CorrelatedPropagation: BasicBlock::removePredecessor can simplify PHI nodes. If the...

Fixes PR13972.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@164818 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp b/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
index 9b0aadb0b5b032bbea22b6ed21b190506847dc81..3ec6f3dcc31b0d98f377acd8ce4e63b08b98ab33 100644 (file)
--- a/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
+++ b/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
@@ -235,6 +235,11 @@ bool CorrelatedValuePropagation::processSwitch(SwitchInst *SI) {
       // This case never fires - remove it.
       CI.getCaseSuccessor()->removePredecessor(BB);
       SI->removeCase(CI); // Does not invalidate the iterator.
+
+      // The condition can be modified by removePredecessor's PHI simplification
+      // logic.
+      Cond = SI->getCondition();
+
       ++NumDeadCases;
       Changed = true;
     } else if (State == LazyValueInfo::True) {

diff --git a/test/Transforms/CorrelatedValuePropagation/crash.ll b/test/Transforms/CorrelatedValuePropagation/crash.ll
index 80c43d0f1da5126676c7952686b33f422d3a5259..9723d18252a7eb4b2792a009fba17d8ec9ba072c 100644 (file)
--- a/test/Transforms/CorrelatedValuePropagation/crash.ll
+++ b/test/Transforms/CorrelatedValuePropagation/crash.ll
@@ -35,3 +35,28 @@ srf.exit.i:
 func_29.exit:
   ret void
 }
+
+; PR13972
+define void @test3() nounwind {
+for.body:
+  br label %return
+
+for.cond.i:                                       ; preds = %if.else.i, %for.body.i
+  %e.2.i = phi i32 [ %e.2.i, %if.else.i ], [ -8, %for.body.i ]
+  br i1 undef, label %return, label %for.body.i
+
+for.body.i:                                       ; preds = %for.cond.i
+  switch i32 %e.2.i, label %for.cond3.i [
+    i32 -3, label %if.else.i
+    i32 0, label %for.cond.i
+  ]
+
+for.cond3.i:                                      ; preds = %for.cond3.i, %for.body.i
+  br label %for.cond3.i
+
+if.else.i:                                        ; preds = %for.body.i
+  br label %for.cond.i
+
+return:                                           ; preds = %for.cond.i, %for.body
+  ret void
+}