[LoongArch] Add codegen support for fsqrt

llvm/lib/Target/LoongArch/LoongArchFloat32InstrInfo.td

 /// 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>;
 def : PatFpr<fabs, FABS_S, FPR32>;
+def : PatFpr<fsqrt, FSQRT_S, FPR32>;
+
+def : Pat<(fdiv fpimm1, (fsqrt FPR32:$fj)), (FRSQRT_S FPR32:$fj)>;
 
 /// Setcc
 
 // Match non-signaling comparison
 
 // TODO: change setcc to any_fsetcc after call is supported because
 // we need to call llvm.experimental.constrained.fcmp.f32 in testcase.
 // See RISCV float-fcmp-strict.ll for reference.

llvm/lib/Target/LoongArch/LoongArchFloat64InstrInfo.td

 /// 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>;
 def : PatFpr<fabs, FABS_D, FPR64>;
+def : PatFpr<fsqrt, FSQRT_D, FPR64>;
+
+def : Pat<(fdiv fpimm1, (fsqrt FPR64:$fj)), (FRSQRT_D FPR64:$fj)>;
 
 /// Setcc
 
 // Match non-signaling comparison
 
 // TODO: Change setcc to any_fsetcc after call is supported because
 // we need to call llvm.experimental.constrained.fcmp.f64 in testcase.
 // See RISCV float-fcmp-strict.ll for reference.

