[v8-dev] ARM: Optimize truncating division and fix sim

src/arm/lithium-codegen-arm.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1395 matching lines @@
       // Do the test only if it hadn't be done above.
       __ cmp(right, Operand::Zero());
     }
     __ b(pl, &positive);
     __ cmp(left, Operand::Zero());
     DeoptimizeIf(eq, instr->environment());
     __ bind(&positive);
   }
 
   // Check for (kMinInt / -1).
-  if (instr->hydrogen()->CheckFlag(HValue::kCanOverflow)) {
+  if (instr->hydrogen()->CheckFlag(HValue::kCanOverflow) &&
+      (!CpuFeatures::IsSupported(SUDIV) ||
+       !instr->hydrogen()->CheckFlag(HValue::kAllUsesTruncatingToInt32))) {
+    // We don't need to check for overflow when truncating with sdiv
+    // support because, on ARM, sdiv kMinInt, -1 -> kMinInt.
     Label left_not_min_int;
     __ cmp(left, Operand(kMinInt));
     __ b(ne, &left_not_min_int);
     __ cmp(right, Operand(-1));
     DeoptimizeIf(eq, instr->environment());
     __ bind(&left_not_min_int);
   }
 
   if (CpuFeatures::IsSupported(SUDIV)) {
     CpuFeatureScope scope(masm(), SUDIV);
@@ skipping 4397 matching lines @@
   __ sub(scratch, result, Operand::PointerOffsetFromSmiKey(index));
   __ ldr(result, FieldMemOperand(scratch,
                                  FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal