static void pop (int);
static void push_regs (HARD_REG_SET *, int);
static int calc_live_regs (HARD_REG_SET *);
-static void mark_use (rtx, rtx *);
static HOST_WIDE_INT rounded_frame_size (int);
static rtx mark_constant_pool_use (rtx);
const struct attribute_spec sh_attribute_table[];
get_fpscr_rtx ()));
}
\f
-/* ??? gcc does flow analysis strictly after common subexpression
- elimination. As a result, common subexpression elimination fails
- when there are some intervening statements setting the same register.
- If we did nothing about this, this would hurt the precision switching
- for SH4 badly. There is some cse after reload, but it is unable to
- undo the extra register pressure from the unused instructions, and
- it cannot remove auto-increment loads.
-
- A C code example that shows this flow/cse weakness for (at least) SH
- and sparc (as of gcc ss-970706) is this:
-
-double
-f(double a)
-{
- double d;
- d = 0.1;
- a += d;
- d = 1.1;
- d = 0.1;
- a *= d;
- return a;
-}
-
- So we add another pass before common subexpression elimination, to
- remove assignments that are dead due to a following assignment in the
- same basic block. */
-
-static void
-mark_use (rtx x, rtx *reg_set_block)
-{
- enum rtx_code code;
-
- if (! x)
- return;
- code = GET_CODE (x);
- switch (code)
- {
- case REG:
- {
- int regno = REGNO (x);
- int nregs = (regno < FIRST_PSEUDO_REGISTER
- ? HARD_REGNO_NREGS (regno, GET_MODE (x))
- : 1);
- do
- {
- reg_set_block[regno + nregs - 1] = 0;
- }
- while (--nregs);
- break;
- }
- case SET:
- {
- rtx dest = SET_DEST (x);
-
- if (GET_CODE (dest) == SUBREG)
- dest = SUBREG_REG (dest);
- if (GET_CODE (dest) != REG)
- mark_use (dest, reg_set_block);
- mark_use (SET_SRC (x), reg_set_block);
- break;
- }
- case CLOBBER:
- break;
- default:
- {
- const char *fmt = GET_RTX_FORMAT (code);
- int i, j;
- for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
- {
- if (fmt[i] == 'e')
- mark_use (XEXP (x, i), reg_set_block);
- else if (fmt[i] == 'E')
- for (j = XVECLEN (x, i) - 1; j >= 0; j--)
- mark_use (XVECEXP (x, i, j), reg_set_block);
- }
- break;
- }
- }
-}
-\f
static rtx get_free_reg (HARD_REG_SET);
/* This function returns a register to use to load the address to load