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reload1.c (reload_cse_regs_1): When deleting a no-op move that loads the function result, substitute with a USE.

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* reload1.c (reload_cse_regs_1): When deleting a no-op move that
	loads the function result, substitute with a USE.

From-SVN: r21951
This commit is contained in:
J"orn Rennecke 1998-08-24 17:03:34 +00:00 committed by Joern Rennecke
parent cce2be438d
commit 54e89d2590
2 changed files with 57 additions and 10 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
Tue Aug 25 00:57:54 1998 J"orn Rennecke <amylaar@cygnus.co.uk>
* reload1.c (reload_cse_regs_1): When deleting a no-op move that
loads the function result, substitute with a USE.
Mon Aug 24 15:20:19 1998 David Edelsohn <edelsohn@mhpcc.edu>
* rs6000.h (GO_IF_LEGITIMATE_ADDRESS): Use TARGET_POWERPC64

62
gcc/reload1.c
View File

@ -8290,9 +8290,27 @@ reload_cse_regs (first)
int count = 0;
if (reload_cse_noop_set_p (body, insn))
{
PUT_CODE (insn, NOTE);
NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
NOTE_SOURCE_FILE (insn) = 0;
/* If this sets the return value of the function, we must keep
a USE around, in case this is in a different basic block
than the final USE. Otherwise, we could loose important
register lifeness information on SMALL_REGISTER_CLASSES
machines, where return registers might be used as spills:
subsequent passes assume that spill registers are dead at
the end of a basic block. */
if (REG_FUNCTION_VALUE_P (SET_DEST (body)))
{
pop_obstacks ();
PATTERN (insn) = gen_rtx_USE (VOIDmode, SET_DEST (body));
INSN_CODE (insn) = -1;
REG_NOTES (insn) = NULL_RTX;
push_obstacks (&reload_obstack, &reload_obstack);
}
else
{
PUT_CODE (insn, NOTE);
NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
NOTE_SOURCE_FILE (insn) = 0;
}
reload_cse_delete_death_notes (insn);
/* We're done with this insn. */
@ -8313,19 +8331,43 @@ reload_cse_regs (first)
else if (GET_CODE (body) == PARALLEL)
{
int count = 0;
rtx value = NULL_RTX;
/* If every action in a PARALLEL is a noop, we can delete
the entire PARALLEL. */
for (i = XVECLEN (body, 0) - 1; i >= 0; --i)
if ((GET_CODE (XVECEXP (body, 0, i)) != SET
|| ! reload_cse_noop_set_p (XVECEXP (body, 0, i), insn))
&& GET_CODE (XVECEXP (body, 0, i)) != CLOBBER)
break;
{
rtx part = XVECEXP (body, 0, i);
if (GET_CODE (part) == SET)
{
if (! reload_cse_noop_set_p (part, insn))
break;
if (REG_FUNCTION_VALUE_P (SET_DEST (part)))
{
if (value)
break;
value = SET_DEST (part);
}
}
else if (GET_CODE (part) != CLOBBER)
break;
}
if (i < 0)
{
PUT_CODE (insn, NOTE);
NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
NOTE_SOURCE_FILE (insn) = 0;
if (value)
{
pop_obstacks ();
PATTERN (insn) = gen_rtx_USE (VOIDmode, value);
INSN_CODE (insn) = -1;
REG_NOTES (insn) = NULL_RTX;
push_obstacks (&reload_obstack, &reload_obstack);
}
else
{
PUT_CODE (insn, NOTE);
NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
NOTE_SOURCE_FILE (insn) = 0;
}
reload_cse_delete_death_notes (insn);
/* We're done with this insn. */