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Reformat load_mems slightly.
From-SVN: r30618
This commit is contained in:
Bernd Schmidt
Bernd Schmidt
parent
19a027a082
commit
328f4006b2
@ -1,3 +1,7 @@
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1999-11-22 Bernd Schmidt <bernds@cygnus.co.uk>
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* loop.c (load_mems): Reformat slightly.
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1999-11-22 Bruce Korb <autogen@linuxbox.com
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* fixinc/mkfisinc.sh(i?86-*-linux): disable script, run fixincl exe
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275
gcc/loop.c
275
gcc/loop.c
@ -9715,165 +9715,164 @@ load_mems (scan_start, end, loop_top, start)
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rtx p;
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rtx label = NULL_RTX;
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rtx end_label = NULL_RTX;
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/* Nonzero if the next instruction may never be executed. */
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int next_maybe_never = 0;
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if (loop_mems_idx > 0)
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if (loop_mems_idx == 0)
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return;
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/* Check to see if it's possible that some instructions in the
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loop are never executed. */
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for (p = next_insn_in_loop (scan_start, scan_start, end, loop_top);
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p != NULL_RTX && !maybe_never;
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p = next_insn_in_loop (p, scan_start, end, loop_top))
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{
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/* Nonzero if the next instruction may never be executed. */
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int next_maybe_never = 0;
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/* Check to see if it's possible that some instructions in the
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loop are never executed. */
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for (p = next_insn_in_loop (scan_start, scan_start, end, loop_top);
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p != NULL_RTX && !maybe_never;
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p = next_insn_in_loop (p, scan_start, end, loop_top))
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if (GET_CODE (p) == CODE_LABEL)
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maybe_never = 1;
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else if (GET_CODE (p) == JUMP_INSN
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/* If we enter the loop in the middle, and scan
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around to the beginning, don't set maybe_never
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for that. This must be an unconditional jump,
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otherwise the code at the top of the loop might
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never be executed. Unconditional jumps are
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followed a by barrier then loop end. */
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&& ! (GET_CODE (p) == JUMP_INSN
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&& JUMP_LABEL (p) == loop_top
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&& NEXT_INSN (NEXT_INSN (p)) == end
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&& simplejump_p (p)))
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{
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if (GET_CODE (p) == CODE_LABEL)
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if (!condjump_p (p))
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/* Something complicated. */
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maybe_never = 1;
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else if (GET_CODE (p) == JUMP_INSN
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/* If we enter the loop in the middle, and scan
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around to the beginning, don't set maybe_never
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for that. This must be an unconditional jump,
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otherwise the code at the top of the loop might
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never be executed. Unconditional jumps are
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followed a by barrier then loop end. */
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&& ! (GET_CODE (p) == JUMP_INSN
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&& JUMP_LABEL (p) == loop_top
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&& NEXT_INSN (NEXT_INSN (p)) == end
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&& simplejump_p (p)))
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else
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/* If there are any more instructions in the loop, they
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might not be reached. */
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next_maybe_never = 1;
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}
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else if (next_maybe_never)
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maybe_never = 1;
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}
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/* Actually move the MEMs. */
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for (i = 0; i < loop_mems_idx; ++i)
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{
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int written = 0;
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rtx reg;
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rtx mem = loop_mems[i].mem;
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rtx mem_list_entry;
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if (MEM_VOLATILE_P (mem)
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|| invariant_p (XEXP (mem, 0)) != 1)
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/* There's no telling whether or not MEM is modified. */
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loop_mems[i].optimize = 0;
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/* Go through the MEMs written to in the loop to see if this
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one is aliased by one of them. */
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mem_list_entry = loop_store_mems;
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while (mem_list_entry)
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{
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if (rtx_equal_p (mem, XEXP (mem_list_entry, 0)))
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written = 1;
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else if (true_dependence (XEXP (mem_list_entry, 0), VOIDmode,
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mem, rtx_varies_p))
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{
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if (!condjump_p (p))
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/* Something complicated. */
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maybe_never = 1;
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else
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/* If there are any more instructions in the loop, they
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might not be reached. */
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next_maybe_never = 1;
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}
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else if (next_maybe_never)
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maybe_never = 1;
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/* MEM is indeed aliased by this store. */
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loop_mems[i].optimize = 0;
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break;
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}
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mem_list_entry = XEXP (mem_list_entry, 1);
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}
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/* Actually move the MEMs. */
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for (i = 0; i < loop_mems_idx; ++i)
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/* If this MEM is written to, we must be sure that there
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are no reads from another MEM that aliases this one. */
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if (loop_mems[i].optimize && written)
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{
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int written = 0;
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rtx reg;
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rtx mem = loop_mems[i].mem;
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rtx mem_list_entry;
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int j;
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if (MEM_VOLATILE_P (mem)
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|| invariant_p (XEXP (mem, 0)) != 1)
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/* There's no telling whether or not MEM is modified. */
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loop_mems[i].optimize = 0;
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/* Go through the MEMs written to in the loop to see if this
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one is aliased by one of them. */
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mem_list_entry = loop_store_mems;
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while (mem_list_entry)
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for (j = 0; j < loop_mems_idx; ++j)
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{
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if (rtx_equal_p (mem, XEXP (mem_list_entry, 0)))
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written = 1;
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else if (true_dependence (XEXP (mem_list_entry, 0), VOIDmode,
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mem, rtx_varies_p))
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if (j == i)
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continue;
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else if (true_dependence (mem,
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VOIDmode,
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loop_mems[j].mem,
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rtx_varies_p))
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{
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/* MEM is indeed aliased by this store. */
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/* It's not safe to hoist loop_mems[i] out of
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the loop because writes to it might not be
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seen by reads from loop_mems[j]. */
