Increase sanity of integer division handling on ARM

src/arm/code-stubs-arm.cc

Index: src/arm/code-stubs-arm.cc
diff --git a/src/arm/code-stubs-arm.cc b/src/arm/code-stubs-arm.cc
index 3fbe0c5ea6d62942970d02438bda6f7fd87e56df..dccce5825ec2f26464504c86e710ead8e9fc00ca 100644
--- a/src/arm/code-stubs-arm.cc
+++ b/src/arm/code-stubs-arm.cc
@@ -1707,6 +1707,7 @@ void BinaryOpStub_GenerateSmiSmiOperation(MacroAssembler* masm,
       __ Ret();
 
       if (CpuFeatures::IsSupported(SUDIV)) {
+        CpuFeatureScope scope(masm, SUDIV);
         Label result_not_zero;
 
         __ bind(&div_with_sdiv);
@@ -1763,6 +1764,7 @@ void BinaryOpStub_GenerateSmiSmiOperation(MacroAssembler* masm,
       __ Ret();
 
       if (CpuFeatures::IsSupported(SUDIV)) {
+        CpuFeatureScope scope(masm, SUDIV);
         __ bind(&modulo_with_sdiv);
         __ mov(scratch2, right);
         // Perform modulus with sdiv and mls.
@@ -2208,22 +2210,11 @@ void BinaryOpStub::GenerateInt32Stub(MacroAssembler* masm) {
             UNREACHABLE();
         }
 
-        if (op_ != Token::DIV) {
-          // These operations produce an integer result.
-          // Try to return a smi if we can.
-          // Otherwise return a heap number if allowed, or jump to type
-          // transition.
-
-          if (result_type_ <= BinaryOpIC::INT32) {
-            __ TryDoubleToInt32Exact(scratch1, d5, d8);
-            // If the ne condition is set, result does
-            // not fit in a 32-bit integer.
-            __ b(ne, &transition);
-          } else {
-            __ vcvt_s32_f64(s8, d5);
-            __ vmov(scratch1, s8);
-          }
-
+        if (result_type_ <= BinaryOpIC::INT32) {
+          __ TryDoubleToInt32Exact(scratch1, d5, d8);
+          // If the ne condition is set, result does
+          // not fit in a 32-bit integer.
+          __ b(ne, &transition);
           // Check if the result fits in a smi.
           __ add(scratch2, scratch1, Operand(0x40000000), SetCC);

[Rodolph Perfetta, 2013/06/10 18:04:07]

a possible improvement:

  __ SmiTag(scratch1, SetCC);  // adds s1, s1, s1
  __ b(vs, &return_heap_number);
  ASSERT(kSmiTag == 0);
  __ b(ne, &not_zero);
  ...
  __ bind(&not_zero);
  __ mov(r0, Operand(scratch1));
  ...

[Jakob Kummerow, 2013/06/11 09:33:13]

Good idea. Done.

           // If not try to return a heap number.
@@ -2242,8 +2233,6 @@ void BinaryOpStub::GenerateInt32Stub(MacroAssembler* masm) {
           // Tag the result and return.
           __ SmiTag(r0, scratch1);
           __ Ret();
-        } else {
-          // DIV just falls through to allocating a heap number.
         }
 
         __ bind(&return_heap_number);