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| author | Richard Sandiford <richard.sandiford@linaro.org> | 2017-10-26 16:12:09 +0000 |
|---|---|---|
| committer | Richard Sandiford <rsandifo@gcc.gnu.org> | 2017-10-26 16:12:09 +0000 |
| commit | 9eaf97d6d7f1511638fb9209b7acf30e8f26a060 (patch) | |
| tree | 16674acba1f8fe4ba22347b1846ccdecf4c4d541 /gcc/combine.c | |
| parent | 7984457f8295811880c37e7861aa7c0454ce9845 (diff) | |
| download | gcc-9eaf97d6d7f1511638fb9209b7acf30e8f26a060.zip gcc-9eaf97d6d7f1511638fb9209b7acf30e8f26a060.tar.gz gcc-9eaf97d6d7f1511638fb9209b7acf30e8f26a060.tar.bz2 | |
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 <richard.sandiford@linaro.org>
Alan Hayward <alan.hayward@arm.com>
David Sherwood <david.sherwood@arm.com>
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 <alan.hayward@arm.com>
Co-Authored-By: David Sherwood <david.sherwood@arm.com>
From-SVN: r254110
Diffstat (limited to 'gcc/combine.c')
| -rw-r--r-- | gcc/combine.c | 19 |
1 files changed, 5 insertions, 14 deletions
diff --git a/gcc/combine.c b/gcc/combine.c index d71e50f..93adfc1 100644 --- a/gcc/combine.c +++ b/gcc/combine.c @@ -579,10 +579,7 @@ find_single_use_1 (rtx dest, rtx *loc) && !REG_P (SET_DEST (x)) && ! (GET_CODE (SET_DEST (x)) == SUBREG && REG_P (SUBREG_REG (SET_DEST (x))) - && (((GET_MODE_SIZE (GET_MODE (SUBREG_REG (SET_DEST (x)))) - + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD) - == ((GET_MODE_SIZE (GET_MODE (SET_DEST (x))) - + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD)))) + && !read_modify_subreg_p (SET_DEST (x)))) break; return find_single_use_1 (dest, &SET_SRC (x)); @@ -7361,15 +7358,12 @@ expand_field_assignment (const_rtx x) } } - /* A SUBREG between two modes that occupy the same numbers of words - can be done by moving the SUBREG to the source. */ + /* If the destination is a subreg that overwrites the whole of the inner + register, we can move the subreg to the source. */ else if (GET_CODE (SET_DEST (x)) == SUBREG /* We need SUBREGs to compute nonzero_bits properly. */ && nonzero_sign_valid - && (((GET_MODE_SIZE (GET_MODE (SET_DEST (x))) - + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD) - == ((GET_MODE_SIZE (GET_MODE (SUBREG_REG (SET_DEST (x)))) - + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD))) + && !read_modify_subreg_p (SET_DEST (x))) { x = gen_rtx_SET (SUBREG_REG (SET_DEST (x)), gen_lowpart @@ -13993,10 +13987,7 @@ move_deaths (rtx x, rtx maybe_kill_insn, int from_luid, rtx_insn *to_insn, if (GET_CODE (dest) == ZERO_EXTRACT || GET_CODE (dest) == STRICT_LOW_PART || (GET_CODE (dest) == SUBREG - && (((GET_MODE_SIZE (GET_MODE (dest)) - + UNITS_PER_WORD - 1) / UNITS_PER_WORD) - == ((GET_MODE_SIZE (GET_MODE (SUBREG_REG (dest))) - + UNITS_PER_WORD - 1) / UNITS_PER_WORD)))) + && !read_modify_subreg_p (dest))) { move_deaths (dest, maybe_kill_insn, from_luid, to_insn, pnotes); return; |