[LoopUnroll] Properly update loop structure in case of successful peeling.

When peeling kicks in, it updates the loop preheader.
Later, a successful full unroll of the loop needs to update a PHI
which i-th argument comes from the loop preheader, so it'd better look
at the correct block. Fixes PR33437.

Differential Revision:  https://reviews.llvm.org/D37153

llvm-svn: 311922

1 files changed, 30 insertions, 0 deletions

diff --git a/llvm/test/Transforms/LoopUnroll/pr33437.ll b/llvm/test/Transforms/LoopUnroll/pr33437.ll
new file mode 100644
index 00000000000..58fa91f4b9a
--- /dev/null
+++ b/llvm/test/Transforms/LoopUnroll/pr33437.ll
@@ -0,0 +1,30 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -loop-unroll %s -S | FileCheck %s
+
+declare zeroext i8 @patatino()
+
+define fastcc void @tinky() {
+; CHECK-LABEL: @tinky(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FOR_COND93:%.*]]
+; CHECK:       for.cond93:
+; CHECK-NEXT:    br label [[FOR_BODY198:%.*]]
+; CHECK:       for.body198:
+; CHECK-NEXT:    [[CALL593:%.*]] = tail call zeroext i8 @patatino()
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.cond93
+
+for.cond93.loopexit:
+  ret void
+
+for.cond93:
+  br label %for.body198
+
+for.body198:
+  %l_249.12 = phi i8 [ undef, %for.cond93 ], [ %call593, %for.body198 ]
+  %l_522.01 = phi i32 [ 0, %for.cond93 ], [ 1, %for.body198 ]
+  %call593 = tail call zeroext i8 @patatino()
+  br i1 false, label %for.body198, label %for.cond93.loopexit
+}