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[VPlan] Reassociate (x & y) & z -> x & (y & z) #155383

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Merged
merged 8 commits into from
Sep 3, 2025
Merged

[VPlan] Reassociate (x & y) & z -> x & (y & z) #155383

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f9f7969
Reassociate header mask
lukel97 Aug 26, 2025
2cd0bb5
Reassociate all ands
lukel97 Sep 1, 2025
94f7b9f
Restrict to multiple users
lukel97 Sep 1, 2025
28162b8
Undo stray change
lukel97 Sep 1, 2025
f66a940
Update comment
lukel97 Sep 1, 2025
7661966
Fix devastating typo
lukel97 Sep 2, 2025
7d0e1cb
Merge branch 'main' into loop-vectorize/simplify-or-and
lukel97 Sep 2, 2025
6a796d0
Merge branch 'main' into loop-vectorize/simplify-or-and
lukel97 Sep 3, 2025
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105 changes: 59 additions & 46 deletions llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -996,7 +996,8 @@ static Value *tryToFoldLiveIns(const VPRecipeBase &R, unsigned Opcode,
}

/// Try to simplify recipe \p R.
static void simplifyRecipe(VPRecipeBase &R, VPTypeAnalysis &TypeInfo) {
static void simplifyRecipe(VPRecipeBase &R, VPTypeAnalysis &TypeInfo,
VPValue *HeaderMask) {
VPlan *Plan = R.getParent()->getPlan();

auto *Def = dyn_cast<VPSingleDefRecipe>(&R);
Expand Down Expand Up @@ -1119,6 +1120,14 @@ static void simplifyRecipe(VPRecipeBase &R, VPTypeAnalysis &TypeInfo) {
return;
}

// Reassociate the header mask so it has more opportunities to be simplified.
// (headermask && x) && y -> headermask && (x && y)
if (HeaderMask && match(Def, m_LogicalAnd(m_LogicalAnd(m_Specific(HeaderMask),
m_VPValue(X)),
m_VPValue(Y))))
return Def->replaceAllUsesWith(
Builder.createLogicalAnd(HeaderMask, Builder.createLogicalAnd(X, Y)));

if (match(Def, m_c_Mul(m_VPValue(A), m_SpecificInt(1))))
return Def->replaceAllUsesWith(A);

Expand Down Expand Up @@ -1263,13 +1272,61 @@ static void simplifyRecipe(VPRecipeBase &R, VPTypeAnalysis &TypeInfo) {
}
}

/// Collect the header mask with the pattern:
/// (ICMP_ULE, WideCanonicalIV, backedge-taken-count)
/// TODO: Introduce explicit recipe for header-mask instead of searching
/// for the header-mask pattern manually.
static VPSingleDefRecipe *findHeaderMask(VPlan &Plan) {
SmallVector<VPValue *> WideCanonicalIVs;
auto *FoundWidenCanonicalIVUser = find_if(Plan.getCanonicalIV()->users(),
IsaPred<VPWidenCanonicalIVRecipe>);
assert(count_if(Plan.getCanonicalIV()->users(),
IsaPred<VPWidenCanonicalIVRecipe>) <= 1 &&
"Must have at most one VPWideCanonicalIVRecipe");
if (FoundWidenCanonicalIVUser != Plan.getCanonicalIV()->users().end()) {
auto *WideCanonicalIV =
cast<VPWidenCanonicalIVRecipe>(*FoundWidenCanonicalIVUser);
WideCanonicalIVs.push_back(WideCanonicalIV);
}

// Also include VPWidenIntOrFpInductionRecipes that represent a widened
// version of the canonical induction.
VPBasicBlock *HeaderVPBB = Plan.getVectorLoopRegion()->getEntryBasicBlock();
for (VPRecipeBase &Phi : HeaderVPBB->phis()) {
auto *WidenOriginalIV = dyn_cast<VPWidenIntOrFpInductionRecipe>(&Phi);
if (WidenOriginalIV && WidenOriginalIV->isCanonical())
WideCanonicalIVs.push_back(WidenOriginalIV);
}