llvm/test/CodeGen/LoongArch/fsqrt.ll

+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc --mtriple=loongarch32 --mattr=+f,-d < %s | FileCheck %s --check-prefix=LA32F
+; RUN: llc --mtriple=loongarch32 --mattr=+d < %s | FileCheck %s --check-prefix=LA32D
+; RUN: llc --mtriple=loongarch64 --mattr=+f,-d < %s | FileCheck %s --check-prefix=LA64F
+; RUN: llc --mtriple=loongarch64 --mattr=+d < %s | FileCheck %s --check-prefix=LA64D
+
+declare float @llvm.sqrt.f32(float)
+declare double @llvm.sqrt.f64(double)
+
+define float @fsqrt_f32(float %a) nounwind {
+; LA32F-LABEL: fsqrt_f32:
+; LA32F:       # %bb.0:
+; LA32F-NEXT:    fsqrt.s $fa0, $fa0
+; LA32F-NEXT:    ret
+;
+; LA32D-LABEL: fsqrt_f32:
+; LA32D:       # %bb.0:
+; LA32D-NEXT:    fsqrt.s $fa0, $fa0
+; LA32D-NEXT:    ret
+;
+; LA64F-LABEL: fsqrt_f32:
+; LA64F:       # %bb.0:
+; LA64F-NEXT:    fsqrt.s $fa0, $fa0
+; LA64F-NEXT:    ret
+;
+; LA64D-LABEL: fsqrt_f32:
+; LA64D:       # %bb.0:
+; LA64D-NEXT:    fsqrt.s $fa0, $fa0
+; LA64D-NEXT:    ret
+  %1 = call float @llvm.sqrt.f32(float %a)
+  ret float %1
+}
+
+define double @fsqrt_f64(double %a) nounwind {
+; LA32F-LABEL: fsqrt_f64:
+; LA32F:       # %bb.0:
+; LA32F-NEXT:    addi.w $sp, $sp, -16
+; LA32F-NEXT:    st.w $ra, $sp, 12 # 4-byte Folded Spill
+; LA32F-NEXT:    bl sqrt
+; LA32F-NEXT:    ld.w $ra, $sp, 12 # 4-byte Folded Reload
+; LA32F-NEXT:    addi.w $sp, $sp, 16
+; LA32F-NEXT:    ret
+;
+; LA32D-LABEL: fsqrt_f64:
+; LA32D:       # %bb.0:
+; LA32D-NEXT:    fsqrt.d $fa0, $fa0
+; LA32D-NEXT:    ret
+;
+; LA64F-LABEL: fsqrt_f64:
+; LA64F:       # %bb.0:
+; LA64F-NEXT:    addi.d $sp, $sp, -16
+; LA64F-NEXT:    st.d $ra, $sp, 8 # 8-byte Folded Spill
+; LA64F-NEXT:    bl sqrt
+; LA64F-NEXT:    ld.d $ra, $sp, 8 # 8-byte Folded Reload
+; LA64F-NEXT:    addi.d $sp, $sp, 16
+; LA64F-NEXT:    ret
+;
+; LA64D-LABEL: fsqrt_f64:
+; LA64D:       # %bb.0:
+; LA64D-NEXT:    fsqrt.d $fa0, $fa0
+; LA64D-NEXT:    ret
+  %1 = call double @llvm.sqrt.f64(double %a)
+  ret double %1
+}
+
+define float @frsqrt_f32(float %a) nounwind {
+; LA32F-LABEL: frsqrt_f32:
+; LA32F:       # %bb.0:
+; LA32F-NEXT:    frsqrt.s $fa0, $fa0
+; LA32F-NEXT:    ret
+;
+; LA32D-LABEL: frsqrt_f32:
+; LA32D:       # %bb.0:
+; LA32D-NEXT:    frsqrt.s $fa0, $fa0
+; LA32D-NEXT:    ret
+;
+; LA64F-LABEL: frsqrt_f32:
+; LA64F:       # %bb.0:
+; LA64F-NEXT:    frsqrt.s $fa0, $fa0
+; LA64F-NEXT:    ret
+;
+; LA64D-LABEL: frsqrt_f32:
+; LA64D:       # %bb.0:
+; LA64D-NEXT:    frsqrt.s $fa0, $fa0
+; LA64D-NEXT:    ret
+  %1 = call float @llvm.sqrt.f32(float %a)
+  %2 = fdiv float 1.0, %1
+  ret float %2
+}
+
+define double @frsqrt_f64(double %a) nounwind {
+; LA32F-LABEL: frsqrt_f64:
+; LA32F:       # %bb.0:
+; LA32F-NEXT:    addi.w $sp, $sp, -16
+; LA32F-NEXT:    st.w $ra, $sp, 12 # 4-byte Folded Spill
+; LA32F-NEXT:    bl sqrt
+; LA32F-NEXT:    move $a2, $a0
+; LA32F-NEXT:    move $a3, $a1
+; LA32F-NEXT:    lu12i.w $a1, 261888
+; LA32F-NEXT:    move $a0, $zero
+; LA32F-NEXT:    bl __divdf3
+; LA32F-NEXT:    ld.w $ra, $sp, 12 # 4-byte Folded Reload
+; LA32F-NEXT:    addi.w $sp, $sp, 16
+; LA32F-NEXT:    ret
+;
+; LA32D-LABEL: frsqrt_f64:
+; LA32D:       # %bb.0:
+; LA32D-NEXT:    frsqrt.d $fa0, $fa0
+; LA32D-NEXT:    ret
+;
+; LA64F-LABEL: frsqrt_f64:
+; LA64F:       # %bb.0:
+; LA64F-NEXT:    addi.d $sp, $sp, -16
+; LA64F-NEXT:    st.d $ra, $sp, 8 # 8-byte Folded Spill
+; LA64F-NEXT:    bl sqrt
+; LA64F-NEXT:    move $a1, $a0
+; LA64F-NEXT:    lu52i.d $a0, $zero, 1023
+; LA64F-NEXT:    bl __divdf3
+; LA64F-NEXT:    ld.d $ra, $sp, 8 # 8-byte Folded Reload
+; LA64F-NEXT:    addi.d $sp, $sp, 16
+; LA64F-NEXT:    ret
+;
+; LA64D-LABEL: frsqrt_f64:
+; LA64D:       # %bb.0:
+; LA64D-NEXT:    frsqrt.d $fa0, $fa0
+; LA64D-NEXT:    ret
+  %1 = call double @llvm.sqrt.f64(double %a)
+  %2 = fdiv double 1.0, %1
+  ret double %2
+}