[llvm] fd26708 - [VPlan] Refactor VPlan creation, add transform introducing region (NFC). (#128419)
via llvm-commits
llvm-commits at lists.llvm.org
Sun Mar 9 08:05:39 PDT 2025
Author: Florian Hahn
Date: 2025-03-09T15:05:35Z
New Revision: fd267082ee6df24aa5d5b4d7790c08a9d50a26b7
URL: https://github.com/llvm/llvm-project/commit/fd267082ee6df24aa5d5b4d7790c08a9d50a26b7
DIFF: https://github.com/llvm/llvm-project/commit/fd267082ee6df24aa5d5b4d7790c08a9d50a26b7.diff
LOG: [VPlan] Refactor VPlan creation, add transform introducing region (NFC). (#128419)
Create an empty VPlan first, then let the HCFG builder create a plain
CFG for the top-level loop (w/o a top-level region). The top-level
region is introduced by a separate VPlan-transform. This is instead of
creating the vector loop region before building the VPlan CFG for the
input loop.
This simplifies the HCFG builder (which should probably be renamed) and
moves along the roadmap ('buildLoop') outlined in [1].
As follow-up, I plan to also preserve the exit branches in the initial
VPlan out of the CFG builder, including connections to the exit blocks.
The conversion from plain CFG with potentially multiple exits to a
single entry/exit region will be done as VPlan transform in a follow-up.
This is needed to enable VPlan-based predication. Currently early exit
support relies on building the block-in masks on the original CFG,
because exiting branches and conditions aren't preserved in the VPlan.
So in order to switch to VPlan-based predication, we will have to
preserve them in the initial plain CFG, so the exit conditions are
available explicitly when we convert to single entry/exit regions.
Another follow-up is updating the outer loop handling to also introduce
VPRegionBlocks for nested loops as transform. Currently the existing
logic in the builder will take care of creating VPRegionBlocks for
nested loops, but not the top-level loop.
[1]
https://llvm.org/devmtg/2023-10/slides/techtalks/Hahn-VPlan-StatusUpdateAndRoadmap.pdf
PR: https://github.com/llvm/llvm-project/pull/128419
Added:
llvm/lib/Transforms/Vectorize/VPlanConstruction.cpp
Modified:
llvm/lib/Transforms/Vectorize/CMakeLists.txt
llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
llvm/lib/Transforms/Vectorize/VPlan.cpp
llvm/lib/Transforms/Vectorize/VPlan.h
llvm/lib/Transforms/Vectorize/VPlanHCFGBuilder.cpp
llvm/lib/Transforms/Vectorize/VPlanTransforms.h
llvm/test/Transforms/LoopVectorize/outer_loop_hcfg_construction.ll
llvm/test/Transforms/LoopVectorize/vplan-printing-outer-loop.ll
llvm/unittests/Transforms/Vectorize/VPlanTestBase.h
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/Vectorize/CMakeLists.txt b/llvm/lib/Transforms/Vectorize/CMakeLists.txt
index f8d08b980edb0..7dac6d0059b26 100644
--- a/llvm/lib/Transforms/Vectorize/CMakeLists.txt
+++ b/llvm/lib/Transforms/Vectorize/CMakeLists.txt
@@ -23,6 +23,7 @@ add_llvm_component_library(LLVMVectorize
VectorCombine.cpp
VPlan.cpp
VPlanAnalysis.cpp
+ VPlanConstruction.cpp
VPlanHCFGBuilder.cpp
VPlanRecipes.cpp
VPlanSLP.cpp
diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index 74ddf906ff9fd..b987863127994 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -9312,14 +9312,17 @@ LoopVectorizationPlanner::tryToBuildVPlanWithVPRecipes(VFRange &Range) {
return !CM.requiresScalarEpilogue(VF.isVector());
},
Range);
- VPlanPtr Plan = VPlan::createInitialVPlan(Legal->getWidestInductionType(),
- PSE, RequiresScalarEpilogueCheck,
- CM.foldTailByMasking(), OrigLoop);
-
+ auto Plan = std::make_unique<VPlan>(OrigLoop);
// Build hierarchical CFG.
+ // Convert to VPlan-transform and consoliate all transforms for VPlan
+ // creation.
VPlanHCFGBuilder HCFGBuilder(OrigLoop, LI, *Plan);
HCFGBuilder.buildHierarchicalCFG();
+ VPlanTransforms::introduceTopLevelVectorLoopRegion(
+ *Plan, Legal->getWidestInductionType(), PSE, RequiresScalarEpilogueCheck,
+ CM.foldTailByMasking(), OrigLoop);
+
// Don't use getDecisionAndClampRange here, because we don't know the UF
// so this function is better to be conservative, rather than to split
// it up into
diff erent VPlans.
