[GlobalISel] Add IRTranslator support for G_FRINT

[paquette]

Summary

Add IRTranslator support for the opcode introduced by D60891.

Add it as a simple intrinsic and update arm64-irtranslator.ll.

llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp

switch (ID) {
     case Intrinsic::log:
       return TargetOpcode::G_FLOG;
     case Intrinsic::log2:
       return TargetOpcode::G_FLOG2;
     case Intrinsic::log10:
       return TargetOpcode::G_FLOG10;
     case Intrinsic::pow:
       return TargetOpcode::G_FPOW;
+    case Intrinsic::rint:
+      return TargetOpcode::G_FRINT;
     case Intrinsic::round:
       return TargetOpcode::G_INTRINSIC_ROUND;
     case Intrinsic::sin:
       return TargetOpcode::G_FSIN;
     case Intrinsic::sqrt:
       return TargetOpcode::G_FSQRT;
     case Intrinsic::trunc:
       return TargetOpcode::G_INTRINSIC_TRUNC;

llvm/test/CodeGen/AArch64/GlobalISel/arm64-irtranslator.ll

define void @test_stacksaverestore() {
   ; CHECK-LABEL: name: test_stacksaverestore
   ; CHECK: [[SAVE:%[0-9]+]]:_(p0) = COPY $sp
   ; CHECK-NEXT: $sp = COPY [[SAVE]](p0)
   ; CHECK-NEXT: RET_ReallyLR
   %sp = call i8* @llvm.stacksave()
   call void @llvm.stackrestore(i8* %sp)
   ret void
 }
+
+declare float @llvm.rint.f32(float)
+define float @test_rint_f32(float %x) {
+  ; CHECK-LABEL: name:            test_rint_f32
+  ; CHECK: %{{[0-9]+}}:_(s32) = G_FRINT %{{[0-9]+}}
+  %y = call float @llvm.rint.f32(float %x)
+  ret float %y
+}