[builtins] Introduce proper Float64Atan and Float64Atan2 operators.

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

Index: src/compiler/arm/code-generator-arm.cc
diff --git a/src/compiler/arm/code-generator-arm.cc b/src/compiler/arm/code-generator-arm.cc
index d6959b3db9ef074ef1429ceaec5520eb9afd850f..411f86c1635a8954de8332675ae7321fde18007f 100644
--- a/src/compiler/arm/code-generator-arm.cc
+++ b/src/compiler/arm/code-generator-arm.cc
@@ -407,6 +407,21 @@ Condition FlagsConditionToCondition(FlagsCondition condition) {
     __ dmb(ISH);                                                      \
   } while (0)
 
+#define ASSEMBLE_IEEE754_BINOP(name)                                           \
+  do {                                                                         \
+    /* TODO(bmeurer): We should really get rid of this special instruction, */ \
+    /* and generate a CallAddress instruction instead. */                      \
+    FrameScope scope(masm(), StackFrame::MANUAL);                              \
+    __ PrepareCallCFunction(0, 2, kScratchReg);                                \
+    __ MovToFloatParameters(i.InputFloat64Register(0),                         \
+                            i.InputFloat64Register(1));                        \
+    __ CallCFunction(ExternalReference::ieee754_##name##_function(isolate()),  \
+                     0, 2);                                                    \
+    /* Move the result in the double result register. */                       \
+    __ MovFromFloatResult(i.OutputFloat64Register());                          \
+    DCHECK_EQ(LeaveCC, i.OutputSBit());                                        \
+  } while (0)
+
 #define ASSEMBLE_IEEE754_UNOP(name)                                            \
   do {                                                                         \
     /* TODO(bmeurer): We should really get rid of this special instruction, */ \
@@ -688,6 +703,12 @@ CodeGenerator::CodeGenResult CodeGenerator::AssembleArchInstruction(
       __ add(i.OutputRegister(0), base, 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;