[ARM] Mark VMINNMA/VMAXNMA as commutative

These operations take Qda and Rn register operands, which are
commutative so long as the instruction is not predicated.

Differential Revision: https://reviews.llvm.org/D85813

llvm/lib/Target/ARM/ARMInstrMVE.td

@@ -4055,6 +4055,8 @@ class MVE_VMAXMINNMA<string iname, string suffix, bit size, bit bit_12,
   let Inst{4} = 0b0;
   let Inst{3-1} = Qm{2-0};
   let Inst{0} = 0b1;
+
+  let isCommutable = 1;
 }
 
 multiclass MVE_VMAXMINNMA_m<string iname, MVEVectorVTInfo VTI,

llvm/lib/Target/ARM/Thumb2InstrInfo.cpp

@@ -258,6 +258,22 @@ void Thumb2InstrInfo::expandLoadStackGuard(
     expandLoadStackGuardBase(MI, ARM::t2MOVi32imm, ARM::t2LDRi12);
 }
 
+MachineInstr *Thumb2InstrInfo::commuteInstructionImpl(MachineInstr &MI,
+                                                      bool NewMI,
+                                                      unsigned OpIdx1,
+                                                      unsigned OpIdx2) const {
+  switch (MI.getOpcode()) {
+  case ARM::MVE_VMAXNMAf16:
+  case ARM::MVE_VMAXNMAf32:
+  case ARM::MVE_VMINNMAf16:
+  case ARM::MVE_VMINNMAf32:
+    // Don't allow predicated instructions to be commuted.
+    if (getVPTInstrPredicate(MI) != ARMVCC::None)
+      return nullptr;
+  }
+  return ARMBaseInstrInfo::commuteInstructionImpl(MI, NewMI, OpIdx1, OpIdx2);
+}
+
 void llvm::emitT2RegPlusImmediate(MachineBasicBlock &MBB,
                                   MachineBasicBlock::iterator &MBBI,
                                   const DebugLoc &dl, Register DestReg,

llvm/lib/Target/ARM/Thumb2InstrInfo.h

@@ -64,6 +64,10 @@ public:
                                SmallPtrSetImpl<MachineInstr *> &SeenMIs,
                                bool) const override;
 
+  MachineInstr *commuteInstructionImpl(MachineInstr &MI, bool NewMI,
+                                       unsigned OpIdx1,
+                                       unsigned OpIdx2) const override;
+
 private:
   void expandLoadStackGuard(MachineBasicBlock::iterator MI) const override;
 };

