[turbofan] ARM64: Use zr to store immediate zero

src/compiler/arm64/code-generator-arm64.cc

 // Copyright 2014 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/compiler/code-generator.h"
 
 #include "src/arm64/frames-arm64.h"
 #include "src/arm64/macro-assembler-arm64.h"
 #include "src/ast/scopes.h"
 #include "src/compiler/code-generator-impl.h"
@@ skipping 15 matching lines @@
       : InstructionOperandConverter(gen, instr) {}
 
   DoubleRegister InputFloat32Register(size_t index) {
     return InputDoubleRegister(index).S();
   }
 
   DoubleRegister InputFloat64Register(size_t index) {
     return InputDoubleRegister(index);
   }
 
+  CPURegister InputFloat32OrZeroRegister(size_t index) {
+    if (instr_->InputAt(index)->IsImmediate()) {
+      DCHECK(instr_->InputAt(index)->IsImmediate() &&
+             (InputFloat32(index) == 0.0f) &&
+             (copysignf(1.0f, InputFloat32(index)) > 0.0f));

[Benedikt Meurer, 2016/05/03 17:33:20]

Use std::signbit or bit_cast<int32_t>(InputFloat32(index)) == 0

[martyn.capewell, 2016/05/04 09:47:47]

Done.

+      return wzr;
+    }
+    DCHECK(instr_->InputAt(index)->IsDoubleRegister());
+    return InputDoubleRegister(index).S();
+  }
+
+  CPURegister InputFloat64OrZeroRegister(size_t index) {
+    if (instr_->InputAt(index)->IsImmediate()) {
+      DCHECK(instr_->InputAt(index)->IsImmediate() &&
+             (InputDouble(index) == 0.0f) &&
+             (copysign(1.0, InputDouble(index)) > 0.0));

[Benedikt Meurer, 2016/05/03 17:33:20]

Use std::signbit or bit_cast<int64_t>(InputFloat64(index)) == 0

[martyn.capewell, 2016/05/04 09:47:47]

Done.

+      return xzr;
+    }
+    DCHECK(instr_->InputAt(index)->IsDoubleRegister());
+    return InputDoubleRegister(index);
+  }
+
   size_t OutputCount() { return instr_->OutputCount(); }
 
   DoubleRegister OutputFloat32Register() { return OutputDoubleRegister().S(); }
 
   DoubleRegister OutputFloat64Register() { return OutputDoubleRegister(); }
 
   Register InputRegister32(size_t index) {
     return ToRegister(instr_->InputAt(index)).W();
   }
 
@@ skipping 363 matching lines @@
     auto buffer = i.InputRegister(0);                        \
     auto offset = i.InputRegister32(1);                      \
     auto length = i.InputOperand32(2);                       \
     __ Cmp(offset, length);                                  \
     auto ool = new (zone()) OutOfLineLoadZero(this, result); \
     __ B(hs, ool->entry());                                  \
     __ asm_instr(result, MemOperand(buffer, offset, UXTW));  \
     __ Bind(ool->exit());                                    \
   } while (0)
 
-
-#define ASSEMBLE_CHECKED_STORE_FLOAT(width)          \
-  do {                                               \
-    auto buffer = i.InputRegister(0);                \
-    auto offset = i.InputRegister32(1);              \
-    auto length = i.InputOperand32(2);               \
-    auto value = i.InputFloat##width##Register(3);   \
-    __ Cmp(offset, length);                          \
-    Label done;                                      \
-    __ B(hs, &done);                                 \
-    __ Str(value, MemOperand(buffer, offset, UXTW)); \
-    __ Bind(&done);                                  \
+#define ASSEMBLE_CHECKED_STORE_FLOAT(width)              \
+  do {                                                   \
+    auto buffer = i.InputRegister(0);                    \
+    auto offset = i.InputRegister32(1);                  \
+    auto length = i.InputOperand32(2);                   \
+    auto value = i.InputFloat##width##OrZeroRegister(3); \
+    __ Cmp(offset, length);                              \
+    Label done;                                          \
+    __ B(hs, &done);                                     \
+    __ Str(value, MemOperand(buffer, offset, UXTW));     \
+    __ Bind(&done);                                      \
   } while (0)
 
-
 #define ASSEMBLE_CHECKED_STORE_INTEGER(asm_instr)          \
   do {                                                     \
     auto buffer = i.InputRegister(0);                      \
     auto offset = i.InputRegister32(1);                    \
     auto length = i.InputOperand32(2);                     \
-    auto value = i.InputRegister32(3);                     \
+    auto value = i.InputOrZeroRegister32(3);               \
     __ Cmp(offset, length);                                \
     Label done;                                            \
     __ B(hs, &done);                                       \
     __ asm_instr(value, MemOperand(buffer, offset, UXTW)); \
     __ Bind(&done);                                        \
   } while (0)
 
-
 #define ASSEMBLE_CHECKED_STORE_INTEGER_64(asm_instr)       \
   do {                                                     \
     auto buffer = i.InputRegister(0);                      \
     auto offset = i.InputRegister32(1);                    \
     auto length = i.InputOperand32(2);                     \
-    auto value = i.InputRegister(3);                       \
+    auto value = i.InputOrZeroRegister64(3);               \
     __ Cmp(offset, length);                                \
     Label done;                                            \
     __ B(hs, &done);                                       \
     __ asm_instr(value, MemOperand(buffer, offset, UXTW)); \
     __ Bind(&done);                                        \
   } while (0)
 
-
 #define ASSEMBLE_SHIFT(asm_instr, width)                                    \
   do {                                                                      \
     if (instr->InputAt(1)->IsRegister()) {                                  \
       __ asm_instr(i.OutputRegister##width(), i.InputRegister##width(0),    \
                    i.InputRegister##width(1));                              \
     } else {                                                                \
       uint32_t imm =                                                        \
           static_cast<uint32_t>(i.InputOperand##width(1).ImmediateValue()); \
       __ asm_instr(i.OutputRegister##width(), i.InputRegister##width(0),    \
                    imm % (width));                                          \
@@ skipping 858 matching lines @@
     case kArm64U64MoveFloat64:
       __ Fmov(i.OutputRegister(), i.InputDoubleRegister(0));
       break;
     case kArm64Ldrb:
       __ Ldrb(i.OutputRegister(), i.MemoryOperand());
       break;
     case kArm64Ldrsb:
       __ Ldrsb(i.OutputRegister(), i.MemoryOperand());
       break;
     case kArm64Strb:
-      __ Strb(i.InputRegister(2), i.MemoryOperand());
+      __ Strb(i.InputOrZeroRegister64(2), i.MemoryOperand());
       break;
     case kArm64Ldrh:
       __ Ldrh(i.OutputRegister(), i.MemoryOperand());
       break;
     case kArm64Ldrsh:
       __ Ldrsh(i.OutputRegister(), i.MemoryOperand());
       break;
     case kArm64Strh:
-      __ Strh(i.InputRegister(2), i.MemoryOperand());
+      __ Strh(i.InputOrZeroRegister64(2), i.MemoryOperand());
       break;
     case kArm64LdrW:
       __ Ldr(i.OutputRegister32(), i.MemoryOperand());
       break;
     case kArm64StrW:
-      __ Str(i.InputRegister32(2), i.MemoryOperand());
+      __ Str(i.InputOrZeroRegister32(2), i.MemoryOperand());
       break;
     case kArm64Ldr:
       __ Ldr(i.OutputRegister(), i.MemoryOperand());
       break;
     case kArm64Str:
-      __ Str(i.InputRegister(2), i.MemoryOperand());
+      __ Str(i.InputOrZeroRegister64(2), i.MemoryOperand());
       break;
     case kArm64LdrS:
       __ Ldr(i.OutputDoubleRegister().S(), i.MemoryOperand());
       break;
     case kArm64StrS:
-      __ Str(i.InputDoubleRegister(2).S(), i.MemoryOperand());
+      __ Str(i.InputFloat32OrZeroRegister(2), i.MemoryOperand());
       break;
     case kArm64LdrD:
       __ Ldr(i.OutputDoubleRegister(), i.MemoryOperand());
       break;
     case kArm64StrD:
-      __ Str(i.InputDoubleRegister(2), i.MemoryOperand());
+      __ Str(i.InputFloat64OrZeroRegister(2), i.MemoryOperand());
       break;
     case kCheckedLoadInt8:
       ASSEMBLE_CHECKED_LOAD_INTEGER(Ldrsb);
       break;
     case kCheckedLoadUint8:
       ASSEMBLE_CHECKED_LOAD_INTEGER(Ldrb);
       break;
     case kCheckedLoadInt16:
       ASSEMBLE_CHECKED_LOAD_INTEGER(Ldrsh);
       break;
@@ skipping 473 matching lines @@
       padding_size -= kInstructionSize;
     }
   }
 }
 
 #undef __
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8