diff options
| -rw-r--r-- | lib/Analysis/ScalarEvolution.cpp | 2 | ||||
| -rw-r--r-- | test/Analysis/ScalarEvolution/how-far-to-zero.ll | 27 |
2 files changed, 28 insertions, 1 deletions
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp index 886812b..0941049 100644 --- a/lib/Analysis/ScalarEvolution.cpp +++ b/lib/Analysis/ScalarEvolution.cpp @@ -5484,7 +5484,7 @@ ScalarEvolution::HowFarToZero(const SCEV *V, const Loop *L) { // to 0, it must be counting down to equal 0. Consequently, N = Start / -Step. // We have not yet seen any such cases. const SCEVConstant *StepC = dyn_cast<SCEVConstant>(Step); - if (StepC == 0) + if (StepC == 0 || StepC->getValue()->equalsInt(0)) return getCouldNotCompute(); // For positive steps (counting up until unsigned overflow): diff --git a/test/Analysis/ScalarEvolution/how-far-to-zero.ll b/test/Analysis/ScalarEvolution/how-far-to-zero.ll new file mode 100644 index 0000000..07af88f --- /dev/null +++ b/test/Analysis/ScalarEvolution/how-far-to-zero.ll @@ -0,0 +1,27 @@ +; RUN: opt < %s -analyze -scalar-evolution | FileCheck %s + +; PR13228 +define void @f() nounwind uwtable readnone { +entry: + br label %for.cond + +for.cond: ; preds = %for.cond, %entry + %c.0 = phi i8 [ 1, %entry ], [ 0, %for.cond ] + %i.0 = phi i8 [ 0, %entry ], [ %inc, %for.cond ] + %lnot = icmp eq i8 %i.0, 0 + %inc = add i8 %i.0, 1 + br i1 %lnot, label %for.cond, label %while.cond + +while.cond: ; preds = %while.body, %for.cond + %b.2 = phi i8 [ %add, %while.body ], [ 0, %for.cond ] + br i1 undef, label %while.end, label %while.body + +while.body: ; preds = %while.cond + %add = add i8 %b.2, %c.0 + %tobool7 = icmp eq i8 %add, 0 + br i1 %tobool7, label %while.end, label %while.cond + +while.end: ; preds = %while.body, %while.cond + ret void +} +;CHECK: Loop %while.cond: <multiple exits> Unpredictable backedge-taken count. |