[SimplifyCFG] Remove all incoming values from OtherDest if OtherDest is unreachable #162677
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@llvm/pr-subscribers-llvm-transforms Author: dianqk (dianqk) ChangesFixes #162585. #161000 changed Full diff: https://github.com/llvm/llvm-project/pull/162677.diff 2 Files Affected:
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index 155fcc50bdebf..9ac3be1e1206a 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -5959,7 +5959,11 @@ bool SimplifyCFGOpt::turnSwitchRangeIntoICmp(SwitchInst *SI,
unsigned PreviousEdges = OtherCases->size();
if (OtherDest == SI->getDefaultDest())
++PreviousEdges;
- for (unsigned I = 0, E = PreviousEdges - 1; I != E; ++I)
+ unsigned E = PreviousEdges - 1;
+ // Remove all incoming values from OtherDest if OtherDest is unreachable.
+ if (NewBI->isUnconditional())
+ ++E;
+ for (unsigned I = 0; I != E; ++I)
cast<PHINode>(BBI)->removeIncomingValue(SI->getParent());
}
diff --git a/llvm/test/Transforms/SimplifyCFG/switch-range-to-icmp.ll b/llvm/test/Transforms/SimplifyCFG/switch-range-to-icmp.ll
index 0fc3c19edd1f3..a43e7625e6736 100644
--- a/llvm/test/Transforms/SimplifyCFG/switch-range-to-icmp.ll
+++ b/llvm/test/Transforms/SimplifyCFG/switch-range-to-icmp.ll
@@ -401,4 +401,27 @@ b:
ret i32 %1
}
+define i32 @else_will_be_unreachable(i1 %arg) {
+; CHECK-LABEL: @else_will_be_unreachable(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[I:%.*]] = select i1 [[ARG:%.*]], i32 0, i32 1
+; CHECK-NEXT: ret i32 [[I]]
+;
+entry:
+ switch i1 %arg, label %else [
+ i1 false, label %if
+ i1 true, label %if
+ ]
+
+if:
+ br i1 %arg, label %else, label %bb
+
+bb:
+ br label %else
+
+else:
+ %i = phi i32 [ 0, %entry ], [ 0, %if ], [ 1, %bb ]
+ ret i32 %i
+}
+
declare void @bar(ptr nonnull dereferenceable(4))
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/65/builds/23806 Here is the relevant piece of the build log for the reference |
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Fixes #162585.
#161000 changed
br i1 true, label %if, label %elsetobr label %if, so we should remove one more incoming value.