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loop_mems[i].optimize = 0;
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break;
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}
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mem_list_entry = XEXP (mem_list_entry, 1);
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}
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}
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if (maybe_never && may_trap_p (mem))
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/* We can't access the MEM outside the loop; it might
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cause a trap that wouldn't have happened otherwise. */
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loop_mems[i].optimize = 0;
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/* If this MEM is written to, we must be sure that there
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are no reads from another MEM that aliases this one. */
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if (loop_mems[i].optimize && written)
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{
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int j;
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if (!loop_mems[i].optimize)
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/* We thought we were going to lift this MEM out of the
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loop, but later discovered that we could not. */
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continue;
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for (j = 0; j < loop_mems_idx; ++j)
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/* Allocate a pseudo for this MEM. We set REG_USERVAR_P in
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order to keep scan_loop from moving stores to this MEM
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out of the loop just because this REG is neither a
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user-variable nor used in the loop test. */
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reg = gen_reg_rtx (GET_MODE (mem));
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REG_USERVAR_P (reg) = 1;
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loop_mems[i].reg = reg;
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/* Now, replace all references to the MEM with the
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corresponding pesudos. */
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for (p = next_insn_in_loop (scan_start, scan_start, end, loop_top);
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p != NULL_RTX;
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p = next_insn_in_loop (p, scan_start, end, loop_top))
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{
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rtx_and_int ri;
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ri.r = p;
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ri.i = i;
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for_each_rtx (&p, replace_loop_mem, &ri);
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}
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if (! apply_change_group ())
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/* We couldn't replace all occurrences of the MEM. */
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loop_mems[i].optimize = 0;
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else
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{
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rtx set;
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/* Load the memory immediately before START, which is
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the NOTE_LOOP_BEG. */
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set = gen_move_insn (reg, mem);
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emit_insn_before (set, start);
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if (written)
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{
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if (label == NULL_RTX)
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{
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if (j == i)
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continue;
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else if (true_dependence (mem,
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VOIDmode,
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loop_mems[j].mem,
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rtx_varies_p))
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{
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/* It's not safe to hoist loop_mems[i] out of
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the loop because writes to it might not be
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seen by reads from loop_mems[j]. */
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loop_mems[i].optimize = 0;
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break;
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}
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/* We must compute the former
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right-after-the-end label before we insert
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the new one. */
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end_label = next_label (end);
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label = gen_label_rtx ();
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emit_label_after (label, end);
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}
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/* Store the memory immediately after END, which is
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the NOTE_LOOP_END. */
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set = gen_move_insn (copy_rtx (mem), reg);
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emit_insn_after (set, label);
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}
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if (maybe_never && may_trap_p (mem))
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/* We can't access the MEM outside the loop; it might
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cause a trap that wouldn't have happened otherwise. */
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loop_mems[i].optimize = 0;
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if (!loop_mems[i].optimize)
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/* We thought we were going to lift this MEM out of the
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loop, but later discovered that we could not. */
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continue;
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/* Allocate a pseudo for this MEM. We set REG_USERVAR_P in
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order to keep scan_loop from moving stores to this MEM
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out of the loop just because this REG is neither a
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user-variable nor used in the loop test. */
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reg = gen_reg_rtx (GET_MODE (mem));
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REG_USERVAR_P (reg) = 1;
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loop_mems[i].reg = reg;
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/* Now, replace all references to the MEM with the
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corresponding pesudos. */
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for (p = next_insn_in_loop (scan_start, scan_start, end, loop_top);
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p != NULL_RTX;
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p = next_insn_in_loop (p, scan_start, end, loop_top))
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if (loop_dump_stream)
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{
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rtx_and_int ri;
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ri.r = p;
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ri.i = i;
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for_each_rtx (&p, replace_loop_mem, &ri);
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}
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if (!apply_change_group ())
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/* We couldn't replace all occurrences of the MEM. */
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loop_mems[i].optimize = 0;
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else
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{
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rtx set;
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/* Load the memory immediately before START, which is
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the NOTE_LOOP_BEG. */
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set = gen_move_insn (reg, mem);
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emit_insn_before (set, start);
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if (written)
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{
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if (label == NULL_RTX)
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{
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/* We must compute the former
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right-after-the-end label before we insert
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the new one. */
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end_label = next_label (end);
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label = gen_label_rtx ();
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emit_label_after (label, end);
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}
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/* Store the memory immediately after END, which is
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the NOTE_LOOP_END. */
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set = gen_move_insn (copy_rtx (mem), reg);
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emit_insn_after (set, label);
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}
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if (loop_dump_stream)
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{
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fprintf (loop_dump_stream, "Hoisted regno %d %s from ",
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REGNO (reg), (written ? "r/w" : "r/o"));
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print_rtl (loop_dump_stream, mem);
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fputc ('\n', loop_dump_stream);
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}
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fprintf (loop_dump_stream, "Hoisted regno %d %s from ",
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REGNO (reg), (written ? "r/w" : "r/o"));
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print_rtl (loop_dump_stream, mem);
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fputc ('\n', loop_dump_stream);
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}
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}
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}
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