MIPS: port Prevent deopt on double value assignment to typed arrays

Ported r8077 (defc4f9b) to mips.

BUG=
TEST=

Review URL: http://codereview.chromium.org//7027023

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@8135 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/mips/macro-assembler-mips.cc

@@ -1044,6 +1044,51 @@ void MacroAssembler::EmitOutOfInt32RangeTruncate(Register result,
 }
 
 
+void MacroAssembler::EmitECMATruncate(Register result,
+                                      FPURegister double_input,
+                                      FPURegister single_scratch,
+                                      Register scratch,
+                                      Register input_high,
+                                      Register input_low) {
+  CpuFeatures::Scope scope(FPU);
+  ASSERT(!input_high.is(result));
+  ASSERT(!input_low.is(result));
+  ASSERT(!input_low.is(input_high));
+  ASSERT(!scratch.is(result) &&
+         !scratch.is(input_high) &&
+         !scratch.is(input_low));
+  ASSERT(!single_scratch.is(double_input));
+
+  Label done;
+  Label manual;
+
+  // Clear cumulative exception flags and save the FCSR.
+  Register scratch2 = input_high;
+  cfc1(scratch2, FCSR);
+  ctc1(zero_reg, FCSR);
+  // Try a conversion to a signed integer.
+  trunc_w_d(single_scratch, double_input);
+  mfc1(result, single_scratch);
+  // Retrieve and restore the FCSR.
+  cfc1(scratch, FCSR);
+  ctc1(scratch2, FCSR);
+  // Check for overflow and NaNs.
+  And(scratch,
+      scratch,
+      kFCSROverflowFlagMask | kFCSRUnderflowFlagMask | kFCSRInvalidOpFlagMask);
+  // If we had no exceptions we are done.
+  Branch(&done, eq, scratch, Operand(zero_reg));
+
+  // Load the double value and perform a manual truncation.
+  Move(input_low, input_high, double_input);
+  EmitOutOfInt32RangeTruncate(result,
+                              input_high,
+                              input_low,
+                              scratch);
+  bind(&done);
+}
+
+
 void MacroAssembler::GetLeastBitsFromSmi(Register dst,
                                          Register src,
                                          int num_least_bits) {

src/mips/macro-assembler-mips.h

@@ -573,6 +573,16 @@ DECLARE_NOTARGET_PROTOTYPE(Ret)
                                    Register input_low,
                                    Register scratch);
 
+  // Performs a truncating conversion of a floating point number as used by
+  // the JS bitwise operations. See ECMA-262 9.5: ToInt32.
+  // Exits with 'result' holding the answer and all other registers clobbered.
+  void EmitECMATruncate(Register result,
+                        FPURegister double_input,
+                        FPURegister single_scratch,
+                        Register scratch,
+                        Register scratch2,
+                        Register scratch3);
+
   // -------------------------------------------------------------------------
   // Activation frames.
 

src/mips/stub-cache-mips.cc

@@ -3934,27 +3934,8 @@ void KeyedStoreStubCompiler::GenerateStoreExternalArray(
         __ addu(t8, a3, t8);
         __ sdc1(f0, MemOperand(t8, 0));
       } else {
-        Label done;
-
-        // Need to perform float-to-int conversion.
-        // Test whether exponent equal to 0x7FF (infinity or NaN).
-
-        __ mfc1(t3, f1);  // Move exponent word of double to t3 (as raw bits).
-        __ li(t1, Operand(0x7FF00000));
-        __ And(t3, t3, Operand(t1));
-        __ Branch(USE_DELAY_SLOT, &done, eq, t3, Operand(t1));
-        __ mov(t3, zero_reg);  // In delay slot.
-
-        // Not infinity or NaN simply convert to int.
-        if (IsElementTypeSigned(array_type)) {
-          __ trunc_w_d(f0, f0);
-          __ mfc1(t3, f0);
-        } else {
-          __ Trunc_uw_d(f0, t3);
-        }
+        __ EmitECMATruncate(t3, f0, f2, t2, t1, t5);
 
-        // t3: HeapNumber converted to integer
-        __ bind(&done);
         switch (array_type) {
           case kExternalByteArray:
           case kExternalUnsignedByteArray: