https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107905
Bug ID: 107905
Summary: 2x slowdown versus CLANG and ICL
Product: gcc
Version: 11.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: sanmayce at sanmayce dot com
Target Milestone: ---
Hi,
I have encountered performance problem with MinGW GCC 11.3.0, nearly 2x
slowdown with a simple C function (being the 3rd fastest wildcard matching
function).
```
int Tcheburaschka_Wildcard_Iterative_Kaze_CaseSensitive (const char* mask,
const char* name) {
const char* maskSTACK;
const char* nameSTACK;
#pragma nounroll
for (name, mask; *name; ++name, ++mask) {
if (*mask == '*') {
goto Backtrack;
//} else if ((*mask != '?') && (*name != *mask)) {
/*
} else if ((*mask - '?') * (*name - *mask)) {
return 0;
}
*/
}
if ((*mask - '?') * (*name - *mask)) {
return 0;
}
}
Backtrack:
#pragma nounroll
for (nameSTACK = name, maskSTACK = mask; *nameSTACK; ++nameSTACK,
++maskSTACK) {
if (*maskSTACK == '*') {
mask = maskSTACK+1;
if (!*mask) return 1;
name = nameSTACK;
goto Backtrack;
//} else if ((*maskSTACK != '?') && (*nameSTACK != *maskSTACK))
{
/*
} else if ((*maskSTACK - '?') * (*nameSTACK - *maskSTACK)) {
name++;
goto Backtrack;
}
*/
}
if ((*maskSTACK - '?') * (*nameSTACK - *maskSTACK)) {
name++;
goto Backtrack;
}
}
while (*maskSTACK == '*') ++maskSTACK;
return (!*maskSTACK);
}
```
```
[CPU: AMD Zen2 Ryzen7 4800H, @2.9GHz, Max. Boost Clock Up to 4.2GHz]
+-------------------------------------------------------------------------------+-------------------+-------------------------+-----------------------+
| Function \ Compiler
| CLANG 14.0.1, -O3 | Intel's ICL 19.0.0, /O3 | MinGW gcc 11.3.0, -O3 |
+-------------------------------------------------------------------------------+-------------------+-------------------------+-----------------------+
| Dogan Kurt's 'Antimalware', 2016, Iterative (wild_iterative)
| 70.605000 s | 102.610000 s | 83.398000 s |
| Dogan Kurt's 'Antimalware', 2016, Iterative Optimised (wild_iterative_opt)
| 61.322000 s | 74.243000 s | 66.538000 s |
| Tcheburaschka_r3, 2022, (Tcheburaschka_Wildcard_Iterative_Kaze_CaseSensitive)
| 72.990000 s | 76.161000 s | 127.717000 s |
| JackHandy_Iterative, 2005, (IterativeWildcards)
| 80.053000 s | 90.872000 s | 70.156000 s |
| Kirk J. Krauss, 2014, DrDobbs (FastWildCompare)
| 44.113000 s | 48.109000 s | 51.018000 s |
| Alessandro Cantatore, 2003, (szWildMatch7)
| 98.729000 s | 85.986000 s | 121.965000 s |
| Nondeterministic Finite Automaton (wild_nfa)
| 162.561000 s | 200.022000 s | 176.440000 s |
+-------------------------------------------------------------------------------+-------------------+-------------------------+-----------------------+
[Note1: All functions returned 1,075,000,000 Matches - that is TRUEs, kinda
means they passed the quality test, no, really, I printed all the 1's and 0's
after each run - the sequences matched.]
[Note2: It is well-known that Maximum Turbo Modes are maintained for some 15-30
seconds, so it is good that each function takes 30+ seconds, to emulate some 8
billion real-world searches.]
```
For more info:
https://github.com/kirkjkrauss/MatchingWildcards/issues/1#issue-1467311771
