SimplifyCFG: Correctly handle switch lookup tables which fully cover the input type and use bit tests to check for holes
When using bit tests for hole checks, we call AddPredecessorToBlock to give the
phi node a value from the bit test block. This would break if we've
previously called removePredecessor on the default destination because the
switch is fully covered.
Test case by Mark Lacey.
llvm-svn: 235771
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index 7c239cb..60ac271 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -4159,10 +4159,8 @@
if (!DefaultIsReachable || GeneratingCoveredLookupTable) {
Builder.CreateBr(LookupBB);
- // We cached PHINodes in PHIs, to avoid accessing deleted PHINodes later,
- // do not delete PHINodes here.
- SI->getDefaultDest()->removePredecessor(SI->getParent(),
- /*DontDeleteUselessPHIs=*/true);
+ // Note: We call removeProdecessor later since we need to be able to get the
+ // PHI value for the default case in case we're using a bit mask.
} else {
Value *Cmp = Builder.CreateICmpULT(TableIndex, ConstantInt::get(
MinCaseVal->getType(), TableSize));
@@ -4214,6 +4212,13 @@
AddPredecessorToBlock(SI->getDefaultDest(), MaskBB, SI->getParent());
}
+ if (!DefaultIsReachable || GeneratingCoveredLookupTable) {
+ // We cached PHINodes in PHIs, to avoid accessing deleted PHINodes later,
+ // do not delete PHINodes here.
+ SI->getDefaultDest()->removePredecessor(SI->getParent(),
+ /*DontDeleteUselessPHIs=*/true);
+ }
+
bool ReturnedEarly = false;
for (size_t I = 0, E = PHIs.size(); I != E; ++I) {
PHINode *PHI = PHIs[I];