#include "toplev.h"
#include "except.h"
#include "integrate.h"
+#include "reload.h"
+#include "ggc.h"
\f
/* Next quantity number available for allocation. */
/* The list of each instruction which initializes this register. */
rtx init_insns;
+
+ /* Nonzero if this had a preexisting REG_EQUIV note. */
+
+ int is_arg_equivalence;
};
/* reg_equiv[N] (where N is a pseudo reg number) is the equivalence
/* Promote REG_EQUAL notes to REG_EQUIV notes and adjust status of affected
registers. */
- if (optimize)
- update_equiv_regs ();
+ update_equiv_regs ();
/* This sets the maximum number of quantities we can have. Quantity
numbers start at zero and we can have one for each pseudo. */
If such a register is only referenced once, try substituting its value
into the using insn. If it succeeds, we can eliminate the register
- completely. */
+ completely.
+
+ Initialize the REG_EQUIV_INIT array of initializing insns. */
static void
update_equiv_regs (void)
reg_equiv = xcalloc (max_regno, sizeof *reg_equiv);
INIT_REG_SET (&cleared_regs);
+ reg_equiv_init = ggc_alloc_cleared (max_regno * sizeof (rtx));
+ reg_equiv_init_size = max_regno;
init_alias_analysis ();
dest = SET_DEST (set);
src = SET_SRC (set);
- /* If this sets a MEM to the contents of a REG that is only used
- in a single basic block, see if the register is always equivalent
- to that memory location and if moving the store from INSN to the
- insn that set REG is safe. If so, put a REG_EQUIV note on the
- initializing insn.
-
- Don't add a REG_EQUIV note if the insn already has one. The existing
- REG_EQUIV is likely more useful than the one we are adding.
-
- If one of the regs in the address has reg_equiv[REGNO].replace set,
- then we can't add this REG_EQUIV note. The reg_equiv[REGNO].replace
- optimization may move the set of this register immediately before
- insn, which puts it after reg_equiv[REGNO].init_insns, and hence
- the mention in the REG_EQUIV note would be to an uninitialized
- pseudo. */
- /* ????? This test isn't good enough; we might see a MEM with a use of
- a pseudo register before we see its setting insn that will cause
- reg_equiv[].replace for that pseudo to be set.
- Equivalences to MEMs should be made in another pass, after the
- reg_equiv[].replace information has been gathered. */
-
- if (MEM_P (dest) && REG_P (src)
- && (regno = REGNO (src)) >= FIRST_PSEUDO_REGISTER
- && REG_BASIC_BLOCK (regno) >= 0
- && REG_N_SETS (regno) == 1
- && reg_equiv[regno].init_insns != 0
- && reg_equiv[regno].init_insns != const0_rtx
- && ! find_reg_note (XEXP (reg_equiv[regno].init_insns, 0),
- REG_EQUIV, NULL_RTX)
- && ! contains_replace_regs (XEXP (dest, 0)))
+ /* See if this is setting up the equivalence between an argument
+ register and its stack slot. */
+ note = find_reg_note (insn, REG_EQUIV, NULL_RTX);
+ if (note)
{
- rtx init_insn = XEXP (reg_equiv[regno].init_insns, 0);
- if (validate_equiv_mem (init_insn, src, dest)
- && ! memref_used_between_p (dest, init_insn, insn))
- REG_NOTES (init_insn)
- = gen_rtx_EXPR_LIST (REG_EQUIV, dest, REG_NOTES (init_insn));
+ gcc_assert (REG_P (dest));
+ regno = REGNO (dest);
+
+ /* Note that we don't want to clear reg_equiv_init even if there
+ are multiple sets of this register. */
+ reg_equiv[regno].is_arg_equivalence = 1;
+
+ /* Record for reload that this is an equivalencing insn. */
+ if (rtx_equal_p (src, XEXP (note, 0)))
+ reg_equiv_init[regno]
+ = gen_rtx_INSN_LIST (VOIDmode, insn, reg_equiv_init[regno]);
+
+ /* Continue normally in case this is a candidate for
+ replacements. */
}
+ if (!optimize)
+ continue;
+
/* We only handle the case of a pseudo register being set
once, or always to the same value. */
/* ??? The mn10200 port breaks if we add equivalences for
|| (regno = REGNO (dest)) < FIRST_PSEUDO_REGISTER
|| reg_equiv[regno].init_insns == const0_rtx
|| (CLASS_LIKELY_SPILLED_P (reg_preferred_class (regno))
- && MEM_P (src)))
+ && MEM_P (src) && ! reg_equiv[regno].is_arg_equivalence))
{
/* This might be setting a SUBREG of a pseudo, a pseudo that is
also set somewhere else to a constant. */
if (note)
{
int regno = REGNO (dest);
+ rtx x = XEXP (note, 0);
+
+ /* If we haven't done so, record for reload that this is an
+ equivalencing insn. */
+ if (!reg_equiv[regno].is_arg_equivalence
+ && (!MEM_P (x) || rtx_equal_p (src, x)))
+ reg_equiv_init[regno]
+ = gen_rtx_INSN_LIST (VOIDmode, insn, reg_equiv_init[regno]);
/* Record whether or not we created a REG_EQUIV note for a LABEL_REF.
