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* [Bug middle-end/114822] New: ldist should produce memcpy/memset/memmove histograms based on loop information converted
@ 2024-04-23 9:44 hubicka at gcc dot gnu.org
0 siblings, 0 replies; only message in thread
From: hubicka at gcc dot gnu.org @ 2024-04-23 9:44 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114822
Bug ID: 114822
Summary: ldist should produce memcpy/memset/memmove histograms
based on loop information converted
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: hubicka at gcc dot gnu.org
Target Milestone: ---
When loop is converted to string builtin we lose information about its size.
This means that we won't expand it inline when the block size is expected to be
small. This causes performance problem i.e. on std::vector and testcase from
PR114821 which at least with profile feedback runs significantly slower than
variant where memcpy is produced early
#include <vector>
typedef unsigned int uint32_t;
int pair;
void
test()
{
std::vector<int> stack;
stack.push_back (pair);
while (!stack.empty()) {
int cur = stack.back();
stack.pop_back();
if (true)
{
cur++;
stack.push_back (cur);
stack.push_back (cur);
}
if (cur > 10000)
break;
}
}
int
main()
{
for (int i = 0; i < 10000; i++)
test();
}
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2024-04-23 9:44 [Bug middle-end/114822] New: ldist should produce memcpy/memset/memmove histograms based on loop information converted hubicka at gcc dot gnu.org
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