Optimize Smi keys for KeyedLoads

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 2764 matching lines @@
 }
 
 
 void LCodeGen::DoLoadKeyedFastElement(LLoadKeyedFastElement* instr) {
   Register elements = ToRegister(instr->elements());
   Register key = EmitLoadRegister(instr->key(), scratch0());
   Register result = ToRegister(instr->result());
   Register scratch = scratch0();
 
   // Load the result.
-  __ add(scratch, elements, Operand(key, LSL, kPointerSizeLog2));
+  if (instr->hydrogen()->key()->representation().IsTagged()) {
+    __ add(scratch, elements, Operand(key, LSL, kPointerSizeLog2 - 1));

[Michael Starzinger, 2012/07/19 21:02:23]

Can we use kSmiTagSize here?

[danno, 2012/07/20 09:51:57]

Done.

+  } else {
+    __ add(scratch, elements, Operand(key, LSL, kPointerSizeLog2));
+  }
   uint32_t offset = FixedArray::kHeaderSize +
                     (instr->additional_index() << kPointerSizeLog2);
   __ ldr(result, FieldMemOperand(scratch, offset));
 
   // Check for the hole value.
   if (instr->hydrogen()->RequiresHoleCheck()) {
     if (IsFastSmiElementsKind(instr->hydrogen()->elements_kind())) {
       __ tst(result, Operand(kSmiTagMask));
       DeoptimizeIf(ne, instr->environment());
     } else {
       __ LoadRoot(scratch, Heap::kTheHoleValueRootIndex);
       __ cmp(result, scratch);
       DeoptimizeIf(eq, instr->environment());
     }
   }
 }
 
 
 void LCodeGen::DoLoadKeyedFastDoubleElement(
     LLoadKeyedFastDoubleElement* instr) {
   Register elements = ToRegister(instr->elements());
   bool key_is_constant = instr->key()->IsConstantOperand();
   Register key = no_reg;
   DwVfpRegister result = ToDoubleRegister(instr->result());
   Register scratch = scratch0();
 
-  int shift_size =
-      ElementsKindToShiftSize(FAST_DOUBLE_ELEMENTS);
+  int element_size_shift = ElementsKindToShiftSize(FAST_DOUBLE_ELEMENTS);
+  int shift_size = (instr->hydrogen()->key()->representation().IsTagged())
+      ? (element_size_shift - 1) : element_size_shift;

[Michael Starzinger, 2012/07/19 21:02:23]

Likewise.

[danno, 2012/07/20 09:51:57]

Done.

   int constant_key = 0;
   if (key_is_constant) {
     constant_key = ToInteger32(LConstantOperand::cast(instr->key()));
     if (constant_key & 0xF0000000) {
       Abort("array index constant value too big.");
     }
   } else {
     key = ToRegister(instr->key());
   }
 
   Operand operand = key_is_constant
-      ? Operand(((constant_key + instr->additional_index()) << shift_size) +
+      ? Operand(((constant_key + instr->additional_index()) <<
+                 element_size_shift) +
                 FixedDoubleArray::kHeaderSize - kHeapObjectTag)
       : Operand(key, LSL, shift_size);
   __ add(elements, elements, operand);
   if (!key_is_constant) {
     __ add(elements, elements,
            Operand((FixedDoubleArray::kHeaderSize - kHeapObjectTag) +
-                   (instr->additional_index() << shift_size)));
+                   (instr->additional_index() << element_size_shift)));
   }
 
   if (instr->hydrogen()->RequiresHoleCheck()) {
     __ ldr(scratch, MemOperand(elements, sizeof(kHoleNanLower32)));
     __ cmp(scratch, Operand(kHoleNanUpper32));
     DeoptimizeIf(eq, instr->environment());
   }
 
   __ vldr(result, elements, 0);
 }
 
 
+MemOperand LCodeGen::PrepareKeyedOperand(Register key,
+                                         Register base,
+                                         bool key_is_constant,
+                                         int constant_key,
+                                         int element_size,
+                                         int shift_size,
+                                         int additional_index,
+                                         int additional_offset) {
+  if (additional_index != 0 && !key_is_constant) {
+    additional_index *= 1 << (element_size - shift_size);
+    __ add(scratch0(), key, Operand(additional_index));
+  }
+
+  if (key_is_constant) {
+    return MemOperand(base,
+                      (constant_key << element_size) + additional_offset);
+  }
+
+  if (additional_index == 0) {
+    if (shift_size >= 0) {
+      return MemOperand(base, key, LSL, shift_size);
+    } else {
+      ASSERT_EQ(-1, shift_size);
+      return MemOperand(base, key, LSR, 1);

[Michael Starzinger, 2012/07/19 21:02:23]

Likewise.

[danno, 2012/07/20 09:51:57]

Done.

+    }
+  }
+
+  if (shift_size >= 0) {
+    return MemOperand(base, scratch0(), LSL, shift_size);
+  } else {
+    ASSERT_EQ(-1, shift_size);
+    return MemOperand(base, scratch0(), LSR, 1);

[Michael Starzinger, 2012/07/19 21:02:23]

Likewise.

