[AArch64] Avoid emitting MOVID when NEON is disabled

[arichardson]

Summary

Previously, creating a zero floating-point constant used MOVID even when
NEON was disabled which resulted in the following fatal error:
Attempting to emit MOVID instruction but the Feature_HasNEON predicate(s) are not met

[dmgreen]

Sounds good to me.

llvm/test/CodeGen/AArch64/movid-no-neon.ll

3

These tests don't usually need -O0 or -filetype=asm

llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp

void AArch64AsmPrinter::LowerFAULTING_OP(const MachineInstr &FaultingMI) {
   }
 
   OutStreamer->AddComment("on-fault: " + HandlerLabel->getName());
   OutStreamer->emitInstruction(MI, getSubtargetInfo());
 }
 
 void AArch64AsmPrinter::emitFMov0(const MachineInstr &MI) {
   Register DestReg = MI.getOperand(0).getReg();
-  if (STI->hasZeroCycleZeroingFP() && !STI->hasZeroCycleZeroingFPWorkaround()) {
+  if (STI->hasZeroCycleZeroingFP() && !STI->hasZeroCycleZeroingFPWorkaround() &&
+      STI->hasNEON()) {
     // Convert H/S register to corresponding D register
     if (AArch64::H0 <= DestReg && DestReg <= AArch64::H31)
       DestReg = AArch64::D0 + (DestReg - AArch64::H0);
     else if (AArch64::S0 <= DestReg && DestReg <= AArch64::S31)
       DestReg = AArch64::D0 + (DestReg - AArch64::S0);
     else
       assert(AArch64::D0 <= DestReg && DestReg <= AArch64::D31);
 

llvm/test/CodeGen/AArch64/movid-no-neon.ll

+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=aarch64 -mattr=+fullfp16,+neon < %s | FileCheck %s --check-prefix=NEON-ENABLED
+; RUN: llc -mtriple=aarch64 -mattr=+fullfp16,-neon < %s | FileCheck %s --check-prefix=NEON-DISABLED
+
+define float @get_float() {
+; NEON-ENABLED-LABEL: get_float:
+; NEON-ENABLED:       // %bb.0:
+; NEON-ENABLED-NEXT:    movi d0, #0000000000000000
+; NEON-ENABLED-NEXT:    ret
+;
+; NEON-DISABLED-LABEL: get_float:
+; NEON-DISABLED:       // %bb.0:
+; NEON-DISABLED-NEXT:    fmov s0, wzr
+; NEON-DISABLED-NEXT:    ret
+  ret float 0.000000e+00
+}
+
+define double @get_double() {
+; NEON-ENABLED-LABEL: get_double:
+; NEON-ENABLED:       // %bb.0:
+; NEON-ENABLED-NEXT:    movi d0, #0000000000000000
+; NEON-ENABLED-NEXT:    ret
+;
+; NEON-DISABLED-LABEL: get_double:
+; NEON-DISABLED:       // %bb.0:
+; NEON-DISABLED-NEXT:    fmov d0, xzr
+; NEON-DISABLED-NEXT:    ret
+  ret double 0.000000e+00
+}
+
+define half @get_half() {
+; NEON-ENABLED-LABEL: get_half:
+; NEON-ENABLED:       // %bb.0:
+; NEON-ENABLED-NEXT:    movi d0, #0000000000000000
+; NEON-ENABLED-NEXT:    ret
+;
+; NEON-DISABLED-LABEL: get_half:
+; NEON-DISABLED:       // %bb.0:
+; NEON-DISABLED-NEXT:    fmov h0, wzr
+; NEON-DISABLED-NEXT:    ret
+  ret half 0.000000e+00
+}