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(newpat_used_regs): New variable. 

(mark_used_regs_combine): New function.
(try_combine): Use them.
(reg_dead_at_p): Registers marked in newpat_used_regs must always be
considered to be live.

From-SVN: r6826
This commit is contained in:
Richard Kenner 1994-03-19 17:13:23 -05:00
parent 1c78fc5220
commit 6e25d15912
1 changed files with 124 additions and 1 deletions
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125
gcc/combine.c
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@ -184,6 +184,11 @@ static rtx subst_prev_insn;
static int subst_low_cuid;
/* This contains any hard registers that are used in newpat; reg_dead_at_p
must consider all these registers to be always live. */
static HARD_REG_SET newpat_used_regs;
/* This is an insn to which a LOG_LINKS entry has been added. If this
insn is the earlier than I2 or I3, combine should rescan starting at
that location. */
@ -433,6 +438,7 @@ static void move_deaths PROTO((rtx, int, rtx, rtx *));
static int reg_bitfield_target_p PROTO((rtx, rtx));
static void distribute_notes PROTO((rtx, rtx, rtx, rtx, rtx, rtx));
static void distribute_links PROTO((rtx));
static void mark_used_regs_combine PROTO((rtx));
/* Main entry point for combiner. F is the first insn of the function.
NREGS is the first unused pseudo-reg number. */
@ -1219,6 +1225,9 @@ try_combine (i3, i2, i1)
accept this combination. */
undobuf.storage = (char *) oballoc (0);
/* Reset the hard register usage information. */
CLEAR_HARD_REG_SET (newpat_used_regs);
/* If I1 and I2 both feed I3, they can be in any order. To simplify the
code below, set I1 to be the earlier of the two insns. */
if (i1 && INSN_CUID (i1) > INSN_CUID (i2))
@ -1640,6 +1649,9 @@ try_combine (i3, i2, i1)
destination of I3. */
validate_replacement:
/* Note which hard regs this insn has as inputs. */
mark_used_regs_combine (newpat);
/* Is the result of combination a valid instruction? */
insn_code_number = recog_for_combine (&newpat, i3, &new_i3_notes);
@ -1999,6 +2011,8 @@ try_combine (i3, i2, i1)
rtx new_other_notes;
rtx note, next;
CLEAR_HARD_REG_SET (newpat_used_regs);
other_code_number = recog_for_combine (&other_pat, undobuf.other_insn,
&new_other_notes);
@ -9875,7 +9889,8 @@ reg_dead_at_p_1 (dest, x)
We scan backwards from INSN. If we hit a REG_DEAD note or a CLOBBER
referencing REG, it is dead. If we hit a SET referencing REG, it is
live. Otherwise, see if it is live or dead at the start of the basic
block we are in. */
block we are in. Hard regs marked as being live in NEWPAT_USED_REGS
must be assumed to be always live. */
static int
reg_dead_at_p (reg, insn)
@ -9893,6 +9908,14 @@ reg_dead_at_p (reg, insn)
reg_dead_flag = 0;
/* Check that reg isn't mentioned in NEWPAT_USED_REGS. */
if (reg_dead_regno < FIRST_PSEUDO_REGISTER)
{
for (i = reg_dead_regno; i < reg_dead_endregno; i++)
if (TEST_HARD_REG_BIT (newpat_used_regs, i))
return 0;
}
/* Scan backwards until we find a REG_DEAD note, SET, CLOBBER, label, or
beginning of function. */
for (; insn && GET_CODE (insn) != CODE_LABEL;
@ -9926,6 +9949,106 @@ reg_dead_at_p (reg, insn)
return 1;
}
/* Note hard registers in X that are used. This code is similar to
that in flow.c, but much simpler since we don't care about pseudos. */
static void
mark_used_regs_combine (x)
rtx x;
{
register RTX_CODE code = GET_CODE (x);
register int regno;
int i;
switch (code)
{
case LABEL_REF:
case SYMBOL_REF:
case CONST_INT:
case CONST:
case CONST_DOUBLE:
case PC:
case ADDR_VEC:
case ADDR_DIFF_VEC:
case ASM_INPUT:
#ifdef HAVE_cc0
/* CC0 must die in the insn after it is set, so we don't need to take
special note of it here. */
case CC0:
#endif
return;
case CLOBBER:
/* If we are clobbering a MEM, mark any hard registers inside the
address as used. */
if (GET_CODE (XEXP (x, 0)) == MEM)
mark_used_regs_combine (XEXP (XEXP (x, 0), 0));
return;
case REG:
regno = REGNO (x);
/* A hard reg in a wide mode may really be multiple registers.
If so, mark all of them just like the first. */
if (regno < FIRST_PSEUDO_REGISTER)
{
/* None of this applies to the stack, frame or arg pointers */
if (regno == STACK_POINTER_REGNUM
#if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
|| regno == HARD_FRAME_POINTER_REGNUM
#endif
#if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
|| (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
#endif
|| regno == FRAME_POINTER_REGNUM)
return;
i = HARD_REGNO_NREGS (regno, GET_MODE (x));
while (i-- > 0)
SET_HARD_REG_BIT (newpat_used_regs, regno + i);
}
return;
case SET:
{
/* If setting a MEM, or a SUBREG of a MEM, then note any hard regs in
the address. */
register rtx testreg = SET_DEST (x);
while (GET_CODE (x) == SUBREG
|| GET_CODE (x) == ZERO_EXTRACT
|| GET_CODE (x) == SIGN_EXTRACT
|| GET_CODE (x) == STRICT_LOW_PART)
testreg = XEXP (testreg, 0);
if (GET_CODE (testreg) == MEM)
mark_used_regs_combine (XEXP (testreg, 0));
mark_used_regs_combine (SET_SRC (x));
return;
}
}
/* Recursively scan the operands of this expression. */
{
register char *fmt = GET_RTX_FORMAT (code);
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
{
if (fmt[i] == 'e')
mark_used_regs_combine (XEXP (x, i));
else if (fmt[i] == 'E')
{
register int j;
for (j = 0; j < XVECLEN (x, i); j++)
mark_used_regs_combine (XVECEXP (x, i, j));
}
}
}
}
/* Remove register number REGNO from the dead registers list of INSN.