@@ -9615,13 +9618,14 @@ VPlanPtr LoopVectorizationPlanner::buildVPlan(VFRange &Range) {
assert(EnableVPlanNativePath && "VPlan-native path is not enabled.");
// Create new empty VPlan
- auto Plan = VPlan::createInitialVPlan(Legal->getWidestInductionType(), PSE,
- true, false, OrigLoop);
-
+ auto Plan = std::make_unique<VPlan>(OrigLoop);
// Build hierarchical CFG
VPlanHCFGBuilder HCFGBuilder(OrigLoop, LI, *Plan);
HCFGBuilder.buildHierarchicalCFG();
+ VPlanTransforms::introduceTopLevelVectorLoopRegion(
+ *Plan, Legal->getWidestInductionType(), PSE, true, false, OrigLoop);
+
for (ElementCount VF : Range)
Plan->addVF(VF);
diff --git a/llvm/lib/Transforms/Vectorize/VPlan.cpp b/llvm/lib/Transforms/Vectorize/VPlan.cpp
index 563784e4af924..944a11b96325d 100644
--- a/llvm/lib/Transforms/Vectorize/VPlan.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlan.cpp
@@ -880,85 +880,6 @@ VPlan::~VPlan() {
delete BackedgeTakenCount;
}
-VPlanPtr VPlan::createInitialVPlan(Type *InductionTy,
- PredicatedScalarEvolution &PSE,
- bool RequiresScalarEpilogueCheck,
- bool TailFolded, Loop *TheLoop) {
- auto Plan = std::make_unique<VPlan>(TheLoop);
- VPBlockBase *ScalarHeader = Plan->getScalarHeader();
-
- // Connect entry only to vector preheader initially. Entry will also be
- // connected to the scalar preheader later, during skeleton creation when
- // runtime guards are added as needed. Note that when executing the VPlan for
- // an epilogue vector loop, the original entry block here will be replaced by
- // a new VPIRBasicBlock wrapping the entry to the epilogue vector loop after
- // generating code for the main vector loop.
- VPBasicBlock *VecPreheader = Plan->createVPBasicBlock("vector.ph");
- VPBlockUtils::connectBlocks(Plan->getEntry(), VecPreheader);
-
- // Create SCEV and VPValue for the trip count.
- // We use the symbolic max backedge-taken-count, which works also when
- // vectorizing loops with uncountable early exits.
- const SCEV *BackedgeTakenCountSCEV = PSE.getSymbolicMaxBackedgeTakenCount();
- assert(!isa<SCEVCouldNotCompute>(BackedgeTakenCountSCEV) &&
- "Invalid loop count");
- ScalarEvolution &SE = *PSE.getSE();
- const SCEV *TripCount = SE.getTripCountFromExitCount(BackedgeTakenCountSCEV,
- InductionTy, TheLoop);
- Plan->TripCount =
- vputils::getOrCreateVPValueForSCEVExpr(*Plan, TripCount, SE);
-
- // Create VPRegionBlock, with empty header and latch blocks, to be filled
- // during processing later.
- VPBasicBlock *HeaderVPBB = Plan->createVPBasicBlock("vector.body");
- VPBasicBlock *LatchVPBB = Plan->createVPBasicBlock("vector.latch");
- VPBlockUtils::insertBlockAfter(LatchVPBB, HeaderVPBB);
- auto *TopRegion = Plan->createVPRegionBlock(
- HeaderVPBB, LatchVPBB, "vector loop", false /*isReplicator*/);
-
- VPBlockUtils::insertBlockAfter(TopRegion, VecPreheader);
- VPBasicBlock *MiddleVPBB = Plan->createVPBasicBlock("middle.block");
- VPBlockUtils::insertBlockAfter(MiddleVPBB, TopRegion);
-
- VPBasicBlock *ScalarPH = Plan->createVPBasicBlock("scalar.ph");
- VPBlockUtils::connectBlocks(ScalarPH, ScalarHeader);
- if (!RequiresScalarEpilogueCheck) {
- VPBlockUtils::connectBlocks(MiddleVPBB, ScalarPH);
- return Plan;
- }
-
- // If needed, add a check in the middle block to see if we have completed
- // all of the iterations in the first vector loop. Three cases:
- // 1) If (N - N%VF) == N, then we *don't* need to run the remainder.
- // Thus if tail is to be folded, we know we don't need to run the
- // remainder and we can set the condition to true.
- // 2) If we require a scalar epilogue, there is no conditional branch as
- // we unconditionally branch to the scalar preheader. Do nothing.
- // 3) Otherwise, construct a runtime check.
- BasicBlock *IRExitBlock = TheLoop->getUniqueLatchExitBlock();
- VPIRBasicBlock *VPExitBlock = Plan->getExitBlock(IRExitBlock);
- // The connection order corresponds to the operands of the conditional branch.
- VPBlockUtils::insertBlockAfter(VPExitBlock, MiddleVPBB);
- VPBlockUtils::connectBlocks(MiddleVPBB, ScalarPH);
-
- auto *ScalarLatchTerm = TheLoop->getLoopLatch()->getTerminator();
- // Here we use the same DebugLoc as the scalar loop latch terminator instead
- // of the corresponding compare because they may have ended up with
- //
diff erent line numbers and we want to avoid awkward line stepping while
- // debugging. Eg. if the compare has got a line number inside the loop.
