[llvm] [LV] Update incoming blocks in VPWidenPHIRecipe in reassociateBlocks (PR #125481)
Luke Lau via llvm-commits
llvm-commits at lists.llvm.org
Mon Feb 3 07:07:48 PST 2025
https://github.com/lukel97 updated https://github.com/llvm/llvm-project/pull/125481
>From 8cfe2f2ea9c827ffb6c7619615c7bf52b80cc785 Mon Sep 17 00:00:00 2001
From: Luke Lau <luke at igalia.com>
Date: Mon, 3 Feb 2025 19:13:33 +0800
Subject: [PATCH 1/3] [LV] Update incoming blocks in VPWidenPHIRecipe in
reassociateBlocks
This is extracted from #118638
After c7ebe4f we will crash in fixNonInductionPHIs if we use a VPWidenPHIRecipe with the vector preheader as an incoming block, because the phi will reference the old non-IRBB vector preheader.
This fixes this by updating VPBlockUtils::reassociateBlocks to update any VPWidenPHIRecipes's incoming blocks.
This assumes that if the VPWidenPHIRecipe is in a VPRegionBlock, it's in the entry block, and that we are replacing a VPBasicBlock with another VPBasicBlock.
---
llvm/lib/Transforms/Vectorize/VPlan.h | 5 +++
llvm/lib/Transforms/Vectorize/VPlanUtils.h | 13 ++++++-
.../Transforms/Vectorize/VPlanTest.cpp | 39 +++++++++++++++++++
3 files changed, 56 insertions(+), 1 deletion(-)
diff --git a/llvm/lib/Transforms/Vectorize/VPlan.h b/llvm/lib/Transforms/Vectorize/VPlan.h
index 459222234bc37f5..cb58abec61c11c9 100644
--- a/llvm/lib/Transforms/Vectorize/VPlan.h
+++ b/llvm/lib/Transforms/Vectorize/VPlan.h
@@ -2347,6 +2347,11 @@ class VPWidenPHIRecipe : public VPSingleDefRecipe {
/// Returns the \p I th incoming VPBasicBlock.
VPBasicBlock *getIncomingBlock(unsigned I) { return IncomingBlocks[I]; }
+ /// Set the \p I th incoming VPBasicBlock to \p IncomingBlock.
+ void setIncomingBlock(unsigned I, VPBasicBlock *IncomingBlock) {
+ IncomingBlocks[I] = IncomingBlock;
+ }
+
/// Returns the \p I th incoming VPValue.
VPValue *getIncomingValue(unsigned I) { return getOperand(I); }
};
diff --git a/llvm/lib/Transforms/Vectorize/VPlanUtils.h b/llvm/lib/Transforms/Vectorize/VPlanUtils.h
index 6ddb88308955f1a..ddbfc50ed961596 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanUtils.h
+++ b/llvm/lib/Transforms/Vectorize/VPlanUtils.h
@@ -169,8 +169,19 @@ class VPBlockUtils {
static void reassociateBlocks(VPBlockBase *Old, VPBlockBase *New) {
for (auto *Pred : to_vector(Old->getPredecessors()))
Pred->replaceSuccessor(Old, New);
- for (auto *Succ : to_vector(Old->getSuccessors()))
+ for (auto *Succ : to_vector(Old->getSuccessors())) {
Succ->replacePredecessor(Old, New);
+
+ // Replace any references to Old in widened phi incoming blocks.
+ while (auto *Region = dyn_cast<VPRegionBlock>(Succ))
+ Succ = Region->getEntry();
+
+ for (auto &R : *cast<VPBasicBlock>(Succ))
+ if (auto *WidenPhiR = dyn_cast<VPWidenPHIRecipe>(&R))
+ for (unsigned I = 0; I < WidenPhiR->getNumOperands(); I++)
+ if (WidenPhiR->getIncomingBlock(I) == Old)
+ WidenPhiR->setIncomingBlock(I, cast<VPBasicBlock>(New));
+ }
New->setPredecessors(Old->getPredecessors());
New->setSuccessors(Old->getSuccessors());
Old->clearPredecessors();
diff --git a/llvm/unittests/Transforms/Vectorize/VPlanTest.cpp b/llvm/unittests/Transforms/Vectorize/VPlanTest.cpp
index e7987a95f1ca26a..09f111ec31a4d4c 100644
--- a/llvm/unittests/Transforms/Vectorize/VPlanTest.cpp
+++ b/llvm/unittests/Transforms/Vectorize/VPlanTest.cpp
@@ -659,6 +659,45 @@ TEST_F(VPBasicBlockTest, TraversingIteratorTest) {
}
}
+TEST_F(VPBasicBlockTest, reassociateBlocks) {
+ {
+ VPlan &Plan = getPlan();
+ VPBasicBlock *VPBB1 = Plan.createVPBasicBlock("VPBB1");
+ VPBasicBlock *VPBB2 = Plan.createVPBasicBlock("VPBB2");
+ VPBlockUtils::connectBlocks(VPBB1, VPBB2);
+
