Jan Hubicka <hubi...@ucw.cz> writes: > Hi, > this patch lets us to remove > void *mem = __builtin_malloc (s); > if (!mem) > __builtin_abort (); > __builtin_free (mem); > > Where we previously stopped on "if (!mem)" marking __builtin_malloc necessary. > This is done by matching such conditional in tree-ssa-dce.cc and playing same > game > as we do for free functions. We consider if itself necessary (since it does > control flow) but we do not propagate necessity over the SSA name. > > In removal stage we check whether SSA name is needed and if not, we replace > it by constant 1, which makes the conditonal to be folded as constant in > cfgccleanup. > > While working on this, I refactored the code a bit to avoid duplicate matching > of allocation functions which made me notice that we handled strdup/strndup > just > half way and this prevented us from removing it, which is also fixed and > tested > in the testcase. > > Note that testcase pr68078.f90 checks that failed allocation is reported > when memory limits are set. We no longer report it since the memory is > unused and that is why I needed to disable DCE. > > I alos tested that with Jakub's patch we now eliminate new operator with > std::nothrow_t. > > Bootstrapped/regtested x86_64-linux, OK?
Very excited to see this and the other work -- thank you! I seem to get this when testing it out: +Running gcc:/gcc/testsuite/gcc.dg/analyzer/analyzer.exp ... +FAIL: gcc.dg/analyzer/pr101837.c (test for warnings, line 10) +FAIL: gcc.dg/analyzer/pr101837.c (test for warnings, line 5) +FAIL: gcc.dg/analyzer/pr101837.c (test for warnings, line 9) I can reproduce it with gcc -c -fanalyzer gcc/testsuite/gcc.dg/analyzer/pr101837.c -O2. Works with trunk, fails with patch applied on trunk. On the one hand, it's good, but it's not so good for the analyzer. I'll keep testing the patch. thanks, sam
