diff options
Diffstat (limited to 'llvm')
| -rw-r--r-- | llvm/lib/Analysis/ScalarEvolutionExpander.cpp | 5 | ||||
| -rw-r--r-- | llvm/test/Transforms/LoopStrengthReduce/scev-after-loopinstsimplify.ll | 43 |
2 files changed, 47 insertions, 1 deletions
diff --git a/llvm/lib/Analysis/ScalarEvolutionExpander.cpp b/llvm/lib/Analysis/ScalarEvolutionExpander.cpp index f2ce0f4aa86..7f76f057216 100644 --- a/llvm/lib/Analysis/ScalarEvolutionExpander.cpp +++ b/llvm/lib/Analysis/ScalarEvolutionExpander.cpp @@ -1169,8 +1169,11 @@ SCEVExpander::getAddRecExprPHILiterally(const SCEVAddRecExpr *Normalized, if (!IsMatchingSCEV && !TryNonMatchingSCEV) continue; + // TODO: this possibly can be reworked to avoid this cast at all. Instruction *TempIncV = - cast<Instruction>(PN.getIncomingValueForBlock(LatchBlock)); + dyn_cast<Instruction>(PN.getIncomingValueForBlock(LatchBlock)); + if (!TempIncV) + continue; // Check whether we can reuse this PHI node. if (LSRMode) { diff --git a/llvm/test/Transforms/LoopStrengthReduce/scev-after-loopinstsimplify.ll b/llvm/test/Transforms/LoopStrengthReduce/scev-after-loopinstsimplify.ll new file mode 100644 index 00000000000..a0dcaadd81b --- /dev/null +++ b/llvm/test/Transforms/LoopStrengthReduce/scev-after-loopinstsimplify.ll @@ -0,0 +1,43 @@ +; RUN: opt %s -indvars -loop-instsimplify -loop-reduce +; We are only checking that there is no crash! + +; https://bugs.llvm.org/show_bug.cgi?id=37936 + +; The problem is as follows: +; 1. indvars marks %dec as NUW. +; 2. loop-instsimplify runs instsimplify, which constant-folds %dec to -1 +; 3. loop-reduce tries to do some further modification, but crashes +; with an type assertion in cast, because %dec is no longer an Instruction, +; even though the SCEV data indicated it was. + +; If the runline is split into two, i.e. -indvars -loop-instsimplify first, that +; stored into a file, and then -loop-reduce is run on that, there is no crash. +; So it looks like the problem is due to -loop-instsimplify not discarding SCEV. + +target datalayout = "n16" + +@a = external global i16, align 1 + +define void @f1() { +entry: + br label %for.cond + +for.cond: ; preds = %land.end, %entry + %c.0 = phi i16 [ 0, %entry ], [ %dec, %land.end ] + br i1 undef, label %for.body, label %for.cond.cleanup + +for.cond.cleanup: ; preds = %for.cond + ret void + +for.body: ; preds = %for.cond + %0 = load i16, i16* @a, align 1 + %cmp = icmp sgt i16 %0, %c.0 + br i1 %cmp, label %land.rhs, label %land.end + +land.rhs: ; preds = %for.body + unreachable + +land.end: ; preds = %for.body + %dec = add nsw i16 %c.0, -1 + br label %for.cond +} |