+ auto *WidenPhi = new VPWidenPHIRecipe(nullptr);
+ IntegerType *Int32 = IntegerType::get(C, 32);
+ VPValue *Val = Plan.getOrAddLiveIn(ConstantInt::get(Int32, 1));
+ WidenPhi->addIncoming(Val, VPBB1);
+ VPBB2->appendRecipe(WidenPhi);
+
+ VPBasicBlock *VPBBNew = Plan.createVPBasicBlock("VPBBNew");
+ VPBlockUtils::reassociateBlocks(VPBB1, VPBBNew);
+ EXPECT_EQ(VPBB2->getSinglePredecessor(), VPBBNew);
+ EXPECT_EQ(WidenPhi->getIncomingBlock(0), VPBBNew);
+ }
+
+ {
+ VPlan &Plan = getPlan();
+ VPBasicBlock *VPBB1 = Plan.createVPBasicBlock("VPBB1");
+ VPBasicBlock *VPBB2 = Plan.createVPBasicBlock("VPBB2");
+ VPRegionBlock *R1 = Plan.createVPRegionBlock(VPBB2, VPBB2, "R1");
+ VPBlockUtils::connectBlocks(VPBB1, R1);
+
+ auto *WidenPhi = new VPWidenPHIRecipe(nullptr);
+ IntegerType *Int32 = IntegerType::get(C, 32);
+ VPValue *Val = Plan.getOrAddLiveIn(ConstantInt::get(Int32, 1));
+ WidenPhi->addIncoming(Val, VPBB1);
+ VPBB2->appendRecipe(WidenPhi);
+
+ VPBasicBlock *VPBBNew = Plan.createVPBasicBlock("VPBBNew");
+ VPBlockUtils::reassociateBlocks(VPBB1, VPBBNew);
+ EXPECT_EQ(R1->getSinglePredecessor(), VPBBNew);
+ EXPECT_EQ(WidenPhi->getIncomingBlock(0), VPBBNew);
+ }
+}
+
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
TEST_F(VPBasicBlockTest, print) {
VPInstruction *TC = new VPInstruction(Instruction::Add, {});
>From 13e49ef452be956396fb43cf31803086fbbc4847 Mon Sep 17 00:00:00 2001
From: Luke Lau <luke at igalia.com>
Date: Mon, 3 Feb 2025 21:00:29 +0800
Subject: [PATCH 2/3] Use Succ->getEntryBasicBlock()->phis(), add comments
---
llvm/lib/Transforms/Vectorize/VPlanUtils.h | 5 +----
llvm/unittests/Transforms/Vectorize/VPlanTest.cpp | 4 ++++
2 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/llvm/lib/Transforms/Vectorize/VPlanUtils.h b/llvm/lib/Transforms/Vectorize/VPlanUtils.h
index ddbfc50ed961596..ac5e1978fcfbe00 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanUtils.h
+++ b/llvm/lib/Transforms/Vectorize/VPlanUtils.h
@@ -173,10 +173,7 @@ class VPBlockUtils {
Succ->replacePredecessor(Old, New);
// Replace any references to Old in widened phi incoming blocks.
- while (auto *Region = dyn_cast<VPRegionBlock>(Succ))
- Succ = Region->getEntry();
-
- for (auto &R : *cast<VPBasicBlock>(Succ))
+ for (auto &R : Succ->getEntryBasicBlock()->phis())
if (auto *WidenPhiR = dyn_cast<VPWidenPHIRecipe>(&R))
for (unsigned I = 0; I < WidenPhiR->getNumOperands(); I++)
if (WidenPhiR->getIncomingBlock(I) == Old)
diff --git a/llvm/unittests/Transforms/Vectorize/VPlanTest.cpp b/llvm/unittests/Transforms/Vectorize/VPlanTest.cpp
index 09f111ec31a4d4c..0b57f8084e5f432 100644
--- a/llvm/unittests/Transforms/Vectorize/VPlanTest.cpp
+++ b/llvm/unittests/Transforms/Vectorize/VPlanTest.cpp
@@ -661,6 +661,8 @@ TEST_F(VPBasicBlockTest, TraversingIteratorTest) {
TEST_F(VPBasicBlockTest, reassociateBlocks) {
{
+ // Ensure that when we reassociate a basic block, we make sure to update any
+ // references to it in VPWidenPHIRecipes' incoming blocks.
VPlan &Plan = getPlan();
VPBasicBlock *VPBB1 = Plan.createVPBasicBlock("VPBB1");
VPBasicBlock *VPBB2 = Plan.createVPBasicBlock("VPBB2");
@@ -679,6 +681,8 @@ TEST_F(VPBasicBlockTest, reassociateBlocks) {
}
{
+ // Ensure that we update VPWidenPHIRecipes that are nested inside a
+ // VPRegionBlock.
VPlan &Plan = getPlan();
VPBasicBlock *VPBB1 = Plan.createVPBasicBlock("VPBB1");
VPBasicBlock *VPBB2 = Plan.createVPBasicBlock("VPBB2");
>From 95e4fb112ec50a1c96b603b7446574f9b5d17851 Mon Sep 17 00:00:00 2001
From: Luke Lau <luke at igalia.com>
Date: Mon, 3 Feb 2025 23:07:03 +0800
Subject: [PATCH 3/3] Empty commit to try to wake up GitHub
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