[danno, 2012/07/20 09:51:57]

Done.

+  }
+}
+
+
 void LCodeGen::DoLoadKeyedSpecializedArrayElement(
     LLoadKeyedSpecializedArrayElement* instr) {
   Register external_pointer = ToRegister(instr->external_pointer());
   Register key = no_reg;
   ElementsKind elements_kind = instr->elements_kind();
   bool key_is_constant = instr->key()->IsConstantOperand();
   int constant_key = 0;
   if (key_is_constant) {
     constant_key = ToInteger32(LConstantOperand::cast(instr->key()));
     if (constant_key & 0xF0000000) {
       Abort("array index constant value too big.");
     }
   } else {
     key = ToRegister(instr->key());
   }
-  int shift_size = ElementsKindToShiftSize(elements_kind);
-  int additional_offset = instr->additional_index() << shift_size;
+  int element_size_shift = ElementsKindToShiftSize(elements_kind);
+  int shift_size = (instr->hydrogen()->key()->representation().IsTagged())
+      ? (element_size_shift - 1) : element_size_shift;

[Michael Starzinger, 2012/07/19 21:02:23]

Likewise.

[danno, 2012/07/20 09:51:57]

Done.

+  int additional_offset = instr->additional_index() << element_size_shift;
 
   if (elements_kind == EXTERNAL_FLOAT_ELEMENTS ||
       elements_kind == EXTERNAL_DOUBLE_ELEMENTS) {
     CpuFeatures::Scope scope(VFP3);
     DwVfpRegister result = ToDoubleRegister(instr->result());
     Operand operand = key_is_constant
-        ? Operand(constant_key << shift_size)
+        ? Operand(constant_key << element_size_shift)
         : Operand(key, LSL, shift_size);
     __ add(scratch0(), external_pointer, operand);
     if (elements_kind == EXTERNAL_FLOAT_ELEMENTS) {
       __ vldr(result.low(), scratch0(), additional_offset);
       __ vcvt_f64_f32(result, result.low());
     } else  {  // i.e. elements_kind == EXTERNAL_DOUBLE_ELEMENTS
       __ vldr(result, scratch0(), additional_offset);
     }
   } else {
     Register result = ToRegister(instr->result());
-    if (instr->additional_index() != 0 && !key_is_constant) {
-      __ add(scratch0(), key, Operand(instr->additional_index()));
-    }
-    MemOperand mem_operand(key_is_constant
-        ? MemOperand(external_pointer,
-                     (constant_key << shift_size) + additional_offset)
-        : (instr->additional_index() == 0
-           ? MemOperand(external_pointer, key, LSL, shift_size)
-           : MemOperand(external_pointer, scratch0(), LSL, shift_size)));
+    MemOperand mem_operand = PrepareKeyedOperand(
+        key, external_pointer, key_is_constant, constant_key,
+        element_size_shift, shift_size,
+        instr->additional_index(), additional_offset);
     switch (elements_kind) {
       case EXTERNAL_BYTE_ELEMENTS:
         __ ldrsb(result, mem_operand);
         break;
       case EXTERNAL_PIXEL_ELEMENTS:
       case EXTERNAL_UNSIGNED_BYTE_ELEMENTS:
         __ ldrb(result, mem_operand);
         break;
       case EXTERNAL_SHORT_ELEMENTS:
         __ ldrsh(result, mem_operand);
@@ skipping 896 matching lines @@
 
   // Do the store.
   if (instr->key()->IsConstantOperand()) {
     ASSERT(!instr->hydrogen()->NeedsWriteBarrier());
     LConstantOperand* const_operand = LConstantOperand::cast(instr->key());
     int offset =
         (ToInteger32(const_operand) + instr->additional_index()) * kPointerSize
         + FixedArray::kHeaderSize;
     __ str(value, FieldMemOperand(elements, offset));
   } else {
-    __ add(scratch, elements, Operand(key, LSL, kPointerSizeLog2));
+    if (instr->hydrogen()->key()->representation().IsTagged()) {
+      __ add(scratch, elements, Operand(key, LSL, kPointerSizeLog2 - 1));

[Michael Starzinger, 2012/07/19 21:02:23]

Likewise.

[danno, 2012/07/20 09:51:57]

Done.

