Reviewers: Yang,
Message:
I modelled this after the webkit version of the same functions. I think
leaving
this is okay for now, but I don't care either way. Everywhere
V8_HOST_CAN_READ_UNALIGNED appears we potentially have big performance
differences on arm. Maybe we should get rid of this difference first.
Description:
Add back ascii fast path for toupper/tolower
[email protected]
BUG=
Please review this at https://codereview.chromium.org/11889007/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files:
M src/runtime.cc
Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index
b508ad3e995ed3f3a39454e69fe1633c41b88214..cd2d2dd5febdabe0430b5ff23970498cdde77033
100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -5803,7 +5803,9 @@ MUST_USE_RESULT static MaybeObject* ConvertCaseHelper(
namespace {
static const uintptr_t kOneInEveryByte = kUintptrAllBitsSet / 0xFF;
-
+#ifdef ENABLE_LATIN_1
+static const uintptr_t kAsciiMask = kOneInEveryByte << 7;
+#endif
// Given a word and two range boundaries returns a word with high bit
// set in every byte iff the corresponding input byte was strictly in
@@ -5817,7 +5819,10 @@ static inline uintptr_t AsciiRangeMask(uintptr_t w,
char m, char n) {
ASSERT((w & (kOneInEveryByte * 0x7F)) == w);
// Use strict inequalities since in edge cases the function could be
// further simplified.
- ASSERT(0 < m && m < n && n < 0x7F);
+ ASSERT(0 < m && m < n);
+#ifndef ENABLE_LATIN_1
+ ASSERT(n < 0x7F);
+#endif
// Has high bit set in every w byte less than n.
uintptr_t tmp1 = kOneInEveryByte * (0x7F + n) - w;
// Has high bit set in every w byte greater than m.
@@ -5834,7 +5839,11 @@ enum AsciiCaseConversion {
template <AsciiCaseConversion dir>
struct FastAsciiConverter {
+#ifdef ENABLE_LATIN_1
+ static bool Convert(char* dst, char* src, int length, bool* changed_out)
{
+#else
static bool Convert(char* dst, char* src, int length) {
+#endif
#ifdef DEBUG
char* saved_dst = dst;
char* saved_src = src;
@@ -5846,12 +5855,18 @@ struct FastAsciiConverter {
const char lo = (dir == ASCII_TO_LOWER) ? 'A' - 1 : 'a' - 1;
const char hi = (dir == ASCII_TO_LOWER) ? 'Z' + 1 : 'z' + 1;
bool changed = false;
+#ifdef ENABLE_LATIN_1
+ uintptr_t or_acc = 0;
+#endif
char* const limit = src + length;
#ifdef V8_HOST_CAN_READ_UNALIGNED
// Process the prefix of the input that requires no conversion one
// (machine) word at a time.
while (src <= limit - sizeof(uintptr_t)) {
uintptr_t w = *reinterpret_cast<uintptr_t*>(src);
+#ifdef ENABLE_LATIN_1
+ or_acc |= w;
+#endif
if (AsciiRangeMask(w, lo, hi) != 0) {
changed = true;
break;
@@ -5864,6 +5879,9 @@ struct FastAsciiConverter {
// required one word at a time.
while (src <= limit - sizeof(uintptr_t)) {
uintptr_t w = *reinterpret_cast<uintptr_t*>(src);
+#ifdef ENABLE_LATIN_1
+ or_acc |= w;
+#endif
uintptr_t m = AsciiRangeMask(w, lo, hi);
// The mask has high (7th) bit set in every byte that needs
// conversion and we know that the distance between cases is
@@ -5877,6 +5895,9 @@ struct FastAsciiConverter {
// unaligned access is not supported).
while (src < limit) {
char c = *src;
+#ifdef ENABLE_LATIN_1
+ or_acc |= c;
+#endif
if (lo < c && c < hi) {
c ^= (1 << 5);
changed = true;
@@ -5885,10 +5906,20 @@ struct FastAsciiConverter {
++src;
++dst;
}
+#ifdef ENABLE_LATIN_1
+ if ((or_acc & kAsciiMask) != 0) {
+ return false;
+ }
+#endif
#ifdef DEBUG
CheckConvert(saved_dst, saved_src, length, changed);
#endif
+#ifdef ENABLE_LATIN_1
+ *changed_out = changed;
+ return true;
+#else
return changed;
+#endif
}
#ifdef DEBUG
@@ -5941,7 +5972,6 @@ MUST_USE_RESULT static MaybeObject* ConvertCase(
// Assume that the string is not empty; we need this assumption later
if (length == 0) return s;
-#ifndef ENABLE_LATIN_1
// Simpler handling of ASCII strings.
//
// NOTE: This assumes that the upper/lower case of an ASCII
@@ -5954,13 +5984,25 @@ MUST_USE_RESULT static MaybeObject* ConvertCase(
if (!maybe_o->ToObject(&o)) return maybe_o;
}
SeqOneByteString* result = SeqOneByteString::cast(o);
+#ifndef ENABLE_LATIN_1
bool has_changed_character = ConvertTraits::AsciiConverter::Convert(
reinterpret_cast<char*>(result->GetChars()),
reinterpret_cast<char*>(SeqOneByteString::cast(s)->GetChars()),
length);
return has_changed_character ? result : s;
- }
+#else
+ bool has_changed_character;
+ bool is_ascii = ConvertTraits::AsciiConverter::Convert(
+ reinterpret_cast<char*>(result->GetChars()),
+ reinterpret_cast<char*>(SeqOneByteString::cast(s)->GetChars()),
+ length,
+ &has_changed_character);
+ // If not ASCII, we discard the result and take the 2 byte path.
+ if (is_ascii) {
+ return has_changed_character ? result : s;
+ }
#endif
+ }
Object* answer;
{ MaybeObject* maybe_answer =
--
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