[DAG][RISCV] Use vp_reduce_fadd/fmul when widening types for FP reductions

preames · preames · commit ef5d932f09df · 2024-08-23T08:08:06.000-07:00
This is a follow up to llvm#105455 which updates the VPIntrinsic mappings for the fadd and fmul cases, and supports both ordered and unordered reductions. This allows the use a single wider operation with a restricted EVL instead of padding the vector with the neutral element. This has all the same tradeoffs as the previous patch.
diff --git a/llvm/include/llvm/IR/VPIntrinsics.def b/llvm/include/llvm/IR/VPIntrinsics.def
@@ -722,27 +722,29 @@ HELPER_REGISTER_REDUCTION_VP(vp_reduce_fminimum, VP_REDUCE_FMINIMUM,
 #error                                                                         \
     "The internal helper macro HELPER_REGISTER_REDUCTION_SEQ_VP is already defined!"
 #endif
-#define HELPER_REGISTER_REDUCTION_SEQ_VP(VPID, VPSD, SEQ_VPSD, INTRIN)         \
+#define HELPER_REGISTER_REDUCTION_SEQ_VP(VPID, VPSD, SEQ_VPSD, SDOPC, SEQ_SDOPC, INTRIN) \
   BEGIN_REGISTER_VP_INTRINSIC(VPID, 2, 3)                                      \
   BEGIN_REGISTER_VP_SDNODE(VPSD, 1, VPID, 2, 3)                                \
   VP_PROPERTY_REDUCTION(0, 1)                                                  \
+  VP_PROPERTY_FUNCTIONAL_SDOPC(SDOPC)                                          \
   END_REGISTER_VP_SDNODE(VPSD)                                                 \
   BEGIN_REGISTER_VP_SDNODE(SEQ_VPSD, 1, VPID, 2, 3)                            \
   HELPER_MAP_VPID_TO_VPSD(VPID, SEQ_VPSD)                                      \
+  VP_PROPERTY_FUNCTIONAL_SDOPC(SEQ_SDOPC)                                      \
   VP_PROPERTY_REDUCTION(0, 1)                                                  \
   END_REGISTER_VP_SDNODE(SEQ_VPSD)                                             \
   VP_PROPERTY_FUNCTIONAL_INTRINSIC(INTRIN)                                     \
   END_REGISTER_VP_INTRINSIC(VPID)
 
 // llvm.vp.reduce.fadd(start,x,mask,vlen)
 HELPER_REGISTER_REDUCTION_SEQ_VP(vp_reduce_fadd, VP_REDUCE_FADD,
-                                 VP_REDUCE_SEQ_FADD,
-                                 vector_reduce_fadd)
+                                 VP_REDUCE_SEQ_FADD, VECREDUCE_FADD,
+                                 VECREDUCE_SEQ_FADD, vector_reduce_fadd)
 
 // llvm.vp.reduce.fmul(start,x,mask,vlen)
 HELPER_REGISTER_REDUCTION_SEQ_VP(vp_reduce_fmul, VP_REDUCE_FMUL,
-                                 VP_REDUCE_SEQ_FMUL,
-                                 vector_reduce_fmul)
+                                 VP_REDUCE_SEQ_FMUL, VECREDUCE_FMUL,
+                                 VECREDUCE_SEQ_FMUL, vector_reduce_fmul)
 
 #undef HELPER_REGISTER_REDUCTION_SEQ_VP
 
diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
@@ -7311,8 +7311,6 @@ SDValue DAGTypeLegalizer::WidenVecOp_VECREDUCE(SDNode *N) {
   // Generate a vp.reduce_op if it is custom/legal for the target.  This avoids
   // needing to pad the source vector, because the inactive lanes can simply be
   // disabled and not contribute to the result.
-  // TODO: VECREDUCE_FADD, VECREDUCE_FMUL aren't currently mapped correctly,
-  // and thus don't take this path.
   if (auto VPOpcode = ISD::getVPForBaseOpcode(Opc);
       VPOpcode && TLI.isOperationLegalOrCustom(*VPOpcode, WideVT)) {
     SDValue Start = NeutralElem;
@@ -7351,6 +7349,7 @@ SDValue DAGTypeLegalizer::WidenVecOp_VECREDUCE_SEQ(SDNode *N) {
   SDValue VecOp = N->getOperand(1);
   SDValue Op = GetWidenedVector(VecOp);
 