- VPBuilder Builder(MiddleVPBB);
- VPValue *Cmp =
- TailFolded
- ? Plan->getOrAddLiveIn(ConstantInt::getTrue(
- IntegerType::getInt1Ty(TripCount->getType()->getContext())))
- : Builder.createICmp(CmpInst::ICMP_EQ, Plan->getTripCount(),
- &Plan->getVectorTripCount(),
- ScalarLatchTerm->getDebugLoc(), "cmp.n");
- Builder.createNaryOp(VPInstruction::BranchOnCond, {Cmp},
- ScalarLatchTerm->getDebugLoc());
- return Plan;
-}
-
void VPlan::prepareToExecute(Value *TripCountV, Value *VectorTripCountV,
VPTransformState &State) {
Type *TCTy = TripCountV->getType();
@@ -1135,11 +1056,13 @@ void VPlan::printLiveIns(raw_ostream &O) const {
}
O << "\n";
- if (TripCount->isLiveIn())
- O << "Live-in ";
- TripCount->printAsOperand(O, SlotTracker);
- O << " = original trip-count";
- O << "\n";
+ if (TripCount) {
+ if (TripCount->isLiveIn())
+ O << "Live-in ";
+ TripCount->printAsOperand(O, SlotTracker);
+ O << " = original trip-count";
+ O << "\n";
+ }
}
LLVM_DUMP_METHOD
diff --git a/llvm/lib/Transforms/Vectorize/VPlan.h b/llvm/lib/Transforms/Vectorize/VPlan.h
index b277ed4816b8e..f68a2283c0c79 100644
--- a/llvm/lib/Transforms/Vectorize/VPlan.h
+++ b/llvm/lib/Transforms/Vectorize/VPlan.h
@@ -3503,21 +3503,6 @@ class VPlan {
VPBB->setPlan(this);
}
- /// Create initial VPlan, having an "entry" VPBasicBlock (wrapping
- /// original scalar pre-header) which contains SCEV expansions that need
- /// to happen before the CFG is modified (when executing a VPlan for the
- /// epilogue vector loop, the original entry needs to be replaced by a new
- /// one); a VPBasicBlock for the vector pre-header, followed by a region for
- /// the vector loop, followed by the middle VPBasicBlock. If a check is needed
- /// to guard executing the scalar epilogue loop, it will be added to the
- /// middle block, together with VPBasicBlocks for the scalar preheader and
- /// exit blocks. \p InductionTy is the type of the canonical induction and
- /// used for related values, like the trip count expression.
- static VPlanPtr createInitialVPlan(Type *InductionTy,
- PredicatedScalarEvolution &PSE,
- bool RequiresScalarEpilogueCheck,
- bool TailFolded, Loop *TheLoop);
-
/// Prepare the plan for execution, setting up the required live-in values.
void prepareToExecute(Value *TripCount, Value *VectorTripCount,
VPTransformState &State);
@@ -3579,11 +3564,18 @@ class VPlan {
return TripCount;
}
+ /// Set the trip count assuming it is currently null; if it is not - use
+ /// resetTripCount().
+ void setTripCount(VPValue *NewTripCount) {
+ assert(!TripCount && NewTripCount && "TripCount should not be set yet.");
+ TripCount = NewTripCount;
+ }
+
/// Resets the trip count for the VPlan. The caller must make sure all uses of
/// the original trip count have been replaced.
void resetTripCount(VPValue *NewTripCount) {
assert(TripCount && NewTripCount && TripCount->getNumUsers() == 0 &&
- "TripCount always must be set");
+ "TripCount must be set when resetting");
TripCount = NewTripCount;
}
diff --git a/llvm/lib/Transforms/Vectorize/VPlanConstruction.cpp b/llvm/lib/Transforms/Vectorize/VPlanConstruction.cpp
new file mode 100644
index 0000000000000..f58f0290b5fa9
--- /dev/null
+++ b/llvm/lib/Transforms/Vectorize/VPlanConstruction.cpp
@@ -0,0 +1,101 @@
+//===-- VPlanConstruction.cpp - Transforms for initial VPlan construction -===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file implements transforms for initial VPlan construction.
+///
+//===----------------------------------------------------------------------===//
+
+#include "LoopVectorizationPlanner.h"
+#include "VPlan.h"
+#include "VPlanCFG.h"
+#include "VPlanTransforms.h"
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Analysis/ScalarEvolution.h"
+
+using namespace llvm;
+
+void VPlanTransforms::introduceTopLevelVectorLoopRegion(
+ VPlan &Plan, Type *InductionTy, PredicatedScalarEvolution &PSE,
+ bool RequiresScalarEpilogueCheck, bool TailFolded, Loop *TheLoop) {
+ // TODO: Generalize to introduce all loop regions.
