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MIPS: Convert String array index/length hash to BitField.

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Port r21533 (736c779)

BUG=
R=plind44@gmail.com

Review URL: https://codereview.chromium.org/297233007

Patch from Balazs Kilvady <kilvadyb@homejinni.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21539 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
plind44@gmail.com 2014-05-27 17:11:33 +00:00
parent 5192a0d0d9
commit 47664dc108
2 changed files with 25 additions and 14 deletions
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9
src/mips/macro-assembler-mips.cc
View File

@ -3999,19 +3999,14 @@ bool MacroAssembler::AllowThisStubCall(CodeStub* stub) {
}
void MacroAssembler::IndexFromHash(Register hash,
Register index) {
void MacroAssembler::IndexFromHash(Register hash, Register index) {
// If the hash field contains an array index pick it out. The assert checks
// that the constants for the maximum number of digits for an array index
// cached in the hash field and the number of bits reserved for it does not
// conflict.
ASSERT(TenToThe(String::kMaxCachedArrayIndexLength) <
(1 << String::kArrayIndexValueBits));
// We want the smi-tagged index in key. kArrayIndexValueMask has zeros in
// the low kHashShift bits.
STATIC_ASSERT(kSmiTag == 0);
Ext(hash, hash, String::kHashShift, String::kArrayIndexValueBits);
sll(index, hash, kSmiTagSize);
DecodeFieldToSmi<String::ArrayIndexValueBits>(index, hash);
}

30
src/mips/macro-assembler-mips.h
View File

@ -1485,13 +1485,7 @@ const Operand& rt = Operand(zero_reg), BranchDelaySlot bd = PROTECT
template<typename Field>
void DecodeField(Register dst, Register src) {
static const int shift = Field::kShift;
static const int mask = Field::kMask >> shift;
static const int size = Field::kSize;
srl(dst, src, shift);
if (shift + size != 32) {
And(dst, dst, Operand(mask));
}
Ext(dst, src, Field::kShift, Field::kSize);
}
template<typename Field>
@ -1499,6 +1493,28 @@ const Operand& rt = Operand(zero_reg), BranchDelaySlot bd = PROTECT
DecodeField<Field>(reg, reg);
}
template<typename Field>
void DecodeFieldToSmi(Register dst, Register src) {
static const int shift = Field::kShift;
static const int mask = Field::kMask >> shift << kSmiTagSize;
STATIC_ASSERT((mask & (0x80000000u >> (kSmiTagSize - 1))) == 0);
STATIC_ASSERT(kSmiTag == 0);
if (shift < kSmiTagSize) {
sll(dst, src, kSmiTagSize - shift);
And(dst, dst, Operand(mask));
} else if (shift > kSmiTagSize) {
srl(dst, src, shift - kSmiTagSize);
And(dst, dst, Operand(mask));
} else {
And(dst, src, Operand(mask));
}
}
template<typename Field>
void DecodeFieldToSmi(Register reg) {
DecodeField<Field>(reg, reg);
}
// Generates function and stub prologue code.
void StubPrologue();
void Prologue(bool code_pre_aging);