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[NewGVN] Fix cyclic dependency in phi-of-ops #141510

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[NewGVN] Fix cyclic dependency in phi-of-ops #141510

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5 changes: 4 additions & 1 deletion llvm/lib/Transforms/Scalar/NewGVN.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3847,7 +3847,10 @@ Value *NewGVN::findPHIOfOpsLeader(const Expression *E,
// Anything that isn't an instruction is always available.
if (!MemberInst)
return Member;
if (DT->dominates(getBlockForValue(MemberInst), BB))
// Cannot use something that appears later in the iteration,
// as it may introduce a cyclic dependency.
if (DT->dominates(getBlockForValue(MemberInst), BB) &&
InstrToDFSNum(MemberInst) <= InstrToDFSNum(OrigInst))
return Member;
}
return nullptr;
Expand Down
22 changes: 12 additions & 10 deletions llvm/test/Transforms/NewGVN/completeness.ll
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Expand Up @@ -227,17 +227,17 @@ define i64 @test5(i64 %arg) {
; CHECK: bb14:
; CHECK-NEXT: br label [[BB15:%.*]]
; CHECK: bb15:
; CHECK-NEXT: [[PHIOFOPS:%.*]] = phi i64 [ [[TMP12]], [[BB14]] ], [ [[TMP25:%.*]], [[BB15]] ]
; CHECK-NEXT: [[TMP16:%.*]] = phi i64 [ [[TMP24:%.*]], [[BB15]] ], [ [[TMP11]], [[BB14]] ]
; CHECK-NEXT: [[TMP17:%.*]] = phi i64 [ [[TMP22:%.*]], [[BB15]] ], [ [[TMP10]], [[BB14]] ]
; CHECK-NEXT: [[TMP18:%.*]] = phi i64 [ [[TMP20:%.*]], [[BB15]] ], [ 0, [[BB14]] ]
; CHECK-NEXT: store i64 [[PHIOFOPS]], ptr [[TMP]], align 8
; CHECK-NEXT: [[TMP19:%.*]] = mul nsw i64 [[TMP16]], [[TMP17]]
; CHECK-NEXT: store i64 [[TMP19]], ptr [[TMP]], align 8
; CHECK-NEXT: [[TMP20]] = add nuw nsw i64 [[TMP18]], 1
; CHECK-NEXT: [[TMP21:%.*]] = getelementptr inbounds [100 x i64], ptr @global, i64 0, i64 [[TMP20]]
; CHECK-NEXT: [[TMP22]] = load i64, ptr [[TMP21]], align 8
; CHECK-NEXT: [[TMP23:%.*]] = getelementptr inbounds [100 x i64], ptr @global.1, i64 0, i64 [[TMP20]]
; CHECK-NEXT: [[TMP24]] = load i64, ptr [[TMP23]], align 8
; CHECK-NEXT: [[TMP25]] = mul nsw i64 [[TMP24]], [[TMP22]]
; CHECK-NEXT: [[TMP25:%.*]] = mul nsw i64 [[TMP24]], [[TMP22]]
; CHECK-NEXT: [[TMP26:%.*]] = icmp eq i64 [[TMP20]], [[TMP25]]
; CHECK-NEXT: br i1 [[TMP26]], label [[BB4:%.*]], label [[BB15]]
; CHECK: bb27:
Expand Down Expand Up @@ -384,8 +384,10 @@ bb1: ; preds = %bb1, %bb
}