+  EVT VT = N->getValueType(0);
   EVT OrigVT = VecOp.getValueType();
   EVT WideVT = Op.getValueType();
   EVT ElemVT = OrigVT.getVectorElementType();
@@ -7364,6 +7363,19 @@ SDValue DAGTypeLegalizer::WidenVecOp_VECREDUCE_SEQ(SDNode *N) {
   unsigned OrigElts = OrigVT.getVectorMinNumElements();
   unsigned WideElts = WideVT.getVectorMinNumElements();
 
+  // Generate a vp.reduce_op if it is custom/legal for the target.  This avoids
+  // needing to pad the source vector, because the inactive lanes can simply be
+  // disabled and not contribute to the result.
+  if (auto VPOpcode = ISD::getVPForBaseOpcode(Opc);
+      VPOpcode && TLI.isOperationLegalOrCustom(*VPOpcode, WideVT)) {
+    EVT WideMaskVT = EVT::getVectorVT(*DAG.getContext(), MVT::i1,
+                                      WideVT.getVectorElementCount());
+    SDValue Mask = DAG.getAllOnesConstant(dl, WideMaskVT);
+    SDValue EVL = DAG.getElementCount(dl, TLI.getVPExplicitVectorLengthTy(),
+                                      OrigVT.getVectorElementCount());
+    return DAG.getNode(*VPOpcode, dl, VT, {AccOp, Op, Mask, EVL}, Flags);
+  }
+
   if (WideVT.isScalableVector()) {
     unsigned GCD = std::gcd(OrigElts, WideElts);
     EVT SplatVT = EVT::getVectorVT(*DAG.getContext(), ElemVT,
@@ -7372,14 +7384,14 @@ SDValue DAGTypeLegalizer::WidenVecOp_VECREDUCE_SEQ(SDNode *N) {
     for (unsigned Idx = OrigElts; Idx < WideElts; Idx = Idx + GCD)
       Op = DAG.getNode(ISD::INSERT_SUBVECTOR, dl, WideVT, Op, SplatNeutral,
                        DAG.getVectorIdxConstant(Idx, dl));
-    return DAG.getNode(Opc, dl, N->getValueType(0), AccOp, Op, Flags);
+    return DAG.getNode(Opc, dl, VT, AccOp, Op, Flags);
   }
 
   for (unsigned Idx = OrigElts; Idx < WideElts; Idx++)
     Op = DAG.getNode(ISD::INSERT_VECTOR_ELT, dl, WideVT, Op, NeutralElem,
                      DAG.getVectorIdxConstant(Idx, dl));
 
-  return DAG.getNode(Opc, dl, N->getValueType(0), AccOp, Op, Flags);
+  return DAG.getNode(Opc, dl, VT, AccOp, Op, Flags);
 }
 
