diff options
| -rw-r--r-- | llvm/lib/Analysis/ScalarEvolution.cpp | 4 | ||||
| -rw-r--r-- | llvm/test/Analysis/ScalarEvolution/smax-br-phi-idioms.ll | 28 |
2 files changed, 31 insertions, 1 deletions
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp index 482d3a6b39f..d3d85b1b399 100644 --- a/llvm/lib/Analysis/ScalarEvolution.cpp +++ b/llvm/lib/Analysis/ScalarEvolution.cpp @@ -4168,7 +4168,9 @@ static bool BrPHIToSelect(DominatorTree &DT, BranchInst *BI, PHINode *Merge, } const SCEV *ScalarEvolution::createNodeFromSelectLikePHI(PHINode *PN) { - if (PN->getNumIncomingValues() == 2) { + auto IsReachable = + [&](BasicBlock *BB) { return DT.isReachableFromEntry(BB); }; + if (PN->getNumIncomingValues() == 2 && all_of(PN->blocks(), IsReachable)) { const Loop *L = LI.getLoopFor(PN->getParent()); // We don't want to break LCSSA, even in a SCEV expression tree. diff --git a/llvm/test/Analysis/ScalarEvolution/smax-br-phi-idioms.ll b/llvm/test/Analysis/ScalarEvolution/smax-br-phi-idioms.ll index 500f3e16c8f..dc24bd1b804 100644 --- a/llvm/test/Analysis/ScalarEvolution/smax-br-phi-idioms.ll +++ b/llvm/test/Analysis/ScalarEvolution/smax-br-phi-idioms.ll @@ -126,3 +126,31 @@ for.cond.0: ret i32 %init } + +define i32 @f6(i32 %x, i32 %y) { +; Do the right thing for unreachable code: + +; CHECK-LABEL: Classifying expressions for: @f6 + entry: + %c0 = icmp sgt i32 %y, 0 + %sum = add i32 %x, %y + br i1 %c0, label %merge, label %leave_1 + + merge: + %v0 = phi i32 [ %sum, %entry ], [ %v1, %unreachable ] + %c1 = icmp slt i32 %y, 0 + br i1 %c1, label %leave_0, label %leave_0_cond + +leave_0_cond: + br label %leave_0 + +leave_0: + %v1 = phi i32 [ %v0, %merge ], [ 0, %leave_0_cond ] + ret i32 0 + +leave_1: + ret i32 0 + +unreachable: + br label %merge +} |
