MIPS64: Improve and fix nan hole checks and canonicalization.

src/mips64/lithium-codegen-mips64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
 #include "src/cpu-profiler.h"
 #include "src/hydrogen-osr.h"
@@ skipping 2345 matching lines @@
     __ li(at, Operand(factory()->the_hole_value()));
     EmitBranch(instr, eq, input_reg, Operand(at));
     return;
   }
 
   DoubleRegister input_reg = ToDoubleRegister(instr->object());
   EmitFalseBranchF(instr, eq, input_reg, input_reg);
 
   Register scratch = scratch0();
   __ FmoveHigh(scratch, input_reg);
-  __ dsll32(scratch, scratch, 0);  // FmoveHigh (mfhc1) sign-extends.
-  __ dsrl32(scratch, scratch, 0);  // Use only low 32-bits.
-  EmitBranch(instr, eq, scratch, Operand(kHoleNanUpper32));
+  EmitBranch(instr, eq, scratch,
+             Operand(static_cast<int32_t>(kHoleNanUpper32)));

[paul.l..., 2015/02/25 16:21:38]

this looks like nice solution to remove some instructions! Curious if this
changes the number of instructions emitted by the li() in the branch, though. Is
our li() clever enough to sign-extend without needing to explicitly load all 4
16-bit chunks?

 }
 
 
 void LCodeGen::DoCompareMinusZeroAndBranch(LCompareMinusZeroAndBranch* instr) {
   Representation rep = instr->hydrogen()->value()->representation();
   DCHECK(!rep.IsInteger32());
   Register scratch = ToRegister(instr->temp());
 
   if (rep.IsDouble()) {
     DoubleRegister value = ToDoubleRegister(instr->value());
@@ skipping 894 matching lines @@
       __ dsra32(at, key, 0);
     } else {
       __ dsra(at, key, -shift_size);
     }
     __ Daddu(scratch, scratch, at);
   }
 
   __ ldc1(result, MemOperand(scratch));
 
   if (instr->hydrogen()->RequiresHoleCheck()) {
-    __ lwu(scratch, MemOperand(scratch, sizeof(kHoleNanLower32)));
+    __ FmoveHigh(scratch, result);
     DeoptimizeIf(eq, instr, Deoptimizer::kHole, scratch,
-                 Operand(kHoleNanUpper32));
+                 Operand(static_cast<int32_t>(kHoleNanUpper32)));
   }
 }
 
 
 void LCodeGen::DoLoadKeyedFixedArray(LLoadKeyed* instr) {
   HLoadKeyed* hinstr = instr->hydrogen();
   Register elements = ToRegister(instr->elements());
   Register result = ToRegister(instr->result());
   Register scratch = scratch0();
   Register store_base = scratch;
@@ skipping 2757 matching lines @@
   __ li(at, scope_info);
   __ Push(at, ToRegister(instr->function()));
   CallRuntime(Runtime::kPushBlockContext, 2, instr);
   RecordSafepoint(Safepoint::kNoLazyDeopt);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal