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https://github.com/reactos/ccache.git
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Improve speed of temporal macro search
This commit is contained in:
Justin Lebar
Joel Rosdahl
parent
90e9de12fa
commit
fe732f041e
172
hashutil.c
172
hashutil.c
@ -19,6 +19,7 @@
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#include "ccache.h"
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#include "hashutil.h"
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#include "murmurhashneutral2.h"
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#include "macroskip.h"
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unsigned
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hash_from_string(void *str)
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@ -45,125 +46,84 @@ file_hashes_equal(struct file_hash *fh1, struct file_hash *fh2)
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&& fh1->size == fh2->size;
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}
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#define HASH(ch) \
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do {\
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hashbuf[hashbuflen] = ch; \
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hashbuflen++; \
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if (hashbuflen == sizeof(hashbuf)) {\
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hash_buffer(hash, hashbuf, sizeof(hashbuf)); \
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hashbuflen = 0; \
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} \
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} while (0)
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/*
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* Search for the strings "__DATE__" and "__TIME__" in str.
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*
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* Returns a bitmask with HASH_SOURCE_CODE_FOUND_DATE and
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* HASH_SOURCE_CODE_FOUND_TIME set appropriately.
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*/
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static int
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check_for_temporal_macros(const char *str, size_t len)
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{
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int result = 0;
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/*
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* We're using the Boyer-Moore-Horspool algorithm, which searches
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* starting from the *end* of the needle. Our needles are 8 characters
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* long, so i starts at 7.
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*/
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size_t i = 7;
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while (i < len) {
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/*
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* Check whether the substring ending at str[i] has the form
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* '__...E__'. On the assumption that 'E' is less common in
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* source than '_', we check str[i-2] first.
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*/
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if (str[i - 2] == 'E' &&
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str[i - 0] == '_' &&
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str[i - 7] == '_' &&
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str[i - 1] == '_' &&
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str[i - 6] == '_') {
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/*
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* Check the remaining characters to see if the
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* substring is '__DATE__' or '__TIME__'.
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*/
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if (str[i - 5] == 'D' && str[i - 4] == 'A' &&
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str[i - 3] == 'T') {
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result |= HASH_SOURCE_CODE_FOUND_DATE;
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}
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else if (str[i - 5] == 'T' && str[i - 4] == 'I' &&
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str[i - 3] == 'M') {
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result |= HASH_SOURCE_CODE_FOUND_TIME;
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}
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}
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/*
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* macro_skip tells us how far we can skip forward upon seeing
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* str[i] at the end of a substring.
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*/
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i += macro_skip[(uint8_t)str[i]];
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}
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return result;
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}
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/*
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* Hash a string ignoring comments. Returns a bitmask of HASH_SOURCE_CODE_*
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* results.
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* Hash a string. Returns a bitmask of HASH_SOURCE_CODE_* results.
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*/
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int
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hash_source_code_string(
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struct mdfour *hash, const char *str, size_t len, const char *path)
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{
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const char *p;
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const char *end;
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char hashbuf[64];
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size_t hashbuflen = 0;
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int result = HASH_SOURCE_CODE_OK;
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extern unsigned sloppiness;
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p = str;
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end = str + len;
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while (1) {
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if (p >= end) {
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goto end;
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}
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switch (*p) {
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/* Potential start of comment. */
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case '/':
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if (p+1 == end) {
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break;
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}
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switch (*(p+1)) {
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case '*':
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HASH(' '); /* Don't paste tokens together when removing the comment. */
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p += 2;
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while (p+1 < end
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&& (*p != '*' || *(p+1) != '/')) {
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if (*p == '\n') {
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/* Keep line numbers. */
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HASH('\n');
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}
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p++;
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}
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if (p+1 == end) {
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goto end;
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}
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p += 2;
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continue;
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case '/':
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p += 2;
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while (p < end
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&& (*p != '\n' || *(p-1) == '\\')) {
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p++;
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}
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continue;
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default:
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break;
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}
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break;
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/* Start of string. */
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case '"':
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HASH(*p);
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p++;
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while (p < end && (*p != '"' || *(p-1) == '\\')) {
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HASH(*p);
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p++;
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}
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if (p == end) {
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goto end;
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}
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break;
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/* Potential start of volatile macro. */
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case '_':
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if (p + 7 < end
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&& p[1] == '_' && p[5] == 'E'
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&& p[6] == '_' && p[7] == '_') {
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if (p[2] == 'D' && p[3] == 'A'
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&& p[4] == 'T') {
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result |= HASH_SOURCE_CODE_FOUND_DATE;
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} else if (p[2] == 'T' && p[3] == 'I'
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&& p[4] == 'M') {
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result |= HASH_SOURCE_CODE_FOUND_TIME;
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}
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/*
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* Of course, we can't be sure that we have found a __{DATE,TIME}__
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* that's actually used, but better safe than sorry. And if you do
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* something like
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*
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* #define TIME __TI ## ME__
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*
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* in your code, you deserve to get a false cache hit.
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*/
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}
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break;
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default:
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break;
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}
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HASH(*p);
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p++;
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/*
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* Check for __DATE__ and __TIME__ if the sloppiness argument tells us
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* we have to.
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*/
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if (!(sloppiness & SLOPPY_TIME_MACROS)) {
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result |= check_for_temporal_macros(str, len);
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}
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end:
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hash_buffer(hash, hashbuf, hashbuflen);
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/*
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* Hash the source string.
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*/
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hash_buffer(hash, str, len);
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if (sloppiness & SLOPPY_TIME_MACROS) {
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return 0;
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}
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if (result & HASH_SOURCE_CODE_FOUND_DATE) {
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/*
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* Make sure that the hash sum changes if the (potential) expansion of
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56
macroskip.h
Normal file
56
macroskip.h
Normal file
@ -0,0 +1,56 @@
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/*
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* A Boyer-Moore-Horspool skip table used for searching for the strings
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* "__TIME__" and "__DATE__".
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*
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* macro_skip[c] = 8 for all c not in "__TIME__" and "__DATE__".
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*
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* The other characters map as follows:
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*
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* _ -> 1
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* A -> 5
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* D -> 6
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* E -> 3
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* I -> 5
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* M -> 4
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* T -> 4
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*
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*
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* This was generated with the following Python script:
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*
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* m = {'_': 1,
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* 'A': 5,
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* 'D': 6,
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* 'E': 3,
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* 'I': 5,
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* 'M': 4,
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* 'T': 4}
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*
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* for i in range(0, 256):
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* if chr(i) in m:
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* num = m[chr(i)]
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* else:
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* num = 8
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* print ("%d, " % num),
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*
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* if i % 16 == 15:
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* print ""
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*/
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static const uint32_t macro_skip[] = {
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8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
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8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
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8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
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8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
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8, 5, 8, 8, 6, 3, 8, 8, 8, 5, 8, 8, 8, 4, 8, 8,
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8, 8, 8, 8, 4, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 1,
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8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
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8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
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8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
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8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
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8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
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8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
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8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
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8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
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8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
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8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
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};
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39
test.sh
39
test.sh
@ -866,45 +866,6 @@ EOF
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checkstat 'cache miss' 1
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checkfile stderr-mf.txt "`cat stderr-orig.txt`"
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##################################################################
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# Check that changes in comments are ignored when hashing.
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testname="changes in comments"
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$CCACHE -C >/dev/null
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$CCACHE -z >/dev/null
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cat <<EOF >comments.h
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/*
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* /* foo comment
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*/
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EOF
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backdate comments.h
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cat <<'EOF' >comments.c
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#include "comments.h"
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char test[] = "\
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/* apple */ // banana"; // foo comment
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EOF
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$CCACHE $COMPILER -c comments.c
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checkstat 'cache hit (direct)' 0
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checkstat 'cache hit (preprocessed)' 0
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checkstat 'cache miss' 1
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sed_in_place 's/foo/ignored/' comments.h comments.c
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backdate comments.h
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$CCACHE $COMPILER -c comments.c
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checkstat 'cache hit (direct)' 1
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checkstat 'cache hit (preprocessed)' 0
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checkstat 'cache miss' 1
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# Check that comment-like string contents are hashed.
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sed_in_place 's/apple/orange/' comments.c
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backdate comments.h
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$CCACHE $COMPILER -c comments.c
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checkstat 'cache hit (direct)' 1
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checkstat 'cache hit (preprocessed)' 0
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checkstat 'cache miss' 2
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##################################################################
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# Check that it is possible to compile and cache an empty source code file.
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testname="empty source file"
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