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local-alloc.c (block_alloc): Slightly retune heuristic to widen qty lifetimes.

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* local-alloc.c (block_alloc): Slightly retune heuristic to widen
        qty lifetimes.
Actually check in the local-alloc patch that goes along with this ChangeLog
entry...

From-SVN: r24171
This commit is contained in:
Jeff Law 1998-12-07 15:38:24 -07:00
parent 70d5ccef06
commit 996e968353
1 changed files with 5 additions and 4 deletions
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9
gcc/local-alloc.c
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@ -1414,8 +1414,8 @@ block_alloc (b)
discourage the register allocator from creating false
dependencies.
The adjustment by the value +-3 indicates precisely that
this qty conflicts with qtys in the instructions immediately
The adjustment value is choosen to indicate that this qty
conflicts with all the qtys in the instructions immediately
before and after the lifetime of this qty.
Experiments have shown that higher values tend to hurt
@ -1423,8 +1423,9 @@ block_alloc (b)
If allocation using the extended lifetime fails we will try
again with the qty's unadjusted lifetime. */
int fake_birth = MAX (0, qty_birth[q] - 3);
int fake_death = MIN (insn_number * 2 + 1, qty_death[q] + 3);
int fake_birth = MAX (0, qty_birth[q] - 2 + qty_birth[q] % 2);
int fake_death = MIN (insn_number * 2 + 1,
qty_death[q] + 2 - qty_death[q] % 2);
#endif
if (N_REG_CLASSES > 1)