 SDValue DAGTypeLegalizer::WidenVecOp_VP_REDUCE(SDNode *N) {
diff --git a/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-reduction-formation.ll b/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-reduction-formation.ll
@@ -791,12 +791,7 @@ define float @reduce_fadd_16xi32_prefix5(ptr %p) {
 ; CHECK-NEXT:    vle32.v v8, (a0)
 ; CHECK-NEXT:    lui a0, 524288
 ; CHECK-NEXT:    vmv.s.x v10, a0
-; CHECK-NEXT:    vsetivli zero, 6, e32, m2, tu, ma
-; CHECK-NEXT:    vslideup.vi v8, v10, 5
-; CHECK-NEXT:    vsetivli zero, 7, e32, m2, tu, ma
-; CHECK-NEXT:    vslideup.vi v8, v10, 6
-; CHECK-NEXT:    vsetivli zero, 8, e32, m2, ta, ma
-; CHECK-NEXT:    vslideup.vi v8, v10, 7
+; CHECK-NEXT:    vsetivli zero, 5, e32, m2, ta, ma
 ; CHECK-NEXT:    vfredusum.vs v8, v8, v10
 ; CHECK-NEXT:    vfmv.f.s fa0, v8
 ; CHECK-NEXT:    ret
@@ -880,7 +875,7 @@ define float @reduce_fadd_4xi32_non_associative(ptr %p) {
 ; CHECK-NEXT:    vfmv.f.s fa5, v9
 ; CHECK-NEXT:    lui a0, 524288
 ; CHECK-NEXT:    vmv.s.x v9, a0
-; CHECK-NEXT:    vslideup.vi v8, v9, 3
+; CHECK-NEXT:    vsetivli zero, 3, e32, m1, ta, ma
 ; CHECK-NEXT:    vfredusum.vs v8, v8, v9
 ; CHECK-NEXT:    vfmv.f.s fa4, v8
 ; CHECK-NEXT:    fadd.s fa0, fa4, fa5
diff --git a/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-reduction-fp.ll b/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-reduction-fp.ll
@@ -98,10 +98,6 @@ define half @vreduce_fadd_v7f16(ptr %x, half %s) {
 ; CHECK:       # %bb.0:
 ; CHECK-NEXT:    vsetivli zero, 7, e16, m1, ta, ma
 ; CHECK-NEXT:    vle16.v v8, (a0)
-; CHECK-NEXT:    lui a0, 1048568
-; CHECK-NEXT:    vmv.s.x v9, a0
-; CHECK-NEXT:    vsetivli zero, 8, e16, m1, ta, ma
-; CHECK-NEXT:    vslideup.vi v8, v9, 7
 ; CHECK-NEXT:    vfmv.s.f v9, fa0
 ; CHECK-NEXT:    vfredusum.vs v8, v8, v9
 ; CHECK-NEXT:    vfmv.f.s fa0, v8
@@ -470,10 +466,6 @@ define float @vreduce_fadd_v7f32(ptr %x, float %s) {
 ; CHECK:       # %bb.0:
 ; CHECK-NEXT:    vsetivli zero, 7, e32, m2, ta, ma
 ; CHECK-NEXT:    vle32.v v8, (a0)
-; CHECK-NEXT:    lui a0, 524288
-; CHECK-NEXT:    vmv.s.x v10, a0
-; CHECK-NEXT:    vsetivli zero, 8, e32, m2, ta, ma
-; CHECK-NEXT:    vslideup.vi v8, v10, 7
 ; CHECK-NEXT:    vfmv.s.f v10, fa0
 ; CHECK-NEXT:    vfredusum.vs v8, v8, v10
 ; CHECK-NEXT:    vfmv.f.s fa0, v8
@@ -488,10 +480,6 @@ define float @vreduce_ord_fadd_v7f32(ptr %x, float %s) {
 ; CHECK:       # %bb.0:
 ; CHECK-NEXT:    vsetivli zero, 7, e32, m2, ta, ma
 ; CHECK-NEXT:    vle32.v v8, (a0)
-; CHECK-NEXT:    lui a0, 524288
-; CHECK-NEXT:    vmv.s.x v10, a0
-; CHECK-NEXT:    vsetivli zero, 8, e32, m2, ta, ma
-; CHECK-NEXT:    vslideup.vi v8, v10, 7
 ; CHECK-NEXT:    vfmv.s.f v10, fa0
 ; CHECK-NEXT:    vfredosum.vs v8, v8, v10
 ; CHECK-NEXT:    vfmv.f.s fa0, v8
diff --git a/llvm/test/CodeGen/RISCV/rvv/vreductions-fp-sdnode.ll b/llvm/test/CodeGen/RISCV/rvv/vreductions-fp-sdnode.ll
@@ -889,17 +889,12 @@ define half @vreduce_ord_fadd_nxv3f16(<vscale x 3 x half> %v, half %s) {
 ; CHECK-NEXT:    csrr a0, vlenb
 ; CHECK-NEXT:    srli a0, a0, 3
 ; CHECK-NEXT:    slli a1, a0, 1
-; CHECK-NEXT:    add a1, a1, a0
 ; CHECK-NEXT:    add a0, a1, a0
-; CHECK-NEXT:    lui a2, 1048568