+ auto *HeaderVPBB = cast<VPBasicBlock>(Plan.getEntry()->getSingleSuccessor());
+ VPBlockUtils::disconnectBlocks(Plan.getEntry(), HeaderVPBB);
+
+ VPBasicBlock *OriginalLatch =
+ cast<VPBasicBlock>(HeaderVPBB->getSinglePredecessor());
+ VPBlockUtils::disconnectBlocks(OriginalLatch, HeaderVPBB);
+ VPBasicBlock *VecPreheader = Plan.createVPBasicBlock("vector.ph");
+ VPBlockUtils::connectBlocks(Plan.getEntry(), VecPreheader);
+ assert(OriginalLatch->getNumSuccessors() == 0 &&
+ "Plan should end at top level latch");
+
+ // Create SCEV and VPValue for the trip count.
+ // We use the symbolic max backedge-taken-count, which works also when
+ // vectorizing loops with uncountable early exits.
+ const SCEV *BackedgeTakenCountSCEV = PSE.getSymbolicMaxBackedgeTakenCount();
+ assert(!isa<SCEVCouldNotCompute>(BackedgeTakenCountSCEV) &&
+ "Invalid loop count");
+ ScalarEvolution &SE = *PSE.getSE();
+ const SCEV *TripCount = SE.getTripCountFromExitCount(BackedgeTakenCountSCEV,
+ InductionTy, TheLoop);
+ Plan.setTripCount(
+ vputils::getOrCreateVPValueForSCEVExpr(Plan, TripCount, SE));
+
+ // Create VPRegionBlock, with existing header and new empty latch block, to be
+ // filled.
+ VPBasicBlock *LatchVPBB = Plan.createVPBasicBlock("vector.latch");
+ VPBlockUtils::insertBlockAfter(LatchVPBB, OriginalLatch);
+ auto *TopRegion = Plan.createVPRegionBlock(
+ HeaderVPBB, LatchVPBB, "vector loop", false /*isReplicator*/);
+ // All VPBB's reachable shallowly from HeaderVPBB belong to top level loop,
+ // because VPlan is expected to end at top level latch.
+ for (VPBlockBase *VPBB : vp_depth_first_shallow(HeaderVPBB))
+ VPBB->setParent(TopRegion);
+
+ VPBlockUtils::insertBlockAfter(TopRegion, VecPreheader);
+ VPBasicBlock *MiddleVPBB = Plan.createVPBasicBlock("middle.block");
+ VPBlockUtils::insertBlockAfter(MiddleVPBB, TopRegion);
+
+ VPBasicBlock *ScalarPH = Plan.createVPBasicBlock("scalar.ph");
+ VPBlockUtils::connectBlocks(ScalarPH, Plan.getScalarHeader());
+ if (!RequiresScalarEpilogueCheck) {
+ VPBlockUtils::connectBlocks(MiddleVPBB, ScalarPH);
+ return;
+ }
+
+ // If needed, add a check in the middle block to see if we have completed
+ // all of the iterations in the first vector loop. Three cases:
+ // 1) If (N - N%VF) == N, then we *don't* need to run the remainder.
+ // Thus if tail is to be folded, we know we don't need to run the
+ // remainder and we can set the condition to true.
+ // 2) If we require a scalar epilogue, there is no conditional branch as
+ // we unconditionally branch to the scalar preheader. Do nothing.
+ // 3) Otherwise, construct a runtime check.
+ BasicBlock *IRExitBlock = TheLoop->getUniqueLatchExitBlock();
+ auto *VPExitBlock = Plan.getExitBlock(IRExitBlock);
+ // The connection order corresponds to the operands of the conditional branch.
+ VPBlockUtils::insertBlockAfter(VPExitBlock, MiddleVPBB);
+ VPBlockUtils::connectBlocks(MiddleVPBB, ScalarPH);
+
+ auto *ScalarLatchTerm = TheLoop->getLoopLatch()->getTerminator();
+ // Here we use the same DebugLoc as the scalar loop latch terminator instead
+ // of the corresponding compare because they may have ended up with
+ //
diff erent line numbers and we want to avoid awkward line stepping while
+ // debugging. Eg. if the compare has got a line number inside the loop.
+ VPBuilder Builder(MiddleVPBB);
+ VPValue *Cmp =
+ TailFolded
+ ? Plan.getOrAddLiveIn(ConstantInt::getTrue(
+ IntegerType::getInt1Ty(TripCount->getType()->getContext())))
+ : Builder.createICmp(CmpInst::ICMP_EQ, Plan.getTripCount(),
+ &Plan.getVectorTripCount(),
+ ScalarLatchTerm->getDebugLoc(), "cmp.n");
+ Builder.createNaryOp(VPInstruction::BranchOnCond, {Cmp},
+ ScalarLatchTerm->getDebugLoc());
+}
diff --git a/llvm/lib/Transforms/Vectorize/VPlanHCFGBuilder.cpp b/llvm/lib/Transforms/Vectorize/VPlanHCFGBuilder.cpp
index a5e8e852bace8..4b8a2420b3037 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanHCFGBuilder.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanHCFGBuilder.cpp
@@ -23,6 +23,7 @@
#include "VPlanHCFGBuilder.h"
#include "LoopVectorizationPlanner.h"
+#include "VPlanCFG.h"
#include "llvm/Analysis/LoopIterator.h"
#define DEBUG_TYPE "loop-vectorize"
@@ -178,9 +179,10 @@ VPBasicBlock *PlainCFGBuilder::getOrCreateVPBB(BasicBlock *BB) {
VPBasicBlock *VPBB = Plan.createVPBasicBlock(Name);
BB2VPBB[BB] = VPBB;
- // Get or create a region for the loop containing BB.
+ // Get or create a region for the loop containing BB, except for the top
+ // region of TheLoop which is created later.
Loop *LoopOfBB = LI->getLoopFor(BB);
- if (!LoopOfBB || !doesContainLoop(LoopOfBB, TheLoop))
+ if (!LoopOfBB || LoopOfBB == TheLoop || !doesContainLoop(LoopOfBB, TheLoop))
return VPBB;
auto *RegionOfVPBB = Loop2Region.lookup(LoopOfBB);
@@ -194,12 +196,8 @@ VPBasicBlock *PlainCFGBuilder::getOrCreateVPBB(BasicBlock *BB) {
assert(!RegionOfVPBB &&
"First visit of a header basic block expects to register its region.");
// Handle a header - take care of its Region.
- if (LoopOfBB == TheLoop) {
- RegionOfVPBB = Plan.getVectorLoopRegion();
- } else {
- RegionOfVPBB = Plan.createVPRegionBlock(Name.str(), false /*isReplicator*/);
- RegionOfVPBB->setParent(Loop2Region[LoopOfBB->getParentLoop()]);
- }
+ RegionOfVPBB = Plan.createVPRegionBlock(Name.str(), false /*isReplicator*/);
+ RegionOfVPBB->setParent(Loop2Region[LoopOfBB->getParentLoop()]);
RegionOfVPBB->setEntry(VPBB);
Loop2Region[LoopOfBB] = RegionOfVPBB;
return VPBB;
@@ -353,29 +351,6 @@ void PlainCFGBuilder::createVPInstructionsForVPBB(VPBasicBlock *VPBB,
// Main interface to build the plain CFG.
void PlainCFGBuilder::buildPlainCFG(
DenseMap<VPBlockBase *, BasicBlock *> &VPB2IRBB) {
- // 0. Reuse the top-level region, vector-preheader and exit VPBBs from the
- // skeleton. These were created directly rather than via getOrCreateVPBB(),
- // revisit them now to update BB2VPBB. Note that header/entry and
- // latch/exiting VPBB's of top-level region have yet to be created.
- VPRegionBlock *TheRegion = Plan.getVectorLoopRegion();
- BasicBlock *ThePreheaderBB = TheLoop->getLoopPreheader();
- assert((ThePreheaderBB->getTerminator()->getNumSuccessors() == 1) &&
- "Unexpected loop preheader");
- auto *VectorPreheaderVPBB =
- cast<VPBasicBlock>(TheRegion->getSinglePredecessor());
- // ThePreheaderBB conceptually corresponds to both Plan.getPreheader() (which
- // wraps the original preheader BB) and Plan.getEntry() (which represents the
- // new vector preheader); here we're interested in setting BB2VPBB to the
- // latter.
- BB2VPBB[ThePreheaderBB] = VectorPreheaderVPBB;
- Loop2Region[LI->getLoopFor(TheLoop->getHeader())] = TheRegion;
-
- // The existing vector region's entry and exiting VPBBs correspond to the loop
- // header and latch.
- VPBasicBlock *VectorHeaderVPBB = TheRegion->getEntryBasicBlock();
- VPBasicBlock *VectorLatchVPBB = TheRegion->getExitingBasicBlock();
- BB2VPBB[TheLoop->getHeader()] = VectorHeaderVPBB;
- VectorHeaderVPBB->clearSuccessors();
// 1. Scan the body of the loop in a topological order to visit each basic
// block after having visited its predecessor basic blocks. Create a VPBB for
@@ -386,6 +361,9 @@ void PlainCFGBuilder::buildPlainCFG(
// Loop PH needs to be explicitly visited since it's not taken into account by
// LoopBlocksDFS.
+ BasicBlock *ThePreheaderBB = TheLoop->getLoopPreheader();
+ assert((ThePreheaderBB->getTerminator()->getNumSuccessors() == 1) &&
+ "Unexpected loop preheader");
for (auto &I : *ThePreheaderBB) {
if (I.getType()->isVoidTy())
continue;
@@ -403,21 +381,18 @@ void PlainCFGBuilder::buildPlainCFG(
// Set VPBB predecessors in the same order as they are in the incoming BB.
if (!isHeaderBB(BB, LoopForBB)) {
setVPBBPredsFromBB(VPBB, BB);
- } else {
- // BB is a loop header, set the predecessor for the region, except for the
- // top region, whose predecessor was set when creating VPlan's skeleton.
- assert(isHeaderVPBB(VPBB) && "isHeaderBB and isHeaderVPBB disagree");
- if (TheRegion != Region)
- setRegionPredsFromBB(Region, BB);
+ } else if (Region) {
+ // BB is a loop header and there's a corresponding region, set the
+ // predecessor for it.