// Walk users of wide canonical IVs and find the single compare of the form
// (ICMP_ULE, WideCanonicalIV, backedge-taken-count).
VPSingleDefRecipe *HeaderMask = nullptr;
for (auto *Wide : WideCanonicalIVs) {
for (VPUser *U : SmallVector<VPUser *>(Wide->users())) {
auto *VPI = dyn_cast<VPInstruction>(U);
if (!VPI || !vputils::isHeaderMask(VPI, Plan))
continue;

assert(VPI->getOperand(0) == Wide &&
"WidenCanonicalIV must be the first operand of the compare");
assert(!HeaderMask && "Multiple header masks found?");
HeaderMask = VPI;
}
}
return HeaderMask;
}

void VPlanTransforms::simplifyRecipes(VPlan &Plan) {
VPValue *HeaderMask = nullptr;
// Ignore post-unrolling as there can be multiple header masks.
if (!Plan.isUnrolled())
HeaderMask = findHeaderMask(Plan);
ReversePostOrderTraversal<VPBlockDeepTraversalWrapper<VPBlockBase *>> RPOT(
Plan.getEntry());
VPTypeAnalysis TypeInfo(Plan);
for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(RPOT)) {
for (VPRecipeBase &R : make_early_inc_range(*VPBB)) {
simplifyRecipe(R, TypeInfo);
simplifyRecipe(R, TypeInfo, HeaderMask);
}
}
}
Expand Down Expand Up @@ -2192,50 +2249,6 @@ static VPActiveLaneMaskPHIRecipe *addVPLaneMaskPhiAndUpdateExitBranch(
return LaneMaskPhi;
}

/// Collect the header mask with the pattern:
/// (ICMP_ULE, WideCanonicalIV, backedge-taken-count)
/// TODO: Introduce explicit recipe for header-mask instead of searching
/// for the header-mask pattern manually.
static VPSingleDefRecipe *findHeaderMask(VPlan &Plan) {
SmallVector<VPValue *> WideCanonicalIVs;
auto *FoundWidenCanonicalIVUser = find_if(Plan.getCanonicalIV()->users(),
IsaPred<VPWidenCanonicalIVRecipe>);
assert(count_if(Plan.getCanonicalIV()->users(),
IsaPred<VPWidenCanonicalIVRecipe>) <= 1 &&
"Must have at most one VPWideCanonicalIVRecipe");
if (FoundWidenCanonicalIVUser != Plan.getCanonicalIV()->users().end()) {
auto *WideCanonicalIV =
cast<VPWidenCanonicalIVRecipe>(*FoundWidenCanonicalIVUser);
WideCanonicalIVs.push_back(WideCanonicalIV);
}

// Also include VPWidenIntOrFpInductionRecipes that represent a widened
// version of the canonical induction.
VPBasicBlock *HeaderVPBB = Plan.getVectorLoopRegion()->getEntryBasicBlock();
for (VPRecipeBase &Phi : HeaderVPBB->phis()) {
auto *WidenOriginalIV = dyn_cast<VPWidenIntOrFpInductionRecipe>(&Phi);
if (WidenOriginalIV && WidenOriginalIV->isCanonical())
WideCanonicalIVs.push_back(WidenOriginalIV);
}

// Walk users of wide canonical IVs and find the single compare of the form
// (ICMP_ULE, WideCanonicalIV, backedge-taken-count).
VPSingleDefRecipe *HeaderMask = nullptr;
for (auto *Wide : WideCanonicalIVs) {
for (VPUser *U : SmallVector<VPUser *>(Wide->users())) {
auto *VPI = dyn_cast<VPInstruction>(U);
if (!VPI || !vputils::isHeaderMask(VPI, Plan))
continue;

assert(VPI->getOperand(0) == Wide &&
"WidenCanonicalIV must be the first operand of the compare");
assert(!HeaderMask && "Multiple header masks found?");
HeaderMask = VPI;
}
}
return HeaderMask;
}

