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sched.c (canon_rtx): Recursively look for equivalences; look for expressions equivalent to MEMs. 

* sched.c (canon_rtx): Recursively look for equivalences;
        look for expressions equivalent to MEMs.
        (true_dependence): Canonicalize inputs before operating
        on their values.
        (anti_dependence, output_dependence): Likewise.

        * jump.c (follow_jumps): Don't follow an unconditional jump
        that is not a simple_jump.

From-SVN: r10793
This commit is contained in:
Jeff Law 1995-12-17 18:31:12 -07:00
parent c0bd9b2439
commit a9cc906124
2 changed files with 21 additions and 2 deletions
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3
gcc/jump.c
View File

@ -3054,7 +3054,8 @@ follow_jumps (label)
(depth < 10
&& (insn = next_active_insn (value)) != 0
&& GET_CODE (insn) == JUMP_INSN
&& (JUMP_LABEL (insn) != 0 || GET_CODE (PATTERN (insn)) == RETURN)
&& ((JUMP_LABEL (insn) != 0 && simplejump_p (insn))
|| GET_CODE (PATTERN (insn)) == RETURN)
&& (next = NEXT_INSN (insn))
&& GET_CODE (next) == BARRIER);
depth++)

20
gcc/sched.c
View File

@ -371,9 +371,11 @@ static rtx
canon_rtx (x)
rtx x;
{
/* Recursively look for equivalences. */
if (GET_CODE (x) == REG && REGNO (x) >= FIRST_PSEUDO_REGISTER
&& REGNO (x) <= reg_known_value_size)
return reg_known_value[REGNO (x)];
return reg_known_value[REGNO (x)] == x
? x : canon_rtx (reg_known_value[REGNO (x)]);
else if (GET_CODE (x) == PLUS)
{
rtx x0 = canon_rtx (XEXP (x, 0));
@ -390,6 +392,16 @@ canon_rtx (x)
return gen_rtx (PLUS, GET_MODE (x), x0, x1);
}
}
/* This gives us much better alias analysis when called from
the loop optimizer. Note we want to leave the original
MEM alone, but need to return the canonicalized MEM with
all the flags with their original values. */
else if (GET_CODE (x) == MEM)
{
rtx copy = copy_rtx (x);
XEXP (copy, 0) = canon_rtx (XEXP (copy, 0));
x = copy;
}
return x;
}
@ -825,6 +837,8 @@ true_dependence (mem, x)
both an unchanging read and an unchanging write. This won't handle all
cases optimally, but the possible performance loss should be
negligible. */
x = canon_rtx (x);
mem = canon_rtx (mem);
if (RTX_UNCHANGING_P (x) && ! RTX_UNCHANGING_P (mem))
return 0;
@ -849,6 +863,8 @@ anti_dependence (mem, x)
/* If MEM is an unchanging read, then it can't possibly conflict with
the store to X, because there is at most one store to MEM, and it must
have occurred somewhere before MEM. */
x = canon_rtx (x);
mem = canon_rtx (mem);
if (RTX_UNCHANGING_P (mem))
return 0;
@ -870,6 +886,8 @@ output_dependence (mem, x)
rtx mem;
rtx x;
{
x = canon_rtx (x);
mem = canon_rtx (mem);
return ((MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
|| (memrefs_conflict_p (SIZE_FOR_MODE (mem), XEXP (mem, 0),
SIZE_FOR_MODE (x), XEXP (x, 0), 0)