[CSSPGO] Avoid repeatedly computing md5 hash code for pseudo probe inline contexts.

Md5 hashing is expansive. Using a hash map to look up already computed GUID for dwarf names. Saw a 2% build time improvement on an internal large application.

Reviewed By: wenlei

Differential Revision: https://reviews.llvm.org/D108722

diff --git a/llvm/lib/CodeGen/AsmPrinter/PseudoProbePrinter.cpp b/llvm/lib/CodeGen/AsmPrinter/PseudoProbePrinter.cpp
index 35a830f..9e6f1a5 100644 (file)
--- a/llvm/lib/CodeGen/AsmPrinter/PseudoProbePrinter.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/PseudoProbePrinter.cpp
@@ -20,6 +20,8 @@
 
 using namespace llvm;
 
+PseudoProbeHandler::~PseudoProbeHandler() = default;
+
 void PseudoProbeHandler::emitPseudoProbe(uint64_t Guid, uint64_t Index,
                                          uint64_t Type, uint64_t Attr,
                                          const DILocation *DebugLoc) {
@@ -35,7 +37,10 @@ void PseudoProbeHandler::emitPseudoProbe(uint64_t Guid, uint64_t Index,
     auto Name = SP->getLinkageName();
     if (Name.empty())
       Name = SP->getName();
-    uint64_t CallerGuid = Function::getGUID(Name);
+    // Use caching to avoid redundant md5 computation for build speed.
+    uint64_t &CallerGuid = NameGuidMap[Name];
+    if (!CallerGuid)
+      CallerGuid = Function::getGUID(Name);
     uint64_t CallerProbeId = PseudoProbeDwarfDiscriminator::extractProbeIndex(
         InlinedAt->getDiscriminator());
     ReversedInlineStack.emplace_back(CallerGuid, CallerProbeId);

diff --git a/llvm/lib/CodeGen/AsmPrinter/PseudoProbePrinter.h b/llvm/lib/CodeGen/AsmPrinter/PseudoProbePrinter.h
index f2026a1..7d5e512 100644 (file)
--- a/llvm/lib/CodeGen/AsmPrinter/PseudoProbePrinter.h
+++ b/llvm/lib/CodeGen/AsmPrinter/PseudoProbePrinter.h
@@ -26,9 +26,12 @@ class DILocation;
 class PseudoProbeHandler : public AsmPrinterHandler {
   // Target of pseudo probe emission.
   AsmPrinter *Asm;
+  // Name to GUID map, used as caching/memoization for speed.
+  DenseMap<StringRef, uint64_t> NameGuidMap;
 
 public:
   PseudoProbeHandler(AsmPrinter *A) : Asm(A){};
+  ~PseudoProbeHandler() override;
 
   void emitPseudoProbe(uint64_t Guid, uint64_t Index, uint64_t Type,
                        uint64_t Attr, const DILocation *DebugLoc);