[PATCH] D149181: [RISCV] Remove one use restriction the scalar from combineBinOpToReduce.

[Craig Topper via Phabricator via llvm-commits]

craig.topper created this revision.
craig.topper added reviewers: reames, frasercrmck, fakepaper56, kito-cheng.
Herald added subscribers: jobnoorman, luke, VincentWu, vkmr, evandro, luismarques, apazos, sameer.abuasal, s.egerton, Jim, benna, psnobl, jocewei, PkmX, the_o, brucehoult, MartinMosbeck, rogfer01, edward-jones, zzheng, jrtc27, shiva0217, niosHD, sabuasal, simoncook, johnrusso, rbar, asb, hiraditya, arichardson.
Herald added a project: All.
craig.topper requested review of this revision.
Herald added subscribers: pcwang-thead, eopXD, MaskRay.
Herald added a project: LLVM.

If multiple reductions use the neutral start value, this prevented
us from optimizing any of them.

This increases the number of scalar->vector operations but reduces
the number of scalar operations.

Note, we were already inconsistent about the one use check when we
peeked through INSERT_SUBVECTORs.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D149181

Files:
  llvm/lib/Target/RISCV/RISCVISelLowering.cpp
  llvm/test/CodeGen/RISCV/rvv/fold-binary-reduce.ll


Index: llvm/test/CodeGen/RISCV/rvv/fold-binary-reduce.ll
===================================================================
--- llvm/test/CodeGen/RISCV/rvv/fold-binary-reduce.ll
+++ llvm/test/CodeGen/RISCV/rvv/fold-binary-reduce.ll
@@ -282,13 +282,12 @@
 ; CHECK-LABEL: reduce_fadd4:
 ; CHECK:       # %bb.0: # %entry
 ; CHECK-NEXT:    vsetivli zero, 4, e32, m1, ta, ma
-; CHECK-NEXT:    vmv.s.x v10, zero
+; CHECK-NEXT:    vfmv.s.f v10, fa0
 ; CHECK-NEXT:    vfredusum.vs v8, v8, v10
 ; CHECK-NEXT:    vfmv.f.s fa5, v8
-; CHECK-NEXT:    vfredusum.vs v8, v9, v10
+; CHECK-NEXT:    vfmv.s.f v8, fa1
+; CHECK-NEXT:    vfredusum.vs v8, v9, v8
 ; CHECK-NEXT:    vfmv.f.s fa4, v8
-; CHECK-NEXT:    fadd.s fa5, fa5, fa0
-; CHECK-NEXT:    fadd.s fa4, fa4, fa1
 ; CHECK-NEXT:    fdiv.s fa0, fa5, fa4
 ; CHECK-NEXT:    ret
 entry:
Index: llvm/lib/Target/RISCV/RISCVISelLowering.cpp
===================================================================
--- llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -9167,9 +9167,6 @@
                          0))
     return SDValue();
 
-  if (!ScalarV.hasOneUse())
-    return SDValue();
-
   SDValue NewStart = N->getOperand(1 - ReduceIdx);
 
   SDLoc DL(N);


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D149181.516868.patch
Type: text/x-patch
Size: 1239 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20230425/a0052b49/attachment.bin>