A64: Optimize LCodeGen::DoMathFloorOfDiv after r18780

src/a64/lithium-codegen-a64.cc

 // Copyright 2013 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 3572 matching lines @@
   __ B(&done, eq);
 
   __ Bind(&deopt);
   Deoptimize(instr->environment());
 
   __ Bind(&done);
 }
 
 
 void LCodeGen::DoMathFloorOfDiv(LMathFloorOfDiv* instr) {
-  const Register result = ToRegister32(instr->result());
-  const Register left = ToRegister32(instr->left());
-  const Register right = ToRegister32(instr->right());
-  const Register remainder = ToRegister32(instr->temp());
+  Register result = ToRegister32(instr->result());
+  Register left = ToRegister32(instr->left());
+  Register right = ToRegister32(instr->right());
+  Register remainder = ToRegister32(instr->temp());
+
+  // This can't cause an exception on ARM, so we can speculatively
+  // execute it already now.
+  __ Sdiv(result, left, right);
 
   // Check for x / 0.
   DeoptimizeIfZero(right, instr->environment());
 
   // Check for (kMinInt / -1).
   if (instr->hydrogen()->CheckFlag(HValue::kCanOverflow)) {
-    __ Cmp(left, kMinInt);
-    __ Ccmp(right, -1, ZFlag, eq);
+    // The V flag will be set iff left == kMinInt.
+    __ Cmp(left, 1);
+    __ Ccmp(right, -1, ZFlag, vs);
     DeoptimizeIf(eq, instr->environment());
   }
 
   // Check for (0 / -x) that will produce negative zero.
   if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
     __ Cmp(right, 0);
     __ Ccmp(left, 0, ZFlag, mi);
     // "right" can't be null because the code would have already been
     // deoptimized. The Z flag is set only if (right < 0) and (left == 0).
     // In this case we need to deoptimize to produce a -0.
     DeoptimizeIf(eq, instr->environment());
   }
 
   Label done;
-  __ Sdiv(result, left, right);
   // If both operands have the same sign then we are done.
-  __ Eor(remainder, left, Operand(right));
+  __ Eor(remainder, left, right);
   __ Tbz(remainder, kWSignBit, &done);
 
   // Check if the result needs to be corrected.
-  __ Mul(remainder, result, right);
-  __ Sub(remainder, remainder, left);
-  __ Cmp(remainder, 0);
-  __ B(eq, &done);
-  __ Sub(result, result, Operand(1));
+  __ Msub(remainder, result, right, left);
+  __ Cbz(remainder, &done);
+  __ Sub(result, result, 1);
 
   __ Bind(&done);
 }
 
 
 void LCodeGen::DoMathLog(LMathLog* instr) {
   ASSERT(ToDoubleRegister(instr->result()).is(d0));
   TranscendentalCacheStub stub(TranscendentalCache::LOG,
                                TranscendentalCacheStub::UNTAGGED);
   CallCode(stub.GetCode(isolate()), RelocInfo::CODE_TARGET, instr);
@@ skipping 1629 matching lines @@
   __ Bind(&out_of_object);
   __ Ldr(result, FieldMemOperand(object, JSObject::kPropertiesOffset));
   // Index is equal to negated out of object property index plus 1.
   __ Sub(result, result, Operand::UntagSmiAndScale(index, kPointerSizeLog2));
   __ Ldr(result, FieldMemOperand(result,
                                  FixedArray::kHeaderSize - kPointerSize));
   __ Bind(&done);
 }
 
 } }  // namespace v8::internal