+    } else {
+      __ add(scratch, elements, Operand(key, LSL, kPointerSizeLog2));
+    }
     if (instr->additional_index() != 0) {
       __ add(scratch,
              scratch,
              Operand(instr->additional_index() << kPointerSizeLog2));
     }
     __ str(value, FieldMemOperand(scratch, FixedArray::kHeaderSize));
   }
 
   if (instr->hydrogen()->NeedsWriteBarrier()) {
     HType type = instr->hydrogen()->value()->type();
@@ skipping 24 matching lines @@
   // Calculate the effective address of the slot in the array to store the
   // double value.
   if (key_is_constant) {
     constant_key = ToInteger32(LConstantOperand::cast(instr->key()));
     if (constant_key & 0xF0000000) {
       Abort("array index constant value too big.");
     }
   } else {
     key = ToRegister(instr->key());
   }
-  int shift_size = ElementsKindToShiftSize(FAST_DOUBLE_ELEMENTS);
+  int element_size_shift = ElementsKindToShiftSize(FAST_DOUBLE_ELEMENTS);
+  int shift_size = (instr->hydrogen()->key()->representation().IsTagged())
+      ? (element_size_shift - 1) : element_size_shift;
   Operand operand = key_is_constant
-      ? Operand((constant_key << shift_size) +
+      ? Operand((constant_key << element_size_shift) +
                 FixedDoubleArray::kHeaderSize - kHeapObjectTag)
       : Operand(key, LSL, shift_size);
   __ add(scratch, elements, operand);
   if (!key_is_constant) {
     __ add(scratch, scratch,
            Operand(FixedDoubleArray::kHeaderSize - kHeapObjectTag));
   }
 
   if (instr->NeedsCanonicalization()) {
     // Check for NaN. All NaNs must be canonicalized.
     __ VFPCompareAndSetFlags(value, value);
     // Only load canonical NaN if the comparison above set the overflow.
     __ Vmov(value,
             FixedDoubleArray::canonical_not_the_hole_nan_as_double(),
             vs);
   }
 
-  __ vstr(value, scratch, instr->additional_index() << shift_size);
+  __ vstr(value, scratch, instr->additional_index() << element_size_shift);
 }
 
 
 void LCodeGen::DoStoreKeyedSpecializedArrayElement(
     LStoreKeyedSpecializedArrayElement* instr) {
 
   Register external_pointer = ToRegister(instr->external_pointer());
   Register key = no_reg;
   ElementsKind elements_kind = instr->elements_kind();
   bool key_is_constant = instr->key()->IsConstantOperand();
   int constant_key = 0;
   if (key_is_constant) {
     constant_key = ToInteger32(LConstantOperand::cast(instr->key()));
     if (constant_key & 0xF0000000) {
       Abort("array index constant value too big.");
     }
   } else {
     key = ToRegister(instr->key());
   }
-  int shift_size = ElementsKindToShiftSize(elements_kind);
-  int additional_offset = instr->additional_index() << shift_size;
+  int element_size_shift = ElementsKindToShiftSize(elements_kind);
+  int shift_size = (instr->hydrogen()->key()->representation().IsTagged())
+      ? (element_size_shift - 1) : element_size_shift;
+  int additional_offset = instr->additional_index() << element_size_shift;
 
   if (elements_kind == EXTERNAL_FLOAT_ELEMENTS ||
       elements_kind == EXTERNAL_DOUBLE_ELEMENTS) {
     CpuFeatures::Scope scope(VFP3);
     DwVfpRegister value(ToDoubleRegister(instr->value()));
-    Operand operand(key_is_constant ? Operand(constant_key << shift_size)
-                                    : Operand(key, LSL, shift_size));
+    Operand operand(key_is_constant
+                    ? Operand(constant_key << element_size_shift)
+                    : Operand(key, LSL, shift_size));
     __ add(scratch0(), external_pointer, operand);
     if (elements_kind == EXTERNAL_FLOAT_ELEMENTS) {
       __ vcvt_f32_f64(double_scratch0().low(), value);
       __ vstr(double_scratch0().low(), scratch0(), additional_offset);
     } else {  // i.e. elements_kind == EXTERNAL_DOUBLE_ELEMENTS
       __ vstr(value, scratch0(), additional_offset);
     }
   } else {
     Register value(ToRegister(instr->value()));
-    if (instr->additional_index() != 0 && !key_is_constant) {
-      __ add(scratch0(), key, Operand(instr->additional_index()));
-    }
-    MemOperand mem_operand(key_is_constant
-        ? MemOperand(external_pointer,
-                     ((constant_key + instr->additional_index())
-                         << shift_size))
-        : (instr->additional_index() == 0
-            ? MemOperand(external_pointer, key, LSL, shift_size)
-            : MemOperand(external_pointer, scratch0(), LSL, shift_size)));
+    MemOperand mem_operand = PrepareKeyedOperand(
+        key, external_pointer, key_is_constant, constant_key,
+        element_size_shift, shift_size,
+        instr->additional_index(), additional_offset);
     switch (elements_kind) {
       case EXTERNAL_PIXEL_ELEMENTS:
       case EXTERNAL_BYTE_ELEMENTS:
       case EXTERNAL_UNSIGNED_BYTE_ELEMENTS:
         __ strb(value, mem_operand);
         break;
       case EXTERNAL_SHORT_ELEMENTS:
       case EXTERNAL_UNSIGNED_SHORT_ELEMENTS:
         __ strh(value, mem_operand);
         break;
@@ skipping 1474 matching lines @@
   __ sub(scratch, result, Operand(index, LSL, kPointerSizeLog2 - kSmiTagSize));
   __ ldr(result, FieldMemOperand(scratch,
                                  FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal