[llvm] [VPlan] Don't apply predication discount to non-originally-predicated blocks (PR #160449)

[Luke Lau via llvm-commits]

================
@@ -284,27 +284,44 @@ define void @sink_replicate_region_4_requires_split_at_end_of_block(i32 %x, ptr
 ; CHECK-NEXT: loop.0:
 ; CHECK-NEXT:   WIDEN-CAST ir<%conv> = sext vp<[[PRED]]> to i32
 ; CHECK-NEXT:   EMIT vp<[[SPLICE:%.+]]> = first-order splice ir<%0>, ir<%conv>
-; CHECK-NEXT: Successor(s): pred.store
+; CHECK-NEXT:   WIDEN ir<%rem> = srem vp<[[SPLICE]]>, ir<%x>
+; CHECK-NEXT: Successor(s): pred.load
 ; CHECK-EMPTY:
-; CHECK:      <xVFxUF> pred.store: {
-; CHECK-NEXT:   pred.store.entry:
+; CHECK:      <xVFxUF> pred.load: {
+; CHECK-NEXT:   pred.load.entry:
 ; CHECK-NEXT:     BRANCH-ON-MASK vp<[[MASK]]>
-; CHECK-NEXT:   Successor(s): pred.store.if, pred.store.continue
+; CHECK-NEXT:   Successor(s): pred.load.if, pred.load.continue
 ; CHECK-EMPTY:
-; CHECK:        pred.store.if:
-; CHECK-NEXT:     REPLICATE ir<%lv.2> = load ir<%gep>
-; CHECK-NEXT:     REPLICATE ir<%rem> = srem vp<[[SPLICE]]>, ir<%x>
-; CHECK-NEXT:     REPLICATE ir<%conv.lv.2> = sext ir<%lv.2>
-; CHECK-NEXT:     REPLICATE ir<%add.1> = add ir<%conv>, ir<%rem>
-; CHECK-NEXT:     REPLICATE ir<%gep.dst> = getelementptr ir<%dst>, vp<[[STEPS]]>
-; CHECK-NEXT:     REPLICATE ir<%add> = add ir<%add.1>, ir<%conv.lv.2>
-; CHECK-NEXT:     REPLICATE store ir<%add>, ir<%gep.dst>
-; CHECK-NEXT:   Successor(s): pred.store.continue
+; CHECK:        pred.load.if:
+; CHECK-NEXT:     REPLICATE ir<%lv.2> = load ir<%gep> (S->V)
+; CHECK-NEXT:   Successor(s): pred.load.continue
 ; CHECK-EMPTY:
-; CHECK:        pred.store.continue:
+; CHECK:        pred.load.continue:
+; CHECK-NEXT:     PHI-PREDICATED-INSTRUCTION vp<%9> = ir<%lv.2>
 ; CHECK-NEXT:   No successors
 ; CHECK-NEXT: }
-; CHECK-NEXT:   Successor(s): loop.2
+; CHECK-NEXT:   Successor(s): loop.1
+; CHECK-EMPTY:
+; CHECK-NEXT:  loop.1:
+; CHECK-NEXT:    WIDEN ir<%add.1> = add ir<%conv>, ir<%rem>
----------------
lukel97 wrote:

This was originally to test splitting at the end of a block but as of today it's not testing it because the conv isn't at the end of the block, I've opened https://github.com/llvm/llvm-project/pull/164636 to move it to a unit test

https://github.com/llvm/llvm-project/pull/160449