Re: [tree-ssa] dead const/pure/alloca call removal

[Gabriel Dos Reis <gdr at integrable-solutions dot net>]

"Zack Weinberg" <zack@codesourcery.com> writes:

| Falk Hueffner <falk.hueffner@student.uni-tuebingen.de> writes:
| 
| > "Zack Weinberg" <zack@codesourcery.com> writes:
| >
| >> I don't know what the right thing is, but I'd point out that this
| >> optimization applies to all functions whose side effect is to
| >> allocate a new block of memory, the sole pointer to which is
| >> returned.  malloc and calloc (but not realloc) are the obvious
| >> examples.
| >
| > No, they set errno.
| 
| Yah, but an s.c. program cannot make any assumptions about the value
| of errno unless it has just called a library function and observed it
| to fail, so if the return value of malloc is ignored, the call to
| malloc can safely be deleted.

very few useful programs are strictly conforming.  I'm NOT convinced GCC
should take that slipery slope.

-- Gaby