[llvm] [RISCV][llvm] Support BUILD_VECTOR codegen for P extension (PR #169083)
Brandon Wu via llvm-commits
llvm-commits at lists.llvm.org
Sat Nov 22 05:28:00 PST 2025
https://github.com/4vtomat updated https://github.com/llvm/llvm-project/pull/169083
>From a291ab21ba087474ca1c2d0811d8fbea25172644 Mon Sep 17 00:00:00 2001
From: Brandon Wu <songwu0813 at gmail.com>
Date: Fri, 21 Nov 2025 10:37:25 -0800
Subject: [PATCH 1/2] [RISCV][llvm] Support BUILD_VECTOR codegen for P
extension
---
llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp | 37 ++++++++++++++
llvm/lib/Target/RISCV/RISCVISelLowering.cpp | 24 ++++++++++
llvm/lib/Target/RISCV/RISCVInstrInfoP.td | 39 +++++++++++++++
llvm/test/CodeGen/RISCV/rvp-ext-rv32.ll | 41 ++++++++++++++++
llvm/test/CodeGen/RISCV/rvp-ext-rv64.ll | 53 +++++++++++++++++++++
5 files changed, 194 insertions(+)
diff --git a/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp b/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp
index 5025122db3681..fc2d034f4d589 100644
--- a/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp
@@ -1867,6 +1867,43 @@ void RISCVDAGToDAGISel::Select(SDNode *Node) {
CurDAG->RemoveDeadNode(Node);
return;
}
+ case RISCVISD::PPACK_DH: {
+ assert(Subtarget->enablePExtCodeGen() && Subtarget->isRV32());
+
+ SDValue Val0 = Node->getOperand(0);
+ SDValue Val1 = Node->getOperand(1);
+ SDValue Val2 = Node->getOperand(2);
+ SDValue Val3 = Node->getOperand(3);
+
+ SDValue Ops[] = {
+ CurDAG->getTargetConstant(RISCV::GPRPairRegClassID, DL, MVT::i32), Val0,
+ CurDAG->getTargetConstant(RISCV::sub_gpr_even, DL, MVT::i32), Val2,
+ CurDAG->getTargetConstant(RISCV::sub_gpr_odd, DL, MVT::i32)};
+ SDValue RegPair0 =
+ SDValue(CurDAG->getMachineNode(TargetOpcode::REG_SEQUENCE, DL,
+ MVT::Untyped, Ops),
+ 0);
+ SDValue Ops1[] = {
+ CurDAG->getTargetConstant(RISCV::GPRPairRegClassID, DL, MVT::i32), Val1,
+ CurDAG->getTargetConstant(RISCV::sub_gpr_even, DL, MVT::i32), Val3,
+ CurDAG->getTargetConstant(RISCV::sub_gpr_odd, DL, MVT::i32)};
+ SDValue RegPair1 =
+ SDValue(CurDAG->getMachineNode(TargetOpcode::REG_SEQUENCE, DL,
+ MVT::Untyped, Ops1),
+ 0);
+
+ MachineSDNode *PackDH = CurDAG->getMachineNode(
+ RISCV::PPACK_DH, DL, MVT::Untyped, {RegPair0, RegPair1});
+
+ SDValue Lo = CurDAG->getTargetExtractSubreg(RISCV::sub_gpr_even, DL,
+ MVT::i32, SDValue(PackDH, 0));
+ SDValue Hi = CurDAG->getTargetExtractSubreg(RISCV::sub_gpr_odd, DL,
+ MVT::i32, SDValue(PackDH, 0));
+ ReplaceUses(SDValue(Node, 0), Lo);
+ ReplaceUses(SDValue(Node, 1), Hi);
+ CurDAG->RemoveDeadNode(Node);
+ return;
+ }
case ISD::INTRINSIC_WO_CHAIN: {
unsigned IntNo = Node->getConstantOperandVal(0);
switch (IntNo) {
diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
index 6020fb6ca16ce..2b814fab6a92e 100644
