[llvm] 6865fbd - [AArch64][SME] Use `fmov` instead of NEON `movi` for FP value.

[Sander de Smalen via llvm-commits]

Author: Sander de Smalen
Date: 2023-07-24T08:48:19Z
New Revision: 6865fbd3da94b3bcf46f37222db53b9f1eb2c406

URL: https://github.com/llvm/llvm-project/commit/6865fbd3da94b3bcf46f37222db53b9f1eb2c406
DIFF: https://github.com/llvm/llvm-project/commit/6865fbd3da94b3bcf46f37222db53b9f1eb2c406.diff

LOG: [AArch64][SME] Use `fmov` instead of NEON `movi` for FP value.

NEON `movi` is not valid in Streaming SVE mode, so use an `fmov`
instruction instead for zero-initializing a FP value.

Reviewed By: hassnaa-arm

Differential Revision: https://reviews.llvm.org/D155432

Added: 
    

Modified: 
    llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
    llvm/test/CodeGen/AArch64/sve-streaming-mode-fixed-length-stores.ll
    llvm/test/CodeGen/AArch64/sve-streaming-mode-test-register-mov.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp b/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
index 1e9eea63f0573e..76f1cc782b2488 100644
--- a/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
+++ b/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
@@ -1330,7 +1330,7 @@ void AArch64AsmPrinter::LowerFAULTING_OP(const MachineInstr &FaultingMI) {
 void AArch64AsmPrinter::emitFMov0(const MachineInstr &MI) {
   Register DestReg = MI.getOperand(0).getReg();
   if (STI->hasZeroCycleZeroingFP() && !STI->hasZeroCycleZeroingFPWorkaround() &&
-      STI->hasNEON()) {
+      STI->isNeonAvailable()) {
     // 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/sve-streaming-mode-fixed-length-stores.ll b/llvm/test/CodeGen/AArch64/sve-streaming-mode-fixed-length-stores.ll
index ca08895b9df276..55ecec520f38f5 100644
--- a/llvm/test/CodeGen/AArch64/sve-streaming-mode-fixed-length-stores.ll
+++ b/llvm/test/CodeGen/AArch64/sve-streaming-mode-fixed-length-stores.ll
@@ -195,7 +195,7 @@ define void @store_v1i64(ptr %a) #0 {
 define void @store_v1f64(ptr %a) #0 {
 ; CHECK-LABEL: store_v1f64:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    movi d0, #0000000000000000
+; CHECK-NEXT:    fmov d0, xzr
 ; CHECK-NEXT:    str d0, [x0]
 ; CHECK-NEXT:    ret
   store <1 x double> zeroinitializer, ptr %a

diff  --git a/llvm/test/CodeGen/AArch64/sve-streaming-mode-test-register-mov.ll b/llvm/test/CodeGen/AArch64/sve-streaming-mode-test-register-mov.ll
index 5f2c3d77f9a0fd..159a085b05ed09 100644
--- a/llvm/test/CodeGen/AArch64/sve-streaming-mode-test-register-mov.ll
+++ b/llvm/test/CodeGen/AArch64/sve-streaming-mode-test-register-mov.ll
@@ -12,4 +12,31 @@ define fp128 @test_streaming_compatible_register_mov(fp128 %q0, fp128 %q1) #0 {
   ret fp128 %q1
 }
 
+; Test that `movi` isn't used (invalid in streaming mode), but fmov or SVE mov instead.
+define double @fp_zero_constant() #0 {
+; CHECK-LABEL: fp_zero_constant:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    fmov d0, xzr
+; CHECK-NEXT:    ret
+  ret double 0.0
+}
+
+define <2 x i64> @fixed_vec_zero_constant() #0 {
+; CHECK-LABEL: fixed_vec_zero_constant:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    mov z0.d, #0 // =0x0
+; CHECK-NEXT:    // kill: def $q0 killed $q0 killed $z0
+; CHECK-NEXT:    ret
+  ret <2 x i64> zeroinitializer
+}
+
+define <2 x double> @fixed_vec_fp_zero_constant() #0 {
+; CHECK-LABEL: fixed_vec_fp_zero_constant:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    mov z0.d, #0 // =0x0
+; CHECK-NEXT:    // kill: def $q0 killed $q0 killed $z0
+; CHECK-NEXT:    ret
+  ret <2 x double> <double 0.0, double 0.0>
+}
+
 attributes #0 = { "target-features"="+sve" }