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| author | Jeff Law <law@redhat.com> | 2018-07-05 21:43:42 -0600 |
|---|---|---|
| committer | Jeff Law <law@gcc.gnu.org> | 2018-07-05 21:43:42 -0600 |
| commit | 99e87c0eef2f6020a3ded2c785389939c07ac04e (patch) | |
| tree | a245e7c3e0faad16a8c4a8d04695015e106fccf9 /gcc/tree-ssa-dse.c | |
| parent | edace3e2295db80d32b1a77676a3697c5029d71b (diff) | |
| download | gcc-99e87c0eef2f6020a3ded2c785389939c07ac04e.zip gcc-99e87c0eef2f6020a3ded2c785389939c07ac04e.tar.gz gcc-99e87c0eef2f6020a3ded2c785389939c07ac04e.tar.bz2 | |
re PR tree-optimization/86010 (redundant memset with smaller size not eliminated)
PR tree-optimization/86010
* tree-ssa-dse.c (compute_trims): More aggressively trim at
both the head and tail of mem* and str* calls.
From-SVN: r262464
Diffstat (limited to 'gcc/tree-ssa-dse.c')
| -rw-r--r-- | gcc/tree-ssa-dse.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/gcc/tree-ssa-dse.c b/gcc/tree-ssa-dse.c index 1af50a0..ebc4a1e 100644 --- a/gcc/tree-ssa-dse.c +++ b/gcc/tree-ssa-dse.c @@ -240,11 +240,14 @@ compute_trims (ao_ref *ref, sbitmap live, int *trim_head, int *trim_tail, /* Now identify how much, if any of the tail we can chop off. */ HOST_WIDE_INT const_size; + int last_live = bitmap_last_set_bit (live); if (ref->size.is_constant (&const_size)) { int last_orig = (const_size / BITS_PER_UNIT) - 1; - int last_live = bitmap_last_set_bit (live); - *trim_tail = (last_orig - last_live) & ~0x1; + /* We can leave inconvenient amounts on the tail as + residual handling in mem* and str* functions is usually + reasonably efficient. */ + *trim_tail = last_orig - last_live; } else *trim_tail = 0; @@ -252,7 +255,12 @@ compute_trims (ao_ref *ref, sbitmap live, int *trim_head, int *trim_tail, /* Identify how much, if any of the head we can chop off. */ int first_orig = 0; int first_live = bitmap_first_set_bit (live); - *trim_head = (first_live - first_orig) & ~0x1; + *trim_head = first_live - first_orig; + + /* If more than a word remains, then make sure to keep the + starting point at least word aligned. */ + if (last_live - first_live > UNITS_PER_WORD) + *trim_head &= (UNITS_PER_WORD - 1); if ((*trim_head || *trim_tail) && dump_file && (dump_flags & TDF_DETAILS)) |