLVMFeatureList(Ret.Features);
   return Ret;
 }
 

clang/lib/Basic/Targets/AArch64.h

@@ -107,6 +107,10 @@ class LLVM_LIBRARY_VISIBILITY AArch64TargetInfo : public TargetInfo {
   unsigned multiVersionSortPriority(StringRef Name) const override;
   unsigned multiVersionFeatureCost() const override;
 
+  bool
+  initFeatureMap(llvm::StringMap<bool> &Features, DiagnosticsEngine &Diags,
+                 StringRef CPU,
+                 const std::vector<std::string> &FeaturesVec) const override;
   bool useFP16ConversionIntrinsics() const override {
     return false;
   }

clang/test/CodeGen/aarch64-cpu-supports-target.c

@@ -48,5 +48,5 @@ int test_versions() {
     return code();
 }
 // CHECK: attributes #0 = { noinline nounwind optnone "no-trapping-math"="true" "stack-protector-buffer-size"="8" }
-// CHECK: attributes #1 = { noinline nounwind optnone "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-features"="+fp-armv8,+neon" }
-// CHECK: attributes #2 = { noinline nounwind optnone "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-features"="+fp-armv8,+fullfp16,+sve" }
+// CHECK: attributes #1 = { noinline nounwind optnone "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-features"="+neon" }
+// CHECK: attributes #2 = { noinline nounwind optnone "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-features"="+fp-armv8,+fullfp16,+neon,+sve" }

clang/test/CodeGen/aarch64-sme-intrinsics/aarch64-sme-attrs.cpp

@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -triple aarch64-none-linux-gnu -target-feature +sme -target-feature +bf16 \
+// RUN: %clang_cc1 -triple aarch64-none-linux-gnu -target-feature +sme \
 // RUN:   -disable-O0-optnone -Werror -emit-llvm -o - %s \
 // RUN: | opt -S -passes=mem2reg \
 // RUN: | opt -S -passes=inline \