x64 support for d-to-i (truncated)

src/x64/code-stubs-x64.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 589 matching lines @@
                             Register second,
                             Register scratch1,
                             Register scratch2,
                             Register scratch3,
                             Label* on_success,
                             Label* on_not_smis,
                             ConvertUndefined convert_undefined);
 };
 
 
-// Get the integer part of a heap number.
-// Overwrites the contents of rdi, rbx and rcx. Result cannot be rdi or rbx.
-void IntegerConvert(MacroAssembler* masm,
-                    Register result,
-                    Register source) {
-  // Result may be rcx. If result and source are the same register, source will
-  // be overwritten.
-  ASSERT(!result.is(rdi) && !result.is(rbx));
-  // TODO(lrn): When type info reaches here, if value is a 32-bit integer, use
-  // cvttsd2si (32-bit version) directly.
-  Register double_exponent = rbx;
-  Register double_value = rdi;
-  Label done, exponent_63_plus;
-  // Get double and extract exponent.
-  __ movq(double_value, FieldOperand(source, HeapNumber::kValueOffset));
-  // Clear result preemptively, in case we need to return zero.
-  __ xorl(result, result);
-  __ movq(xmm0, double_value);  // Save copy in xmm0 in case we need it there.
-  // Double to remove sign bit, shift exponent down to least significant bits.
-  // and subtract bias to get the unshifted, unbiased exponent.
-  __ lea(double_exponent, Operand(double_value, double_value, times_1, 0));
-  __ shr(double_exponent, Immediate(64 - HeapNumber::kExponentBits));
-  __ subl(double_exponent, Immediate(HeapNumber::kExponentBias));
-  // Check whether the exponent is too big for a 63 bit unsigned integer.
-  __ cmpl(double_exponent, Immediate(63));
-  __ j(above_equal, &exponent_63_plus, Label::kNear);
-  // Handle exponent range 0..62.
-  __ cvttsd2siq(result, xmm0);
-  __ jmp(&done, Label::kNear);
+void DoubleToIStub::Generate(MacroAssembler* masm) {
+    Register input_reg = this->source();
+    Register final_result_reg = this->destination();
+    ASSERT(is_truncating());
 
-  __ bind(&exponent_63_plus);
-  // Exponent negative or 63+.
-  __ cmpl(double_exponent, Immediate(83));
-  // If exponent negative or above 83, number contains no significant bits in
-  // the range 0..2^31, so result is zero, and rcx already holds zero.
-  __ j(above, &done, Label::kNear);
+    Label check_negative, process_64_bits, done;
 
-  // Exponent in rage 63..83.
-  // Mantissa * 2^exponent contains bits in the range 2^0..2^31, namely
-  // the least significant exponent-52 bits.
+    int double_offset = offset();
 
-  // Negate low bits of mantissa if value is negative.
-  __ addq(double_value, double_value);  // Move sign bit to carry.
-  __ sbbl(result, result);  // And convert carry to -1 in result register.
-  // if scratch2 is negative, do (scratch2-1)^-1, otherwise (scratch2-0)^0.
-  __ addl(double_value, result);
-  // Do xor in opposite directions depending on where we want the result
-  // (depending on whether result is rcx or not).
+    // Account for return address and saved regs if input is rsp.
+    if (input_reg.is(rsp)) double_offset += 3 * kPointerSize;
 
-  if (result.is(rcx)) {
-    __ xorl(double_value, result);
-    // Left shift mantissa by (exponent - mantissabits - 1) to save the
-    // bits that have positional values below 2^32 (the extra -1 comes from the
-    // doubling done above to move the sign bit into the carry flag).
-    __ leal(rcx, Operand(double_exponent, -HeapNumber::kMantissaBits - 1));
-    __ shll_cl(double_value);
-    __ movl(result, double_value);
-  } else {
-    // As the then-branch, but move double-value to result before shifting.
-    __ xorl(result, double_value);
-    __ leal(rcx, Operand(double_exponent, -HeapNumber::kMantissaBits - 1));
-    __ shll_cl(result);
-  }
+    MemOperand mantissa_operand(MemOperand(input_reg, double_offset));
+    MemOperand exponent_operand(MemOperand(input_reg,
+                                           double_offset + kDoubleSize / 2));
 