void VPlanTransforms::addActiveLaneMask(
VPlan &Plan, bool UseActiveLaneMaskForControlFlow,
bool DataAndControlFlowWithoutRuntimeCheck) {
Expand Down
12 changes: 3 additions & 9 deletions llvm/test/Transforms/LoopVectorize/RISCV/blocks-with-dead-instructions.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -436,23 +436,17 @@ define void @multiple_blocks_with_dead_inst_multiple_successors_6(ptr %src, i1 %
; CHECK-NEXT: [[VEC_IND:%.*]] = phi <vscale x 8 x i64> [ [[INDUCTION]], %[[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], %[[VECTOR_BODY]] ]
; CHECK-NEXT: [[AVL:%.*]] = phi i64 [ [[TMP2]], %[[VECTOR_PH]] ], [ [[AVL_NEXT:%.*]], %[[VECTOR_BODY]] ]
; CHECK-NEXT: [[TMP27:%.*]] = call i32 @llvm.experimental.get.vector.length.i64(i64 [[AVL]], i32 8, i1 true)
; CHECK-NEXT: [[BROADCAST_SPLATINSERT3:%.*]] = insertelement <vscale x 8 x i32> poison, i32 [[TMP27]], i64 0
; CHECK-NEXT: [[BROADCAST_SPLAT4:%.*]] = shufflevector <vscale x 8 x i32> [[BROADCAST_SPLATINSERT3]], <vscale x 8 x i32> poison, <vscale x 8 x i32> zeroinitializer
; CHECK-NEXT: [[TMP12:%.*]] = zext i32 [[TMP27]] to i64
; CHECK-NEXT: [[TMP16:%.*]] = mul i64 3, [[TMP12]]
; CHECK-NEXT: [[DOTSPLATINSERT:%.*]] = insertelement <vscale x 8 x i64> poison, i64 [[TMP16]], i64 0
; CHECK-NEXT: [[DOTSPLAT:%.*]] = shufflevector <vscale x 8 x i64> [[DOTSPLATINSERT]], <vscale x 8 x i64> poison, <vscale x 8 x i32> zeroinitializer
; CHECK-NEXT: [[TMP14:%.*]] = call <vscale x 8 x i32> @llvm.stepvector.nxv8i32()
; CHECK-NEXT: [[TMP15:%.*]] = icmp ult <vscale x 8 x i32> [[TMP14]], [[BROADCAST_SPLAT4]]
; CHECK-NEXT: [[TMP20:%.*]] = getelementptr i16, ptr [[SRC]], <vscale x 8 x i64> [[VEC_IND]]
; CHECK-NEXT: [[WIDE_MASKED_GATHER:%.*]] = call <vscale x 8 x i16> @llvm.vp.gather.nxv8i16.nxv8p0(<vscale x 8 x ptr> align 2 [[TMP20]], <vscale x 8 x i1> splat (i1 true), i32 [[TMP27]])
; CHECK-NEXT: [[TMP17:%.*]] = icmp eq <vscale x 8 x i16> [[WIDE_MASKED_GATHER]], zeroinitializer
; CHECK-NEXT: [[TMP18:%.*]] = select <vscale x 8 x i1> [[TMP15]], <vscale x 8 x i1> [[TMP17]], <vscale x 8 x i1> zeroinitializer
; CHECK-NEXT: [[TMP19:%.*]] = select <vscale x 8 x i1> [[TMP18]], <vscale x 8 x i1> [[TMP8]], <vscale x 8 x i1> zeroinitializer
; CHECK-NEXT: [[TMP29:%.*]] = select <vscale x 8 x i1> [[TMP17]], <vscale x 8 x i1> [[TMP8]], <vscale x 8 x i1> zeroinitializer
; CHECK-NEXT: [[TMP28:%.*]] = xor <vscale x 8 x i1> [[TMP17]], splat (i1 true)
; CHECK-NEXT: [[TMP21:%.*]] = select <vscale x 8 x i1> [[TMP15]], <vscale x 8 x i1> [[TMP28]], <vscale x 8 x i1> zeroinitializer
; CHECK-NEXT: [[TMP22:%.*]] = or <vscale x 8 x i1> [[TMP19]], [[TMP21]]
; CHECK-NEXT: [[TMP23:%.*]] = select <vscale x 8 x i1> [[TMP18]], <vscale x 8 x i1> [[BROADCAST_SPLAT]], <vscale x 8 x i1> zeroinitializer
; CHECK-NEXT: [[TMP22:%.*]] = or <vscale x 8 x i1> [[TMP29]], [[TMP28]]