-; CHECK-NEXT:    vsetvli a3, zero, e16, m1, ta, ma
-; CHECK-NEXT:    vmv.v.x v9, a2
-; CHECK-NEXT:    vsetvli zero, a0, e16, m1, ta, ma
-; CHECK-NEXT:    vslideup.vx v8, v9, a1
-; CHECK-NEXT:    vsetvli a0, zero, e16, m1, ta, ma
+; CHECK-NEXT:    vsetivli zero, 1, e16, m1, ta, ma
 ; CHECK-NEXT:    vfmv.s.f v9, fa0
-; CHECK-NEXT:    vfredosum.vs v8, v8, v9
-; CHECK-NEXT:    vfmv.f.s fa0, v8
+; CHECK-NEXT:    vsetvli zero, a0, e16, m1, ta, ma
+; CHECK-NEXT:    vfredosum.vs v9, v8, v9
+; CHECK-NEXT:    vfmv.f.s fa0, v9
 ; CHECK-NEXT:    ret
   %red = call half @llvm.vector.reduce.fadd.nxv3f16(half %s, <vscale x 3 x half> %v)
   ret half %red
@@ -910,18 +905,15 @@ declare half @llvm.vector.reduce.fadd.nxv6f16(half, <vscale x 6 x half>)
 define half @vreduce_ord_fadd_nxv6f16(<vscale x 6 x half> %v, half %s) {
 ; CHECK-LABEL: vreduce_ord_fadd_nxv6f16:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    lui a0, 1048568
-; CHECK-NEXT:    vsetvli a1, zero, e16, m1, ta, ma
-; CHECK-NEXT:    vmv.v.x v10, a0
 ; CHECK-NEXT:    csrr a0, vlenb
-; CHECK-NEXT:    srli a0, a0, 2
-; CHECK-NEXT:    add a1, a0, a0
-; CHECK-NEXT:    vsetvli zero, a1, e16, m1, ta, ma
-; CHECK-NEXT:    vslideup.vx v9, v10, a0
-; CHECK-NEXT:    vsetvli a0, zero, e16, m2, ta, ma
+; CHECK-NEXT:    srli a1, a0, 3
+; CHECK-NEXT:    slli a1, a1, 1
+; CHECK-NEXT:    sub a0, a0, a1
+; CHECK-NEXT:    vsetivli zero, 1, e16, m1, ta, ma
 ; CHECK-NEXT:    vfmv.s.f v10, fa0
-; CHECK-NEXT:    vfredosum.vs v8, v8, v10
-; CHECK-NEXT:    vfmv.f.s fa0, v8
+; CHECK-NEXT:    vsetvli zero, a0, e16, m2, ta, ma
+; CHECK-NEXT:    vfredosum.vs v10, v8, v10
+; CHECK-NEXT:    vfmv.f.s fa0, v10
 ; CHECK-NEXT:    ret
   %red = call half @llvm.vector.reduce.fadd.nxv6f16(half %s, <vscale x 6 x half> %v)
   ret half %red
@@ -932,22 +924,15 @@ declare half @llvm.vector.reduce.fadd.nxv10f16(half, <vscale x 10 x half>)
 define half @vreduce_ord_fadd_nxv10f16(<vscale x 10 x half> %v, half %s) {
 ; CHECK-LABEL: vreduce_ord_fadd_nxv10f16:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    lui a0, 1048568
-; CHECK-NEXT:    vsetvli a1, zero, e16, m1, ta, ma
-; CHECK-NEXT:    vmv.v.x v12, a0
 ; CHECK-NEXT:    csrr a0, vlenb
-; CHECK-NEXT:    srli a0, a0, 2
-; CHECK-NEXT:    add a1, a0, a0
-; CHECK-NEXT:    vsetvli zero, a1, e16, m1, ta, ma
-; CHECK-NEXT:    vslideup.vx v10, v12, a0
-; CHECK-NEXT:    vsetvli zero, a0, e16, m1, tu, ma
-; CHECK-NEXT:    vmv.v.v v11, v12
-; CHECK-NEXT:    vsetvli zero, a1, e16, m1, ta, ma
-; CHECK-NEXT:    vslideup.vx v11, v12, a0
-; CHECK-NEXT:    vsetvli a0, zero, e16, m4, ta, ma
+; CHECK-NEXT:    srli a0, a0, 3
+; CHECK-NEXT:    li a1, 10
+; CHECK-NEXT:    mul a0, a0, a1
+; CHECK-NEXT:    vsetivli zero, 1, e16, m1, ta, ma
 ; CHECK-NEXT:    vfmv.s.f v12, fa0
-; CHECK-NEXT:    vfredosum.vs v8, v8, v12
-; CHECK-NEXT:    vfmv.f.s fa0, v8
+; CHECK-NEXT:    vsetvli zero, a0, e16, m4, ta, ma
+; CHECK-NEXT:    vfredosum.vs v12, v8, v12
+; CHECK-NEXT:    vfmv.f.s fa0, v12
 ; CHECK-NEXT:    ret
   %red = call half @llvm.vector.reduce.fadd.nxv10f16(half %s, <vscale x 10 x half> %v)
   ret half %red
@@ -958,13 +943,16 @@ declare half @llvm.vector.reduce.fadd.nxv12f16(half, <vscale x 12 x half>)
