2011/10/4 Richard Henderson <r...@redhat.com>: > On 10/04/2011 08:42 AM, Joseph S. Myers wrote: >> On Tue, 4 Oct 2011, Ilya Tocar wrote: >> >>> Hi everyone, >>> >>> This patch fixes PR 50038 (redundant zero extensions) by modifying >>> implicit-zee pass >>> to also remove unneeded zero extensions from QImode to SImode. >> >> Hardcoding particular modes like this in the target-independent parts of >> the compiler is fundamentally ill-conceived. Right now it hardcodes the >> (SImode, DImode) pair. You're adding hardcoding of (QImode, SImode) as >> well. But really it should consider all pairs of (integer mode, wider >> integer mode), with the machine description (or target hooks) determining >> which pairs are relevant on a particular target. Changing it not to >> hardcode particular modes would be better than adding a second pair. >> > > That along with not hard-coding ZERO_EXTEND. > > Both MIPS and Alpha have much the same free operations, but with SIGN_EXTEND. > > I remember rejecting one iteration of this pass with this hard-coded, but the > pass was apparently approved by someone else without that being corrected. > > > r~ >
Hello guys,
Could you please look at my patch version? I tried to remove all
unnecessary mode restrictions and cover SIGN_EXTEND case. I did not
test this patch yet, just checked it worked on reproducer from
PR50038.
Thanks
Ilya
---
gcc/
* implicit-zee.c (ext_cand): New.
(ext_cand_pool): Likewise.
(add_ext_candidate): Likewise.
(zee_init): Likewise.
(zee_cleanup): Likewise.
(combine_set_zero_extend): Get extend candidate as new parameter.
Now handle sign extend cases and all modes.
(transform_ifelse): Likewise.
(merge_def_and_ze): Likewise.
(combine_reaching_defs): Change parameter type.
(zero_extend_info): Changed insn_list type.
(add_removable_zero_extend): Relaxed mode and code filter.
(find_removable_zero_extends): Changed return type.
(find_and_remove_ze): Var type changes.
(rest_of_handle_zee): Initialization and cleanup added.
PR50038.diff
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