[LoopVer] Update all existing PHIs in the exit block

We only used to add the edge from the cloned loop to PHIs that
corresponded to values defined by the loop.  We need to do this for all
PHIs obviously since we need a PHI operand for each incoming edge.

This includes things like PHIs with a constant value or with values
defined before the original loop (see the testcases).

After the patch the PHIs are added to the exit block in two passes.

In the first pass we ensure there is a single-operand (LCSSA) PHI for
each value defined by the loop.

In the second pass we loop through each (single-operand) PHI and add the
value for the edge from the cloned loop.  If the value is defined in the
loop we'll use the cloned instruction from the cloned loop.

Fixes PR28037

llvm-svn: 272649

1 files changed, 62 insertions, 0 deletions

diff --git a/llvm/test/Transforms/LoopVersioning/incorrect-phi.ll b/llvm/test/Transforms/LoopVersioning/incorrect-phi.ll
new file mode 100644
index 00000000000..fcecdb34900
--- /dev/null
+++ b/llvm/test/Transforms/LoopVersioning/incorrect-phi.ll
@@ -0,0 +1,62 @@
+; RUN: opt -loop-versioning -S < %s | FileCheck %s
+
+; Make sure all PHIs are properly updated in the exit block.  Based on
+; PR28037.
+
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@x = external global [2 x [3 x [5 x i16]]]
+
+; CHECK-LABEL: @phi_with_undef
+define void @phi_with_undef() {
+bb6.lr.ph:                                        ; preds = %bb5.preheader
+  br label %bb6
+
+bb6:                                              ; preds = %bb6.lr.ph, %bb6
+  %_tmp1423 = phi i16 [ undef, %bb6.lr.ph ], [ %_tmp142, %bb6 ]
+  %_tmp123 = getelementptr [2 x [3 x [5 x i16]]], [2 x [3 x [5 x i16]]]* @x, i16 0, i64 undef
+  %_tmp125 = sext i16 %_tmp1423 to i64
+  %_tmp126 = getelementptr [3 x [5 x i16]], [3 x [5 x i16]]* %_tmp123, i16 0, i64 %_tmp125
+  %_tmp129 = getelementptr [5 x i16], [5 x i16]* %_tmp126, i16 0, i64 undef
+  %_tmp130 = load i16, i16* %_tmp129
+  store i16 undef, i16* getelementptr ([2 x [3 x [5 x i16]]], [2 x [3 x [5 x i16]]]* @x, i64 0, i64 undef, i64 undef, i64 undef)
+  %_tmp142 = add i16 %_tmp1423, 1
+  br i1 false, label %bb6, label %loop.exit
+
+loop.exit:                                ; preds = %bb6
+  %_tmp142.lcssa = phi i16 [ %_tmp142, %bb6 ]
+  %split = phi i16 [ undef, %bb6 ]
+; CHECK: %split = phi i16 [ undef, %bb6 ], [ undef, %bb6.lver.orig ]
+  br label %bb9
+
+bb9:                                              ; preds = %bb9.loopexit, %bb1
+  ret void
+}
+
+; CHECK-LABEL: @phi_with_non_loop_defined_value
+define void @phi_with_non_loop_defined_value() {
+bb6.lr.ph:                                        ; preds = %bb5.preheader
+  %t = add i16 1, 1
+  br label %bb6
+
+bb6:                                              ; preds = %bb6.lr.ph, %bb6
+  %_tmp1423 = phi i16 [ undef, %bb6.lr.ph ], [ %_tmp142, %bb6 ]
+  %_tmp123 = getelementptr [2 x [3 x [5 x i16]]], [2 x [3 x [5 x i16]]]* @x, i16 0, i64 undef
+  %_tmp125 = sext i16 %_tmp1423 to i64
+  %_tmp126 = getelementptr [3 x [5 x i16]], [3 x [5 x i16]]* %_tmp123, i16 0, i64 %_tmp125
+  %_tmp129 = getelementptr [5 x i16], [5 x i16]* %_tmp126, i16 0, i64 undef
+  %_tmp130 = load i16, i16* %_tmp129
+  store i16 undef, i16* getelementptr ([2 x [3 x [5 x i16]]], [2 x [3 x [5 x i16]]]* @x, i64 0, i64 undef, i64 undef, i64 undef)
+  %_tmp142 = add i16 %_tmp1423, 1
+  br i1 false, label %bb6, label %loop.exit
+
+loop.exit:                                ; preds = %bb6
+  %_tmp142.lcssa = phi i16 [ %_tmp142, %bb6 ]
+  %split = phi i16 [ %t, %bb6 ]
+; CHECK: %split = phi i16 [ %t, %bb6 ], [ %t, %bb6.lver.orig ]
+  br label %bb9
+
+bb9:                                              ; preds = %bb9.loopexit, %bb1
+  ret void
+}