On 8/12/19 2:14 PM, Matthew Beliveau wrote:
> This patch improves DSE to handle missing optimizations for zero
> initializations.
>
> Thank you,
> Matthew Beliveau
>
>
> DSE.patch
>
> Bootstrapped/regtested on x86_64-linux, ok for trunk?
>
> 2019-08-12 Matthew Beliveau <mbeli...@redhat.com>
>
> PR c++/DSE.patch
> * tree-ssa-dse.c (dse_optimize_redundant_stores): Improved check to
> catch more redundant zero initalization cases.
> (dse_dom_walker::dse_optimize_stmt): Improved check to catch more
> redundant zero initialization cases.
>
> * gcc.dg/tree-ssa/redundant-assign-zero-1.c: New test.
> * gcc.dg/tree-ssa/redundant-assign-zero-2.c: New test.
>
> @@ -1027,15 +1024,13 @@ dse_dom_walker::dse_optimize_stmt
> (gimple_stmt_iterator *gsi)
> {
> bool by_clobber_p = false;
>
> - /* First see if this store is a CONSTRUCTOR and if there
> - are subsequent CONSTRUCTOR stores which are totally
> - subsumed by this statement. If so remove the subsequent
> - CONSTRUCTOR store.
> + /* Check if this store initalizes zero, or some aggregate of zeros,
> + and check if there are subsequent stores which are subsumed by this
> + statement. If so, remove the subsequent store.
Perhaps...
/* Check if this statement stores zero to a memory location
and if there is a subsequent store of zero to the same
memory location. If so delete the subsequent store. */
With the ChangeLog nits noted by Marek and the comment fix this is fine
for the trunk.
jeff