llvm/test/CodeGen/Thumb2/mve-vmaxnma-commute.ll

@@ -17,8 +17,7 @@ define arm_aapcs_vfpcc <4 x float> @maxf32(<4 x float> %a, <4 x float> %b) {
 define arm_aapcs_vfpcc <4 x float> @maxf32_c(<4 x float> %a, <4 x float> %b) {
 ; CHECK-LABEL: maxf32_c:
 ; CHECK:       @ %bb.0:
-; CHECK-NEXT:    vmaxnma.f32 q1, q0
+; CHECK-NEXT:    vmaxnma.f32 q0, q1
-; CHECK-NEXT:    vmov q0, q1
 ; CHECK-NEXT:    bx lr
   %aa = tail call fast <4 x float> @llvm.fabs.v4f32(<4 x float> %a)
   %bb = tail call fast <4 x float> @llvm.fabs.v4f32(<4 x float> %b)
@@ -40,8 +39,7 @@ define arm_aapcs_vfpcc <4 x float> @minf32(<4 x float> %a, <4 x float> %b) {
 define arm_aapcs_vfpcc <4 x float> @minf32_c(<4 x float> %a, <4 x float> %b) {
 ; CHECK-LABEL: minf32_c:
 ; CHECK:       @ %bb.0:
-; CHECK-NEXT:    vminnma.f32 q1, q0
+; CHECK-NEXT:    vminnma.f32 q0, q1
-; CHECK-NEXT:    vmov q0, q1
 ; CHECK-NEXT:    bx lr
   %aa = tail call fast <4 x float> @llvm.fabs.v4f32(<4 x float> %a)
   %bb = tail call fast <4 x float> @llvm.fabs.v4f32(<4 x float> %b)
@@ -114,8 +112,7 @@ define arm_aapcs_vfpcc <8 x half> @maxf16(<8 x half> %a, <8 x half> %b) {
 define arm_aapcs_vfpcc <8 x half> @maxf16_c(<8 x half> %a, <8 x half> %b) {
 ; CHECK-LABEL: maxf16_c:
 ; CHECK:       @ %bb.0:
-; CHECK-NEXT:    vmaxnma.f16 q1, q0
+; CHECK-NEXT:    vmaxnma.f16 q0, q1
-; CHECK-NEXT:    vmov q0, q1
 ; CHECK-NEXT:    bx lr
   %aa = tail call fast <8 x half> @llvm.fabs.v8f16(<8 x half> %a)
   %bb = tail call fast <8 x half> @llvm.fabs.v8f16(<8 x half> %b)
@@ -137,8 +134,7 @@ define arm_aapcs_vfpcc <8 x half> @minf16(<8 x half> %a, <8 x half> %b) {
 define arm_aapcs_vfpcc <8 x half> @minf16_c(<8 x half> %a, <8 x half> %b) {
 ; CHECK-LABEL: minf16_c:
 ; CHECK:       @ %bb.0:
-; CHECK-NEXT:    vminnma.f16 q1, q0
+; CHECK-NEXT:    vminnma.f16 q0, q1
-; CHECK-NEXT:    vmov q0, q1
 ; CHECK-NEXT:    bx lr
   %aa = tail call fast <8 x half> @llvm.fabs.v8f16(<8 x half> %a)
   %bb = tail call fast <8 x half> @llvm.fabs.v8f16(<8 x half> %b)
@@ -254,11 +250,10 @@ define void @loop_absmax32_c(float* nocapture readonly %0, i32 %1, float* nocapt
 ; CHECK-NEXT:    lsr.w lr, r1, #3
 ; CHECK-NEXT:    wls lr, lr, .LBB17_3
 ; CHECK-NEXT:  @ %bb.1: @ %.preheader
-; CHECK-NEXT:    vmov.i32 q1, #0x0
+; CHECK-NEXT:    vmov.i32 q0, #0x0
 ; CHECK-NEXT:  .LBB17_2: @ =>This Inner Loop Header: Depth=1
-; CHECK-NEXT:    vldrw.u32 q0, [r0], #16
+; CHECK-NEXT:    vldrw.u32 q1, [r0], #16
 ; CHECK-NEXT:    vmaxnma.f32 q0, q1
-; CHECK-NEXT:    vmov q1, q0
 ; CHECK-NEXT:    le lr, .LBB17_2
 ; CHECK-NEXT:  .LBB17_3:
 ; CHECK-NEXT:    vldr s4, .LCPI17_0
@@ -447,11 +442,10 @@ define void @loop_absmax16_c(half* nocapture readonly %0, i32 %1, half* nocaptur
 ; CHECK-NEXT:    lsr.w lr, r1, #3
 ; CHECK-NEXT:    wls lr, lr, .LBB21_3
 ; CHECK-NEXT:  @ %bb.1: @ %.preheader
-; CHECK-NEXT:    vmov.i32 q1, #0x0
+; CHECK-NEXT:    vmov.i32 q0, #0x0
 ; CHECK-NEXT:  .LBB21_2: @ =>This Inner Loop Header: Depth=1
-; CHECK-NEXT:    vldrw.u32 q0, [r0], #8
+; CHECK-NEXT:    vldrw.u32 q1, [r0], #8
 ; CHECK-NEXT:    vmaxnma.f16 q0, q1
-; CHECK-NEXT:    vmov q1, q0
 ; CHECK-NEXT:    le lr, .LBB21_2
 ; CHECK-NEXT:  .LBB21_3:
 ; CHECK-NEXT:    vldr.16 s4, .LCPI21_0