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re PR rtl-optimization/22258 (combine causes spill failure on return value register) 

PR rtl-optimization/22258
	* combine.c (likely_spilled_retval_1, likely_spilled_retval_p):
	New functions.
	(try_combine): Use likely_spilled_retval_p.

From-SVN: r102279
This commit is contained in:
J"orn Rennecke 2005-07-22 11:55:42 +00:00 committed by Joern Rennecke
parent db8697336f
commit 45002e594c
2 changed files with 87 additions and 0 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
2005-07-22 J"orn Rennecke <joern.rennecke@st.com>
PR rtl-optimization/22258
* combine.c (likely_spilled_retval_1, likely_spilled_retval_p):
New functions.
(try_combine): Use likely_spilled_retval_p.
2005-07-22 Paul Woegerer <paul.woegerer@nsc.com>
* config.gcc: Add crx-elf support.

80
gcc/combine.c
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@ -1557,6 +1557,85 @@ cant_combine_insn_p (rtx insn)
return 0;
}
struct likely_spilled_retval_info
{
unsigned regno, nregs;
unsigned mask;
};
/* Called via note_stores by likely_spilled_retval_p. Remove from info->mask
hard registers that are known to be written to / clobbered in full. */
static void
likely_spilled_retval_1 (rtx x, rtx set, void *data)
{
struct likely_spilled_retval_info *info = data;
unsigned regno, nregs;
unsigned new_mask;
if (!REG_P (XEXP (set, 0)))
return;
regno = REGNO (x);
if (regno >= info->regno + info->nregs)
return;
nregs = hard_regno_nregs[regno][GET_MODE (x)];
if (regno + nregs <= info->regno)
return;
new_mask = (2U << (nregs - 1)) - 1;
if (regno < info->regno)
new_mask >>= info->regno - regno;
else
new_mask <<= regno - info->regno;
info->mask &= new_mask;
}
/* Return nonzero iff part of the return value is live during INSN, and
it is likely spilled. This can happen when more than one insn is needed
to copy the return value, e.g. when we consider to combine into the
second copy insn for a complex value. */
static int
likely_spilled_retval_p (rtx insn)
{
rtx use = BB_END (this_basic_block);
rtx reg, p;
unsigned regno, nregs;
/* We assume here that no machine mode needs more than
32 hard registers when the value overlaps with a register
for which FUNCTION_VALUE_REGNO_P is true. */
unsigned mask;
struct likely_spilled_retval_info info;
if (!NONJUMP_INSN_P (use) || GET_CODE (PATTERN (use)) != USE || insn == use)
return 0;
reg = XEXP (PATTERN (use), 0);
if (!REG_P (reg) || !FUNCTION_VALUE_REGNO_P (REGNO (reg)))
return 0;
regno = REGNO (reg);
nregs = hard_regno_nregs[regno][GET_MODE (reg)];
if (nregs == 1)
return 0;
mask = (2U << (nregs - 1)) - 1;
/* Disregard parts of the return value that are set later. */
info.regno = regno;
info.nregs = nregs;
info.mask = mask;
for (p = PREV_INSN (use); info.mask && p != insn; p = PREV_INSN (p))
note_stores (PATTERN (insn), likely_spilled_retval_1, &info);
mask = info.mask;
/* Check if any of the (probably) live return value registers is
likely spilled. */
nregs --;
do
{
if ((mask & 1 << nregs)
&& CLASS_LIKELY_SPILLED_P (REGNO_REG_CLASS (regno + nregs)))
return 1;
} while (nregs--);
return 0;
}
/* Adjust INSN after we made a change to its destination.
Changing the destination can invalidate notes that say something about
@ -1644,6 +1723,7 @@ try_combine (rtx i3, rtx i2, rtx i1, int *new_direct_jump_p)
if (cant_combine_insn_p (i3)
|| cant_combine_insn_p (i2)
|| (i1 && cant_combine_insn_p (i1))
|| likely_spilled_retval_p (i3)
/* We also can't do anything if I3 has a
REG_LIBCALL note since we don't want to disrupt the contiguity of a
libcall. */