[llvm] b9d9811 - [profcheck] Exclude `naked`, asm-only functions from profcheck (#168447)

[via llvm-commits]

Author: Mircea Trofin
Date: 2025-11-20T08:32:57-08:00
New Revision: b9d98110e198c864616593966d1dadc79a606309

URL: https://github.com/llvm/llvm-project/commit/b9d98110e198c864616593966d1dadc79a606309
DIFF: https://github.com/llvm/llvm-project/commit/b9d98110e198c864616593966d1dadc79a606309.diff

LOG: [profcheck] Exclude `naked`, asm-only functions from profcheck (#168447)

We can't do anything meaningful to such functions: they aren't optimizable, and even if inlined, they would bring no code open to optimization.

Added: 
    llvm/test/Transforms/PGOProfile/profcheck-exclusions.ll

Modified: 
    llvm/lib/Transforms/Utils/ProfileVerify.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Utils/ProfileVerify.cpp b/llvm/lib/Transforms/Utils/ProfileVerify.cpp
index c7cf8256d393c..ca6bd91b1f530 100644
--- a/llvm/lib/Transforms/Utils/ProfileVerify.cpp
+++ b/llvm/lib/Transforms/Utils/ProfileVerify.cpp
@@ -65,11 +65,26 @@ class ProfileInjector {
   ProfileInjector(Function &F, FunctionAnalysisManager &FAM) : F(F), FAM(FAM) {}
   bool inject();
 };
+
+bool isAsmOnly(const Function &F) {
+  if (!F.hasFnAttribute(Attribute::AttrKind::Naked))
+    return false;
+  for (const auto &BB : F)
+    for (const auto &I : drop_end(BB.instructionsWithoutDebug())) {
+      const auto *CB = dyn_cast<CallBase>(&I);
+      if (!CB || !CB->isInlineAsm())
+        return false;
+    }
+  return true;
+}
 } // namespace
 
 // FIXME: currently this injects only for terminators. Select isn't yet
 // supported.
 bool ProfileInjector::inject() {
+  // skip purely asm functions
+  if (isAsmOnly(F))
+    return false;
   // Get whatever branch probability info can be derived from the given IR -
   // whether it has or not metadata. The main intention for this pass is to
   // ensure that other passes don't drop or "forget" to update MD_prof. We do
@@ -176,6 +191,10 @@ PreservedAnalyses ProfileInjectorPass::run(Function &F,
 
 PreservedAnalyses ProfileVerifierPass::run(Function &F,
                                            FunctionAnalysisManager &FAM) {
+  // skip purely asm functions
+  if (isAsmOnly(F))
+    return PreservedAnalyses::all();
+
   const auto EntryCount = F.getEntryCount(/*AllowSynthetic=*/true);
   if (!EntryCount) {
     auto *MD = F.getMetadata(LLVMContext::MD_prof);

diff  --git a/llvm/test/Transforms/PGOProfile/profcheck-exclusions.ll b/llvm/test/Transforms/PGOProfile/profcheck-exclusions.ll
new file mode 100644
index 0000000000000..a2420be4fac30
--- /dev/null
+++ b/llvm/test/Transforms/PGOProfile/profcheck-exclusions.ll
@@ -0,0 +1,10 @@
+; RUN: opt -passes=prof-inject %s -S -o - | FileCheck %s
+; RUN: opt -passes=prof-verify %s --disable-output
+
+
+define void @bar(i1 %c) #0 {
+  ret void
+}
+
+attributes #0 = { naked }
+; CHECK-NOT: !prof