[llvm] [DAG] Add generic m_TernaryOp() / m_c_TernaryOp() matchers (PR #165520)

[via llvm-commits]

https://github.com/Michael-Chen-NJU created https://github.com/llvm/llvm-project/pull/165520

Similar to the m_BinOp/m_c_BinOp matchers, this patch introduces
generic matchers for SelectionDAG nodes with three operands.

This includes:
- Adding m_TernaryOp() and m_c_TernaryOp() templates in SDPatternMatch.h.
- Adding comprehensive test coverage in SelectionDAGPatternMatchTest.cpp.

Fixes #165378

>From 324cca20a5d025ee1b8aaaa8112e9d5578107356 Mon Sep 17 00:00:00 2001
From: Michael-Chen-NJU <2802328816 at qq.com>
Date: Wed, 29 Oct 2025 14:57:06 +0800
Subject: [PATCH] [DAG] Add generic m_TernaryOp() / m_c_TernaryOp() matchers
 and corresponding tests

---
 llvm/include/llvm/CodeGen/SDPatternMatch.h    | 12 ++++
 .../CodeGen/SelectionDAGPatternMatchTest.cpp  | 70 +++++++++++++++++++
 2 files changed, 82 insertions(+)

diff --git a/llvm/include/llvm/CodeGen/SDPatternMatch.h b/llvm/include/llvm/CodeGen/SDPatternMatch.h
index 0dcf400962393..9a6bf5ffdd227 100644
--- a/llvm/include/llvm/CodeGen/SDPatternMatch.h
+++ b/llvm/include/llvm/CodeGen/SDPatternMatch.h
@@ -583,6 +583,18 @@ m_InsertSubvector(const LHS &Base, const RHS &Sub, const IDX &Idx) {
   return TernaryOpc_match<LHS, RHS, IDX>(ISD::INSERT_SUBVECTOR, Base, Sub, Idx);
 }
 
+template <typename T0_P, typename T1_P, typename T2_P>
+inline TernaryOpc_match<T0_P, T1_P, T2_P>
+m_TernaryOp(unsigned Opc, const T0_P &Op0, const T1_P &Op1, const T2_P &Op2) {
+  return TernaryOpc_match<T0_P, T1_P, T2_P>(Opc, Op0, Op1, Op2);
+}
+
+template <typename T0_P, typename T1_P, typename T2_P>
+inline TernaryOpc_match<T0_P, T1_P, T2_P, true>
+m_c_TernaryOp(unsigned Opc, const T0_P &Op0, const T1_P &Op1, const T2_P &Op2) {
+  return TernaryOpc_match<T0_P, T1_P, T2_P, true>(Opc, Op0, Op1, Op2);
+}
+
 template <typename LTy, typename RTy, typename TTy, typename FTy, typename CCTy>
 inline auto m_SelectCC(const LTy &L, const RTy &R, const TTy &T, const FTy &F,
                        const CCTy &CC) {
diff --git a/llvm/unittests/CodeGen/SelectionDAGPatternMatchTest.cpp b/llvm/unittests/CodeGen/SelectionDAGPatternMatchTest.cpp
index aa56aafa2812c..ceaee52a3948b 100644
--- a/llvm/unittests/CodeGen/SelectionDAGPatternMatchTest.cpp
+++ b/llvm/unittests/CodeGen/SelectionDAGPatternMatchTest.cpp
@@ -354,6 +354,76 @@ TEST_F(SelectionDAGPatternMatchTest, matchBinaryOp) {
       sd_match(InsertELT, m_InsertElt(m_Value(), m_Value(), m_SpecificInt(1))));
 }
 