; CHECK-NEXT: [[TMP23:%.*]] = select <vscale x 8 x i1> [[TMP17]], <vscale x 8 x i1> [[BROADCAST_SPLAT]], <vscale x 8 x i1> zeroinitializer
; CHECK-NEXT: [[TMP24:%.*]] = or <vscale x 8 x i1> [[TMP22]], [[TMP23]]
; CHECK-NEXT: call void @llvm.vp.scatter.nxv8i16.nxv8p0(<vscale x 8 x i16> zeroinitializer, <vscale x 8 x ptr> align 2 [[TMP20]], <vscale x 8 x i1> [[TMP24]], i32 [[TMP27]])
; CHECK-NEXT: [[TMP25:%.*]] = zext i32 [[TMP27]] to i64
Expand Down
11 changes: 5 additions & 6 deletions ...t/Transforms/LoopVectorize/RISCV/pr87378-vpinstruction-or-drop-poison-generating-flags.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -34,17 +34,16 @@ define void @pr87378_vpinstruction_or_drop_poison_generating_flags(ptr %arg, i64
; CHECK-NEXT: [[TMP10:%.*]] = call <vscale x 8 x i32> @llvm.stepvector.nxv8i32()
; CHECK-NEXT: [[TMP11:%.*]] = icmp ult <vscale x 8 x i32> [[TMP10]], [[BROADCAST_SPLAT8]]
; CHECK-NEXT: [[TMP13:%.*]] = icmp ule <vscale x 8 x i64> [[VEC_IND]], [[BROADCAST_SPLAT]]
; CHECK-NEXT: [[TMP28:%.*]] = select <vscale x 8 x i1> [[TMP11]], <vscale x 8 x i1> [[TMP13]], <vscale x 8 x i1> zeroinitializer
; CHECK-NEXT: [[TMP14:%.*]] = icmp ule <vscale x 8 x i64> [[VEC_IND]], [[BROADCAST_SPLAT2]]
; CHECK-NEXT: [[TMP15:%.*]] = select <vscale x 8 x i1> [[TMP28]], <vscale x 8 x i1> [[TMP14]], <vscale x 8 x i1> zeroinitializer
; CHECK-NEXT: [[TMP9:%.*]] = select <vscale x 8 x i1> [[TMP13]], <vscale x 8 x i1> [[TMP14]], <vscale x 8 x i1> zeroinitializer
; CHECK-NEXT: [[TMP16:%.*]] = xor <vscale x 8 x i1> [[TMP13]], splat (i1 true)
; CHECK-NEXT: [[TMP29:%.*]] = select <vscale x 8 x i1> [[TMP11]], <vscale x 8 x i1> [[TMP16]], <vscale x 8 x i1> zeroinitializer
; CHECK-NEXT: [[TMP17:%.*]] = or <vscale x 8 x i1> [[TMP15]], [[TMP29]]
; CHECK-NEXT: [[TMP17:%.*]] = or <vscale x 8 x i1> [[TMP9]], [[TMP16]]
; CHECK-NEXT: [[TMP18:%.*]] = icmp ule <vscale x 8 x i64> [[VEC_IND]], [[BROADCAST_SPLAT4]]
; CHECK-NEXT: [[TMP19:%.*]] = select <vscale x 8 x i1> [[TMP17]], <vscale x 8 x i1> [[TMP18]], <vscale x 8 x i1> zeroinitializer
; CHECK-NEXT: [[TMP20:%.*]] = xor <vscale x 8 x i1> [[TMP14]], splat (i1 true)
; CHECK-NEXT: [[TMP21:%.*]] = select <vscale x 8 x i1> [[TMP28]], <vscale x 8 x i1> [[TMP20]], <vscale x 8 x i1> zeroinitializer
; CHECK-NEXT: [[TMP22:%.*]] = or <vscale x 8 x i1> [[TMP19]], [[TMP21]]
; CHECK-NEXT: [[TMP28:%.*]] = select <vscale x 8 x i1> [[TMP13]], <vscale x 8 x i1> [[TMP20]], <vscale x 8 x i1> zeroinitializer
; CHECK-NEXT: [[TMP21:%.*]] = select <vscale x 8 x i1> [[TMP11]], <vscale x 8 x i1> [[TMP28]], <vscale x 8 x i1> zeroinitializer
; CHECK-NEXT: [[TMP22:%.*]] = or <vscale x 8 x i1> [[TMP19]], [[TMP28]]
; CHECK-NEXT: [[TMP23:%.*]] = extractelement <vscale x 8 x i1> [[TMP21]], i32 0
; CHECK-NEXT: [[PREDPHI:%.*]] = select i1 [[TMP23]], i64 poison, i64 [[INDEX]]
; CHECK-NEXT: [[TMP24:%.*]] = getelementptr i16, ptr [[ARG]], i64 [[PREDPHI]]
Expand Down
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