[llvm] 2b09f53 - [RISCV] Remove overly restrictive assert from negateFMAOpcode.

[Craig Topper via llvm-commits]

Author: Craig Topper
Date: 2023-06-06T18:55:58-07:00
New Revision: 2b09f53b32a5eea3ff1c33319fb541aa570e456b

URL: https://github.com/llvm/llvm-project/commit/2b09f53b32a5eea3ff1c33319fb541aa570e456b
DIFF: https://github.com/llvm/llvm-project/commit/2b09f53b32a5eea3ff1c33319fb541aa570e456b.diff

LOG: [RISCV] Remove overly restrictive assert from negateFMAOpcode.

It's possible that both multiplicands are being negated. This won't
change the opcode, but we can delete the two negates. Allow this
case to get through negateFMAOpcode.

I think D152260 will also fix this test case, but in the future
it may be possible for an fneg to appear after we've already converted
to RISCVISD opcodes in which case D152260 won't help.

Reviewed By: fakepaper56

Differential Revision: https://reviews.llvm.org/D152296

Added: 
    

Modified: 
    llvm/lib/Target/RISCV/RISCVISelLowering.cpp
    llvm/test/CodeGen/RISCV/rvv/vfma-vp.ll

Removed: 
    


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diff  --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
index a756689252a69..168c9ab46528d 100644
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -11412,8 +11412,6 @@ static SDValue performBITREVERSECombine(SDNode *N, SelectionDAG &DAG,
 // multiply result and/or the accumulator.
 // NOTE: Only supports RVV operations with VL.
 static unsigned negateFMAOpcode(unsigned Opcode, bool NegMul, bool NegAcc) {
-  assert((NegMul || NegAcc) && "Not negating anything?");
-
   // Negating the multiply result changes ADD<->SUB and toggles 'N'.
   if (NegMul) {
     // clang-format off

diff  --git a/llvm/test/CodeGen/RISCV/rvv/vfma-vp.ll b/llvm/test/CodeGen/RISCV/rvv/vfma-vp.ll
index 0deabf01a8602..b29781f7f7ce5 100644
--- a/llvm/test/CodeGen/RISCV/rvv/vfma-vp.ll
+++ b/llvm/test/CodeGen/RISCV/rvv/vfma-vp.ll
@@ -7708,3 +7708,16 @@ define <vscale x 8 x double> @vfnmsub_vf_nxv8f64_neg_splat_unmasked_commute(<vsc
   %v = call <vscale x 8 x double> @llvm.vp.fma.nxv8f64(<vscale x 8 x double> %negvb, <vscale x 8 x double> %va, <vscale x 8 x double> %vc, <vscale x 8 x i1> %m, i32 %evl)
   ret <vscale x 8 x double> %v
 }
+
+define <vscale x 1 x half> @vfma_vv_nxv1f16_double_neg(<vscale x 1 x half> %a, <vscale x 1 x half> %b, <vscale x 1 x half> %c, <vscale x 1 x i1> %m, i32 zeroext %evl) {
+; CHECK-LABEL: vfma_vv_nxv1f16_double_neg:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    vsetvli zero, a0, e16, mf4, ta, ma
+; CHECK-NEXT:    vfmadd.vv v9, v8, v10, v0.t
+; CHECK-NEXT:    vmv1r.v v8, v9
+; CHECK-NEXT:    ret
+  %nega = call <vscale x 1 x half> @llvm.vp.fneg.nxv1f16(<vscale x 1 x half> %a, <vscale x 1 x i1> %m, i32 %evl)
+  %negb = call <vscale x 1 x half> @llvm.vp.fneg.nxv1f16(<vscale x 1 x half> %b, <vscale x 1 x i1> %m, i32 %evl)
+  %v = call <vscale x 1 x half> @llvm.vp.fma.nxv1f16(<vscale x 1 x half> %nega, <vscale x 1 x half> %negb, <vscale x 1 x half> %c, <vscale x 1 x i1> %m, i32 %evl)
+  ret <vscale x 1 x half> %v
+}