diff options
| -rw-r--r-- | lib/Transforms/Scalar/LoopUnswitch.cpp | 19 | ||||
| -rw-r--r-- | test/Transforms/LoopUnswitch/crash.ll | 19 |
2 files changed, 33 insertions, 5 deletions
diff --git a/lib/Transforms/Scalar/LoopUnswitch.cpp b/lib/Transforms/Scalar/LoopUnswitch.cpp index 3918738cc8..de124d10aa 100644 --- a/lib/Transforms/Scalar/LoopUnswitch.cpp +++ b/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: diff --git a/test/Transforms/LoopUnswitch/crash.ll b/test/Transforms/LoopUnswitch/crash.ll index fac55a6bb1..101fb7a2c2 100644 --- a/test/Transforms/LoopUnswitch/crash.ll +++ b/test/Transforms/LoopUnswitch/crash.ll @@ -45,3 +45,22 @@ for.body: ; preds = %for.body, %bb.nph for.end: ; preds = %for.body, %entry ret void } + +; PR6879 +define i32* @test3(i32** %p_45, i16 zeroext %p_46, i64 %p_47, i64 %p_48, i16 signext %p_49) nounwind { +entry: + br label %for.cond + +for.cond: ; preds = %for.cond4, %entry + br i1 false, label %for.cond4, label %for.end88 + +for.cond4: ; preds = %for.cond + %conv46 = trunc i32 0 to i8 ; <i8> [#uses=2] + %cmp60 = icmp sgt i8 %conv46, 124 ; <i1> [#uses=1] + %or.cond = and i1 undef, %cmp60 ; <i1> [#uses=1] + %cond = select i1 %or.cond, i8 %conv46, i8 undef ; <i8> [#uses=0] + br label %for.cond + +for.end88: ; preds = %for.cond + ret i32* undef +} |