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[MachinePipeliner] Fix Phi refers to Phi in same stage in 1st epilogue 

Summary:
This is exposed by functional testing on PowerPC.
In some pipelined loops, Phi refer to phi did not get value defined by
the Phi, hence getting wrong value later.

As the comment mentioned, we should "use the value defined by the Phi,
unless we're generating the firstepilog and the Phi refers to a Phi
 in a different stage.", so Phi refering to same stage Phi should use
the value defined by the Phi here.

Reviewers: bcahoon, hfinkel

Reviewed By: hfinkel

Subscribers: MaskRay, wuzish, nemanjai, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D64035

llvm-svn: 365428
This commit is contained in:
Jinsong Ji 2019-07-09 02:27:35 +00:00
parent 18301fa82b
commit cbd64f7648
2 changed files with 2 additions and 2 deletions
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2
llvm/lib/CodeGen/MachinePipeliner.cpp
View File

@ -2430,7 +2430,7 @@ void SwingSchedulerDAG::generateExistingPhis(
// Use the value defined by the Phi, unless we're generating the first
// epilog and the Phi refers to a Phi in a different stage.
else if (VRMap[PrevStage - np].count(Def) &&
(!LoopDefIsPhi || PrevStage != LastStageNum))
(!LoopDefIsPhi || (PrevStage != LastStageNum) || (LoopValStage == StageScheduled)))
PhiOp2 = VRMap[PrevStage - np][Def];
}

2
llvm/test/CodeGen/PowerPC/sms-phi.ll
View File

@ -8,7 +8,7 @@ define dso_local void @sha512() #0 {
;CHECK: epilog:
;CHECK: %23:g8rc_and_g8rc_nox0 = PHI %5:g8rc_and_g8rc_nox0, %bb.3, %18:g8rc_and_g8rc_nox0, %bb.4
;CHECK-NEXT: %24:g8rc = PHI %6:g8rc, %bb.3, %16:g8rc, %bb.4
;CHECK-NEXT: %25:g8rc = PHI %6:g8rc, %bb.3, %16:g8rc, %bb.4
;CHECK-NEXT: %25:g8rc = PHI %6:g8rc, %bb.3, %19:g8rc, %bb.4
br label %1
1: ; preds = %1, %0