diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp index 8bf0d118da575..125c96c3f8008 100644 --- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp +++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp @@ -19208,6 +19208,49 @@ static SDValue combineADDToMAT_PCREL_ADDR(SDNode *N, SelectionDAG &DAG, return MatPCRel; } +// Transform (add X, (build_vector (T 1), (T 1), ...)) -> (sub X, (XXLEQVOnes)) +// XXLEQVOnes creates an all-1s vector (0xFFFFFFFF...) efficiently via xxleqv +// Mathematical identity: X + 1 = X - (-1) +// Applies to v4i32, v2i64, v8i16, v16i8 where all elements are constant 1 +// Requirement: VSX feature for efficient xxleqv generation +static SDValue combineADDToSUB(SDNode *N, SelectionDAG &DAG, + const PPCSubtarget &Subtarget) { + + EVT VT = N->getValueType(0); + if (!Subtarget.hasVSX()) + return SDValue(); + + // Handle v2i64, v4i32, v8i16 and v16i8 types + if (!(VT == MVT::v8i16 || VT == MVT::v16i8 || VT == MVT::v4i32 || + VT == MVT::v2i64)) + return SDValue(); + + SDValue LHS = N->getOperand(0); + SDValue RHS = N->getOperand(1); + + // Check if RHS is BUILD_VECTOR + if (RHS.getOpcode() != ISD::BUILD_VECTOR) + return SDValue(); + + // Check if all the elements are 1 + unsigned NumOfEles = RHS.getNumOperands(); + for (unsigned i = 0; i < NumOfEles; ++i) { + auto *CN = dyn_cast(RHS.getOperand(i)); + if (!CN || CN->getSExtValue() != 1) + return SDValue(); + } + SDLoc DL(N); + + SDValue MinusOne = DAG.getConstant(APInt::getAllOnes(32), DL, MVT::i32); + SmallVector Ops(4, MinusOne); + SDValue AllOnesVec = DAG.getBuildVector(MVT::v4i32, DL, Ops); + + // Bitcast to the target vector type + SDValue Bitcast = DAG.getNode(ISD::BITCAST, DL, VT, AllOnesVec); + + return DAG.getNode(ISD::SUB, DL, VT, LHS, Bitcast); +} + SDValue PPCTargetLowering::combineADD(SDNode *N, DAGCombinerInfo &DCI) const { if (auto Value = combineADDToADDZE(N, DCI.DAG, Subtarget)) return Value; @@ -19215,6 +19258,8 @@ SDValue PPCTargetLowering::combineADD(SDNode *N, DAGCombinerInfo &DCI) const { if (auto Value = combineADDToMAT_PCREL_ADDR(N, DCI.DAG, Subtarget)) return Value; + if (auto Value = combineADDToSUB(N, DCI.DAG, Subtarget)) + return Value; return SDValue(); } diff --git a/llvm/test/CodeGen/PowerPC/addition-vector-all-ones.ll b/llvm/test/CodeGen/PowerPC/addition-vector-all-ones.ll index e67d031b1813f..4ec54fa8a0dee 100644 --- a/llvm/test/CodeGen/PowerPC/addition-vector-all-ones.ll +++ b/llvm/test/CodeGen/PowerPC/addition-vector-all-ones.ll @@ -8,15 +8,14 @@ ; RUN: llc -verify-machineinstrs -O3 -mcpu=pwr9 -mtriple=powerpc-ibm-aix \ ; RUN: -ppc-asm-full-reg-names --ppc-vsr-nums-as-vr < %s | FileCheck %s -; The addition of vector `A` with vector of 1s currently uses `vspltisw` to generate vector of 1s followed by add operation. +; Optimized version which `xxleqv` and `vsubu` to generate vector of -1s to leverage the identity A - (-1) = A + 1. ; Function for the vector type v2i64 `a + {1, 1}` define <2 x i64> @test_v2i64(<2 x i64> %a) { ; CHECK-LABEL: test_v2i64: ; CHECK: # %bb.0: # %entry -; CHECK-NEXT: vspltisw v3, 1 -; CHECK-NEXT: vupklsw v3, v3 -; CHECK-NEXT: vaddudm v2, v2, v3 +; CHECK-NEXT: xxleqv v3, v3, v3 +; CHECK-NEXT: vsubudm v2, v2, v3 ; CHECK-NEXT: blr entry: %add = add <2 x i64> %a, splat (i64 1) @@ -27,8 +26,8 @@ entry: define <4 x i32> @test_v4i32(<4 x i32> %a) { ; CHECK-LABEL: test_v4i32: ; CHECK: # %bb.0: # %entry -; CHECK-NEXT: vspltisw v3, 1 -; CHECK-NEXT: vadduwm v2, v2, v3 +; CHECK-NEXT: xxleqv v3, v3, v3 +; CHECK-NEXT: vsubuwm v2, v2, v3 ; CHECK-NEXT: blr entry: %add = add <4 x i32> %a, splat (i32 1) @@ -39,8 +38,8 @@ entry: define <8 x i16> @test_v8i16(<8 x i16> %a) { ; CHECK-LABEL: test_v8i16: ; CHECK: # %bb.0: # %entry -; CHECK-NEXT: vspltish v3, 1 -; CHECK-NEXT: vadduhm v2, v2, v3 +; CHECK-NEXT: xxleqv v3, v3, v3 +; CHECK-NEXT: vsubuhm v2, v2, v3 ; CHECK-NEXT: blr entry: %add = add <8 x i16> %a, splat (i16 1) @@ -51,8 +50,8 @@ entry: define <16 x i8> @test_16i8(<16 x i8> %a) { ; CHECK-LABEL: test_16i8: ; CHECK: # %bb.0: # %entry -; CHECK-NEXT: xxspltib v3, 1 -; CHECK-NEXT: vaddubm v2, v2, v3 +; CHECK-NEXT: xxleqv v3, v3, v3 +; CHECK-NEXT: vsububm v2, v2, v3 ; CHECK-NEXT: blr entry: %add = add <16 x i8> %a, splat (i8 1) diff --git a/llvm/test/CodeGen/PowerPC/vec_add_sub_doubleword.ll b/llvm/test/CodeGen/PowerPC/vec_add_sub_doubleword.ll index 210aee13486c3..d56b1be539b05 100644 --- a/llvm/test/CodeGen/PowerPC/vec_add_sub_doubleword.ll +++ b/llvm/test/CodeGen/PowerPC/vec_add_sub_doubleword.ll @@ -16,9 +16,8 @@ define <2 x i64> @test_add(<2 x i64> %x, <2 x i64> %y) nounwind { define <2 x i64> @increment_by_one(<2 x i64> %x) nounwind { ; VSX-LABEL: increment_by_one: ; VSX: # %bb.0: -; VSX-NEXT: vspltisw 3, 1 -; VSX-NEXT: vupklsw 3, 3 -; VSX-NEXT: vaddudm 2, 2, 3 +; VSX-NEXT: xxleqv 35, 35, 35 +; VSX-NEXT: vsubudm 2, 2, 3 ; VSX-NEXT: blr ; ; NOVSX-LABEL: increment_by_one: