From: Eric Botcazou Date: Sun, 7 Dec 2014 21:55:47 +0000 (+0000) Subject: compare-elim.c: Fix head comment. X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=6c6a593dc0a410ffdda14ce97e1518ea3dcb83d5;p=gcc.git compare-elim.c: Fix head comment. * compare-elim.c: Fix head comment. (conforming_compare): Remove redundant test. (can_eliminate_compare): New function extracted from... (before_dom_children): ...here. Use it, replace direct uses of flag_non_call_exceptions and tidy up. (maybe_select_cc_mode): Tidy up. From-SVN: r218468 --- diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 41e6f3ea16e..46e41ec9892 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,12 @@ +2014-12-07 Eric Botcazou + + * compare-elim.c: Fix head comment. + (conforming_compare): Remove redundant test. + (can_eliminate_compare): New function extracted from... + (before_dom_children): ...here. Use it, replace direct uses of + flag_non_call_exceptions and tidy up. + (maybe_select_cc_mode): Tidy up. + 2014-12-07 Felix Yang Shanyao Chen diff --git a/gcc/compare-elim.c b/gcc/compare-elim.c index d4c0e6884c1..4b307807c4e 100644 --- a/gcc/compare-elim.c +++ b/gcc/compare-elim.c @@ -35,7 +35,7 @@ along with GCC; see the file COPYING3. If not see (1) All comparison patterns are represented as - [(set (reg:CC) (compare:CC (reg) (immediate)))] + [(set (reg:CC) (compare:CC (reg) (reg_or_immediate)))] (2) All insn patterns that modify the flags are represented as @@ -157,7 +157,6 @@ conforming_compare (rtx_insn *insn) return NULL; if (REG_P (XEXP (src, 0)) - && REG_P (XEXP (src, 0)) && (REG_P (XEXP (src, 1)) || CONSTANT_P (XEXP (src, 1)))) return src; @@ -266,6 +265,45 @@ public: virtual void before_dom_children (basic_block); }; +/* Return true if conforming COMPARE with EH_NOTE is redundant with comparison + CMP and can thus be eliminated. */ + +static bool +can_eliminate_compare (rtx compare, rtx eh_note, struct comparison *cmp) +{ + /* Take care that it's in the same EH region. */ + if (cfun->can_throw_non_call_exceptions + && !rtx_equal_p (eh_note, cmp->eh_note)) + return false; + + /* Make sure the compare is redundant with the previous. */ + if (!rtx_equal_p (XEXP (compare, 0), cmp->in_a) + || !rtx_equal_p (XEXP (compare, 1), cmp->in_b)) + return false; + + /* New mode must be compatible with the previous compare mode. */ + enum machine_mode new_mode + = targetm.cc_modes_compatible (GET_MODE (compare), cmp->orig_mode); + + if (new_mode == VOIDmode) + return false; + + if (cmp->orig_mode != new_mode) + { + /* Generate new comparison for substitution. */ + rtx flags = gen_rtx_REG (new_mode, targetm.flags_regnum); + rtx x = gen_rtx_COMPARE (new_mode, cmp->in_a, cmp->in_b); + x = gen_rtx_SET (VOIDmode, flags, x); + + if (!validate_change (cmp->insn, &PATTERN (cmp->insn), x, false)) + return false; + + cmp->orig_mode = new_mode; + } + + return true; +} + /* Identify comparison instructions within BB. If the flags from the last compare in the BB is live at the end of the block, install the compare in BB->AUX. Called via dom_walker.walk (). */ @@ -317,62 +355,26 @@ find_comparison_dom_walker::before_dom_children (basic_block bb) src = conforming_compare (insn); if (src) { - machine_mode src_mode = GET_MODE (src); rtx eh_note = NULL; - if (flag_non_call_exceptions) + if (cfun->can_throw_non_call_exceptions) eh_note = find_reg_note (insn, REG_EH_REGION, NULL); - if (!last_cmp_valid) - goto dont_delete; - - /* Take care that it's in the same EH region. */ - if (flag_non_call_exceptions - && !rtx_equal_p (eh_note, last_cmp->eh_note)) - goto dont_delete; - - /* Make sure the compare is redundant with the previous. */ - if (!rtx_equal_p (last_cmp->in_a, XEXP (src, 0)) - || !rtx_equal_p (last_cmp->in_b, XEXP (src, 1))) - goto dont_delete; - - /* New mode must be compatible with the previous compare mode. */ - { - machine_mode new_mode - = targetm.cc_modes_compatible (last_cmp->orig_mode, src_mode); - if (new_mode == VOIDmode) - goto dont_delete; - - if (new_mode != last_cmp->orig_mode) - { - rtx x, flags = gen_rtx_REG (src_mode, targetm.flags_regnum); - - /* Generate new comparison for substitution. */ - x = gen_rtx_COMPARE (new_mode, XEXP (src, 0), XEXP (src, 1)); - x = gen_rtx_SET (VOIDmode, flags, x); - - if (!validate_change (last_cmp->insn, - &PATTERN (last_cmp->insn), x, false)) - goto dont_delete; - - last_cmp->orig_mode = new_mode; - } - } - - /* All tests and substitutions succeeded! */ - if (eh_note) - need_purge = true; - delete_insn (insn); - continue; + if (last_cmp_valid && can_eliminate_compare (src, eh_note, last_cmp)) + { + if (eh_note) + need_purge = true; + delete_insn (insn); + continue; + } - dont_delete: last_cmp = XCNEW (struct comparison); last_cmp->insn = insn; last_cmp->prev_clobber = last_clobber; last_cmp->in_a = XEXP (src, 0); last_cmp->in_b = XEXP (src, 1); last_cmp->eh_note = eh_note; - last_cmp->orig_mode = src_mode; + last_cmp->orig_mode = GET_MODE (src); all_compares.safe_push (last_cmp); /* It's unusual, but be prepared for comparison patterns that @@ -391,7 +393,6 @@ find_comparison_dom_walker::before_dom_children (basic_block bb) /* In either case, the previous compare is no longer valid. */ last_cmp = NULL; last_cmp_valid = false; - continue; } /* Notice if this instruction uses the flags register. */ @@ -425,8 +426,7 @@ find_comparison_dom_walker::before_dom_children (basic_block bb) FOR_EACH_EDGE (e, ei, bb->succs) { basic_block dest = e->dest; - if (bitmap_bit_p (df_get_live_in (bb), - targetm.flags_regnum) + if (bitmap_bit_p (df_get_live_in (bb), targetm.flags_regnum) && !single_pred_p (dest)) { last_cmp->missing_uses = true; @@ -498,8 +498,7 @@ maybe_select_cc_mode (struct comparison *cmp, rtx a ATTRIBUTE_UNUSED, sel_mode = SELECT_CC_MODE (cmp->uses[0].code, a, b); for (i = 1; i < n; ++i) { - machine_mode new_mode; - new_mode = SELECT_CC_MODE (cmp->uses[i].code, a, b); + machine_mode new_mode = SELECT_CC_MODE (cmp->uses[i].code, a, b); if (new_mode != sel_mode) { sel_mode = targetm.cc_modes_compatible (sel_mode, new_mode); @@ -507,7 +506,7 @@ maybe_select_cc_mode (struct comparison *cmp, rtx a ATTRIBUTE_UNUSED, return NULL; } } - + if (sel_mode != cmp->orig_mode) { flags = gen_rtx_REG (sel_mode, targetm.flags_regnum); @@ -633,7 +632,7 @@ try_eliminate_compare (struct comparison *cmp) validate_change (insn, &XVECEXP (PATTERN (insn), 0, 1), x, true); if (!apply_change_group ()) return false; - + /* Success. Delete the compare insn... */ delete_insn (cmp->insn);