+ setRegionPredsFromBB(Region, BB);
}
// Create VPInstructions for BB.
createVPInstructionsForVPBB(VPBB, BB);
- if (TheLoop->getLoopLatch() == BB) {
- VPBB->setOneSuccessor(VectorLatchVPBB);
- VectorLatchVPBB->clearPredecessors();
- VectorLatchVPBB->setPredecessors({VPBB});
+ if (BB == TheLoop->getLoopLatch()) {
+ VPBasicBlock *HeaderVPBB = getOrCreateVPBB(LoopForBB->getHeader());
+ VPBlockUtils::connectBlocks(VPBB, HeaderVPBB);
continue;
}
@@ -451,9 +426,8 @@ void PlainCFGBuilder::buildPlainCFG(
if (BB == LoopForBB->getLoopLatch()) {
// For a latch we need to set the successor of the region rather than that
// of VPBB and it should be set to the exit, i.e., non-header successor,
- // except for the top region, whose successor was set when creating
- // VPlan's skeleton.
- assert(TheRegion != Region &&
+ // except for the top region, which is handled elsewhere.
+ assert(LoopForBB != TheLoop &&
"Latch of the top region should have been handled earlier");
Region->setOneSuccessor(isHeaderVPBB(Successor0) ? Successor1
: Successor0);
@@ -482,6 +456,9 @@ void PlainCFGBuilder::buildPlainCFG(
// corresponding VPlan operands.
fixHeaderPhis();
+ VPBlockUtils::connectBlocks(Plan.getEntry(),
+ getOrCreateVPBB(TheLoop->getHeader()));
+
for (const auto &[IRBB, VPB] : BB2VPBB)
VPB2IRBB[VPB] = IRBB;
}
diff --git a/llvm/lib/Transforms/Vectorize/VPlanTransforms.h b/llvm/lib/Transforms/Vectorize/VPlanTransforms.h
index a48bf31cd0af3..8a9a81e00fe23 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanTransforms.h
+++ b/llvm/lib/Transforms/Vectorize/VPlanTransforms.h
@@ -52,6 +52,21 @@ struct VPlanTransforms {
verifyVPlanIsValid(Plan);
}
+ /// Introduce the top-level VPRegionBlock for the main loop in \p Plan. Coming
+ /// into this function, \p Plan's top-level loop is modeled using a plain CFG.
+ /// This transform wraps the plain CFG of the top-level loop within a
+ /// VPRegionBlock and creates a VPValue expression for the original trip
+ /// count. It will also introduce a dedicated VPBasicBlock for the vector
+ /// pre-header as well a VPBasicBlock as exit block of the region
+ /// (middle.block). If a check is needed to guard executing the scalar
+ /// epilogue loop, it will be added to the middle block, together with
+ /// VPBasicBlocks for the scalar preheader and exit blocks. \p InductionTy is
+ /// the type of the canonical induction and used for related values, like the
+ /// trip count expression.
+ static void introduceTopLevelVectorLoopRegion(
+ VPlan &Plan, Type *InductionTy, PredicatedScalarEvolution &PSE,
+ bool RequiresScalarEpilogueCheck, bool TailFolded, Loop *TheLoop);
+
/// Replaces the VPInstructions in \p Plan with corresponding
/// widen recipes.
static void
diff --git a/llvm/test/Transforms/LoopVectorize/outer_loop_hcfg_construction.ll b/llvm/test/Transforms/LoopVectorize/outer_loop_hcfg_construction.ll
index 4e5fc3126435d..7e90724744fb3 100644
--- a/llvm/test/Transforms/LoopVectorize/outer_loop_hcfg_construction.ll
+++ b/llvm/test/Transforms/LoopVectorize/outer_loop_hcfg_construction.ll
@@ -32,10 +32,10 @@ define void @non_outermost_loop_hcfg_construction(i64 %n, ptr %a) {
; CHECK: vector.ph:
; CHECK-NEXT: [[N_MOD_VF:%.*]] = urem i64 [[N]], 4
; CHECK-NEXT: [[N_VEC:%.*]] = sub i64 [[N]], [[N_MOD_VF]]
-; CHECK-NEXT: [[BROADCAST_SPLATINSERT2:%.*]] = insertelement <4 x i64> poison, i64 [[N]], i64 0
