[Clang][AArch64] Add pessimistic vscale_range for sve/sme (#137624)

The "target-features" function attribute is not currently considered
when adding vscale_range to a function. When +sve/+sme are pushed onto
functions with "#pragma attribute push(+sve/+sme)", the function
potentially misses out on optimizations that rely on vscale_range being
present.

5 files changed, 21 insertions, 9 deletions

diff --git a/clang/lib/Basic/Targets/AArch64.cpp b/clang/lib/Basic/Targets/AArch64.cpp
index 3633bab..e1f6c7b 100644
--- a/clang/lib/Basic/Targets/AArch64.cpp
+++ b/clang/lib/Basic/Targets/AArch64.cpp
@@ -794,12 +794,17 @@ AArch64TargetInfo::getTargetBuiltins() const {
 
 std::optional<std::pair<unsigned, unsigned>>
 AArch64TargetInfo::getVScaleRange(const LangOptions &LangOpts,
-                                  bool IsArmStreamingFunction) const {
+                                  bool IsArmStreamingFunction,
+                                  llvm::StringMap<bool> *FeatureMap) const {
   if (LangOpts.VScaleMin || LangOpts.VScaleMax)
     return std::pair<unsigned, unsigned>(
         LangOpts.VScaleMin ? LangOpts.VScaleMin : 1, LangOpts.VScaleMax);
 
-  if (hasFeature("sve") || (IsArmStreamingFunction && hasFeature("sme")))
+  if (hasFeature("sve") || (FeatureMap && (FeatureMap->lookup("sve"))))
+    return std::pair<unsigned, unsigned>(1, 16);
+
+  if (IsArmStreamingFunction &&
+      (hasFeature("sme") || (FeatureMap && (FeatureMap->lookup("sme")))))
     return std::pair<unsigned, unsigned>(1, 16);
 
   return std::nullopt;
diff --git a/clang/lib/Basic/Targets/AArch64.h b/clang/lib/Basic/Targets/AArch64.h
index 2fab88c..6eeac69 100644
--- a/clang/lib/Basic/Targets/AArch64.h
+++ b/clang/lib/Basic/Targets/AArch64.h
@@ -187,8 +187,8 @@ public:
   llvm::SmallVector<Builtin::InfosShard> getTargetBuiltins() const override;
 
   std::optional<std::pair<unsigned, unsigned>>
-  getVScaleRange(const LangOptions &LangOpts,
-                 bool IsArmStreamingFunction) const override;
+  getVScaleRange(const LangOptions &LangOpts, bool IsArmStreamingFunction,
+                 llvm::StringMap<bool> *FeatureMap = nullptr) const override;
   bool doesFeatureAffectCodeGen(StringRef Name) const override;
   bool validateCpuSupports(StringRef FeatureStr) const override;
   bool hasFeature(StringRef Feature) const override;
diff --git a/clang/lib/Basic/Targets/RISCV.cpp b/clang/lib/Basic/Targets/RISCV.cpp
index 390ef0f..a1a2437 100644
--- a/clang/lib/Basic/Targets/RISCV.cpp
+++ b/clang/lib/Basic/Targets/RISCV.cpp
@@ -332,7 +332,8 @@ bool RISCVTargetInfo::initFeatureMap(
 
 std::optional<std::pair<unsigned, unsigned>>
 RISCVTargetInfo::getVScaleRange(const LangOptions &LangOpts,
-                                bool IsArmStreamingFunction) const {
+                                bool IsArmStreamingFunction,
+                                llvm::StringMap<bool> *FeatureMap) const {
   // RISCV::RVVBitsPerBlock is 64.
   unsigned VScaleMin = ISAInfo->getMinVLen() / llvm::RISCV::RVVBitsPerBlock;
 
diff --git a/clang/lib/Basic/Targets/RISCV.h b/clang/lib/Basic/Targets/RISCV.h
index c26aa19..0b36c9d 100644
--- a/clang/lib/Basic/Targets/RISCV.h
+++ b/clang/lib/Basic/Targets/RISCV.h
@@ -99,8 +99,8 @@ public:
                  const std::vector<std::string> &FeaturesVec) const override;
 
   std::optional<std::pair<unsigned, unsigned>>
-  getVScaleRange(const LangOptions &LangOpts,
-                 bool IsArmStreamingFunction) const override;
+  getVScaleRange(const LangOptions &LangOpts, bool IsArmStreamingFunction,
+                 llvm::StringMap<bool> *FeatureMap = nullptr) const override;
 
   bool hasFeature(StringRef Feature) const override;
 
diff --git a/clang/lib/CodeGen/CodeGenFunction.cpp b/clang/lib/CodeGen/CodeGenFunction.cpp
index d773cdd..ac40aab 100644
--- a/clang/lib/CodeGen/CodeGenFunction.cpp
+++ b/clang/lib/CodeGen/CodeGenFunction.cpp
@@ -1115,9 +1115,15 @@ void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy,
     Fn->removeFnAttr("zero-call-used-regs");
 
   // Add vscale_range attribute if appropriate.
+  llvm::StringMap<bool> FeatureMap;
+  bool IsArmStreaming = false;
+  if (FD) {
+    getContext().getFunctionFeatureMap(FeatureMap, FD);
+    IsArmStreaming = IsArmStreamingFunction(FD, true);
+  }
   std::optional<std::pair<unsigned, unsigned>> VScaleRange =
-      getContext().getTargetInfo().getVScaleRange(
-          getLangOpts(), FD ? IsArmStreamingFunction(FD, true) : false);
+      getContext().getTargetInfo().getVScaleRange(getLangOpts(), IsArmStreaming,
+                                                  &FeatureMap);
   if (VScaleRange) {
     CurFn->addFnAttr(llvm::Attribute::getWithVScaleRangeArgs(
         getLLVMContext(), VScaleRange->first, VScaleRange->second));