We might end up substituting the LABEL_REF for uses of the
pseudo here or later. That kind of transformation may turn an
indirect jump into a direct jump, in which case we must rerun the
jump optimizer to ensure that the JUMP_LABEL fields are valid. */
- if (GET_CODE (XEXP (note, 0)) == LABEL_REF
- || (GET_CODE (XEXP (note, 0)) == CONST
- && GET_CODE (XEXP (XEXP (note, 0), 0)) == PLUS
- && (GET_CODE (XEXP (XEXP (XEXP (note, 0), 0), 0))
- == LABEL_REF)))
+ if (GET_CODE (x) == LABEL_REF
+ || (GET_CODE (x) == CONST
+ && GET_CODE (XEXP (x, 0)) == PLUS
+ && (GET_CODE (XEXP (XEXP (x, 0), 0)) == LABEL_REF)))
recorded_label_ref = 1;
- reg_equiv[regno].replacement = XEXP (note, 0);
+ reg_equiv[regno].replacement = x;
reg_equiv[regno].src_p = &SET_SRC (set);
reg_equiv[regno].loop_depth = loop_depth;
in local-alloc! */
REG_LIVE_LENGTH (regno) *= 2;
-
/* If the register is referenced exactly twice, meaning it is
set once and used once, indicate that the reference may be
replaced by the equivalence we computed above. Do this
and to reduce the number of registers alive across
calls. */
- if (REG_N_REFS (regno) == 2
- && (rtx_equal_p (XEXP (note, 0), src)
- || ! equiv_init_varies_p (src))
- && NONJUMP_INSN_P (insn)
- && equiv_init_movable_p (PATTERN (insn), regno))
- reg_equiv[regno].replace = 1;
+ if (REG_N_REFS (regno) == 2
+ && (rtx_equal_p (x, src)
+ || ! equiv_init_varies_p (src))
+ && NONJUMP_INSN_P (insn)
+ && equiv_init_movable_p (PATTERN (insn), regno))
+ reg_equiv[regno].replace = 1;
}
}
}
}
+ if (!optimize)
+ goto out;
+
+ /* A second pass, to gather additional equivalences with memory. This needs
+ to be done after we know which registers we are going to replace. */
+
+ for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
+ {
+ rtx set, src, dest;
+ unsigned regno;
+
+ if (! INSN_P (insn))
+ continue;
+
+ set = single_set (insn);
+ if (! set)
+ continue;
+
+ dest = SET_DEST (set);
+ src = SET_SRC (set);
+
+ /* If this sets a MEM to the contents of a REG that is only used
+ in a single basic block, see if the register is always equivalent
+ to that memory location and if moving the store from INSN to the
+ insn that set REG is safe. If so, put a REG_EQUIV note on the
+ initializing insn.
+
+ Don't add a REG_EQUIV note if the insn already has one. The existing
+ REG_EQUIV is likely more useful than the one we are adding.
