[LoopVersioning] Relax an assert for LCSSA PHIs

When you have multiple LCSSA (single-operand) PHIs that are converted
into two-operand PHIs due to versioning, only assert that the PHI
currently being converted has a single operand.  I.e. we don't want to
check PHIs that were converted earlier in the loop.

Fixes PR27023.

Thanks to Karl-Johan Karlsson for the minimized testcase!

llvm-svn: 264081

1 files changed, 35 insertions, 0 deletions

diff --git a/llvm/test/Transforms/LoopVersioning/lcssa.ll b/llvm/test/Transforms/LoopVersioning/lcssa.ll
new file mode 100644
index 00000000000..2cd4662c371
--- /dev/null
+++ b/llvm/test/Transforms/LoopVersioning/lcssa.ll
@@ -0,0 +1,35 @@
+; RUN: opt -basicaa -loop-versioning -S < %s | FileCheck %s
+target triple = "x86_64-unknown-linux-gnu"
+
+define void @fill(i8** %ls1.20, i8** %ls2.21, i8* %cse3.22) {
+; CHECK: bb1.lver.check:
+; CHECK:   br i1 %memcheck.conflict, label %bb1.ph.lver.orig, label %bb1.ph
+bb1.ph:
+  %ls1.20.promoted = load i8*, i8** %ls1.20
+  %ls2.21.promoted = load i8*, i8** %ls2.21
+  br label %bb1
+
+bb1:
+  %_tmp302 = phi i8* [ %ls2.21.promoted, %bb1.ph ], [ %_tmp30, %bb1 ]
+  %_tmp281 = phi i8* [ %ls1.20.promoted, %bb1.ph ], [ %_tmp28, %bb1 ]
+  %_tmp14 = getelementptr i8, i8* %_tmp281, i16 -1
+  %_tmp15 = load i8, i8* %_tmp14
+  %add = add i8 %_tmp15, 1
+  store i8 %add, i8* %_tmp281
+  store i8 %add, i8* %_tmp302
+  %_tmp28 = getelementptr i8, i8* %_tmp281, i16 1
+  %_tmp30 = getelementptr i8, i8* %_tmp302, i16 1
+  br i1 false, label %bb1, label %bb3.loopexit
+
+bb3.loopexit:
+  %_tmp30.lcssa = phi i8* [ %_tmp30, %bb1 ]
+  %_tmp15.lcssa = phi i8 [ %_tmp15, %bb1 ]
+  %_tmp28.lcssa = phi i8* [ %_tmp28, %bb1 ]
+  store i8* %_tmp28.lcssa, i8** %ls1.20
+  store i8 %_tmp15.lcssa, i8* %cse3.22
+  store i8* %_tmp30.lcssa, i8** %ls2.21
+  br label %bb3
+
+bb3:
+  ret void
+}