[LoopReroll] Don't crash on dead code
If a PHI has no users, don't crash; bail gracefully. This shouldn't
happen often, but we can make no guarantees that previous passes didn't leave
dead code around.
llvm-svn: 229405
diff --git a/llvm/test/Transforms/LoopReroll/reduction.ll b/llvm/test/Transforms/LoopReroll/reduction.ll
index c9991c7..a4f168a 100644
--- a/llvm/test/Transforms/LoopReroll/reduction.ll
+++ b/llvm/test/Transforms/LoopReroll/reduction.ll
@@ -92,5 +92,41 @@
ret float %add12
}
+define i32 @foo_unusedphi(i32* nocapture readonly %x) #0 {
+entry:
+ br label %for.body
+
+for.body: ; preds = %entry, %for.body
+ %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
+ %r.029 = phi i32 [ 0, %entry ], [ %add12, %for.body ]
+ %arrayidx = getelementptr inbounds i32* %x, i64 %indvars.iv
+ %0 = load i32* %arrayidx, align 4
+ %add = add nsw i32 %0, %0
+ %1 = or i64 %indvars.iv, 1
+ %arrayidx3 = getelementptr inbounds i32* %x, i64 %1
+ %2 = load i32* %arrayidx3, align 4
+ %add4 = add nsw i32 %add, %2
+ %3 = or i64 %indvars.iv, 2
+ %arrayidx7 = getelementptr inbounds i32* %x, i64 %3
+ %4 = load i32* %arrayidx7, align 4
+ %add8 = add nsw i32 %add4, %4
+ %5 = or i64 %indvars.iv, 3
+ %arrayidx11 = getelementptr inbounds i32* %x, i64 %5
+ %6 = load i32* %arrayidx11, align 4
+ %add12 = add nsw i32 %add8, %6
+ %indvars.iv.next = add nuw nsw i64 %indvars.iv, 4
+ %7 = trunc i64 %indvars.iv.next to i32
+ %cmp = icmp slt i32 %7, 400
+ br i1 %cmp, label %for.body, label %for.end
+
+; CHECK-LABEL: @foo_unusedphi
+; The above is just testing for a crash - no specific output expected.
+
+; CHECK: ret
+
+for.end: ; preds = %for.body
+ ret i32 %add12
+}
+
attributes #0 = { nounwind readonly uwtable }