[llvm] [VPlan] Introduce m_ICmp matcher (PR #151540)

Ramkumar Ramachandra via llvm-commits llvm-commits at lists.llvm.org
Fri Aug 1 03:35:57 PDT 2025


https://github.com/artagnon updated https://github.com/llvm/llvm-project/pull/151540

>From 85dd2747585392adeb6608c933d49f2e25764b6c Mon Sep 17 00:00:00 2001
From: Ramkumar Ramachandra <ramkumar.ramachandra at codasip.com>
Date: Thu, 31 Jul 2025 16:21:36 +0100
Subject: [PATCH 1/2] [VPlan] Introduce m_ICmp matcher

---
 .../Transforms/Vectorize/VPlanPatternMatch.h  |  6 ++++++
 .../Transforms/Vectorize/VPlanTransforms.cpp  | 21 ++++++++-----------
 2 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/llvm/lib/Transforms/Vectorize/VPlanPatternMatch.h b/llvm/lib/Transforms/Vectorize/VPlanPatternMatch.h
index d133610ef4f75..7e6d83c09f860 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanPatternMatch.h
+++ b/llvm/lib/Transforms/Vectorize/VPlanPatternMatch.h
@@ -461,6 +461,12 @@ m_c_BinaryOr(const Op0_t &Op0, const Op1_t &Op1) {
   return m_BinaryOr<Op0_t, Op1_t, /*Commutative*/ true>(Op0, Op1);
 }
 
+template <typename Op0_t, typename Op1_t>
+inline AllBinaryRecipe_match<Op0_t, Op1_t, Instruction::ICmp, false>
+m_ICmp(const Op0_t &Op0, const Op1_t &Op1) {
+  return m_Binary<Instruction::ICmp, Op0_t, Op1_t, false>(Op0, Op1);
+}
+
 template <typename Op0_t, typename Op1_t>
 using GEPLikeRecipe_match =
     BinaryRecipe_match<Op0_t, Op1_t, Instruction::GetElementPtr, false,
diff --git a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
index a1d12a3a01e5e..253144e64f9f1 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
@@ -1383,11 +1383,10 @@ static bool optimizeVectorInductionWidthForTCAndVFUF(VPlan &Plan,
 
     // Currently only handle cases where the single user is a header-mask
     // comparison with the backedge-taken-count.
-    if (!match(
-            *WideIV->user_begin(),
-            m_Binary<Instruction::ICmp>(
-                m_Specific(WideIV),
-                m_Broadcast(m_Specific(Plan.getOrCreateBackedgeTakenCount())))))
+    if (!match(*WideIV->user_begin(),
+               m_ICmp(m_Specific(WideIV),
+                      m_Broadcast(
+                          m_Specific(Plan.getOrCreateBackedgeTakenCount())))))
       continue;
 
     // Update IV operands and comparison bound to use new narrower type.
@@ -1420,9 +1419,8 @@ static bool isConditionTrueViaVFAndUF(VPValue *Cond, VPlan &Plan,
     });
 
   auto *CanIV = Plan.getCanonicalIV();
-  if (!match(Cond, m_Binary<Instruction::ICmp>(
-                       m_Specific(CanIV->getBackedgeValue()),
-                       m_Specific(&Plan.getVectorTripCount()))) ||
+  if (!match(Cond, m_ICmp(m_Specific(CanIV->getBackedgeValue()),
+                          m_Specific(&Plan.getVectorTripCount()))) ||
       cast<VPRecipeWithIRFlags>(Cond->getDefiningRecipe())->getPredicate() !=
           CmpInst::ICMP_EQ)
     return false;
@@ -1835,7 +1833,7 @@ void VPlanTransforms::truncateToMinimalBitwidths(
         VPW->dropPoisonGeneratingFlags();
 
       if (OldResSizeInBits != NewResSizeInBits &&
-          !match(&R, m_Binary<Instruction::ICmp>(m_VPValue(), m_VPValue()))) {
+          !match(&R, m_ICmp(m_VPValue(), m_VPValue()))) {
         // Extend result to original width.
         auto *Ext =
             new VPWidenCastRecipe(Instruction::ZExt, ResultVPV, OldResTy);
@@ -1844,9 +1842,8 @@ void VPlanTransforms::truncateToMinimalBitwidths(
         Ext->setOperand(0, ResultVPV);
         assert(OldResSizeInBits > NewResSizeInBits && "Nothing to shrink?");
       } else {
-        assert(
-            match(&R, m_Binary<Instruction::ICmp>(m_VPValue(), m_VPValue())) &&
-            "Only ICmps should not need extending the result.");
+        assert(match(&R, m_ICmp(m_VPValue(), m_VPValue())) &&
+               "Only ICmps should not need extending the result.");
       }
 
       assert(!isa<VPWidenStoreRecipe>(&R) && "stores cannot be narrowed");

