[SCEVExpander] Fix a failed cast<> assertion

SCEVExpander::replaceCongruentIVs assumes the backedge value of an
SCEV-analysable PHI to always be an instruction, when this is not
necessarily true.  For now address this by bailing out of the
optimization if the backedge value of the PHI is a non-Instruction.

llvm-svn: 269213

1 files changed, 70 insertions, 0 deletions

diff --git a/llvm/test/Analysis/ScalarEvolution/expander-replace-congruent-ivs.ll b/llvm/test/Analysis/ScalarEvolution/expander-replace-congruent-ivs.ll
index 887b9db7f25..0adb92d671b 100644
--- a/llvm/test/Analysis/ScalarEvolution/expander-replace-congruent-ivs.ll
+++ b/llvm/test/Analysis/ScalarEvolution/expander-replace-congruent-ivs.ll
@@ -39,3 +39,73 @@ loop_1:
 leave:
   ret void
 }
+
+
+; @ReplaceArg_0 and @ReplaceArg_1 used to trigger a failed cast<>
+; assertion in SCEVExpander.
+
+define void @ReplaceArg_0(i32 %val) {
+; CHECK-LABEL: @ReplaceArg_0(
+entry:
+  br i1 undef, label %loop_0.cond, label %for.body.us
+
+for.body.us:
+  br label %loop_0.cond
+
+loop_0.cond:
+  br i1 true, label %loop_0.ph, label %loop_1.ph
+
+loop_0.ph:
+  br label %loop_0
+
+loop_1.exit:
+  br label %loop_1.ph
+
+loop_1.ph:
+  %c.lcssa = phi i32 [ 0, %loop_0.cond ], [ %val, %loop_1.exit ]
+  br label %loop_1
+
+loop_0:
+  br i1 undef, label %loop_0, label %loop_1.exit
+
+loop_1:
+  %d.1 = phi i32 [ %c.lcssa, %loop_1 ], [ %val, %loop_1.ph ]
+  %t.1 = phi i32 [ %val, %loop_1 ], [ %c.lcssa, %loop_1.ph ]
+  br i1 undef, label %leave, label %loop_1
+
+leave:
+  ret void
+}
+
+define void @ReplaceArg_1(i32 %val) {
+; CHECK-LABEL: @ReplaceArg_1(
+entry:
+  br i1 undef, label %loop_0.cond, label %for.body.us
+
+for.body.us:
+  br label %loop_0.cond
+
+loop_0.cond:
+  br i1 true, label %loop_0.ph, label %loop_1.ph
+
+loop_0.ph:
+  br label %loop_0
+
+loop_1.exit:
+  br label %loop_1.ph
+
+loop_1.ph:
+  %c.lcssa = phi i32 [ 0, %loop_0.cond ], [ %val, %loop_1.exit ]
+  br label %loop_1
+
+loop_0:
+  br i1 undef, label %loop_0, label %loop_1.exit
+
+loop_1:
+  %t.1 = phi i32 [ %val, %loop_1 ], [ %c.lcssa, %loop_1.ph ]
+  %d.1 = phi i32 [ %c.lcssa, %loop_1 ], [ %val, %loop_1.ph ]
+  br i1 undef, label %leave, label %loop_1
+
+leave:
+  ret void
+}