NewGVN: Clean up how we handle the INITIAL class so that everything in

it is dead or unreachable, as it should be.
This also makes the leader of INITIAL undef, enabling us to handle
irreducibility properly.

Summary:
This lets us verify, more than we do now, that we didn't screw up
value numbering.

Reviewers: davide

Subscribers: Prazek, llvm-commits

Differential Revision: https://reviews.llvm.org/D29842

llvm-svn: 294844

1 files changed, 38 insertions, 4 deletions

diff --git a/llvm/test/Transforms/NewGVN/basic-cyclic-opt.ll b/llvm/test/Transforms/NewGVN/basic-cyclic-opt.ll
index 4901a305e5a..7830d7ea78a 100644
--- a/llvm/test/Transforms/NewGVN/basic-cyclic-opt.ll
+++ b/llvm/test/Transforms/NewGVN/basic-cyclic-opt.ll
@@ -228,8 +228,8 @@ bb23:                                             ; preds = %bb4
 }
 
 ;; This is an irreducible test case that will cause a memoryphi node loop
-;; in the two block.
-;; it's equivalent to something like
+;; in the two blocks.
+;; It's equivalent to something like
 ;; *a = 0
 ;; if (<....>) goto loopmiddle
 ;; loopstart:
@@ -245,8 +245,8 @@ bb23:                                             ; preds = %bb4
 ;; Both loads should equal 0, but it requires being
 ;; completely optimistic about MemoryPhis, otherwise
 ;; we will not be able to see through the cycle.
-define i8 @quux(i8* noalias %arg, i8* noalias %arg2) {
-; CHECK-LABEL: @quux(
+define i8 @irreducible_memoryphi(i8* noalias %arg, i8* noalias %arg2) {
+; CHECK-LABEL: @irreducible_memoryphi(
 ; CHECK-NEXT:  bb:
 ; CHECK-NEXT:    store i8 0, i8* [[ARG:%.*]]
 ; CHECK-NEXT:    br i1 undef, label [[BB2:%.*]], label [[BB1:%.*]]
@@ -274,6 +274,40 @@ bb3:                                              ; preds = %bb2
   %tmp3 = add i8 %tmp, %tmp2
   ret i8 %tmp3
 }
+;; This is an irreducible test case that will cause a phi node loop
+;; in the two blocks
+;;
+;; It should return 0, but it requires being
+;; completely optimistic about phis, otherwise
+;; we will not be able to see through the cycle.
+define i32 @irreducible_phi(i32 %arg) {
+; CHECK-LABEL: @irreducible_phi(
+; CHECK-NEXT:  bb:
+; CHECK-NEXT:    br i1 undef, label [[BB2:%.*]], label [[BB1:%.*]]
+; CHECK:       bb1:
+; CHECK-NEXT:    br label [[BB2]]
+; CHECK:       bb2:
+; CHECK-NEXT:    br i1 undef, label [[BB1]], label [[BB3:%.*]]
+; CHECK:       bb3:
+; CHECK-NEXT:    ret i32 0
+;
+bb:
+  %tmp = add i32 0, %arg
+  br i1 undef, label %bb2, label %bb1
+
+bb1:                                              ; preds = %bb2, %bb
+  %phi1 = phi i32 [%tmp, %bb], [%phi2, %bb2]
+  br label %bb2
+
+bb2:                                              ; preds = %bb1, %bb
+  %phi2 = phi i32 [%tmp, %bb], [%phi1, %bb1]
+  br i1 undef, label %bb1, label %bb3
+
+bb3:                                              ; preds = %bb2
+  ; This should be zero
+  %tmp3 = sub i32 %tmp, %phi2
+  ret i32 %tmp3
+}
 attributes #0 = { nounwind ssp uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
 
 !llvm.ident = !{!0, !0, !0}