diff options
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/ChangeLog | 8 | ||||
| -rw-r--r-- | gcc/ira-lives.c | 86 |
2 files changed, 80 insertions, 14 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index ce91585..798d16c 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,5 +1,13 @@ 2019-10-07 Richard Sandiford <richard.sandiford@arm.com> + * ira-lives.c (check_and_make_def_conflict): Handle cases in which + DEF is not a true earlyclobber but is tied to a specific input + operand, and so is effectively earlyclobber wrt inputs that have + different values. + (make_early_clobber_and_input_conflicts): Pass this case to the above. + +2019-10-07 Richard Sandiford <richard.sandiford@arm.com> + * machmode.h (opt_mode): Mark constructors with CONSTEXPR. (pod_mode): Mark operators likewise. (scalar_int_mode): Mark non-default constructors and diff --git a/gcc/ira-lives.c b/gcc/ira-lives.c index cce73a1..098b0e7 100644 --- a/gcc/ira-lives.c +++ b/gcc/ira-lives.c @@ -633,9 +633,28 @@ check_and_make_def_use_conflict (rtx dreg, rtx orig_dreg, /* Check and make if necessary conflicts for definition DEF of class DEF_CL of the current insn with input operands. Process only - constraints of alternative ALT. */ + constraints of alternative ALT. + + One of three things is true when this function is called: + + (1) DEF is an earlyclobber for alternative ALT. Input operands then + conflict with DEF in ALT unless they explicitly match DEF via 0-9 + constraints. + + (2) DEF matches (via 0-9 constraints) an operand that is an + earlyclobber for alternative ALT. Other input operands then + conflict with DEF in ALT. + + (3) [FOR_TIE_P] Some input operand X matches DEF for alternative ALT. + Input operands with a different value from X then conflict with + DEF in ALT. + + However, there's still a judgement call to make when deciding + whether a conflict in ALT is important enough to be reflected + in the pan-alternative allocno conflict set. */ static void -check_and_make_def_conflict (int alt, int def, enum reg_class def_cl) +check_and_make_def_conflict (int alt, int def, enum reg_class def_cl, + bool for_tie_p) { int use, use_match; ira_allocno_t a; @@ -669,14 +688,40 @@ check_and_make_def_conflict (int alt, int def, enum reg_class def_cl) if (use == def || recog_data.operand_type[use] == OP_OUT) continue; + /* An earlyclobber on DEF doesn't apply to an input operand X if X + explicitly matches DEF, but it applies to other input operands + even if they happen to be the same value as X. + + In contrast, if an input operand X is tied to a non-earlyclobber + DEF, there's no conflict with other input operands that have the + same value as X. */ + if (op_alt[use].matches == def + || (for_tie_p + && rtx_equal_p (recog_data.operand[use], + recog_data.operand[op_alt[def].matched]))) + continue; + if (op_alt[use].anything_ok) use_cl = ALL_REGS; else use_cl = op_alt[use].cl; + if (use_cl == NO_REGS) + continue; + + /* If DEF is simply a tied operand, ignore cases in which this + alternative requires USE to have a likely-spilled class. + Adding a conflict would just constrain USE further if DEF + happens to be allocated first. */ + if (for_tie_p && targetm.class_likely_spilled_p (use_cl)) + continue; /* If there's any alternative that allows USE to match DEF, do not record a conflict. If that causes us to create an invalid - instruction due to the earlyclobber, reload must fix it up. */ + instruction due to the earlyclobber, reload must fix it up. + + Likewise, if we're treating a tied DEF like a partial earlyclobber, + do not record a conflict if there's another alternative in which + DEF is neither tied nor earlyclobber. */ for (alt1 = 0; alt1 < recog_data.n_alternatives; alt1++) { if (!TEST_BIT (preferred_alternatives, alt1)) @@ -691,6 +736,12 @@ check_and_make_def_conflict (int alt, int def, enum reg_class def_cl) && recog_data.constraints[use - 1][0] == '%' && op_alt1[use - 1].matches == def)) break; + if (for_tie_p + && !op_alt1[def].earlyclobber + && op_alt1[def].matched < 0 + && alternative_class (op_alt1, def) != NO_REGS + && alternative_class (op_alt1, use) != NO_REGS) + break; } if (alt1 < recog_data.n_alternatives) @@ -701,8 +752,7 @@ check_and_make_def_conflict (int alt, int def, enum reg_class def_cl) if ((use_match = op_alt[use].matches) >= 0) { - if (use_match == def) - continue; + gcc_checking_assert (use_match != def); if (op_alt[use_match].anything_ok) use_cl = ALL_REGS; @@ -717,7 +767,11 @@ check_and_make_def_conflict (int alt, int def, enum reg_class def_cl) /* Make conflicts of early clobber pseudo registers of the current insn with its inputs. Avoid introducing unnecessary conflicts by checking classes of the constraints and pseudos because otherwise - significant code degradation is possible for some targets. */ + significant code degradation is possible for some targets. + + For these purposes, tying an input to an output makes that output act + like an earlyclobber for inputs with a different value, since the output + register then has a predetermined purpose on input to the instruction. */ static void make_early_clobber_and_input_conflicts (void) { @@ -732,15 +786,19 @@ make_early_clobber_and_input_conflicts (void) if (TEST_BIT (preferred_alternatives, alt)) for (def = 0; def < n_operands; def++) { - def_cl = NO_REGS; - if (op_alt[def].earlyclobber) + if (op_alt[def].anything_ok) + def_cl = ALL_REGS; + else + def_cl = op_alt[def].cl; + if (def_cl != NO_REGS) { - if (op_alt[def].anything_ok) - def_cl = ALL_REGS; - else - def_cl = op_alt[def].cl; - check_and_make_def_conflict (alt, def, def_cl); + if (op_alt[def].earlyclobber) + check_and_make_def_conflict (alt, def, def_cl, false); + else if (op_alt[def].matched >= 0 + && !targetm.class_likely_spilled_p (def_cl)) + check_and_make_def_conflict (alt, def, def_cl, true); } + if ((def_match = op_alt[def].matches) >= 0 && (op_alt[def_match].earlyclobber || op_alt[def].earlyclobber)) @@ -749,7 +807,7 @@ make_early_clobber_and_input_conflicts (void) def_cl = ALL_REGS; else def_cl = op_alt[def_match].cl; - check_and_make_def_conflict (alt, def, def_cl); + check_and_make_def_conflict (alt, def, def_cl, false); } } } |