;; Make sure we handle the case where we later come up with an expression that we need
;; for a phi of ops.
;; Handling the case where an expression from a previous iteration is
;; needed for a phi of ops is tricky, as this expression might depend
;; on the instruction for which we are creating the phi of ops,
;; potentially creating a cyclic dependency. (See PR69211)
define void @test9(i1 %arg) {
; CHECK-LABEL: @test9(
; CHECK-NEXT: bb:
Expand All @@ -395,10 +397,10 @@ define void @test9(i1 %arg) {
; CHECK: bb2:
; CHECK-NEXT: br label [[BB6:%.*]]
; CHECK: bb6:
; CHECK-NEXT: [[PHIOFOPS:%.*]] = phi i32 [ -13, [[BB2]] ], [ [[TMP11:%.*]], [[BB6]] ]
; CHECK-NEXT: [[TMP7:%.*]] = phi i32 [ 1, [[BB2]] ], [ [[TMP8:%.*]], [[BB6]] ]
; CHECK-NEXT: [[TMP8]] = add nuw nsw i32 [[TMP7]], 1
; CHECK-NEXT: [[TMP11]] = add i32 -14, [[TMP8]]
; CHECK-NEXT: [[TMP9:%.*]] = add i32 -14, [[TMP7]]
; CHECK-NEXT: [[TMP11:%.*]] = add i32 -14, [[TMP8]]
; CHECK-NEXT: br label [[BB6]]
;
bb:
Expand Down Expand Up @@ -566,13 +568,13 @@ define void @test13() {
; CHECK-NEXT: [[TMP:%.*]] = load i8, ptr null, align 1
; CHECK-NEXT: br label [[BB3:%.*]]
; CHECK: bb3:
; CHECK-NEXT: [[PHIOFOPS:%.*]] = phi i8 [ [[TMP]], [[BB1]] ], [ [[TMP10:%.*]], [[BB3]] ]
; CHECK-NEXT: [[TMP4:%.*]] = phi ptr [ null, [[BB1]] ], [ [[TMP6:%.*]], [[BB3]] ]
; CHECK-NEXT: [[TMP5:%.*]] = phi i32 [ undef, [[BB1]] ], [ [[TMP9:%.*]], [[BB3]] ]
; CHECK-NEXT: [[TMP6]] = getelementptr i8, ptr [[TMP4]], i64 1
; CHECK-NEXT: [[TMP8:%.*]] = sext i8 [[PHIOFOPS]] to i32
; CHECK-NEXT: [[TMP7:%.*]] = load i8, ptr [[TMP4]], align 1
; CHECK-NEXT: [[TMP8:%.*]] = sext i8 [[TMP7]] to i32
; CHECK-NEXT: [[TMP9]] = mul i32 [[TMP5]], [[TMP8]]
; CHECK-NEXT: [[TMP10]] = load i8, ptr [[TMP6]], align 1
; CHECK-NEXT: [[TMP10:%.*]] = load i8, ptr [[TMP6]], align 1
; CHECK-NEXT: [[TMP11:%.*]] = icmp eq i8 [[TMP10]], 0
; CHECK-NEXT: br i1 [[TMP11]], label [[BB12:%.*]], label [[BB3]]
; CHECK: bb12:
Expand Down
5 changes: 2 additions & 3 deletions llvm/test/Transforms/NewGVN/pr33461.ll
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Expand Up @@ -8,12 +8,11 @@ define void @patatino() {
; CHECK-NEXT: entry:
; CHECK-NEXT: br i1 false, label [[FOR_COND1:%.*]], label [[FOR_INC:%.*]]
; CHECK: for.cond1:
; CHECK-NEXT: [[PHIOFOPS:%.*]] = phi i16 [ poison, [[ENTRY:%.*]] ], [ [[INC:%.*]], [[FOR_INC]] ]
; CHECK-NEXT: store i16 [[PHIOFOPS]], ptr @b, align 2
; CHECK-NEXT: [[TMP1:%.*]] = load i16, ptr @b, align 2
; CHECK-NEXT: br label [[FOR_INC]]
; CHECK: for.inc:
; CHECK-NEXT: [[TMP0:%.*]] = load i16, ptr @b, align 2
; CHECK-NEXT: [[INC]] = add i16 [[TMP0]], 1
; CHECK-NEXT: [[INC:%.*]] = add i16 [[TMP0]], 1
; CHECK-NEXT: store i16 [[INC]], ptr @b, align 2
; CHECK-NEXT: br label [[FOR_COND1]]
;
Expand Down
123 changes: 123 additions & 0 deletions llvm/test/Transforms/NewGVN/pr69211.ll
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@@ -0,0 +1,123 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
; RUN: opt -passes=newgvn -S < %s | FileCheck %s

define i64 @snork() {
; CHECK-LABEL: define i64 @snork() {
; CHECK-NEXT: [[BB:.*]]:
; CHECK-NEXT: br label %[[BB1:.*]]
; CHECK: [[BB1]]:
; CHECK-NEXT: [[PHI:%.*]] = phi i64 [ 0, %[[BB]] ], [ [[ADD:%.*]], %[[BB1]] ]
; CHECK-NEXT: [[ADD]] = add i64 [[PHI]], 1
; CHECK-NEXT: [[ADD2:%.*]] = add i64 [[ADD]], 1
; CHECK-NEXT: [[ICMP:%.*]] = icmp slt i64 [[ADD]], 100
; CHECK-NEXT: br i1 [[ICMP]], label %[[BB1]], label %[[BB4:.*]]
; CHECK: [[BB4]]:
; CHECK-NEXT: ret i64 [[ADD2]]
;
bb:
br label %bb1

