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mudflap cache question
- From: Herman ten Brugge <hermantenbrugge at home dot nl>
- To: gcc at gcc dot gnu dot org
- Date: Tue, 14 Jun 2005 22:33:35 +0200
- Subject: mudflap cache question
I just read the mudflap pdf file and wanted to know how the cache was
I looked at the code in mf-runtime.c and found the cache functions. The
code for the
__mf_uncache_object looks strange to me however.
The code looks like:
__mf_uncache_object (__mf_object_t *old_obj)
/* Remove any low/high pointers for this object from the lookup cache. */
/* Can it possibly exist in the cache? */
if (LIKELY (old_obj->read_count + old_obj->write_count))
uintptr_t low = old_obj->low;
uintptr_t high = old_obj->high;
unsigned idx_low = __MF_CACHE_INDEX (low);
unsigned idx_high = __MF_CACHE_INDEX (high);
for (i = idx_low; i <= idx_high; i++)
struct __mf_cache *entry = & __mf_lookup_cache [i];
/* NB: the "||" in the following test permits this code to
tolerate the situation introduced by __mf_check over
contiguous objects, where a cache entry spans several
if (entry->low == low || entry->high == high)
entry->low = MAXPTR;
entry->high = MINPTR;
__MF_CACHE_INDEX(ptr) is (ptr >> 2) & 0x3ff at startup.
Suppose we have an old_obj->low of 0x10000 and an old_obj->high of
0x20000. Then the
cache entries we look at is just entry 0. Which I believe is just wrong.
between 0x10000 and 0x20000 must fill other cache entries. It gets even
the old_obj->low = 0x1fff0 and object high is 0x20000. Then we probably
invalidate any cache entry.
Should I write a bug report?