[LoongArch] Add codegen support for fneg

[SixWeining]

Summary

Reference:
https://llvm.org/docs/LangRef.html#fneg-instruction

Depends on D127199

[rengolin]

LGTM, simple and straightforward.

[xen0n]

This is just one fneg so you may change the title to just "[LoongArch] Add codegen support for fneg" instead.

Otherwise it looks good!

[SixWeining]

In D127200#3569120, @xen0n wrote:

This is just one fneg so you may change the title to just "[LoongArch] Add codegen support for fneg" instead.

Otherwise it looks good!

Thanks. I just updated the title.

[SixWeining]

Remove the patch number in the title. (I already remove it in Phabricator yesterday.)

[MaskRay]

llvm/test/CodeGen/LoongArch/ir-instruction/fneg.ll

2

Consider placing some arithmetic tests in one file, instead of one file for each instruction.
This may run llc too many times, slowing down testsuite execution.

5

For some test directories, we use ;; to emphasize non-RUN non-CHECK lines.
This may help update_*_checks.py tools or improve FileCheck to detect some error-prone usage.

[SixWeining]

Address @MaskRay's comment: use ;; to emphasize non-RUN non-CHECK lines.

[SixWeining]

adjust the dependency

[xen0n]

still LGTM after rebase

llvm/lib/Target/LoongArch/LoongArchFloat32InstrInfo.td

 } // Predicates = [HasBasicF]
 
 //===----------------------------------------------------------------------===//
 // Pseudo-instructions and codegen patterns
 //===----------------------------------------------------------------------===//
 
 /// Generic pattern classes
 
+class PatFpr<SDPatternOperator OpNode, LAInst Inst, RegisterClass RegTy>
+    : Pat<(OpNode RegTy:$fj), (Inst $fj)>;
 class PatFprFpr<SDPatternOperator OpNode, LAInst Inst, RegisterClass RegTy>
     : Pat<(OpNode RegTy:$fj, RegTy:$fk), (Inst $fj, $fk)>;
 
 let Predicates = [HasBasicF] in {
 
 /// Float arithmetic operations
 
 def : PatFprFpr<fadd, FADD_S, FPR32>;
 def : PatFprFpr<fsub, FSUB_S, FPR32>;
 def : PatFprFpr<fmul, FMUL_S, FPR32>;
 def : PatFprFpr<fdiv, FDIV_S, FPR32>;
+def : PatFpr<fneg, FNEG_S, FPR32>;
 
 } // Predicates = [HasBasicF]

llvm/lib/Target/LoongArch/LoongArchFloat64InstrInfo.td

 let Predicates = [HasBasicD] in {
 
 /// Float arithmetic operations
 
 def : PatFprFpr<fadd, FADD_D, FPR64>;
 def : PatFprFpr<fsub, FSUB_D, FPR64>;
 def : PatFprFpr<fmul, FMUL_D, FPR64>;
 def : PatFprFpr<fdiv, FDIV_D, FPR64>;
+def : PatFpr<fneg, FNEG_D, FPR64>;
 
 } // Predicates = [HasBasicD]

llvm/test/CodeGen/LoongArch/ir-instruction/fneg.ll

+; RUN: llc --mtriple=loongarch32 --mattr=+d < %s | FileCheck %s --check-prefix=LA32
+; RUN: llc --mtriple=loongarch64 --mattr=+d < %s | FileCheck %s --check-prefix=LA64
+
+;; Exercise the 'fneg' LLVM IR: https://llvm.org/docs/LangRef.html#fneg-instruction
+
+define float @fneg_s(float %x) {
+; LA32-LABEL: fneg_s:
+; LA32:       # %bb.0:
+; LA32-NEXT:    fneg.s $fa0, $fa0
+; LA32-NEXT:    jirl $zero, $ra, 0
+;
+; LA64-LABEL: fneg_s:
+; LA64:       # %bb.0:
+; LA64-NEXT:    fneg.s $fa0, $fa0
+; LA64-NEXT:    jirl $zero, $ra, 0
+  %neg = fneg float %x
+  ret float %neg
+}
+
+define double @fneg_d(double %x) {
+; LA32-LABEL: fneg_d:
+; LA32:       # %bb.0:
+; LA32-NEXT:    fneg.d $fa0, $fa0
+; LA32-NEXT:    jirl $zero, $ra, 0
+;
+; LA64-LABEL: fneg_d:
+; LA64:       # %bb.0:
+; LA64-NEXT:    fneg.d $fa0, $fa0
+; LA64-NEXT:    jirl $zero, $ra, 0
+  %neg = fneg double %x
+  ret double %neg
+}

llvm/test/CodeGen/LoongArch/ir-instruction/fsub.ll

 ;
 ; LA64-LABEL: fsub_d:
 ; LA64:       # %bb.0:
 ; LA64-NEXT:    fsub.d $fa0, $fa0, $fa1
 ; LA64-NEXT:    jirl $zero, $ra, 0
   %sub = fsub double %x, %y
   ret double %sub
 }
+
+define float @fneg_s(float %x) {
+; LA32-LABEL: fneg_s:
+; LA32:       # %bb.0:
+; LA32-NEXT:    fneg.s $fa0, $fa0
+; LA32-NEXT:    jirl $zero, $ra, 0
+;
+; LA64-LABEL: fneg_s:
+; LA64:       # %bb.0:
+; LA64-NEXT:    fneg.s $fa0, $fa0
+; LA64-NEXT:    jirl $zero, $ra, 0
+    %res = fsub float -0.0, %x
+    ret float %res
+}
+
+define double @fneg_d(double %x) {
+; LA32-LABEL: fneg_d:
+; LA32:       # %bb.0:
+; LA32-NEXT:    fneg.d $fa0, $fa0
+; LA32-NEXT:    jirl $zero, $ra, 0
+;
+; LA64-LABEL: fneg_d:
+; LA64:       # %bb.0:
+; LA64-NEXT:    fneg.d $fa0, $fa0
+; LA64-NEXT:    jirl $zero, $ra, 0
+    %res = fsub double -0.0, %x
+    ret double %res
+}