diff options
Diffstat (limited to 'llvm/lib/Transforms/Scalar/LoopUnswitch.cpp')
| -rw-r--r-- | llvm/lib/Transforms/Scalar/LoopUnswitch.cpp | 19 |
1 files changed, 14 insertions, 5 deletions
diff --git a/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp b/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp index 3918738cc8b..de124d10aaa 100644 --- a/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp +++ b/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp @@ -677,15 +677,22 @@ void LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val, LoopProcessWorklist.push_back(NewLoop); redoLoop = true; + // Keep a WeakVH holding onto LIC. If the first call to RewriteLoopBody + // deletes the instruction (for example by simplifying a PHI that feeds into + // the condition that we're unswitching on), we don't rewrite the second + // iteration. + WeakVH LICHandle(LIC); + // Now we rewrite the original code to know that the condition is true and the // new code to know that the condition is false. RewriteLoopBodyWithConditionConstant(L, LIC, Val, false); - - // It's possible that simplifying one loop could cause the other to be - // deleted. If so, don't simplify it. - if (!LoopProcessWorklist.empty() && LoopProcessWorklist.back() == NewLoop) - RewriteLoopBodyWithConditionConstant(NewLoop, LIC, Val, true); + // It's possible that simplifying one loop could cause the other to be + // changed to another value or a constant. If its a constant, don't simplify + // it. + if (!LoopProcessWorklist.empty() && LoopProcessWorklist.back() == NewLoop && + LICHandle && !isa<Constant>(LICHandle)) + RewriteLoopBodyWithConditionConstant(NewLoop, LICHandle, Val, true); } /// RemoveFromWorklist - Remove all instances of I from the worklist vector @@ -981,6 +988,8 @@ void LoopUnswitch::SimplifyCode(std::vector<Instruction*> &Worklist, Loop *L) { continue; } + // FIXME: Change this to use instruction simplify interfaces! + // Special case hacks that appear commonly in unswitched code. switch (I->getOpcode()) { case Instruction::Select: |
