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[taken from gcc-2.95.3-latest-cvs]

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Wed Aug 25 15:27:22 1999  Gavin Romig-Koch  <gavin@cygnus.com>
	* combine.c (nonzero_bits) : Allow single-ly set registers to be
	anywere in the function only if they are pseudos and set before
	being used (not live at the start of the function).
	(num_sign_bit_copies) : Same.
	(get_last_value_validate) : Same.
	(get_last_value) : Same.


git-svn-id: file:///srv/svn/repos/haiku/trunk/buildtools@9588 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Oliver Tappe 2004-10-28 18:21:13 +00:00
parent ab0de848b4
commit cf64b0106b
1 changed files with 28 additions and 11 deletions
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39
gcc/gcc/combine.c
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@ -7580,8 +7580,11 @@ nonzero_bits (x, mode)
if (reg_last_set_value[REGNO (x)] != 0
&& reg_last_set_mode[REGNO (x)] == mode
&& (REG_N_SETS (REGNO (x)) == 1
|| reg_last_set_label[REGNO (x)] == label_tick)
&& (reg_last_set_label[REGNO (x)] == label_tick
|| (REGNO (x) >= FIRST_PSEUDO_REGISTER
&& REG_N_SETS (REGNO (x)) == 1
&& ! REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start,
REGNO (x))))
&& INSN_CUID (reg_last_set[REGNO (x)]) < subst_low_cuid)
return reg_last_set_nonzero_bits[REGNO (x)];
@ -7970,8 +7973,11 @@ num_sign_bit_copies (x, mode)
if (reg_last_set_value[REGNO (x)] != 0
&& reg_last_set_mode[REGNO (x)] == mode
&& (REG_N_SETS (REGNO (x)) == 1
|| reg_last_set_label[REGNO (x)] == label_tick)
&& (reg_last_set_label[REGNO (x)] == label_tick
|| (REGNO (x) >= FIRST_PSEUDO_REGISTER
&& REG_N_SETS (REGNO (x)) == 1
&& ! REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start,
REGNO (x))))
&& INSN_CUID (reg_last_set[REGNO (x)]) < subst_low_cuid)
return reg_last_set_sign_bit_copies[REGNO (x)];
@ -10819,9 +10825,11 @@ get_last_value_validate (loc, insn, tick, replace)
for (j = regno; j < endregno; j++)
if (reg_last_set_invalid[j]
/* If this is a pseudo-register that was only set once, it is
always valid. */
|| (! (regno >= FIRST_PSEUDO_REGISTER && REG_N_SETS (regno) == 1)
/* If this is a pseudo-register that was only set once and not
live at the beginning of the function, it is always valid. */
|| (! (regno >= FIRST_PSEUDO_REGISTER
&& REG_N_SETS (regno) == 1
&& ! REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno))
&& reg_last_set_label[j] > tick))
{
if (replace)
@ -10880,12 +10888,21 @@ get_last_value (x)
regno = REGNO (x);
value = reg_last_set_value[regno];
/* If we don't have a value or if it isn't for this basic block,
return 0. */
/* If we don't have a value, or if it isn't for this basic block and
it's either a hard register, set more than once, or it's a live
at the beginning of the function, return 0.
Because if it's not live at the beginnning of the function then the reg
is always set before being used (is never used without being set).
And, if it's set only once, and it's always set before use, then all
uses must have the same last value, even if it's not from this basic
block. */
if (value == 0
|| (REG_N_SETS (regno) != 1
&& reg_last_set_label[regno] != label_tick))
|| (reg_last_set_label[regno] != label_tick
&& (regno < FIRST_PSEUDO_REGISTER
|| REG_N_SETS (regno) != 1
|| REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno))))
return 0;
/* If the value was set in a later insn than the ones we are processing,