[llvm] [NFC][Fuzzer] Extract CreateGateBranch method. (PR #117236)

[via llvm-commits]

https://github.com/thetruestblue updated https://github.com/llvm/llvm-project/pull/117236

>From 6b63903d3325b95fa4cbbc9361fc7879ea95a896 Mon Sep 17 00:00:00 2001
From: Blue Gaston <bgaston2 at apple.com>
Date: Thu, 21 Nov 2024 12:28:43 -0800
Subject: [PATCH 1/2] [NFC][Fuzzer] Extract CreateGateBranch method.

---
 .../Instrumentation/SanitizerCoverage.cpp     | 27 ++++++++++++++++---
 1 file changed, 24 insertions(+), 3 deletions(-)

diff --git a/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp b/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
index 34006bfda96c5f..4689cb29236f06 100644
--- a/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
+++ b/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
@@ -244,12 +244,14 @@ class ModuleSanitizerCoverage {
   void InjectTraceForSwitch(Function &F,
                             ArrayRef<Instruction *> SwitchTraceTargets);
   bool InjectCoverage(Function &F, ArrayRef<BasicBlock *> AllBlocks,
-                      bool IsLeafFunc = true);
+                      Value *&FunctionGateCmp, bool IsLeafFunc = true);
   GlobalVariable *CreateFunctionLocalArrayInSection(size_t NumElements,
                                                     Function &F, Type *Ty,
                                                     const char *Section);
   GlobalVariable *CreatePCArray(Function &F, ArrayRef<BasicBlock *> AllBlocks);
   void CreateFunctionLocalArrays(Function &F, ArrayRef<BasicBlock *> AllBlocks);
+  Instruction *CreateGateBranch(Function &F, Value *&FunctionGateCmp,
+                                Instruction *I);
   Value *CreateFunctionLocalGateCmp(IRBuilder<> &IRB);
   void InjectCoverageAtBlock(Function &F, BasicBlock &BB, size_t Idx,
                              Value *&FunctionGateCmp, bool IsLeafFunc = true);
@@ -723,7 +725,8 @@ void ModuleSanitizerCoverage::instrumentFunction(Function &F) {
   if (Options.CollectControlFlow)
     createFunctionControlFlow(F);
 
-  InjectCoverage(F, BlocksToInstrument, IsLeafFunc);
+  Value *FunctionGateCmp = nullptr;
+  InjectCoverage(F, BlocksToInstrument, FunctionGateCmp, IsLeafFunc);
   InjectCoverageForIndirectCalls(F, IndirCalls);
   InjectTraceForCmp(F, CmpTraceTargets);
   InjectTraceForSwitch(F, SwitchTraceTargets);
@@ -815,12 +818,30 @@ Value *ModuleSanitizerCoverage::CreateFunctionLocalGateCmp(IRBuilder<> &IRB) {
   return Cmp;
 }
 
+Instruction *ModuleSanitizerCoverage::CreateGateBranch(Function &F,
+                                                       Value *&FunctionGateCmp,
+                                                      Instruction *IP) {
+ if (!FunctionGateCmp) {
+    // Create this in the entry block
+    BasicBlock &BB = F.getEntryBlock();
+    BasicBlock::iterator IP = BB.getFirstInsertionPt();
+    IP = PrepareToSplitEntryBlock(BB, IP);
+    IRBuilder<> EntryIRB(&*IP);
+    FunctionGateCmp = CreateFunctionLocalGateCmp(EntryIRB);
+  }
+  // Set the branch weights in order to minimize the price paid when the
+  // gate is turned off, allowing the default enablement of this
+  // instrumentation with as little of a performance cost as possible
+  auto Weights = MDBuilder(*C).createBranchWeights(1, 100000);
+  return SplitBlockAndInsertIfThen(FunctionGateCmp, IP, false, Weights);
+}
+
 bool ModuleSanitizerCoverage::InjectCoverage(Function &F,
                                              ArrayRef<BasicBlock *> AllBlocks,
+                                             Value *&FunctionGateCmp,
                                              bool IsLeafFunc) {
   if (AllBlocks.empty()) return false;
   CreateFunctionLocalArrays(F, AllBlocks);
-  Value *FunctionGateCmp = nullptr;
   for (size_t i = 0, N = AllBlocks.size(); i < N; i++)
     InjectCoverageAtBlock(F, *AllBlocks[i], i, FunctionGateCmp, IsLeafFunc);
   return true;

>From 79189bc74a38f55d2d92f82cadfd28abb69e526c Mon Sep 17 00:00:00 2001
From: thetruestblue <bblueconway at gmail.com>
Date: Thu, 21 Nov 2024 12:58:10 -0800
Subject: [PATCH 2/2] Update SanitizerCoverage.cpp

fix spacing...
---
 llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp b/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
index 4689cb29236f06..2c29e7bd094884 100644
--- a/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
+++ b/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
@@ -820,8 +820,8 @@ Value *ModuleSanitizerCoverage::CreateFunctionLocalGateCmp(IRBuilder<> &IRB) {
 
 Instruction *ModuleSanitizerCoverage::CreateGateBranch(Function &F,
                                                        Value *&FunctionGateCmp,
-                                                      Instruction *IP) {
- if (!FunctionGateCmp) {
+                                                       Instruction *IP) {
+  if (!FunctionGateCmp) {
     // Create this in the entry block
     BasicBlock &BB = F.getEntryBlock();
     BasicBlock::iterator IP = BB.getFirstInsertionPt();