+TEST_F(SelectionDAGPatternMatchTest, matchGenericTernaryOp) {
+  SDLoc DL;
+  auto Float32VT = EVT::getFloatingPointVT(32);
+
+  SDValue Op0 = DAG->getCopyFromReg(DAG->getEntryNode(), DL, 1, Float32VT);
+  SDValue Op1 = DAG->getCopyFromReg(DAG->getEntryNode(), DL, 2, Float32VT);
+  SDValue Op2 = DAG->getCopyFromReg(DAG->getEntryNode(), DL, 3, Float32VT);
+
+  SDValue FMA = DAG->getNode(ISD::FMA, DL, Float32VT, Op0, Op1, Op2);
+  SDValue FAdd = DAG->getNode(ISD::FADD, DL, Float32VT, Op0, Op1);
+
+  using namespace SDPatternMatch;
+  SDValue A, B, C;
+
+  EXPECT_TRUE(sd_match(FMA, m_TernaryOp(ISD::FMA, m_Specific(Op0),
+                                        m_Specific(Op1), m_Specific(Op2))));
+  EXPECT_FALSE(sd_match(FMA, m_TernaryOp(ISD::FADD, m_Specific(Op0),
+                                         m_Specific(Op1), m_Specific(Op2))));
+  EXPECT_FALSE(
+      sd_match(FAdd, m_TernaryOp(ISD::FMA, m_Value(), m_Value(), m_Value())));
+  EXPECT_FALSE(sd_match(FMA, m_TernaryOp(ISD::FMA, m_Specific(Op1),
+                                         m_Specific(Op0), m_Specific(Op2))));
+
+  EXPECT_TRUE(
+      sd_match(FMA, m_TernaryOp(ISD::FMA, m_Value(A), m_Value(B), m_Value(C))));
+  EXPECT_EQ(A, Op0);
+  EXPECT_EQ(B, Op1);
+  EXPECT_EQ(C, Op2);
+
+  A = B = C = SDValue();
+
+  EXPECT_TRUE(sd_match(FMA, m_c_TernaryOp(ISD::FMA, m_Specific(Op0),
+                                          m_Specific(Op1), m_Specific(Op2))));
+  EXPECT_TRUE(sd_match(FMA, m_c_TernaryOp(ISD::FMA, m_Specific(Op1),
+                                          m_Specific(Op0), m_Specific(Op2))));
+
+  EXPECT_FALSE(sd_match(FMA, m_c_TernaryOp(ISD::FMA, m_Specific(Op2),
+                                           m_Specific(Op1), m_Specific(Op0))));
+  EXPECT_FALSE(sd_match(FMA, m_c_TernaryOp(ISD::FMA, m_Specific(Op2),
+                                           m_Specific(Op0), m_Specific(Op1))));
+
+  EXPECT_FALSE(sd_match(FMA, m_c_TernaryOp(ISD::FMA, m_Specific(Op0),
+                                           m_Specific(Op2), m_Specific(Op1))));
+  EXPECT_FALSE(sd_match(FMA, m_c_TernaryOp(ISD::FMA, m_Specific(Op1),
+                                           m_Specific(Op2), m_Specific(Op0))));
+
+  EXPECT_TRUE(sd_match(
+      FMA, m_c_TernaryOp(ISD::FMA, m_Value(A), m_Value(B), m_Value(C))));
+  EXPECT_EQ(A, Op0);
+  EXPECT_EQ(B, Op1);
+  EXPECT_EQ(C, Op2);
+
+  A = B = C = SDValue();
+  EXPECT_TRUE(sd_match(
+      FMA, m_c_TernaryOp(ISD::FMA, m_Value(B), m_Value(A), m_Value(C))));
+  EXPECT_EQ(A, Op1);
+  EXPECT_EQ(B, Op0);
+  EXPECT_EQ(C, Op2);
+
+  A = B = C = SDValue();
+  EXPECT_TRUE(sd_match(
+      FMA, m_c_TernaryOp(ISD::FMA, m_Value(A), m_Value(B), m_Value(C))));
+  EXPECT_EQ(A, Op0);
+  EXPECT_EQ(B, Op1);
+  EXPECT_EQ(C, Op2);
+
+  EXPECT_FALSE(
+      sd_match(FAdd, m_c_TernaryOp(ISD::FMA, m_Value(), m_Value(), m_Value())));
+}
+
 TEST_F(SelectionDAGPatternMatchTest, matchUnaryOp) {
   SDLoc DL;
   auto Int32VT = EVT::getIntegerVT(Context, 32);