[PATCH] D84620: [StackProtector] Speed up RequiresStackProtector

[Nadav Rotem via Phabricator via llvm-commits]

nadav created this revision.
Herald added subscribers: llvm-commits, hiraditya.
Herald added a project: LLVM.

Speed up the method RequiresStackProtector by saving the value of
Intrinsic::getDeclaration. This method calls getName() that returns an
allocating std::string.  This change removes about 96072 std::string instances
when compiling sqlite3.c; The function was discovered with a Facebook-internal
performance tool.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D84620

Files:
  llvm/lib/CodeGen/StackProtector.cpp


Index: llvm/lib/CodeGen/StackProtector.cpp
===================================================================
--- llvm/lib/CodeGen/StackProtector.cpp
+++ llvm/lib/CodeGen/StackProtector.cpp
@@ -249,11 +249,12 @@
 /// Search for the first call to the llvm.stackprotector intrinsic and return it
 /// if present.
 static const CallInst *findStackProtectorIntrinsic(Function &F) {
+  Function *StackProtectorDecl =
+      Intrinsic::getDeclaration(F.getParent(), Intrinsic::stackprotector);
   for (const BasicBlock &BB : F)
     for (const Instruction &I : BB)
       if (const CallInst *CI = dyn_cast<CallInst>(&I))
-        if (CI->getCalledFunction() ==
-            Intrinsic::getDeclaration(F.getParent(), Intrinsic::stackprotector))
+        if (CI->getCalledFunction() == StackProtectorDecl)
           return CI;
   return nullptr;
 }


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