>From eef11317bfd83ed688fa8bf6d1c460bc28b60e75 Mon Sep 17 00:00:00 2001
From: Ramkumar Ramachandra <ramkumar.ramachandra at codasip.com>
Date: Fri, 1 Aug 2025 11:34:27 +0100
Subject: [PATCH 2/2] [VPlan/PatternMatch] Introduce ICmp_match for pred

---
 .../Transforms/Vectorize/VPlanPatternMatch.h  | 49 +++++++++++++++++--
 .../Transforms/Vectorize/VPlanTransforms.cpp  |  6 +--
 2 files changed, 49 insertions(+), 6 deletions(-)

diff --git a/llvm/lib/Transforms/Vectorize/VPlanPatternMatch.h b/llvm/lib/Transforms/Vectorize/VPlanPatternMatch.h
index 7e6d83c09f860..fc88d7c8d798c 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanPatternMatch.h
+++ b/llvm/lib/Transforms/Vectorize/VPlanPatternMatch.h
@@ -461,10 +461,53 @@ m_c_BinaryOr(const Op0_t &Op0, const Op1_t &Op1) {
   return m_BinaryOr<Op0_t, Op1_t, /*Commutative*/ true>(Op0, Op1);
 }
 
+/// ICmp_match is a variant of BinaryRecipe_match that also binds the
+/// comparison predicate.
+template <typename Op0_t, typename Op1_t, bool Commutable = false>
+struct ICmp_match {
+  CmpPredicate *Predicate = nullptr;
+  Op0_t Op0;
+  Op1_t Op1;
+
+  ICmp_match(CmpPredicate &Pred, const Op0_t &Op0, const Op1_t &Op1)
+      : Predicate(&Pred), Op0(Op0), Op1(Op1) {}
+  ICmp_match(const Op0_t &Op0, const Op1_t &Op1) : Op0(Op0), Op1(Op1) {}
+
+  bool match(const VPValue *V) const {
+    auto *DefR = V->getDefiningRecipe();
+    return DefR && match(DefR);
+  }
+
+  bool match(const VPSingleDefRecipe *R) const {
+    return match(static_cast<const VPRecipeBase *>(R));
+  }
+
+  bool match(const VPRecipeBase *V) const {
+    if (m_Binary<Instruction::ICmp>(Op0, Op1).match(V)) {
+      if (Predicate)
+        *Predicate = cast<VPRecipeWithIRFlags>(V)->getPredicate();
+      return true;
+    }
+    if (Commutable && m_Binary<Instruction::ICmp>(Op1, Op0).match(V)) {
+      if (Predicate)
+        *Predicate = CmpPredicate::getSwapped(
+            cast<VPRecipeWithIRFlags>(V)->getPredicate());
+      return true;
+    }
+    return false;
+  }
+};
+
+template <typename Op0_t, typename Op1_t>
+inline ICmp_match<Op0_t, Op1_t, false> m_ICmp(const Op0_t &Op0,
+                                              const Op1_t &Op1) {
+  return ICmp_match<Op0_t, Op1_t>(Op0, Op1);
+}
+
 template <typename Op0_t, typename Op1_t>
-inline AllBinaryRecipe_match<Op0_t, Op1_t, Instruction::ICmp, false>
-m_ICmp(const Op0_t &Op0, const Op1_t &Op1) {
-  return m_Binary<Instruction::ICmp, Op0_t, Op1_t, false>(Op0, Op1);
+inline ICmp_match<Op0_t, Op1_t, false>
+m_ICmp(CmpPredicate &Pred, const Op0_t &Op0, const Op1_t &Op1) {
+  return ICmp_match<Op0_t, Op1_t>(Pred, Op0, Op1);
 }
 
 template <typename Op0_t, typename Op1_t>
diff --git a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
index 253144e64f9f1..66ad051d156c5 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
@@ -1419,10 +1419,10 @@ static bool isConditionTrueViaVFAndUF(VPValue *Cond, VPlan &Plan,
     });
 
   auto *CanIV = Plan.getCanonicalIV();
-  if (!match(Cond, m_ICmp(m_Specific(CanIV->getBackedgeValue()),
+  CmpPredicate Pred;
+  if (!match(Cond, m_ICmp(Pred, m_Specific(CanIV->getBackedgeValue()),
                           m_Specific(&Plan.getVectorTripCount()))) ||
-      cast<VPRecipeWithIRFlags>(Cond->getDefiningRecipe())->getPredicate() !=
-          CmpInst::ICMP_EQ)
+      Pred != CmpInst::ICMP_EQ)
     return false;
 
   // The compare checks CanIV + VFxUF == vector trip count. The vector trip



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