VM: Support fast calls to atan and atan2 in optimized code.

runtime/vm/intermediate_language.cc

Index: runtime/vm/intermediate_language.cc
diff --git a/runtime/vm/intermediate_language.cc b/runtime/vm/intermediate_language.cc
index 9aa7cd5d10e11a570dc91fc0a9d07ec9f3fca82d..604417eb08655d160af4abe1772aefe05a4c7934 100644
--- a/runtime/vm/intermediate_language.cc
+++ b/runtime/vm/intermediate_language.cc
@@ -3543,9 +3543,11 @@ intptr_t InvokeMathCFunctionInstr::ArgumentCountFor(
       return 1;
     }
     case MethodRecognizer::kDoubleRound:
+    case MethodRecognizer::kMathAtan:
       return 1;
     case MethodRecognizer::kDoubleMod:
     case MethodRecognizer::kMathDoublePow:
+    case MethodRecognizer::kMathAtan2:
       return 2;
     default:
       UNREACHABLE();
@@ -3565,6 +3567,10 @@ DEFINE_RAW_LEAF_RUNTIME_ENTRY(DartModulo, 2, true /* is_float */,
     reinterpret_cast<RuntimeFunction>(
         static_cast<BinaryMathCFunction>(&DartModulo)));
 
+DEFINE_RAW_LEAF_RUNTIME_ENTRY(LibcAtan2, 2, true /* is_float */,
+    reinterpret_cast<RuntimeFunction>(
+        static_cast<BinaryMathCFunction>(&atan2)));

[Vyacheslav Egorov (Google), 2016/02/04 10:30:58]

I think this has to call to atan2_ieee to workaround some Windows specific
stuff.

[Florian Schneider, 2016/02/04 21:41:49]

Yes. Done.

+
 DEFINE_RAW_LEAF_RUNTIME_ENTRY(LibcFloor, 1, true /* is_float */,
     reinterpret_cast<RuntimeFunction>(
         static_cast<UnaryMathCFunction>(&floor)));
@@ -3596,6 +3602,10 @@ const RuntimeEntry& InvokeMathCFunctionInstr::TargetFunction() const {
       return kLibcPowRuntimeEntry;
     case MethodRecognizer::kDoubleMod:
       return kDartModuloRuntimeEntry;
+    case MethodRecognizer::kMathAtan:
+      return kLibcAtanRuntimeEntry;
+    case MethodRecognizer::kMathAtan2:
+      return kLibcAtan2RuntimeEntry;
     default:
       UNREACHABLE();
   }
@@ -3611,6 +3621,9 @@ DEFINE_RAW_LEAF_RUNTIME_ENTRY(LibcSin, 1, true /* is_float */,
     reinterpret_cast<RuntimeFunction>(
         static_cast<UnaryMathCFunction>(&sin)));
 
+DEFINE_RAW_LEAF_RUNTIME_ENTRY(LibcAtan, 1, true /* is_float */,
+    reinterpret_cast<RuntimeFunction>(
+        static_cast<UnaryMathCFunction>(&atan)));
 
 const RuntimeEntry& MathUnaryInstr::TargetFunction() const {
   switch (kind()) {