-  __ bind(&done);
+    Register scratch1;
+    Register scratch_candidates[3] = { rbx, rdx, rdi };
+    for (int i = 0; i < 3; i++) {
+      scratch1 = scratch_candidates[i];
+      if (!final_result_reg.is(scratch1) && !input_reg.is(scratch1)) break;
+    }
+
+    // Since we must use rcx for shifts below, use some other register (rax)
+    // to calculate the result if ecx is the requested return register.
+    Register result_reg = final_result_reg.is(rcx) ? rax : final_result_reg;
+    // Save ecx if it isn't the return register and therefore volatile, or if it
+    // is the return register, then save the temp register we use in its stead
+    // for the result.
+    Register save_reg = final_result_reg.is(rcx) ? rax : rcx;
+    __ push(scratch1);
+    __ push(save_reg);
+
+    bool stash_exponent_copy = !input_reg.is(rsp);
+    __ movl(scratch1, mantissa_operand);
+    __ movsd(xmm0, mantissa_operand);
+    __ movl(rcx, exponent_operand);
+    if (stash_exponent_copy) __ push(rcx);
+
+    __ andl(rcx, Immediate(HeapNumber::kExponentMask));
+    __ shrl(rcx, Immediate(HeapNumber::kExponentShift));
+    __ leal(result_reg, MemOperand(rcx, -HeapNumber::kExponentBias));
+    __ cmpl(result_reg, Immediate(HeapNumber::kMantissaBits));
+    __ j(below, &process_64_bits);
+
+    // Result is entirely in lower 32-bits of mantissa
+    int delta = HeapNumber::kExponentBias + Double::kPhysicalSignificandSize;
+    __ subl(rcx, Immediate(delta));
+    __ xorl(result_reg, result_reg);
+    __ cmpl(rcx, Immediate(31));
+    __ j(above, &done);
+    __ shll_cl(scratch1);
+    __ jmp(&check_negative);
+
+    __ bind(&process_64_bits);
+    __ cvttsd2siq(result_reg, xmm0);
+    __ jmp(&done, Label::kNear);
+
+    // If the double was negative, negate the integer result.
+    __ bind(&check_negative);
+    __ movl(result_reg, scratch1);
+    __ negl(result_reg);
+    if (stash_exponent_copy) {
+        __ cmpl(MemOperand(rsp, 0), Immediate(0));
+    } else {
+        __ cmpl(exponent_operand, Immediate(0));
+    }
+    __ cmovl(greater, result_reg, scratch1);
+
+    // Restore registers
+    __ bind(&done);
+    if (stash_exponent_copy) {
+        __ addq(rsp, Immediate(kDoubleSize));
+    }
+    if (!final_result_reg.is(result_reg)) {
+        ASSERT(final_result_reg.is(rcx));
+        __ movl(final_result_reg, result_reg);
+    }
+    __ pop(save_reg);
+    __ pop(scratch1);
+    __ ret(0);
 }
 
 
 void BinaryOpStub::Initialize() {}
 
 
 void BinaryOpStub::GenerateTypeTransition(MacroAssembler* masm) {
   __ pop(rcx);  // Save return address.
   __ push(rdx);
   __ push(rax);
@@ skipping 865 matching lines @@
   Label done;
   Label rax_is_smi;
   Label rax_is_object;
   Label rdx_is_object;
 
   __ JumpIfNotSmi(rdx, &rdx_is_object);
   __ SmiToInteger32(rdx, rdx);
   __ JumpIfSmi(rax, &rax_is_smi);
 
   __ bind(&rax_is_object);
-  IntegerConvert(masm, rcx, rax);  // Uses rdi, rcx and rbx.
+  DoubleToIStub stub1(rax, rcx, HeapNumber::kValueOffset - kHeapObjectTag,
+                     true);
+  __ call(stub1.GetCode(masm->isolate()), RelocInfo::CODE_TARGET);
+
   __ jmp(&done);
 
   __ bind(&rdx_is_object);
-  IntegerConvert(masm, rdx, rdx);  // Uses rdi, rcx and rbx.
+  DoubleToIStub stub2(rdx, rdx, HeapNumber::kValueOffset - kHeapObjectTag,
+                     true);
+  __ call(stub1.GetCode(masm->isolate()), RelocInfo::CODE_TARGET);
   __ JumpIfNotSmi(rax, &rax_is_object);
+
   __ bind(&rax_is_smi);
   __ SmiToInteger32(rcx, rax);
 