 define half @vreduce_ord_fadd_nxv12f16(<vscale x 12 x half> %v, half %s) {
 ; CHECK-LABEL: vreduce_ord_fadd_nxv12f16:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    lui a0, 1048568
-; CHECK-NEXT:    vsetvli a1, zero, e16, m1, ta, ma
-; CHECK-NEXT:    vmv.v.x v11, a0
+; CHECK-NEXT:    csrr a0, vlenb
+; CHECK-NEXT:    srli a0, a0, 3
+; CHECK-NEXT:    slli a1, a0, 2
+; CHECK-NEXT:    slli a0, a0, 4
+; CHECK-NEXT:    sub a0, a0, a1
+; CHECK-NEXT:    vsetivli zero, 1, e16, m1, ta, ma
 ; CHECK-NEXT:    vfmv.s.f v12, fa0
-; CHECK-NEXT:    vsetvli a0, zero, e16, m4, ta, ma
-; CHECK-NEXT:    vfredosum.vs v8, v8, v12
-; CHECK-NEXT:    vfmv.f.s fa0, v8
+; CHECK-NEXT:    vsetvli zero, a0, e16, m4, ta, ma
+; CHECK-NEXT:    vfredosum.vs v12, v8, v12
+; CHECK-NEXT:    vfmv.f.s fa0, v12
 ; CHECK-NEXT:    ret
   %red = call half @llvm.vector.reduce.fadd.nxv12f16(half %s, <vscale x 12 x half> %v)
   ret half %red
@@ -977,17 +965,14 @@ define half @vreduce_fadd_nxv3f16(<vscale x 3 x half> %v, half %s) {
 ; CHECK-NEXT:    csrr a0, vlenb
 ; CHECK-NEXT:    srli a0, a0, 3
 ; CHECK-NEXT:    slli a1, a0, 1
-; CHECK-NEXT:    add a1, a1, a0
 ; CHECK-NEXT:    add a0, a1, a0
-; CHECK-NEXT:    lui a2, 1048568
-; CHECK-NEXT:    vsetvli a3, zero, e16, m1, ta, ma
-; CHECK-NEXT:    vmv.v.x v9, a2
-; CHECK-NEXT:    vsetvli zero, a0, e16, m1, ta, ma
-; CHECK-NEXT:    vslideup.vx v8, v9, a1
-; CHECK-NEXT:    vsetvli a0, zero, e16, m1, ta, ma
+; CHECK-NEXT:    vsetivli zero, 1, e16, m1, ta, ma
 ; CHECK-NEXT:    vfmv.s.f v9, fa0
-; CHECK-NEXT:    vfredusum.vs v8, v8, v9
-; CHECK-NEXT:    vfmv.f.s fa0, v8
+; CHECK-NEXT:    lui a1, 1048568
+; CHECK-NEXT:    vmv.s.x v10, a1
+; CHECK-NEXT:    vsetvli zero, a0, e16, m1, ta, ma
+; CHECK-NEXT:    vfredusum.vs v10, v8, v9
+; CHECK-NEXT:    vfmv.f.s fa0, v10
 ; CHECK-NEXT:    ret
   %red = call reassoc half @llvm.vector.reduce.fadd.nxv3f16(half %s, <vscale x 3 x half> %v)
   ret half %red
@@ -996,18 +981,17 @@ define half @vreduce_fadd_nxv3f16(<vscale x 3 x half> %v, half %s) {
 define half @vreduce_fadd_nxv6f16(<vscale x 6 x half> %v, half %s) {
 ; CHECK-LABEL: vreduce_fadd_nxv6f16:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    lui a0, 1048568
-; CHECK-NEXT:    vsetvli a1, zero, e16, m1, ta, ma
-; CHECK-NEXT:    vmv.v.x v10, a0
 ; CHECK-NEXT:    csrr a0, vlenb
-; CHECK-NEXT:    srli a0, a0, 2
-; CHECK-NEXT:    add a1, a0, a0
-; CHECK-NEXT:    vsetvli zero, a1, e16, m1, ta, ma
-; CHECK-NEXT:    vslideup.vx v9, v10, a0
-; CHECK-NEXT:    vsetvli a0, zero, e16, m2, ta, ma
+; CHECK-NEXT:    srli a1, a0, 3
+; CHECK-NEXT:    slli a1, a1, 1
+; CHECK-NEXT:    sub a0, a0, a1
+; CHECK-NEXT:    vsetivli zero, 1, e16, m1, ta, ma
 ; CHECK-NEXT:    vfmv.s.f v10, fa0
-; CHECK-NEXT:    vfredusum.vs v8, v8, v10
-; CHECK-NEXT:    vfmv.f.s fa0, v8
+; CHECK-NEXT:    lui a1, 1048568
+; CHECK-NEXT:    vmv.s.x v11, a1
+; CHECK-NEXT:    vsetvli zero, a0, e16, m2, ta, ma
+; CHECK-NEXT:    vfredusum.vs v11, v8, v10
+; CHECK-NEXT:    vfmv.f.s fa0, v11
 ; CHECK-NEXT:    ret
   %red = call reassoc half @llvm.vector.reduce.fadd.nxv6f16(half %s, <vscale x 6 x half> %v)
   ret half %red
