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(cse_insn): Don't record a SRC that's a MEM and the same as a 

REG_EQUIV note if DEST is set more than once.

From-SVN: r14074
This commit is contained in:
Richard Kenner 1997-05-17 15:13:18 -04:00
parent a89974a23e
commit 50196afaca
1 changed files with 15 additions and 0 deletions
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15
gcc/cse.c
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@ -6477,6 +6477,21 @@ cse_insn (insn, in_libcall_block)
sets[i].src_in_memory = hash_arg_in_memory;
sets[i].src_in_struct = hash_arg_in_struct;
/* If SRC is a MEM, there is a REG_EQUIV note for SRC, and DEST is
a pseudo that is set more than once, do not record SRC. Using
SRC as a replacement for anything else will be incorrect in that
situation. Note that this usually occurs only for stack slots,
in which case all the RTL would be refering to SRC, so we don't
lose any optimization opportunities by not having SRC in the
hash table. */
if (GET_CODE (src) == MEM
&& find_reg_note (insn, REG_EQUIV, src) != 0
&& GET_CODE (dest) == REG
&& REGNO (dest) >= FIRST_PSEUDO_REGISTER
&& reg_n_sets[REGNO (dest)] != 1)
sets[i].src_volatile = 1;
#if 0
/* It is no longer clear why we used to do this, but it doesn't
appear to still be needed. So let's try without it since this