diff options
| -rw-r--r-- | lib/Analysis/ValueTracking.cpp | 4 | ||||
| -rw-r--r-- | test/Transforms/JumpThreading/degenerate-phi.ll | 24 |
2 files changed, 28 insertions, 0 deletions
diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp index 44c1b53..32d2c88 100644 --- a/lib/Analysis/ValueTracking.cpp +++ b/lib/Analysis/ValueTracking.cpp @@ -590,6 +590,10 @@ void llvm::ComputeMaskedBits(Value *V, const APInt &Mask, } } + // Unreachable blocks may have zero-operand PHI nodes. + if (P->getNumIncomingValues() == 0) + return; + // Otherwise take the unions of the known bit sets of the operands, // taking conservative care to avoid excessive recursion. if (Depth < MaxDepth - 1 && !KnownZero && !KnownOne) { diff --git a/test/Transforms/JumpThreading/degenerate-phi.ll b/test/Transforms/JumpThreading/degenerate-phi.ll new file mode 100644 index 0000000..35d9fde --- /dev/null +++ b/test/Transforms/JumpThreading/degenerate-phi.ll @@ -0,0 +1,24 @@ +; RUN: opt -jump-threading -disable-output %s +; PR9112 + +; This is actually a test for value tracking. Jump threading produces +; "%phi = phi i16" when it removes all edges leading to %unreachable. +; The .ll parser won't let us write that directly since it's invalid code. + +define void @func() nounwind { +entry: + br label %bb + +bb: + br label %bb + +unreachable: + %phi = phi i16 [ %add, %unreachable ], [ 0, %next ] + %add = add i16 0, %phi + %cmp = icmp slt i16 %phi, 0 + br i1 %cmp, label %unreachable, label %next + +next: + br label %unreachable +} + |