+
+ If one of the regs in the address has reg_equiv[REGNO].replace set,
+ then we can't add this REG_EQUIV note. The reg_equiv[REGNO].replace
+ optimization may move the set of this register immediately before
+ insn, which puts it after reg_equiv[REGNO].init_insns, and hence
+ the mention in the REG_EQUIV note would be to an uninitialized
+ pseudo. */
+
+ if (MEM_P (dest) && REG_P (src)
+ && (regno = REGNO (src)) >= FIRST_PSEUDO_REGISTER
+ && REG_BASIC_BLOCK (regno) >= 0
+ && REG_N_SETS (regno) == 1
+ && reg_equiv[regno].init_insns != 0
+ && reg_equiv[regno].init_insns != const0_rtx
+ && ! find_reg_note (XEXP (reg_equiv[regno].init_insns, 0),
+ REG_EQUIV, NULL_RTX)
+ && ! contains_replace_regs (XEXP (dest, 0)))
+ {
+ rtx init_insn = XEXP (reg_equiv[regno].init_insns, 0);
+ if (validate_equiv_mem (init_insn, src, dest)
+ && ! memref_used_between_p (dest, init_insn, insn))
+ {
+ REG_NOTES (init_insn)
+ = gen_rtx_EXPR_LIST (REG_EQUIV, dest,
+ REG_NOTES (init_insn));
+ /* This insn makes the equivalence, not the one initializing
+ the register. */
+ reg_equiv_init[regno]
+ = gen_rtx_INSN_LIST (VOIDmode, insn, NULL_RTX);
+ }
+ }
+ }
+
/* Now scan all regs killed in an insn to see if any of them are
registers only used that once. If so, see if we can replace the
reference with the equivalent form. If we can, delete the
info. */
SET_REGNO_REG_SET (&cleared_regs, regno);
clear_regnos++;
+ reg_equiv_init[regno] = NULL_RTX;
}
/* Move the initialization of the register to just before
INSN. Update the flow information. */
info. */
SET_REGNO_REG_SET (&cleared_regs, regno);
clear_regnos++;
+ reg_equiv_init[regno] = NULL_RTX;
}
}
}
}
}
+ out:
/* Clean up. */
end_alias_analysis ();
CLEAR_REG_SET (&cleared_regs);
list = reg_equiv[regno].init_insns;
if (list == const0_rtx)
return;
+ reg_equiv[regno].init_insns = const0_rtx;
+ reg_equiv[regno].replacement = NULL_RTX;
+ /* This doesn't matter for equivalences made for argument registers, we
+ should keep their initialization insns. */
+ if (reg_equiv[regno].is_arg_equivalence)
+ return;
+ reg_equiv_init[regno] = NULL_RTX;
for (; list; list = XEXP (list, 1))
{
rtx insn = XEXP (list, 0);
remove_note (insn, find_reg_note (insn, REG_EQUIV, NULL_RTX));
}
- reg_equiv[regno].init_insns = const0_rtx;
- reg_equiv[regno].replacement = NULL_RTX;
}
\f
/* Allocate hard regs to the pseudo regs used only within block number B.
/* Element N is the list of insns that initialized reg N from its equivalent
constant or memory slot. */
-static rtx *reg_equiv_init;
+rtx *reg_equiv_init;
+int reg_equiv_init_size;
/* Vector to remember old contents of reg_renumber before spilling. */
static short *reg_old_renumber;
reg_equiv_constant = xcalloc (max_regno, sizeof (rtx));
reg_equiv_mem = xcalloc (max_regno, sizeof (rtx));
- reg_equiv_init = xcalloc (max_regno, sizeof (rtx));
reg_equiv_address = xcalloc (max_regno, sizeof (rtx));
reg_max_ref_width = xcalloc (max_regno, sizeof (int));
reg_old_renumber = xcalloc (max_regno, sizeof (short));
&& GET_MODE (insn) != VOIDmode)
PUT_MODE (insn, VOIDmode);
+ if (INSN_P (insn))
+ scan_paradoxical_subregs (PATTERN (insn));
+
if (set != 0 && REG_P (SET_DEST (set)))
{
rtx note = find_reg_note (insn, REG_EQUIV, NULL_RTX);
- if (note
- && (! function_invariant_p (XEXP (note, 0))
- || ! flag_pic
- /* A function invariant is often CONSTANT_P but may
- include a register. We promise to only pass
- CONSTANT_P objects to LEGITIMATE_PIC_OPERAND_P. */
- || (CONSTANT_P (XEXP (note, 0))
- && LEGITIMATE_PIC_OPERAND_P (XEXP (note, 0)))))
+ rtx x;
+
+ if (! note)
+ continue;
+
+ i = REGNO (SET_DEST (set));
+ x = XEXP (note, 0);
+
+ if (i <= LAST_VIRTUAL_REGISTER)
+ continue;
+
+ if (! function_invariant_p (x)
+ || ! flag_pic
+ /* A function invariant is often CONSTANT_P but may
+ include a register. We promise to only pass
+ CONSTANT_P objects to LEGITIMATE_PIC_OPERAND_P. */
+ || (CONSTANT_P (x)
+ && LEGITIMATE_PIC_OPERAND_P (x)))
{
- rtx x = XEXP (note, 0);
- i = REGNO (SET_DEST (set));
- if (i > LAST_VIRTUAL_REGISTER)
+ /* It can happen that a REG_EQUIV note contains a MEM
