From 22576e2ccec60af6d27d8fd95ad3ca721b914815 Mon Sep 17 00:00:00 2001
From: Matthew Devereau <matthew.devereau@arm.com>
Date: Fri, 16 May 2025 09:39:07 +0100
Subject: [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.
---
 clang/lib/CodeGen/CodeGenFunction.cpp | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

(limited to 'clang/lib/CodeGen/CodeGenFunction.cpp')

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));
-- 
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