bb1:
%phi = phi i64 [ 0, %bb ], [ %add3, %bb1 ]
%add = add i64 %phi, 1
%add2 = add i64 %add, 1
%add3 = add i64 %phi, 1
%icmp = icmp slt i64 %add3, 100
br i1 %icmp, label %bb1, label %bb4

bb4:
ret i64 %add2
}

define i64 @wobble() {
; CHECK-LABEL: define i64 @wobble() {
; CHECK-NEXT: [[BB:.*]]:
; CHECK-NEXT: br label %[[BB1:.*]]
; CHECK: [[BB1]]:
; CHECK-NEXT: [[PHI:%.*]] = phi i64 [ 0, %[[BB]] ], [ [[ADD:%.*]], %[[BB1]] ]
; CHECK-NEXT: [[ADD]] = add i64 [[PHI]], 1
; CHECK-NEXT: [[ADD2:%.*]] = add i64 [[ADD]], 1
; CHECK-NEXT: [[ADD4:%.*]] = add i64 [[ADD2]], 1
; CHECK-NEXT: [[ICMP:%.*]] = icmp slt i64 [[ADD]], 100
; CHECK-NEXT: br i1 [[ICMP]], label %[[BB1]], label %[[BB6:.*]]
; CHECK: [[BB6]]:
; CHECK-NEXT: ret i64 [[ADD4]]
;
bb:
br label %bb1

bb1:
%phi = phi i64 [ 0, %bb ], [ %add5, %bb1 ]
%add = add i64 %phi, 1
%add2 = add i64 %add, 1
%add3 = add i64 %add, 1
%add4 = add i64 %add2, 1
%add5 = add i64 %phi, 1
%icmp = icmp slt i64 %add5, 100
br i1 %icmp, label %bb1, label %bb6

bb6:
ret i64 %add4
}

define i64 @wobble.1(i64 %arg) {
; CHECK-LABEL: define i64 @wobble.1(
; CHECK-SAME: i64 [[ARG:%.*]]) {
; CHECK-NEXT: [[BB:.*]]:
; CHECK-NEXT: br label %[[BB1:.*]]
; CHECK: [[BB1]]:
; CHECK-NEXT: [[PHI:%.*]] = phi i64 [ 0, %[[BB]] ], [ [[ADD:%.*]], %[[BB1]] ]
; CHECK-NEXT: [[ADD]] = add i64 [[PHI]], 1
; CHECK-NEXT: [[ADD2:%.*]] = add i64 [[ADD]], 1
; CHECK-NEXT: [[ICMP:%.*]] = icmp slt i64 [[ADD]], 100
; CHECK-NEXT: br i1 [[ICMP]], label %[[BB1]], label %[[BB5:.*]]
; CHECK: [[BB5]]:
; CHECK-NEXT: ret i64 [[ADD2]]
;
bb:
br label %bb1

bb1:
%phi = phi i64 [ 0, %bb ], [ %add4, %bb1 ]
%add = add i64 %phi, 1
%add2 = add i64 %add, 1
%sub = sub i64 %add2, 1
%add3 = add i64 %sub, 1
%add4 = add i64 %phi, 1
%icmp = icmp slt i64 %add4, 100
br i1 %icmp, label %bb1, label %bb5

bb5:
ret i64 %add3
}

define i64 @pluto(i64 %arg) {
; CHECK-LABEL: define i64 @pluto(
; CHECK-SAME: i64 [[ARG:%.*]]) {
; CHECK-NEXT: [[BB:.*]]:
; CHECK-NEXT: br label %[[BB1:.*]]
; CHECK: [[BB1]]:
; CHECK-NEXT: [[PHI:%.*]] = phi i64 [ 0, %[[BB]] ], [ [[ADD:%.*]], %[[BB1]] ]
; CHECK-NEXT: [[ADD]] = add i64 [[PHI]], 1
; CHECK-NEXT: [[ADD2:%.*]] = add i64 [[ADD]], 1
; CHECK-NEXT: [[ICMP:%.*]] = icmp slt i64 [[ADD]], 100
; CHECK-NEXT: br i1 [[ICMP]], label %[[BB1]], label %[[BB5:.*]]
; CHECK: [[BB5]]:
; CHECK-NEXT: ret i64 [[ADD2]]
;
bb:
br label %bb1

bb1:
%phi = phi i64 [ 0, %bb ], [ %add4, %bb1 ]
%add = add i64 %phi, 1
%add2 = add i64 %add, 1
%sub = sub i64 %add2, 1
%add3 = add i64 %sub, 1
%add4 = add i64 %phi, 1
%icmp = icmp slt i64 %add4, 100
br i1 %icmp, label %bb1, label %bb5

bb5:
ret i64 %add3
}