+ that is not a legitimate memory operand. As later
+ stages of reload assume that all addresses found
+ in the reg_equiv_* arrays were originally legitimate,
+ we ignore such REG_EQUIV notes. */
+ if (memory_operand (x, VOIDmode))
{
- /* It can happen that a REG_EQUIV note contains a MEM
- that is not a legitimate memory operand. As later
- stages of reload assume that all addresses found
- in the reg_equiv_* arrays were originally legitimate,
-
- It can also happen that a REG_EQUIV note contains a
- readonly memory location. If the destination pseudo
- is set from some other value (typically a different
- pseudo), and the destination pseudo does not get a
- hard reg, then reload will replace the destination
- pseudo with its equivalent memory location. This
- is horribly bad as it creates a store to a readonly
- memory location and a runtime segfault. To avoid
- this problem we reject readonly memory locations
- for equivalences. This is overly conservative as
- we could find all sets of the destination pseudo
- and remove them as they should be redundant. */
- if (memory_operand (x, VOIDmode) && ! MEM_READONLY_P (x))
+ /* Always unshare the equivalence, so we can
+ substitute into this insn without touching the
+ equivalence. */
+ reg_equiv_memory_loc[i] = copy_rtx (x);
+ }
+ else if (function_invariant_p (x))
+ {
+ if (GET_CODE (x) == PLUS)
{
- /* Always unshare the equivalence, so we can
- substitute into this insn without touching the
- equivalence. */
- reg_equiv_memory_loc[i] = copy_rtx (x);
+ /* This is PLUS of frame pointer and a constant,
+ and might be shared. Unshare it. */
+ reg_equiv_constant[i] = copy_rtx (x);
+ num_eliminable_invariants++;
}
- else if (function_invariant_p (x))
+ else if (x == frame_pointer_rtx
+ || x == arg_pointer_rtx)
{
- if (GET_CODE (x) == PLUS)
- {
- /* This is PLUS of frame pointer and a constant,
- and might be shared. Unshare it. */
- reg_equiv_constant[i] = copy_rtx (x);
- num_eliminable_invariants++;
- }
- else if (x == frame_pointer_rtx
- || x == arg_pointer_rtx)
- {
- reg_equiv_constant[i] = x;
- num_eliminable_invariants++;
- }
- else if (LEGITIMATE_CONSTANT_P (x))
- reg_equiv_constant[i] = x;
- else
- {
- reg_equiv_memory_loc[i]
- = force_const_mem (GET_MODE (SET_DEST (set)), x);
- if (!reg_equiv_memory_loc[i])
- continue;
- }
+ reg_equiv_constant[i] = x;
+ num_eliminable_invariants++;
}
+ else if (LEGITIMATE_CONSTANT_P (x))
+ reg_equiv_constant[i] = x;
else
- continue;
-
- /* If this register is being made equivalent to a MEM
- and the MEM is not SET_SRC, the equivalencing insn
- is one with the MEM as a SET_DEST and it occurs later.
- So don't mark this insn now. */
- if (!MEM_P (x)
- || rtx_equal_p (SET_SRC (set), x))
- reg_equiv_init[i]
- = gen_rtx_INSN_LIST (VOIDmode, insn, reg_equiv_init[i]);
+ {
+ reg_equiv_memory_loc[i]
+ = force_const_mem (GET_MODE (SET_DEST (set)), x);
+ if (! reg_equiv_memory_loc[i])
+ reg_equiv_init[i] = NULL_RTX;
+ }
+ }
+ else
+ {
+ reg_equiv_init[i] = NULL_RTX;
+ continue;
}
}
+ else
+ reg_equiv_init[i] = NULL_RTX;
}
-
- /* If this insn is setting a MEM from a register equivalent to it,
- this is the equivalencing insn. */
- else if (set && MEM_P (SET_DEST (set))
- && REG_P (SET_SRC (set))
- && reg_equiv_memory_loc[REGNO (SET_SRC (set))]
- && rtx_equal_p (SET_DEST (set),
- reg_equiv_memory_loc[REGNO (SET_SRC (set))]))
- reg_equiv_init[REGNO (SET_SRC (set))]
- = gen_rtx_INSN_LIST (VOIDmode, insn,
- reg_equiv_init[REGNO (SET_SRC (set))]);
-
- if (INSN_P (insn))
- scan_paradoxical_subregs (PATTERN (insn));
}
+ if (dump_file)
+ for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
+ if (reg_equiv_init[i])
+ {
+ fprintf (dump_file, "init_insns for %u: ", i);
+ print_inline_rtx (dump_file, reg_equiv_init[i], 20);
+ fprintf (dump_file, "\n");
+ }
+
init_elim_table ();
first_label_num = get_first_label_num ();
free (offsets_at);
free (reg_equiv_mem);
- free (reg_equiv_init);
+ reg_equiv_init = 0;
free (reg_equiv_address);
free (reg_max_ref_width);
free (reg_old_renumber);
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