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(reload): Clear forbidden_regs earlier. 

(new_spill_reg): Mention in error message that asm clauses can also
cause the compiler to run out of spill regs.
(scan_paradoxical_regs): If SMALL_REGISTER_CLASSES, forbid hard regs
used in explicit user variables.

From-SVN: r7132
This commit is contained in:
Richard Kenner 1994-04-21 18:45:38 -04:00
parent c448a43e24
commit 56f58d3a43
1 changed files with 20 additions and 8 deletions
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28
gcc/reload1.c
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@ -526,9 +526,14 @@ reload (first, global, dumpfile)
cannot_omit_stores = (char *) alloca (max_regno);
bzero (cannot_omit_stores, max_regno);
#ifdef SMALL_REGISTER_CLASSES
CLEAR_HARD_REG_SET (forbidden_regs);
#endif
/* Look for REG_EQUIV notes; record what each pseudo is equivalent to.
Also find all paradoxical subregs
and find largest such for each pseudo. */
Also find all paradoxical subregs and find largest such for each pseudo.
On machines with small register classes, record hard registers that
are used for user variables. These can never be used for spills. */
for (insn = first; insn; insn = NEXT_INSN (insn))
{
@ -690,9 +695,7 @@ reload (first, global, dumpfile)
rtl as a spill register. But on some, we have to. Those will have
taken care to keep the life of hard regs as short as possible. */
#ifdef SMALL_REGISTER_CLASSES
CLEAR_HARD_REG_SET (forbidden_regs);
#else
#ifndef SMALL_REGISTER_CLASSES
COPY_HARD_REG_SET (forbidden_regs, bad_spill_regs);
#endif
@ -2168,7 +2171,8 @@ new_spill_reg (i, class, max_needs, max_nongroups, global, dumpfile)
if (fixed_regs[regno] || TEST_HARD_REG_BIT (forbidden_regs, regno))
fatal ("fixed or forbidden register was spilled.\n\
This may be due to a compiler bug or to impossible asm statements.");
This may be due to a compiler bug or to impossible asm\n\
statements or clauses.");
/* Make reg REGNO an additional reload reg. */
@ -3406,7 +3410,9 @@ spill_hard_reg (regno, global, dumpfile, cant_eliminate)
return something_changed;
}
/* Find all paradoxical subregs within X and update reg_max_ref_width. */
/* Find all paradoxical subregs within X and update reg_max_ref_width.
Also mark any hard registers used to store user variables as
forbidden from being used for spill registers. */
static void
scan_paradoxical_subregs (x)
@ -3418,6 +3424,13 @@ scan_paradoxical_subregs (x)
switch (code)
{
case REG:
#ifdef SMALL_REGISTER_CLASSES
if (REGNO (x) < FIRST_PSEUDO_REGISTER && REG_USERVAR_P (x))
SET_HARD_REG_BIT (forbidden_regs, REGNO (x));
#endif
return;
case CONST_INT:
case CONST:
case SYMBOL_REF:
@ -3425,7 +3438,6 @@ scan_paradoxical_subregs (x)
case CONST_DOUBLE:
case CC0:
case PC:
case REG:
case USE:
case CLOBBER:
return;