diff options
| -rw-r--r-- | llvm/lib/Analysis/ValueTracking.cpp | 7 | ||||
| -rw-r--r-- | llvm/test/Transforms/JumpThreading/pr22086.ll | 28 |
2 files changed, 33 insertions, 2 deletions
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp index 6fdf4afebc2..b292af6cee7 100644 --- a/llvm/lib/Analysis/ValueTracking.cpp +++ b/llvm/lib/Analysis/ValueTracking.cpp @@ -1821,13 +1821,16 @@ unsigned ComputeNumSignBits(Value *V, const DataLayout *TD, case Instruction::PHI: { PHINode *PN = cast<PHINode>(U); + unsigned NumIncomingValues = PN->getNumIncomingValues(); // Don't analyze large in-degree PHIs. - if (PN->getNumIncomingValues() > 4) break; + if (NumIncomingValues > 4) break; + // Unreachable blocks may have zero-operand PHI nodes. + if (NumIncomingValues == 0) break; // Take the minimum of all incoming values. This can't infinitely loop // because of our depth threshold. Tmp = ComputeNumSignBits(PN->getIncomingValue(0), TD, Depth+1, Q); - for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i) { + for (unsigned i = 1, e = NumIncomingValues; i != e; ++i) { if (Tmp == 1) return Tmp; Tmp = std::min(Tmp, ComputeNumSignBits(PN->getIncomingValue(i), TD, diff --git a/llvm/test/Transforms/JumpThreading/pr22086.ll b/llvm/test/Transforms/JumpThreading/pr22086.ll new file mode 100644 index 00000000000..35d9aa5b184 --- /dev/null +++ b/llvm/test/Transforms/JumpThreading/pr22086.ll @@ -0,0 +1,28 @@ +; RUN: opt -S -jump-threading < %s | FileCheck %s + + +; CHECK-LABEL: @f( +; CHECK-LABEL: entry: +; CHECK-NEXT: br label %[[loop:.*]] +; CHECK: [[loop]]: +; CHECK-NEXT: br label %[[loop]] + +define void @f() { +entry: + br label %for.cond1 + +if.end16: + %phi1 = phi i32 [ undef, %for.cond1 ] + %g.3 = phi i32 [ %g.1, %for.cond1 ] + %sext = shl i32 %g.3, 16 + %conv20 = ashr exact i32 %sext, 16 + %tobool21 = icmp eq i32 %phi1, 0 + br i1 %tobool21, label %lor.rhs, label %for.cond1 + +for.cond1: + %g.1 = phi i32 [ 0, %entry ], [ 0, %lor.rhs ], [ %g.3, %if.end16 ] + br i1 undef, label %lor.rhs, label %if.end16 + +lor.rhs: + br label %for.cond1 +} |