-; CHECK-NEXT: [[BROADCAST_SPLAT3:%.*]] = shufflevector <4 x i64> [[BROADCAST_SPLATINSERT2]], <4 x i64> poison, <4 x i32> zeroinitializer
; CHECK-NEXT: [[BROADCAST_SPLATINSERT:%.*]] = insertelement <4 x i32> poison, i32 [[TMP2]], i64 0
; CHECK-NEXT: [[BROADCAST_SPLAT:%.*]] = shufflevector <4 x i32> [[BROADCAST_SPLATINSERT]], <4 x i32> poison, <4 x i32> zeroinitializer
+; CHECK-NEXT: [[BROADCAST_SPLATINSERT2:%.*]] = insertelement <4 x i64> poison, i64 [[N]], i64 0
+; CHECK-NEXT: [[BROADCAST_SPLAT3:%.*]] = shufflevector <4 x i64> [[BROADCAST_SPLATINSERT2]], <4 x i64> poison, <4 x i32> zeroinitializer
; CHECK-NEXT: br label [[VECTOR_BODY:%.*]]
; CHECK: vector.body:
; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[MIDDLE_LOOP_LATCH4:%.*]] ]
@@ -173,10 +173,10 @@ define void @non_outermost_loop_hcfg_construction_other_loops_at_same_level(i64
; CHECK: vector.ph:
; CHECK-NEXT: [[N_MOD_VF:%.*]] = urem i64 [[N]], 4
; CHECK-NEXT: [[N_VEC:%.*]] = sub i64 [[N]], [[N_MOD_VF]]
-; CHECK-NEXT: [[BROADCAST_SPLATINSERT2:%.*]] = insertelement <4 x i64> poison, i64 [[N]], i64 0
-; CHECK-NEXT: [[BROADCAST_SPLAT3:%.*]] = shufflevector <4 x i64> [[BROADCAST_SPLATINSERT2]], <4 x i64> poison, <4 x i32> zeroinitializer
; CHECK-NEXT: [[BROADCAST_SPLATINSERT:%.*]] = insertelement <4 x i64> poison, i64 [[ADD]], i64 0
; CHECK-NEXT: [[BROADCAST_SPLAT:%.*]] = shufflevector <4 x i64> [[BROADCAST_SPLATINSERT]], <4 x i64> poison, <4 x i32> zeroinitializer
+; CHECK-NEXT: [[BROADCAST_SPLATINSERT2:%.*]] = insertelement <4 x i64> poison, i64 [[N]], i64 0
+; CHECK-NEXT: [[BROADCAST_SPLAT3:%.*]] = shufflevector <4 x i64> [[BROADCAST_SPLATINSERT2]], <4 x i64> poison, <4 x i32> zeroinitializer
; CHECK-NEXT: br label [[VECTOR_BODY:%.*]]
; CHECK: vector.body:
; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[MIDDLE_LOOP_J0_CLEANUP4:%.*]] ]
diff --git a/llvm/test/Transforms/LoopVectorize/vplan-printing-outer-loop.ll b/llvm/test/Transforms/LoopVectorize/vplan-printing-outer-loop.ll
index 52b2bcd9aac11..625a32c098f94 100644
--- a/llvm/test/Transforms/LoopVectorize/vplan-printing-outer-loop.ll
+++ b/llvm/test/Transforms/LoopVectorize/vplan-printing-outer-loop.ll
@@ -8,62 +8,33 @@
define void @foo(i64 %n) {
; CHECK: VPlan 'HCFGBuilder: Plain CFG
; CHECK-NEXT: {
-; CHECK-NEXT: Live-in vp<[[VTC:%.+]]> = vector-trip-count
-; CHECK-NEXT: Live-in ir<8> = original trip-count
; CHECK-EMPTY:
; CHECK-NEXT: ir-bb<entry>:
-; CHECK-NEXT: Successor(s): vector.ph
+; CHECK-NEXT: Successor(s): vector.body
; CHECK-EMPTY:
-; CHECK-NEXT: vector.ph:
-; CHECK-NEXT: Successor(s): vector loop
+; CHECK-NEXT: vector.body:
+; CHECK-NEXT: WIDEN-PHI ir<%outer.iv> = phi ir<0>, ir<%outer.iv.next>
+; CHECK-NEXT: EMIT ir<%gep.1> = getelementptr ir<@arr2>, ir<0>, ir<%outer.iv>
+; CHECK-NEXT: EMIT store ir<%outer.iv>, ir<%gep.1>
+; CHECK-NEXT: EMIT ir<%add> = add ir<%outer.iv>, ir<%n>
+; CHECK-NEXT: Successor(s): inner
; CHECK-EMPTY:
-; CHECK-NEXT: <x1> vector loop: {
-; CHECK-NEXT: vector.body:
-; CHECK-NEXT: WIDEN-PHI ir<%outer.iv> = phi ir<0>, ir<%outer.iv.next>
-; CHECK-NEXT: EMIT ir<%gep.1> = getelementptr ir<@arr2>, ir<0>, ir<%outer.iv>
-; CHECK-NEXT: EMIT store ir<%outer.iv>, ir<%gep.1>
-; CHECK-NEXT: EMIT ir<%add> = add ir<%outer.iv>, ir<%n>
-; CHECK-NEXT: Successor(s): inner
-; CHECK-EMPTY:
-; CHECK-NEXT: <x1> inner: {
-; CHECK-NEXT: inner:
-; CHECK-NEXT: WIDEN-PHI ir<%inner.iv> = phi ir<0>, ir<%inner.iv.next>
