[llvm] [HWASAN] Implement selective instrumentation based on profiling information (PR #83503)

[Vitaly Buka via llvm-commits]

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@@ -1501,11 +1520,39 @@ bool HWAddressSanitizer::instrumentStack(memtag::StackInfo &SInfo,
 
 void HWAddressSanitizer::sanitizeFunction(Function &F,
                                           FunctionAnalysisManager &FAM) {
-  if (&F == HwasanCtorFunction)
+  NumTotalFuncs++;
+  if (&F == HwasanCtorFunction) {
+    NumHwasanCtors++;
     return;
+  }
 
-  if (!F.hasFnAttribute(Attribute::SanitizeHWAddress))
+  if (!F.hasFnAttribute(Attribute::SanitizeHWAddress)) {
+    NumNoSanitizeFuncs++;
     return;
+  }
+
+  NumConsideredFuncs++;
+  if (CSkipHotCode) {
+    auto &MAMProxy = FAM.getResult<ModuleAnalysisManagerFunctionProxy>(F);
+    ProfileSummaryInfo *PSI =
+        MAMProxy.getCachedResult<ProfileSummaryAnalysis>(*F.getParent());
+    if (PSI != nullptr && PSI->hasProfileSummary()) {
+      auto &BFI = FAM.getResult<BlockFrequencyAnalysis>(F);
+      const bool is_hot =
+          (HotPercentileCutoff.getNumOccurrences() && HotPercentileCutoff >= 0)
+              ? PSI->isFunctionHotInCallGraphNthPercentile(HotPercentileCutoff,
+                                                           &F, BFI)
+              : PSI->isFunctionEntryHot(&F);
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vitalybuka wrote:

isFunctionEntryHot -> isFunctionHotInCallGraph

https://github.com/llvm/llvm-project/pull/83503