[stack protector] Set edge weights for newly created basic blocks.
This commit fixes a bug in stack protector pass where edge weights were not set
when new basic blocks were added to lists of successor basic blocks.
Differential Revision: http://reviews.llvm.org/D5766
llvm-svn: 222987
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 3ab89f6..fbc1502 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -7763,6 +7763,7 @@
SelectionDAGBuilder::StackProtectorDescriptor::
AddSuccessorMBB(const BasicBlock *BB,
MachineBasicBlock *ParentMBB,
+ bool IsLikely,
MachineBasicBlock *SuccMBB) {
// If SuccBB has not been created yet, create it.
if (!SuccMBB) {
@@ -7772,6 +7773,7 @@
MF->insert(++BBI, SuccMBB);
}
// Add it as a successor of ParentMBB.
- ParentMBB->addSuccessor(SuccMBB);
+ ParentMBB->addSuccessor(
+ SuccMBB, BranchProbabilityInfo::getBranchWeightStackProtector(IsLikely));
return SuccMBB;
}
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
index f74e652..b2215f2 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
@@ -417,8 +417,8 @@
assert(!shouldEmitStackProtector() && "Stack Protector Descriptor is "
"already initialized!");
ParentMBB = MBB;
- SuccessMBB = AddSuccessorMBB(BB, MBB);
- FailureMBB = AddSuccessorMBB(BB, MBB, FailureMBB);
+ SuccessMBB = AddSuccessorMBB(BB, MBB, /* IsLikely */ true);
+ FailureMBB = AddSuccessorMBB(BB, MBB, /* IsLikely */ false, FailureMBB);
if (!Guard)
Guard = StackProtCheckCall.getArgOperand(0);
}
@@ -487,9 +487,10 @@
/// Add a successor machine basic block to ParentMBB. If the successor mbb
/// has not been created yet (i.e. if SuccMBB = 0), then the machine basic
- /// block will be created.
+ /// block will be created. Assign a large weight if IsLikely is true.
MachineBasicBlock *AddSuccessorMBB(const BasicBlock *BB,
MachineBasicBlock *ParentMBB,
+ bool IsLikely,
MachineBasicBlock *SuccMBB = nullptr);
};
diff --git a/llvm/lib/CodeGen/StackProtector.cpp b/llvm/lib/CodeGen/StackProtector.cpp
index 3fc0a36..58e4ad9 100644
--- a/llvm/lib/CodeGen/StackProtector.cpp
+++ b/llvm/lib/CodeGen/StackProtector.cpp
@@ -17,6 +17,7 @@
#include "llvm/CodeGen/StackProtector.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/BranchProbabilityInfo.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/CodeGen/Analysis.h"
#include "llvm/CodeGen/Passes.h"
@@ -31,6 +32,7 @@
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Intrinsics.h"
+#include "llvm/IR/MDBuilder.h"
#include "llvm/IR/Module.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Target/TargetSubtargetInfo.h"
@@ -459,7 +461,13 @@
LoadInst *LI1 = B.CreateLoad(StackGuardVar);
LoadInst *LI2 = B.CreateLoad(AI);
Value *Cmp = B.CreateICmpEQ(LI1, LI2);
- B.CreateCondBr(Cmp, NewBB, FailBB);
+ unsigned SuccessWeight =
+ BranchProbabilityInfo::getBranchWeightStackProtector(true);
+ unsigned FailureWeight =
+ BranchProbabilityInfo::getBranchWeightStackProtector(false);
+ MDNode *Weights = MDBuilder(F->getContext())
+ .createBranchWeights(SuccessWeight, FailureWeight);
+ B.CreateCondBr(Cmp, NewBB, FailBB, Weights);
}
}