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -519,6 +519,7 @@ RISCVTargetLowering::RISCVTargetLowering(const TargetMachine &TM,
setTruncStoreAction(MVT::v4i16, MVT::v4i8, Expand);
} else {
VTs.append({MVT::v2i16, MVT::v4i8});
+ setOperationAction(ISD::BUILD_VECTOR, MVT::v4i8, Custom);
}
setOperationAction(ISD::UADDSAT, VTs, Legal);
setOperationAction(ISD::SADDSAT, VTs, Legal);
@@ -4434,6 +4435,29 @@ static SDValue lowerBUILD_VECTOR(SDValue Op, SelectionDAG &DAG,
SDLoc DL(Op);
+ if (Subtarget.isRV32() && Subtarget.enablePExtCodeGen()) {
+ if (VT != MVT::v4i8)
+ return SDValue();
+
+ // <4 x i8> BUILD_VECTOR a, b, c, d -> PACK(PPACK.DH pair(a, b), pair(c, d))
+ SDValue Val0 = DAG.getNode(ISD::BITCAST, DL, MVT::v4i8, Op->getOperand(0));
+ SDValue Val1 = DAG.getNode(ISD::BITCAST, DL, MVT::v4i8, Op->getOperand(1));
+ SDValue Val2 = DAG.getNode(ISD::BITCAST, DL, MVT::v4i8, Op->getOperand(2));
+ SDValue Val3 = DAG.getNode(ISD::BITCAST, DL, MVT::v4i8, Op->getOperand(3));
+ SDValue PackDH =
+ DAG.getNode(RISCVISD::PPACK_DH, DL, {MVT::v2i16, MVT::v2i16},
+ {Val0, Val1, Val2, Val3});
+
+ return DAG.getNode(
+ ISD::BITCAST, DL, MVT::v4i8,
+ SDValue(
+ DAG.getMachineNode(
+ RISCV::PACK, DL, MVT::i32,
+ {DAG.getNode(ISD::BITCAST, DL, MVT::i32, PackDH.getValue(0)),
+ DAG.getNode(ISD::BITCAST, DL, MVT::i32, PackDH.getValue(1))}),
+ 0));
+ }
+
// Proper support for f16 requires Zvfh. bf16 always requires special
// handling. We need to cast the scalar to integer and create an integer
// build_vector.
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfoP.td b/llvm/lib/Target/RISCV/RISCVInstrInfoP.td
index 51339d66f6de1..db5bc19aa4487 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfoP.td
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfoP.td
@@ -24,6 +24,13 @@ def SImm8UnsignedAsmOperand : SImmAsmOperand<8, "Unsigned"> {
let RenderMethod = "addSImm8UnsignedOperands";
}
+// (<2 x i16>, <2 x i16>) PPACK_DH (<4 x i8>, <4 x i8>, <4 x i8>, <4 x i8>)
+def SDT_RISCVPPackDH
+ : SDTypeProfile<2, 4, [SDTCisVT<0, v2i16>, SDTCisSameAs<0, 1>,
+ SDTCisVT<2, v4i8>, SDTCisSameAs<0, 3>,
+ SDTCisSameAs<0, 4>, SDTCisSameAs<0, 5>]>;
+def riscv_ppack_dh : RVSDNode<"PPACK_DH", SDT_RISCVPPackDH>;
+
// A 8-bit signed immediate allowing range [-128, 255]
// but represented as [-128, 127].
def simm8_unsigned : RISCVOp, ImmLeaf<XLenVT, "return isInt<8>(Imm);"> {
@@ -1530,6 +1537,13 @@ let Predicates = [HasStdExtP, IsRV32] in {
def : StPat<store, SW, GPR, v2i16>;
def : LdPat<load, LW, v4i8>;
def : LdPat<load, LW, v2i16>;
+
+ // Build vector patterns
+ def : Pat<(v4i8 (build_vector (XLenVT GPR:$a), (XLenVT GPR:$b),
+ (XLenVT GPR:$c), (XLenVT GPR:$d))),
+ (PACK (PPACK_H GPR:$a, GPR:$b), (PPACK_H GPR:$c, GPR:$d))>;
+ def : Pat<(v2i16 (build_vector (XLenVT GPR:$a), (XLenVT GPR:$b))),
+ (PACK GPR:$a, GPR:$b)>;
} // Predicates = [HasStdExtP, IsRV32]
let Predicates = [HasStdExtP, IsRV64] in {
@@ -1566,4 +1580,29 @@ let Predicates = [HasStdExtP, IsRV64] in {
def : LdPat<load, LD, v8i8>;
def : LdPat<load, LD, v4i16>;
def : LdPat<load, LD, v2i32>;
+
+ // Build vector patterns
+ def : Pat<(v8i8 (build_vector (XLenVT GPR:$a), (XLenVT GPR:$b),
+ (XLenVT GPR:$c), (XLenVT GPR:$d),
+ (XLenVT undef), (XLenVT undef),
+ (XLenVT undef), (XLenVT undef))),
+ (PPACK_W (PPACK_H GPR:$a, GPR:$b), (PPACK_H GPR:$c, GPR:$d))>;
+
+ def : Pat<(v8i8 (build_vector (XLenVT GPR:$a), (XLenVT GPR:$b),
+ (XLenVT GPR:$c), (XLenVT GPR:$d),
+ (XLenVT GPR:$e), (XLenVT GPR:$f),
+ (XLenVT GPR:$g), (XLenVT GPR:$h))),
+ (PACK(PPACK_W (PPACK_H GPR:$a, GPR:$b), (PPACK_H GPR:$c, GPR:$d)),
+ (PPACK_W (PPACK_H GPR:$e, GPR:$f), (PPACK_H GPR:$g, GPR:$h)))>;
+
+ def : Pat<(v4i16 (build_vector (XLenVT GPR:$a), (XLenVT GPR:$b),
+ (XLenVT undef), (XLenVT undef))),
+ (PPACK_W GPR:$a, GPR:$b)>;
+
+ def : Pat<(v4i16 (build_vector (XLenVT GPR:$a), (XLenVT GPR:$b),
+ (XLenVT GPR:$c), (XLenVT GPR:$d))),
+ (PACK (PPACK_W GPR:$a, GPR:$b), (PPACK_W GPR:$c, GPR:$d))>;
+
+ def : Pat<(v2i32 (build_vector (XLenVT GPR:$a), (XLenVT GPR:$b))),
+ (PACK GPR:$a, GPR:$b)>;
} // Predicates = [HasStdExtP, IsRV64]
diff --git a/llvm/test/CodeGen/RISCV/rvp-ext-rv32.ll b/llvm/test/CodeGen/RISCV/rvp-ext-rv32.ll
index bb3e691311cd8..79cf5b7903454 100644
--- a/llvm/test/CodeGen/RISCV/rvp-ext-rv32.ll
+++ b/llvm/test/CodeGen/RISCV/rvp-ext-rv32.ll
@@ -523,6 +523,47 @@ define void @test_non_const_splat_i16(ptr %ret_ptr, ptr %a_ptr, i16 %elt) {
ret void
}
+define void @test_build_vector_i8(i8 %a, i8 %c, i8 %b, i8 %d, ptr %ret_ptr) {
+; CHECK-RV32-LABEL: test_build_vector_i8:
+; CHECK-RV32: # %bb.0:
+; CHECK-RV32-NEXT: ppack.dh a0, a0, a2
+; CHECK-RV32-NEXT: pack a0, a0, a1
+; CHECK-RV32-NEXT: sw a0, 0(a4)
+; CHECK-RV32-NEXT: ret
+;
+; CHECK-RV64-LABEL: test_build_vector_i8:
+; CHECK-RV64: # %bb.0:
+; CHECK-RV64-NEXT: ppack.h a1, a1, a3
+; CHECK-RV64-NEXT: ppack.h a0, a0, a2
+; CHECK-RV64-NEXT: ppack.w a0, a0, a1
+; CHECK-RV64-NEXT: sw a0, 0(a4)
+; CHECK-RV64-NEXT: ret
+ %v0 = insertelement <4 x i8> poison, i8 %a, i32 0
+ %v1 = insertelement <4 x i8> %v0, i8 %b, i32 1
+ %v2 = insertelement <4 x i8> %v1, i8 %c, i32 2
+ %v3 = insertelement <4 x i8> %v2, i8 %d, i32 3
+ store <4 x i8> %v3, ptr %ret_ptr
+ ret void
+}
+
+define void @test_build_vector_i16(ptr %ret_ptr, i16 %a, i16 %b) {
+; CHECK-RV32-LABEL: test_build_vector_i16:
+; CHECK-RV32: # %bb.0:
+; CHECK-RV32-NEXT: pack a1, a1, a2
+; CHECK-RV32-NEXT: sw a1, 0(a0)
+; CHECK-RV32-NEXT: ret
+;
+; CHECK-RV64-LABEL: test_build_vector_i16:
+; CHECK-RV64: # %bb.0:
+; CHECK-RV64-NEXT: ppack.w a1, a1, a2
+; CHECK-RV64-NEXT: sw a1, 0(a0)
