On Thu, 8 Sep 2011, Richard Guenther wrote:
>
> This implements removal of malloc/free pairs when allowed for a
> subset of all possible cases. The idea is to identify possible
> candidates (we free the return value of an allocation call) and
> for them do not make the allocation function necessary because
> of the free. If nothing else made the allocation necessary,
> go ahead and make the free call not necessary as well after
> propagation.
>
> Integrating this with control-dependence is much harder but
> would then handle also if (p) free (p). The testcases contain
> some tricky cases that break when you do it too simple-minded.
>
> Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.
And we hit gcc.dg/errno-1.c, adjusted as follows
Index: gcc/testsuite/gcc.dg/errno-1.c
===================================================================
--- gcc/testsuite/gcc.dg/errno-1.c (revision 178684)
+++ gcc/testsuite/gcc.dg/errno-1.c (working copy)
@@ -6,7 +6,7 @@
int main()
{
- void *p;
+ void * volatile p;
errno = 0;
p = malloc (-1);
if (errno != 0)
which keeps the malloc live. The testcase wants to verify
that we don't CSE errno across malloc.
Committed.
Richard.
