From 9eaf97d6d7f1511638fb9209b7acf30e8f26a060 Mon Sep 17 00:00:00 2001 From: Richard Sandiford Date: Thu, 26 Oct 2017 16:12:09 +0000 Subject: Make more use of df_read_modify_subreg_p This patch uses df_read_modify_subreg_p to check whether writing to a subreg would preserve some of the existing contents. This has the effect of putting more emphasis on the REGMODE_NATURAL_SIZE-based definition of whether something can be partially modified, instead of using UNITS_PER_WORD unconditionally. This becomes important for SVE, where UNITS_PER_WORD has no significance for subregs of multi-register LD2/ST2, LD3/ST3 and LD4/ST4 tuples. 2017-10-26 Richard Sandiford Alan Hayward David Sherwood gcc/ * caller-save.c (mark_referenced_regs): Use read_modify_subreg_p. * combine.c (find_single_use_1): Likewise. (expand_field_assignment): Likewise. (move_deaths): Likewise. * lra-constraints.c (simplify_operand_subreg): Likewise. (curr_insn_transform): Likewise. * lra.c (collect_non_operand_hard_regs): Likewise. (add_regs_to_insn_regno_info): Likewise. * rtlanal.c (reg_referenced_p): Likewise. (covers_regno_no_parallel_p): Likewise. Co-Authored-By: Alan Hayward Co-Authored-By: David Sherwood From-SVN: r254110 --- gcc/lra.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-) (limited to 'gcc/lra.c') diff --git a/gcc/lra.c b/gcc/lra.c index 3122f2c..04acf88 100644 --- a/gcc/lra.c +++ b/gcc/lra.c @@ -832,14 +832,12 @@ collect_non_operand_hard_regs (rtx *x, lra_insn_recog_data_t data, subreg_p = false; if (code == SUBREG) { + if (read_modify_subreg_p (op)) + subreg_p = true; op = SUBREG_REG (op); code = GET_CODE (op); if (GET_MODE_SIZE (mode) < GET_MODE_SIZE (GET_MODE (op))) - { - mode = GET_MODE (op); - if (GET_MODE_SIZE (mode) > REGMODE_NATURAL_SIZE (mode)) - subreg_p = true; - } + mode = GET_MODE (op); } if (REG_P (op)) { @@ -1427,14 +1425,12 @@ add_regs_to_insn_regno_info (lra_insn_recog_data_t data, rtx x, int uid, subreg_p = false; if (GET_CODE (x) == SUBREG) { + if (read_modify_subreg_p (x)) + subreg_p = true; x = SUBREG_REG (x); code = GET_CODE (x); if (GET_MODE_SIZE (mode) < GET_MODE_SIZE (GET_MODE (x))) - { - mode = GET_MODE (x); - if (GET_MODE_SIZE (mode) > REGMODE_NATURAL_SIZE (mode)) - subreg_p = true; - } + mode = GET_MODE (x); } if (REG_P (x)) { -- cgit v1.1