[llvm] f39256e - [CSSPGO] Avoid repeatedly computing md5 hash code for pseudo probe inline contexts.

[Hongtao Yu via llvm-commits]

Author: Hongtao Yu
Date: 2021-08-30T10:11:47-07:00
New Revision: f39256e3a5dd1f3d7311703003608340ffdb42bc

URL: https://github.com/llvm/llvm-project/commit/f39256e3a5dd1f3d7311703003608340ffdb42bc
DIFF: https://github.com/llvm/llvm-project/commit/f39256e3a5dd1f3d7311703003608340ffdb42bc.diff

LOG: [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

Added: 
    

Modified: 
    llvm/lib/CodeGen/AsmPrinter/PseudoProbePrinter.cpp
    llvm/lib/CodeGen/AsmPrinter/PseudoProbePrinter.h

Removed: 
    


################################################################################
diff  --git a/llvm/lib/CodeGen/AsmPrinter/PseudoProbePrinter.cpp b/llvm/lib/CodeGen/AsmPrinter/PseudoProbePrinter.cpp
index 35a830f416f6..9e6f1a537de3 100644
--- 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 f2026a118bf5..7d5e51218693 100644
--- 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);