From c8b44600c5ec358fe5d5eeb1f3c83c8e435b94e3 Mon Sep 17 00:00:00 2001
From: Alex Richardson <alexrichardson@google.com>
Date: Thu, 12 May 2022 10:23:10 +0000
Subject: [PATCH] [AArch64] Avoid emitting MOVID when NEON is disabled

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`

Reviewed By: dmgreen

Differential Revision: https://reviews.llvm.org/D125237
---
 llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp |  3 +-
 llvm/test/CodeGen/AArch64/movid-no-neon.ll    | 42 +++++++++++++++++++++++++++
 2 files changed, 44 insertions(+), 1 deletion(-)
 create mode 100644 llvm/test/CodeGen/AArch64/movid-no-neon.ll

diff --git a/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp b/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
index b54a0eab..de71c93 100644
--- a/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
+++ b/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
@@ -1129,7 +1129,8 @@ void AArch64AsmPrinter::LowerFAULTING_OP(const MachineInstr &FaultingMI) {
 
 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);
diff --git a/llvm/test/CodeGen/AArch64/movid-no-neon.ll b/llvm/test/CodeGen/AArch64/movid-no-neon.ll
new file mode 100644
index 0000000..581b0fb
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/movid-no-neon.ll
@@ -0,0 +1,42 @@
+; 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
+}
-- 
2.7.4