+; CHECK-RV64-NEXT: ret
+ %v0 = insertelement <2 x i16> poison, i16 %a, i32 0
+ %v1 = insertelement <2 x i16> %v0, i16 %b, i32 1
+ store <2 x i16> %v1, ptr %ret_ptr
+ ret void
+}
+
; Intrinsic declarations
declare <2 x i16> @llvm.sadd.sat.v2i16(<2 x i16>, <2 x i16>)
declare <2 x i16> @llvm.uadd.sat.v2i16(<2 x i16>, <2 x i16>)
diff --git a/llvm/test/CodeGen/RISCV/rvp-ext-rv64.ll b/llvm/test/CodeGen/RISCV/rvp-ext-rv64.ll
index f989b025a12dc..36996f0ac7ac8 100644
--- a/llvm/test/CodeGen/RISCV/rvp-ext-rv64.ll
+++ b/llvm/test/CodeGen/RISCV/rvp-ext-rv64.ll
@@ -685,6 +685,59 @@ define void @test_non_const_splat_i32(ptr %ret_ptr, ptr %a_ptr, i32 %elt) {
ret void
}
+define void @test_build_vector_i8(ptr %ret_ptr, i8 %a, i8 %b, i8 %c, i8 %d, i8 %e, i8 %f, i8 %g, i8 %h) {
+; CHECK-LABEL: test_build_vector_i8:
+; CHECK: # %bb.0:
+; CHECK-NEXT: lbu t0, 0(sp)
+; CHECK-NEXT: ppack.h a5, a5, a6
+; CHECK-NEXT: ppack.h a3, a3, a4
+; CHECK-NEXT: ppack.h a1, a1, a2
+; CHECK-NEXT: ppack.h a2, a7, t0
+; CHECK-NEXT: ppack.w a2, a5, a2
+; CHECK-NEXT: ppack.w a1, a1, a3
+; CHECK-NEXT: pack a1, a1, a2
+; CHECK-NEXT: sd a1, 0(a0)
+; CHECK-NEXT: ret
+ %v0 = insertelement <8 x i8> poison, i8 %a, i32 0
+ %v1 = insertelement <8 x i8> %v0, i8 %b, i32 1
+ %v2 = insertelement <8 x i8> %v1, i8 %c, i32 2
+ %v3 = insertelement <8 x i8> %v2, i8 %d, i32 3
+ %v4 = insertelement <8 x i8> %v3, i8 %e, i32 4
+ %v5 = insertelement <8 x i8> %v4, i8 %f, i32 5
+ %v6 = insertelement <8 x i8> %v5, i8 %g, i32 6
+ %v7 = insertelement <8 x i8> %v6, i8 %h, i32 7
+ store <8 x i8> %v7, ptr %ret_ptr
+ ret void
+}
+
+define void @test_build_vector_i16(ptr %ret_ptr, i16 %a, i16 %b, i16 %c, i16 %d) {
+; CHECK-LABEL: test_build_vector_i16:
+; CHECK: # %bb.0:
+; CHECK-NEXT: ppack.w a3, a3, a4
+; CHECK-NEXT: ppack.w a1, a1, a2
+; CHECK-NEXT: pack a1, a1, a3
+; CHECK-NEXT: sd a1, 0(a0)
+; CHECK-NEXT: ret
+ %v0 = insertelement <4 x i16> poison, i16 %a, i32 0
+ %v1 = insertelement <4 x i16> %v0, i16 %b, i32 1
+ %v2 = insertelement <4 x i16> %v1, i16 %c, i32 2
+ %v3 = insertelement <4 x i16> %v2, i16 %d, i32 3
+ store <4 x i16> %v3, ptr %ret_ptr
+ ret void
+}
+
+define void @test_build_vector_i32(ptr %ret_ptr, i32 %a, i32 %b) {
+; CHECK-LABEL: test_build_vector_i32:
+; CHECK: # %bb.0:
+; CHECK-NEXT: pack a1, a1, a2
+; CHECK-NEXT: sd a1, 0(a0)
+; CHECK-NEXT: ret
+ %v0 = insertelement <2 x i32> poison, i32 %a, i32 0
+ %v1 = insertelement <2 x i32> %v0, i32 %b, i32 1
+ store <2 x i32> %v1, ptr %ret_ptr
+ ret void
+}
+
; Intrinsic declarations
declare <4 x i16> @llvm.sadd.sat.v4i16(<4 x i16>, <4 x i16>)
declare <4 x i16> @llvm.uadd.sat.v4i16(<4 x i16>, <4 x i16>)
>From 1383c0c2e66742358ab0dbc521ec62e9f74ee851 Mon Sep 17 00:00:00 2001
From: Brandon Wu <songwu0813 at gmail.com>
Date: Sat, 22 Nov 2025 05:27:48 -0800
Subject: [PATCH 2/2] fixup! redundant pattern, scalar_to_vector
---
llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp | 3 ++-
llvm/lib/Target/RISCV/RISCVISelLowering.cpp | 12 ++++++++----
llvm/lib/Target/RISCV/RISCVInstrInfoP.td | 3 ---
3 files changed, 10 insertions(+), 8 deletions(-)
diff --git a/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp b/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp
index fc2d034f4d589..7cf6f203fda89 100644
--- a/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp
@@ -2733,7 +2733,8 @@ void RISCVDAGToDAGISel::Select(SDNode *Node) {
case ISD::SCALAR_TO_VECTOR:
if (Subtarget->enablePExtCodeGen()) {
MVT SrcVT = Node->getOperand(0).getSimpleValueType();
- if (VT == MVT::v2i32 && SrcVT == MVT::i64) {
+ if ((VT == MVT::v2i32 && SrcVT == MVT::i64) ||
+ (VT == MVT::v4i8 && SrcVT == MVT::i32)) {
ReplaceUses(SDValue(Node, 0), Node->getOperand(0));
CurDAG->RemoveDeadNode(Node);
return;
diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
index 2b814fab6a92e..dd9be0de88737 100644
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -4440,10 +4440,14 @@ static SDValue lowerBUILD_VECTOR(SDValue Op, SelectionDAG &DAG,
return SDValue();
// <4 x i8> BUILD_VECTOR a, b, c, d -> PACK(PPACK.DH pair(a, b), pair(c, d))
- SDValue Val0 = DAG.getNode(ISD::BITCAST, DL, MVT::v4i8, Op->getOperand(0));
- SDValue Val1 = DAG.getNode(ISD::BITCAST, DL, MVT::v4i8, Op->getOperand(1));
- SDValue Val2 = DAG.getNode(ISD::BITCAST, DL, MVT::v4i8, Op->getOperand(2));
- SDValue Val3 = DAG.getNode(ISD::BITCAST, DL, MVT::v4i8, Op->getOperand(3));
+ SDValue Val0 =
+ DAG.getNode(ISD::SCALAR_TO_VECTOR, DL, MVT::v4i8, Op->getOperand(0));
+ SDValue Val1 =
+ DAG.getNode(ISD::SCALAR_TO_VECTOR, DL, MVT::v4i8, Op->getOperand(1));
+ SDValue Val2 =
+ DAG.getNode(ISD::SCALAR_TO_VECTOR, DL, MVT::v4i8, Op->getOperand(2));
+ SDValue Val3 =
+ DAG.getNode(ISD::SCALAR_TO_VECTOR, DL, MVT::v4i8, Op->getOperand(3));
SDValue PackDH =
DAG.getNode(RISCVISD::PPACK_DH, DL, {MVT::v2i16, MVT::v2i16},
{Val0, Val1, Val2, Val3});
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfoP.td b/llvm/lib/Target/RISCV/RISCVInstrInfoP.td
index db5bc19aa4487..de278aa51d19b 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfoP.td
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfoP.td
@@ -1539,9 +1539,6 @@ let Predicates = [HasStdExtP, IsRV32] in {
def : LdPat<load, LW, v2i16>;
// Build vector patterns
- def : Pat<(v4i8 (build_vector (XLenVT GPR:$a), (XLenVT GPR:$b),
- (XLenVT GPR:$c), (XLenVT GPR:$d))),
- (PACK (PPACK_H GPR:$a, GPR:$b), (PPACK_H GPR:$c, GPR:$d))>;
def : Pat<(v2i16 (build_vector (XLenVT GPR:$a), (XLenVT GPR:$b))),
(PACK GPR:$a, GPR:$b)>;
} // Predicates = [HasStdExtP, IsRV32]
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