   __ bind(&done);
   __ movl(rax, rdx);
 }
 
 
 // Input: rdx, rax are the left and right objects of a bit op.
 // Output: rax, rcx are left and right integers for a bit op.
@@ skipping 14 matching lines @@
   __ bind(&check_undefined_arg1);
   __ CompareRoot(rdx, Heap::kUndefinedValueRootIndex);
   __ j(not_equal, conversion_failure);
   __ Set(r8, 0);
   __ jmp(&load_arg2);
 
   __ bind(&arg1_is_object);
   __ cmpq(FieldOperand(rdx, HeapObject::kMapOffset), heap_number_map);
   __ j(not_equal, &check_undefined_arg1);
   // Get the untagged integer version of the rdx heap number in rcx.
-  IntegerConvert(masm, r8, rdx);
+  DoubleToIStub stub1(rdx, r8, HeapNumber::kValueOffset - kHeapObjectTag,
+                      true);
+  __ call(stub1.GetCode(masm->isolate()), RelocInfo::CODE_TARGET);
 
   // Here r8 has the untagged integer, rax has a Smi or a heap number.
   __ bind(&load_arg2);
   // Test if arg2 is a Smi.
   __ JumpIfNotSmi(rax, &arg2_is_object);
   __ SmiToInteger32(rcx, rax);
   __ jmp(&done);
 
   // If the argument is undefined it converts to zero (ECMA-262, section 9.5).
   __ bind(&check_undefined_arg2);
   __ CompareRoot(rax, Heap::kUndefinedValueRootIndex);
   __ j(not_equal, conversion_failure);
   __ Set(rcx, 0);
   __ jmp(&done);
 
   __ bind(&arg2_is_object);
   __ cmpq(FieldOperand(rax, HeapObject::kMapOffset), heap_number_map);
   __ j(not_equal, &check_undefined_arg2);
   // Get the untagged integer version of the rax heap number in rcx.
-  IntegerConvert(masm, rcx, rax);
+  DoubleToIStub stub2(rax, rcx, HeapNumber::kValueOffset - kHeapObjectTag,
+                      true);
+  __ call(stub2.GetCode(masm->isolate()), RelocInfo::CODE_TARGET);
+
   __ bind(&done);
   __ movl(rax, r8);
 }
 
 
 void FloatingPointHelper::LoadSSE2SmiOperands(MacroAssembler* masm) {
   __ SmiToInteger32(kScratchRegister, rdx);
   __ cvtlsi2sd(xmm0, kScratchRegister);
   __ SmiToInteger32(kScratchRegister, rax);
   __ cvtlsi2sd(xmm1, kScratchRegister);
@@ skipping 1698 matching lines @@
 
       // If either operand is a JSObject or an oddball value, then they are not
       // equal since their pointers are different
       // There is no test for undetectability in strict equality.
 
       // If the first object is a JS object, we have done pointer comparison.
       STATIC_ASSERT(LAST_TYPE == LAST_SPEC_OBJECT_TYPE);
       Label first_non_object;
       __ CmpObjectType(rax, FIRST_SPEC_OBJECT_TYPE, rcx);
       __ j(below, &first_non_object, Label::kNear);
-      // Return non-zero (eax (not rax) is not zero)
+      // Return non-zero (rax (not rax) is not zero)
       Label return_not_equal;
       STATIC_ASSERT(kHeapObjectTag != 0);
       __ bind(&return_not_equal);
       __ ret(0);
 
       __ bind(&first_non_object);
       // Check for oddballs: true, false, null, undefined.
       __ CmpInstanceType(rcx, ODDBALL_TYPE);
       __ j(equal, &return_not_equal);
 
@@ skipping 41 matching lines @@
 
   // Fast negative check for internalized-to-internalized equality.
   Label check_for_strings;
   if (cc == equal) {
     BranchIfNotInternalizedString(
         masm, &check_for_strings, rax, kScratchRegister);
     BranchIfNotInternalizedString(
         masm, &check_for_strings, rdx, kScratchRegister);
 
     // We've already checked for object identity, so if both operands are
-    // internalized strings they aren't equal. Register eax (not rax) already
+    // internalized strings they aren't equal. Register rax (not rax) already
     // holds a non-zero value, which indicates not equal, so just return.
     __ ret(0);
   }
 
   __ bind(&check_for_strings);
 
   __ JumpIfNotBothSequentialAsciiStrings(
       rdx, rax, rcx, rbx, &check_unequal_objects);
 
   // Inline comparison of ASCII strings.
@@ skipping 3388 matching lines @@
   __ bind(&fast_elements_case);
   GenerateCase(masm, FAST_ELEMENTS);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64