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(schedule_insns): Don't zero reg_n_calls_crossed for 

pseudos live across multiple blocks.

From-SVN: r5515
This commit is contained in:
Jim Wilson 1993-09-28 15:57:44 -07:00
parent 3b8b3c98b0
commit b5e9625567
1 changed files with 25 additions and 7 deletions
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32
gcc/sched.c
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@ -4678,20 +4678,38 @@ schedule_insns (dump_file)
regno, reg_live_length[regno],
sched_reg_live_length[regno]);
if (reg_n_calls_crossed[regno]
&& ! sched_reg_n_calls_crossed[regno])
fprintf (dump_file,
";; register %d no longer crosses calls\n", regno);
else if (! reg_n_calls_crossed[regno]
&& sched_reg_n_calls_crossed[regno])
if (! reg_n_calls_crossed[regno]
&& sched_reg_n_calls_crossed[regno])
fprintf (dump_file,
";; register %d now crosses calls\n", regno);
else if (reg_n_calls_crossed[regno]
&& ! sched_reg_n_calls_crossed[regno]
&& reg_basic_block[regno] != REG_BLOCK_GLOBAL)
fprintf (dump_file,
";; register %d no longer crosses calls\n", regno);
}
/* Negative values are special; don't overwrite the current
reg_live_length value if it is negative. */
if (reg_live_length[regno] >= 0)
reg_live_length[regno] = sched_reg_live_length[regno];
reg_n_calls_crossed[regno] = sched_reg_n_calls_crossed[regno];
/* We can't change the value of reg_n_calls_crossed to zero for
pseudos which are live in more than one block.
This is because combine might have made an optimization which
invalidated basic_block_live_at_start and reg_n_calls_crossed,
but it does not update them. If we update reg_n_calls_crossed
here, the two variables are now inconsistent, and this might
confuse the caller-save code into saving a register that doesn't
need to be saved. This is only a problem when we zero calls
crossed for a pseudo live in multiple basic blocks.
Alternatively, we could try to correctly update basic block live
at start here in sched, but that seems complicated. */
if (sched_reg_n_calls_crossed[regno]
|| reg_basic_block[regno] != REG_BLOCK_GLOBAL)
reg_n_calls_crossed[regno] = sched_reg_n_calls_crossed[regno];
}
}
}