RepoMirrors/gperftools
1
0
Fork 0
mirror of https://github.com/gperftools/gperftools synced 2025-02-17 20:56:53 +00:00
Code Issues Packages Projects Releases Wiki Activity

issue-483: Speed up accesses to ClassIndex()

Browse Source 
Making its return type unsigned can save a conversion from
signed to unsigned, and getting rid of the ternary operators
seems to help a little bit as well. Various gcc versions weren't
generating conditional moves for them as one would expect.


git-svn-id: http://gperftools.googlecode.com/svn/trunk@183 6b5cf1ce-ec42-a296-1ba9-69fdba395a50
This commit is contained in:
chappedm@gmail.com 2012-12-22 18:25:58 +00:00
parent 8de78fd85b
commit ad5aa05838
2 changed files with 32 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
src/base/basictypes.h
View File

@ -1,10 +1,10 @@
// Copyright (c) 2005, Google Inc.
// 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
@ -14,7 +14,7 @@
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
@ -358,4 +358,21 @@ namespace base {
enum LinkerInitialized { LINKER_INITIALIZED };
}
// Macros for performing optimizations based on branch prediction.
#if defined(__GNUC__) && ((__GNUC__ * 100 + __GNUC_MINOR__) >= 303)
#ifndef LIKELY
# define LIKELY(x) __builtin_expect(!!(x), 1)
#endif
#ifndef UNLIKELY
# define UNLIKELY(x) __builtin_expect(!!(x), 0)
#endif
#else // not !defined(__GNUC__) && ((__GNUC__ * 100 + __GNUC_MINOR__) >= 303)
#ifndef LIKELY
# define LIKELY(x) (x)
#endif
#ifndef UNLIKELY
# define UNLIKELY(x) (x)
#endif
#endif // defined(__GNUC__) && ((__GNUC__ * 100 + __GNUC_MINOR__) >= 303)
#endif // _BASICTYPES_H_

21
src/common.h
View File

@ -1,10 +1,10 @@
// Copyright (c) 2008, Google Inc.
// 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
@ -14,7 +14,7 @@
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
@ -41,6 +41,7 @@
#include <stdint.h> // for uintptr_t, uint64_t
#endif
#include "internal_logging.h" // for ASSERT, etc
#include "base/basictypes.h" // for LIKELY, etc
// Type that can hold a page number
typedef uintptr_t PageID;
@ -74,7 +75,7 @@ static const size_t kPageShift = 13;
static const size_t kNumClasses = 93;
// Unless we force to use 8 bytes alignment we use an alignment of
// at least 16 bytes to statisfy requirements for some SSE types.
// Keep in mind when using the 16 bytes alignment you can have a space
// Keep in mind when using the 16 bytes alignment you can have a space
// waste due alignment of 25%. (eg malloc of 24 bytes will get 32 bytes)
static const size_t kMinAlign = 8;
#else
@ -183,13 +184,15 @@ class SizeMap {
unsigned char class_array_[kClassArraySize];
// Compute index of the class_array[] entry for a given size
static inline int ClassIndex(int s) {
static inline size_t ClassIndex(int s) {
// Use unsigned arithmetic to avoid unnecessary sign extensions.
ASSERT(0 <= s);
ASSERT(s <= kMaxSize);
const bool big = (s > kMaxSmallSize);
const int add_amount = big ? (127 + (120<<7)) : 7;
const int shift_amount = big ? 7 : 3;
return (s + add_amount) >> shift_amount;
if (LIKELY(s <= kMaxSmallSize)) {
return (static_cast<uint32_t>(s) + 7) >> 3;
} else {
return (static_cast<uint32_t>(s) + 127 + (120 << 7)) >> 7;
}
}
int NumMoveSize(size_t size);