From 7bac1be089a8a64dbbaeba20856e5441b5f1794d Mon Sep 17 00:00:00 2001 From: Richard Kenner Date: Sat, 5 Feb 1994 08:05:42 -0500 Subject: (memory_extend_rtx): New variable. (cse_main): Initialize it. (cse_insn): See if we have already loaded a MEM in a wider mode. From-SVN: r6484 --- gcc/cse.c | 61 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 60 insertions(+), 1 deletion(-) (limited to 'gcc') diff --git a/gcc/cse.c b/gcc/cse.c index 45e7d44..e2a49ef 100644 --- a/gcc/cse.c +++ b/gcc/cse.c @@ -348,6 +348,12 @@ static int cse_jumps_altered; static int do_not_record; +#ifdef LOAD_EXTEND_OP + +/* Scratch rtl used when looking for load-extended copy of a MEM. */ +static rtx memory_extend_rtx; +#endif + /* canon_hash stores 1 in hash_arg_in_memory if it notices a reference to memory within the expression being hashed. */ @@ -6378,7 +6384,53 @@ cse_insn (insn, in_libcall_block) } } } - + +#ifdef LOAD_EXTEND_OP + /* See if a MEM has already been loaded with a widening operation; + if it has, we can use a subreg of that. Many CISC machines + also have such operations, but this is only likely to be + beneficial these machines. */ + + if (flag_expensive_optimizations && src_related == 0 + && (GET_MODE_SIZE (mode) < UNITS_PER_WORD) + && GET_MODE_CLASS (mode) == MODE_INT + && GET_CODE (src) == MEM && ! do_not_record + && LOAD_EXTEND_OP (mode) != NIL) + { + enum machine_mode tmode; + + /* Set what we are trying to extend and the operation it might + have been extended with. */ + PUT_CODE (memory_extend_rtx, LOAD_EXTEND_OP (mode)); + XEXP (memory_extend_rtx, 0) = src; + + for (tmode = GET_MODE_WIDER_MODE (mode); + GET_MODE_SIZE (tmode) <= UNITS_PER_WORD; + tmode = GET_MODE_WIDER_MODE (tmode)) + { + struct table_elt *larger_elt; + + PUT_MODE (memory_extend_rtx, tmode); + larger_elt = lookup (memory_extend_rtx, + HASH (memory_extend_rtx, tmode), tmode); + if (larger_elt == 0) + continue; + + for (larger_elt = larger_elt->first_same_value; + larger_elt; larger_elt = larger_elt->next_same_value) + if (GET_CODE (larger_elt->exp) == REG) + { + src_related = gen_lowpart_if_possible (mode, + larger_elt->exp); + break; + } + + if (src_related) + break; + } + } +#endif /* LOAD_EXTEND_OP */ + if (src == src_folded) src_folded = 0; @@ -7916,6 +7968,13 @@ cse_main (f, nregs, after_loop, file) reg_in_table = (int *) alloca (nregs * sizeof (int)); reg_tick = (int *) alloca (nregs * sizeof (int)); +#ifdef LOAD_EXTEND_OP + + /* Allocate scratch rtl here. cse_insn will fill in the memory reference + and change the code and mode as appropriate. */ + memory_extend_rtx = gen_rtx (ZERO_EXTEND, VOIDmode, 0); +#endif + /* Discard all the free elements of the previous function since they are allocated in the temporarily obstack. */ bzero (table, sizeof table); -- cgit v1.1