[llvm] r367699 - [SimplifyCFG] Cleanup redundant conditions [NFC].
Alina Sbirlea via llvm-commits
llvm-commits at lists.llvm.org
Fri Aug 2 11:06:54 PDT 2019
Author: asbirlea
Date: Fri Aug 2 11:06:54 2019
New Revision: 367699
URL: http://llvm.org/viewvc/llvm-project?rev=367699&view=rev
Log:
[SimplifyCFG] Cleanup redundant conditions [NFC].
Summary:
Since the for loop iterates over BB's predecessors, the branch conditions found must have BB as one of the successors.
For an unconditional branch the successor must be BB, added `assert`.
For a conditional branch, one of the two successors must be BB, simplify `else if` to `else` and `assert`.
Sink common instructions outside the if/else block.
Reviewers: sanjoy.google
Subscribers: jlebar, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65596
Modified:
llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
Modified: llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp?rev=367699&r1=367698&r2=367699&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp Fri Aug 2 11:06:54 2019
@@ -4178,24 +4178,22 @@ bool SimplifyCFGOpt::SimplifyUnreachable
IRBuilder<> Builder(TI);
if (auto *BI = dyn_cast<BranchInst>(TI)) {
if (BI->isUnconditional()) {
- if (BI->getSuccessor(0) == BB) {
- new UnreachableInst(TI->getContext(), TI);
- TI->eraseFromParent();
- Changed = true;
- }
+ assert(BI->getSuccessor(0) == BB && "Incorrect CFG");
+ new UnreachableInst(TI->getContext(), TI);
+ TI->eraseFromParent();
+ Changed = true;
} else {
Value* Cond = BI->getCondition();
if (BI->getSuccessor(0) == BB) {
Builder.CreateAssumption(Builder.CreateNot(Cond));
Builder.CreateBr(BI->getSuccessor(1));
- EraseTerminatorAndDCECond(BI);
- Changed = true;
- } else if (BI->getSuccessor(1) == BB) {
+ } else {
+ assert(BI->getSuccessor(1) == BB && "Incorrect CFG");
Builder.CreateAssumption(Cond);
Builder.CreateBr(BI->getSuccessor(0));
- EraseTerminatorAndDCECond(BI);
- Changed = true;
}
+ EraseTerminatorAndDCECond(BI);
+ Changed = true;
}
} else if (auto *SI = dyn_cast<SwitchInst>(TI)) {
SwitchInstProfUpdateWrapper SU(*SI);
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