[builtins] Introduce proper Float64Atan and Float64Atan2 operators.

src/compiler/mips64/code-generator-mips64.cc

Index: src/compiler/mips64/code-generator-mips64.cc
diff --git a/src/compiler/mips64/code-generator-mips64.cc b/src/compiler/mips64/code-generator-mips64.cc
index afa221db59a6698ddb528c83474c61c3be049c71..47a766e8c2c9983e8cefa1f5ca5254167532cd2b 100644
--- a/src/compiler/mips64/code-generator-mips64.cc
+++ b/src/compiler/mips64/code-generator-mips64.cc
@@ -496,6 +496,18 @@ FPUCondition FlagsConditionToConditionCmpFPU(bool& predicate,
     __ sync();                                           \
   } while (0)
 
+#define ASSEMBLE_IEEE754_BINOP(name)                                          \
+  do {                                                                        \
+    FrameScope scope(masm(), StackFrame::MANUAL);                             \
+    __ PrepareCallCFunction(0, 2, kScratchReg);                               \
+    __ MovToFloatParameters(i.InputDoubleRegister(0),                         \
+                            i.InputDoubleRegister(1));                        \
+    __ CallCFunction(ExternalReference::ieee754_##name##_function(isolate()), \
+                     0, 2);                                                   \
+    /* Move the result in the double result register. */                      \
+    __ MovFromFloatResult(i.OutputDoubleRegister());                          \
+  } while (0)
+
 #define ASSEMBLE_IEEE754_UNOP(name)                                           \
   do {                                                                        \
     FrameScope scope(masm(), StackFrame::MANUAL);                             \
@@ -738,6 +750,12 @@ CodeGenerator::CodeGenResult CodeGenerator::AssembleArchInstruction(
                Operand(offset.offset()));
       break;
     }
+    case kIeee754Float64Atan:
+      ASSEMBLE_IEEE754_UNOP(atan);
+      break;
+    case kIeee754Float64Atan2:
+      ASSEMBLE_IEEE754_BINOP(atan2);
+      break;
     case kIeee754Float64Log:
       ASSEMBLE_IEEE754_UNOP(log);
       break;