[ARM] Added additional patterns to VABD instruction

[MeeraN]

Summary

Added additional patterns to VABD instruction so that it will be selected in place of VSUB then VABS.

[SjoerdMeijer]

Hi Meera, two comments:

• you're adding patterns for f16 and f32 vectors, so would be good to cover both cases and thus have tests for vabd.f16 and vabd.f32.
• since we're just matchings a fabs + fsub patterrn, can you reduce the test case?

[MeeraN]

Added second test for f16 case and made test cases much shorter. Also moved position of pattern definition so that the size is handled clearly

[SjoerdMeijer]

Cheers, this is exactly what I was expecting, one nit inlined.

llvm/test/CodeGen/Thumb2/mve-vabd.ll

2

For bonus points: probably best to add an extra RUN line with just -mattr=+mve so that we test this case too, i.e. HasMVEFloat isn't set.

[SjoerdMeijer]

llvm/test/CodeGen/Thumb2/mve-vabd.ll

25

one more question: is it strictly necessary to add the fast attribute?

[MeeraN]

Removed fast attributes and added test cases for when the floating point flag is not set.

[SjoerdMeijer]

Cheers, LGTM.

llvm/lib/Target/ARM/ARMInstrMVE.td

 }
 
 multiclass MVE_VABD_fp_m<MVEVectorVTInfo VTI>
   : MVE_VABDT_fp_m<VTI, int_arm_mve_vabd, int_arm_mve_abd_predicated>;
 
 defm MVE_VABDf32 : MVE_VABD_fp_m<MVE_v4f32>;
 defm MVE_VABDf16 : MVE_VABD_fp_m<MVE_v8f16>;
 
+let Predicates = [HasMVEFloat] in {
+  def : Pat<(v8f16 (fabs (fsub (v8f16 MQPR:$Qm), (v8f16 MQPR:$Qn)))),
+        (MVE_VABDf16 MQPR:$Qm, MQPR:$Qn)>;
+  def : Pat<(v4f32 (fabs (fsub (v4f32 MQPR:$Qm), (v4f32 MQPR:$Qn)))),
+        (MVE_VABDf32 MQPR:$Qm, MQPR:$Qn)>;
+}
+
 class MVE_VCVT_fix<string suffix, bit fsi, bit U, bit op,
                    Operand imm_operand_type>
   : MVE_float<"vcvt", suffix,
               (outs MQPR:$Qd), (ins MQPR:$Qm, imm_operand_type:$imm6),
               "$Qd, $Qm, $imm6", vpred_r, "", []> {
   bits<4> Qd;
   bits<6> imm6;
 

llvm/test/CodeGen/Thumb2/mve-vabd.ll

+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=thumbv8.1m.main-arm-none-eabi -mattr=+mve.fp %s -o - | FileCheck %s
+
+define arm_aapcs_vfpcc void @vabd_v4f32(<4 x float> %x, <4 x float> %y, <4 x float>* %z) {
+; CHECK-LABEL: vabd_v4f32
+; CHECK:       @ %bb.0: @ %entry
+; CHECK-NEXT:  vabd.f32 q0, q0, q1
+; CHECK-NEXT:  vstrw.32 q0, [r0]
+; CHECK-NEXT:  bx lr
+entry:
+  %0 = fsub fast <4 x float> %x, %y
+  %1 = call fast <4 x float> @llvm.fabs.v4f32(<4 x float> %0)
+  store <4 x float> %1, <4 x float>* %z, align 4
+  ret void
+}
+
+define arm_aapcs_vfpcc void @vabd_v8f16(<8 x half> %x, <8 x half> %y, <8 x half>* %z) {
+; CHECK-LABEL: vabd_v8f16
+; CHECK:       @ %bb.0: @ %entry
+; CHECK-NEXT:  vabd.f16 q0, q0, q1
+; CHECK-NEXT:  vstrw.32 q0, [r0]
+; CHECK-NEXT:  bx lr
+entry:
+  %0 = fsub fast <8 x half> %x, %y
+  %1 = call fast <8 x half> @llvm.fabs.v8f16(<8 x half> %0)
+  store <8 x half> %1, <8 x half>* %z
+  ret void
+}
+
+declare <4 x float> @llvm.fabs.v4f32(<4 x float>)
+declare <8 x half> @llvm.fabs.v8f16(<8 x half>)