-; CHECK-NEXT: EMIT ir<%gep.2> = getelementptr ir<@arr>, ir<0>, ir<%inner.iv>, ir<%outer.iv>
-; CHECK-NEXT: EMIT store ir<%add>, ir<%gep.2>
-; CHECK-NEXT: EMIT ir<%inner.iv.next> = add ir<%inner.iv>, ir<1>
-; CHECK-NEXT: EMIT ir<%inner.ec> = icmp ir<%inner.iv.next>, ir<8>
-; CHECK-NEXT: EMIT branch-on-cond ir<%inner.ec>
-; CHECK-NEXT: No successors
-; CHECK-NEXT: }
-; CHECK-NEXT: Successor(s): outer.latch
-; CHECK-EMPTY:
-; CHECK-NEXT: outer.latch:
-; CHECK-NEXT: EMIT ir<%outer.iv.next> = add ir<%outer.iv>, ir<1>
-; CHECK-NEXT: EMIT ir<%outer.ec> = icmp ir<%outer.iv.next>, ir<8>
-; CHECK-NEXT: Successor(s): vector.latch
-; CHECK-EMPTY:
-; CHECK-NEXT: vector.latch:
+; CHECK-NEXT: <x1> inner: {
+; CHECK-NEXT: inner:
+; CHECK-NEXT: WIDEN-PHI ir<%inner.iv> = phi ir<0>, ir<%inner.iv.next>
+; CHECK-NEXT: EMIT ir<%gep.2> = getelementptr ir<@arr>, ir<0>, ir<%inner.iv>, ir<%outer.iv>
+; CHECK-NEXT: EMIT store ir<%add>, ir<%gep.2>
+; CHECK-NEXT: EMIT ir<%inner.iv.next> = add ir<%inner.iv>, ir<1>
+; CHECK-NEXT: EMIT ir<%inner.ec> = icmp ir<%inner.iv.next>, ir<8>
+; CHECK-NEXT: EMIT branch-on-cond ir<%inner.ec>
; CHECK-NEXT: No successors
-; CHECK-NEXT: }
-; CHECK-NEXT: Successor(s): middle.block
-; CHECK-EMPTY:
-; CHECK-NEXT: middle.block:
-; CHECK-NEXT: EMIT vp<[[C:%.+]]> = icmp eq ir<8>, vp<[[VTC]]>
-; CHECK-NEXT: EMIT branch-on-cond vp<[[C]]>
-; CHECK-NEXT: Successor(s): ir-bb<exit>, scalar.ph
-; CHECK-EMPTY:
-; CHECK-NEXT: scalar.ph:
-; CHECK-NEXT: Successor(s): ir-bb<outer.header>
-; CHECK-EMPTY:
-; CHECK-NEXT: ir-bb<outer.header>:
-; CHECK-NEXT: IR %outer.iv = phi i64 [ 0, %entry ], [ %outer.iv.next, %outer.latch ]
-; CHECK-NEXT: IR %gep.1 = getelementptr inbounds [8 x i64], ptr @arr2, i64 0, i64 %outer.iv
-; CHECK-NEXT: IR store i64 %outer.iv, ptr %gep.1, align 4
-; CHECK-NEXT: IR %add = add nsw i64 %outer.iv, %n
-; CHECK-NEXT: No successors
+; CHECK-NEXT: }
+; CHECK-NEXT: Successor(s): outer.latch
; CHECK-EMPTY:
-; CHECK-NEXT: ir-bb<exit>:
-; CHECK-NEXT: No successors
+; CHECK-NEXT: outer.latch:
+; CHECK-NEXT: EMIT ir<%outer.iv.next> = add ir<%outer.iv>, ir<1>
+; CHECK-NEXT: EMIT ir<%outer.ec> = icmp ir<%outer.iv.next>, ir<8>
+; CHECK-NEXT: Successor(s): vector.body
; CHECK-NEXT: }
entry:
br label %outer.header
diff --git a/llvm/unittests/Transforms/Vectorize/VPlanTestBase.h b/llvm/unittests/Transforms/Vectorize/VPlanTestBase.h
index 8d03e91fb26c3..caf5d2357411d 100644
--- a/llvm/unittests/Transforms/Vectorize/VPlanTestBase.h
+++ b/llvm/unittests/Transforms/Vectorize/VPlanTestBase.h
@@ -14,6 +14,7 @@
#include "../lib/Transforms/Vectorize/VPlan.h"
#include "../lib/Transforms/Vectorize/VPlanHCFGBuilder.h"
+#include "../lib/Transforms/Vectorize/VPlanTransforms.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/BasicAliasAnalysis.h"
#include "llvm/Analysis/LoopInfo.h"
@@ -70,10 +71,11 @@ class VPlanTestIRBase : public testing::Test {
Loop *L = LI->getLoopFor(LoopHeader);
PredicatedScalarEvolution PSE(*SE, *L);
- auto Plan = VPlan::createInitialVPlan(IntegerType::get(*Ctx, 64), PSE, true,
- false, L);
+ auto Plan = std::make_unique<VPlan>(L);
VPlanHCFGBuilder HCFGBuilder(L, LI.get(), *Plan);
HCFGBuilder.buildHierarchicalCFG();
+ VPlanTransforms::introduceTopLevelVectorLoopRegion(
+ *Plan, IntegerType::get(*Ctx, 64), PSE, true, false, L);
return Plan;
}
};
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