[AArch64] Look through copy in MachineCombiner FMUL patterns.

This is a small addition to D99662, which added machine combiner
patterns for FMUL(DUP(..)). Due to the way these are generated from
ISel, they may also be FMUL(COPY(DUP(..))), which this patch now
ignores the no-op COPY in.

Differential Revision: https://reviews.llvm.org/D126632

Author: davemgreen

llvm/lib/Target/AArch64/AArch64InstrInfo.cpp

@@ -5170,6 +5170,10 @@ static bool getFMULPatterns(MachineInstr &Root,
     MachineInstr *MI = nullptr;
     if (MO.isReg() && Register::isVirtualRegister(MO.getReg()))
       MI = MRI.getUniqueVRegDef(MO.getReg());
+    // Ignore No-op COPYs in FMUL(COPY(DUP(..)))
+    if (MI && MI->getOpcode() == TargetOpcode::COPY &&
+        MI->getOperand(1).getReg().isVirtual())
+      MI = MRI.getUniqueVRegDef(MI->getOperand(1).getReg());
     if (MI && MI->getOpcode() == Opcode) {
       Patterns.push_back(Pattern);
       return true;
@@ -5441,6 +5445,9 @@ genIndexedMultiply(MachineInstr &Root,
   MachineInstr *Dup =
       MF.getRegInfo().getUniqueVRegDef(Root.getOperand(IdxDupOp).getReg());
 
+  if (Dup->getOpcode() == TargetOpcode::COPY)
+    Dup = MRI.getUniqueVRegDef(Dup->getOperand(1).getReg());
+
   Register DupSrcReg = Dup->getOperand(1).getReg();
   MRI.clearKillFlags(DupSrcReg);
   MRI.constrainRegClass(DupSrcReg, RC);

llvm/test/CodeGen/AArch64/machine-combiner-copy.ll

@@ -18,16 +18,15 @@ define void @fma_dup_f16(ptr noalias nocapture noundef readonly %A, half noundef
 ; CHECK-NEXT:    add x10, x1, #16
 ; CHECK-NEXT:    add x11, x0, #16
 ; CHECK-NEXT:    mov x12, x9
-; CHECK-NEXT:    dup v1.8h, v0.h[0]
 ; CHECK-NEXT:  .LBB0_4: // %vector.body
 ; CHECK-NEXT:    // =>This Inner Loop Header: Depth=1
-; CHECK-NEXT:    ldp q2, q3, [x11, #-16]
+; CHECK-NEXT:    ldp q1, q2, [x11, #-16]
 ; CHECK-NEXT:    subs x12, x12, #16
 ; CHECK-NEXT:    add x11, x11, #32
-; CHECK-NEXT:    ldp q4, q5, [x10, #-16]
-; CHECK-NEXT:    fmla v4.8h, v2.8h, v1.8h
-; CHECK-NEXT:    fmla v5.8h, v3.8h, v0.h[0]
-; CHECK-NEXT:    stp q4, q5, [x10, #-16]
+; CHECK-NEXT:    ldp q3, q4, [x10, #-16]
+; CHECK-NEXT:    fmla v3.8h, v1.8h, v0.h[0]
+; CHECK-NEXT:    fmla v4.8h, v2.8h, v0.h[0]
+; CHECK-NEXT:    stp q3, q4, [x10, #-16]
 ; CHECK-NEXT:    add x10, x10, #32
 ; CHECK-NEXT:    b.ne .LBB0_4
 ; CHECK-NEXT:  // %bb.5: // %middle.block

llvm/test/CodeGen/AArch64/machine-combiner-fmul-dup.mir

@@ -588,12 +588,12 @@ body:             |
   ; CHECK-NEXT:   [[INSERT_SUBREG:%[0-9]+]]:fpr128 = INSERT_SUBREG [[DEF]], [[COPY3]], %subreg.dsub
   ; CHECK-NEXT:   [[COPY4:%[0-9]+]]:fpr64 = COPY [[COPY1]]
   ; CHECK-NEXT:   [[COPY5:%[0-9]+]]:fpr64 = COPY [[COPY2]]
-  ; CHECK-NEXT:   [[DUPv2i32lane:%[0-9]+]]:fpr64 = DUPv2i32lane killed [[INSERT_SUBREG]], 0
+  ; CHECK-NEXT:   [[DUPv2i32lane:%[0-9]+]]:fpr64 = DUPv2i32lane [[INSERT_SUBREG]], 0
   ; CHECK-NEXT:   [[COPY6:%[0-9]+]]:fpr64 = COPY [[DUPv2i32lane]]
   ; CHECK-NEXT: {{  $}}
   ; CHECK-NEXT: bb.1:
-  ; CHECK-NEXT:   [[FMULv2f32_:%[0-9]+]]:fpr64 = FMULv2f32 [[COPY5]], [[COPY6]]
-  ; CHECK-NEXT:   [[FADDv2f32_:%[0-9]+]]:fpr64 = FADDv2f32 killed [[FMULv2f32_]], [[COPY4]]
+  ; CHECK-NEXT:   [[FMULv2i32_indexed:%[0-9]+]]:fpr64 = FMULv2i32_indexed [[COPY5]], [[INSERT_SUBREG]], 0
+  ; CHECK-NEXT:   [[FADDv2f32_:%[0-9]+]]:fpr64 = FADDv2f32 killed [[FMULv2i32_indexed]], [[COPY4]]
   ; CHECK-NEXT:   STRDui killed [[FADDv2f32_]], [[COPY]], 0 :: (store (s64), align 16)
   ; CHECK-NEXT:   B %bb.1
   bb.0: