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Garbage collect constant pool entries and don't output unnecessary ones

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From-SVN: r13550
This commit is contained in:
Ian Lance Taylor 1997-01-24 21:43:41 +00:00
parent 38734e55b3
commit 91674c376c
1 changed files with 96 additions and 0 deletions
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96
gcc/varasm.c
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@ -143,6 +143,8 @@ static int compare_constant_rtx PROTO((enum machine_mode, rtx,
static struct constant_descriptor *record_constant_rtx PROTO((enum machine_mode,
rtx));
static struct pool_constant *find_pool_constant PROTO((rtx));
static void mark_constant_pool PROTO((void));
static void mark_constants PROTO((rtx));
static int output_addressed_constants PROTO((tree));
static void output_after_function_constants PROTO((void));
static void bc_assemble_integer PROTO((tree, int));
@ -3116,6 +3118,7 @@ struct pool_constant
int labelno;
int align;
int offset;
int mark;
};
/* Pointers to first and last constant in pool. */
@ -3483,6 +3486,7 @@ force_const_mem (mode, x)
pool->labelno = const_labelno;
pool->align = align;
pool->offset = pool_offset;
pool->mark = 0;
pool->next = 0;
if (last_pool == 0)
@ -3596,6 +3600,12 @@ output_constant_pool (fnname, fndecl)
rtx x;
union real_extract u;
/* It is possible for gcc to call force_const_mem and then to later
discard the instructions which refer to the constant. In such a
case we do not need to output the constant. */
if (flag_expensive_optimizations)
mark_constant_pool ();
#ifdef ASM_OUTPUT_POOL_PROLOGUE
ASM_OUTPUT_POOL_PROLOGUE (asm_out_file, fnname, fndecl, pool_offset);
#endif
@ -3604,6 +3614,9 @@ output_constant_pool (fnname, fndecl)
{
x = pool->constant;
if (flag_expensive_optimizations && ! pool->mark)
continue;
/* See if X is a LABEL_REF (or a CONST referring to a LABEL_REF)
whose CODE_LABEL has been deleted. This can occur if a jump table
is eliminated by optimization. If so, write a constant of zero
@ -3666,6 +3679,89 @@ output_constant_pool (fnname, fndecl)
/* Done with this pool. */
first_pool = last_pool = 0;
}
/* Look through the instructions for this function, and mark all the
entries in the constant pool which are actually being used. */
static void
mark_constant_pool ()
{
register rtx insn;
if (first_pool == 0)
return;
for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
mark_constants (PATTERN (insn));
for (insn = current_function_epilogue_delay_list;
insn;
insn = XEXP (insn, 1))
if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
mark_constants (PATTERN (insn));
}
static void
mark_constants (x)
register rtx x;
{
register int i;
register char *format_ptr;
if (x == 0)
return;
if (GET_CODE (x) == SYMBOL_REF)
{
if (CONSTANT_POOL_ADDRESS_P (x))
find_pool_constant (x)->mark = 1;
return;
}
/* Insns may appear inside a SEQUENCE. Only check the patterns of
insns, not any notes that may be attached. We don't want to mark
a constant just because it happens to appear in a REG_EQUIV note. */
if (GET_RTX_CLASS (GET_CODE (x)) == 'i')
{
mark_constants (PATTERN (x));
return;
}
format_ptr = GET_RTX_FORMAT (GET_CODE (x));
for (i = 0; i < GET_RTX_LENGTH (GET_CODE (x)); i++)
{
switch (*format_ptr++)
{
case 'e':
mark_constants (XEXP (x, i));
break;
case 'E':
if (XVEC (x, i) != 0)
{
register int j;
for (j = 0; j < XVECLEN (x, i); j++)
mark_constants (XVECEXP (x, i, j));
}
break;
case 'S':
case 's':
case '0':
case 'i':
case 'w':
case 'n':
case 'u':
break;
default:
abort ();
}
}
}
/* Find all the constants whose addresses are referenced inside of EXP,
and make sure assembler code with a label has been output for each one.