Message ID | yw8jbkjljy58.fsf@arm.com |
---|---|
State | New |
Headers | show |
Series | constraint: fix relaxed memory and repeated constraint handling | expand |
"Victor L. Do Nascimento" <victor.donascimento@arm.com> writes: > The function `constrain_operands' lacked the logic to consider relaxed > memory constraints when "traditional" memory constraints were not > satisfied, creating potential issues as observed during the reload > compilation pass. > > In addition, it was observed that while `constrain_operands' chooses > to disregard constraints when more than one alternative is provided, > e.g. "m,r" using CONSTRAINT__UNKNOWN, it has no checks in place to > determine whether the multiple constraints in a given string are in > fact repetitions of the same constraint and should thus in fact be > treated as a single constraint, as ought to be the case for something > like "m,m". > > Both of these issues are dealt with here, thus ensuring that we get > appropriate pattern matching. > > Tested on aarch64-linux-gnu & x86_64-linux-gnu. OK to install? > > Victor > > gcc/ > * lra-constraints.cc (constraint_unique): New. > (process_address_1): Apply constraint_unique test. > * recog.cc (constrain_operands): Allow relaxed memory > constaints. > --- > gcc/lra-constraints.cc | 40 +++++++++++++++++++++++++++++++++++++--- > gcc/recog.cc | 3 ++- > 2 files changed, 39 insertions(+), 4 deletions(-) > > diff --git a/gcc/lra-constraints.cc b/gcc/lra-constraints.cc > index dd4f68bbfc0..6a13e64d7e1 100644 > --- a/gcc/lra-constraints.cc > +++ b/gcc/lra-constraints.cc > @@ -3448,6 +3448,42 @@ skip_constraint_modifiers (const char *str) > } > } > > +/* Takes a string of 0 or more comma-separated constraints and the > + constraint_num correspondig to the first constraint. When more corresponding > + than one constraint present, evaluate whether they all correspond is present > + to a single, repeated constraint (e.g. "r,r") or whether we have > + more than one distinct constraints (e.g. "r,m"). */ > +static bool > +constraint_unique (const char *cstr) > +{ > + enum constraint_num ca, cb; > + ca = CONSTRAINT__UNKNOWN; > + for (;;) > + { > + cstr = skip_constraint_modifiers (cstr); > + if (*cstr == '\0' || *cstr == ',') > + cb = CONSTRAINT_X; > + else > + { > + cb = lookup_constraint (cstr); > + if (cb == CONSTRAINT__UNKNOWN) > + return false; > + cstr += CONSTRAINT_LEN (cstr[0], cstr); > + } > + /* Treat the special case of an uninitialized ca. */ Maybe: /* Handle the first iteration of the loop. */ > + if (ca == CONSTRAINT__UNKNOWN) > + ca = cb; > + /* Treat the general case of comparing ca with subsequent > + constraints. */ s/Treat/Handle/ OK with those changes, thanks. Richard > + else if (ca != cb) > + return false; > + if (*cstr == '\0') > + return true; > + if (*cstr == ',') > + cstr += 1; > + } > +} > + > /* Major function to make reloads for an address in operand NOP or > check its correctness (If CHECK_ONLY_P is true). The supported > cases are: > @@ -3507,9 +3543,7 @@ process_address_1 (int nop, bool check_only_p, > operand has one address constraint, probably all others constraints are > address ones. */ > if (constraint[0] != '\0' && get_constraint_type (cn) != CT_ADDRESS > - && *skip_constraint_modifiers (constraint > - + CONSTRAINT_LEN (constraint[0], > - constraint)) != '\0') > + && !constraint_unique (constraint)) > cn = CONSTRAINT__UNKNOWN; > if (insn_extra_address_constraint (cn) > /* When we find an asm operand with an address constraint that > diff --git a/gcc/recog.cc b/gcc/recog.cc > index 200cf4214f1..3ddeab59d92 100644 > --- a/gcc/recog.cc > +++ b/gcc/recog.cc > @@ -3234,7 +3234,8 @@ constrain_operands (int strict, alternative_mask alternatives) > else if (constraint_satisfied_p (op, cn)) > win = 1; > > - else if (insn_extra_memory_constraint (cn) > + else if ((insn_extra_memory_constraint (cn) > + || insn_extra_relaxed_memory_constraint (cn)) > /* Every memory operand can be reloaded to fit. */ > && ((strict < 0 && MEM_P (op)) > /* Before reload, accept what reload can turn
diff --git a/gcc/lra-constraints.cc b/gcc/lra-constraints.cc index dd4f68bbfc0..6a13e64d7e1 100644 --- a/gcc/lra-constraints.cc +++ b/gcc/lra-constraints.cc @@ -3448,6 +3448,42 @@ skip_constraint_modifiers (const char *str) } } +/* Takes a string of 0 or more comma-separated constraints and the + constraint_num correspondig to the first constraint. When more + than one constraint present, evaluate whether they all correspond + to a single, repeated constraint (e.g. "r,r") or whether we have + more than one distinct constraints (e.g. "r,m"). */ +static bool +constraint_unique (const char *cstr) +{ + enum constraint_num ca, cb; + ca = CONSTRAINT__UNKNOWN; + for (;;) + { + cstr = skip_constraint_modifiers (cstr); + if (*cstr == '\0' || *cstr == ',') + cb = CONSTRAINT_X; + else + { + cb = lookup_constraint (cstr); + if (cb == CONSTRAINT__UNKNOWN) + return false; + cstr += CONSTRAINT_LEN (cstr[0], cstr); + } + /* Treat the special case of an uninitialized ca. */ + if (ca == CONSTRAINT__UNKNOWN) + ca = cb; + /* Treat the general case of comparing ca with subsequent + constraints. */ + else if (ca != cb) + return false; + if (*cstr == '\0') + return true; + if (*cstr == ',') + cstr += 1; + } +} + /* Major function to make reloads for an address in operand NOP or check its correctness (If CHECK_ONLY_P is true). The supported cases are: @@ -3507,9 +3543,7 @@ process_address_1 (int nop, bool check_only_p, operand has one address constraint, probably all others constraints are address ones. */ if (constraint[0] != '\0' && get_constraint_type (cn) != CT_ADDRESS - && *skip_constraint_modifiers (constraint - + CONSTRAINT_LEN (constraint[0], - constraint)) != '\0') + && !constraint_unique (constraint)) cn = CONSTRAINT__UNKNOWN; if (insn_extra_address_constraint (cn) /* When we find an asm operand with an address constraint that diff --git a/gcc/recog.cc b/gcc/recog.cc index 200cf4214f1..3ddeab59d92 100644 --- a/gcc/recog.cc +++ b/gcc/recog.cc @@ -3234,7 +3234,8 @@ constrain_operands (int strict, alternative_mask alternatives) else if (constraint_satisfied_p (op, cn)) win = 1; - else if (insn_extra_memory_constraint (cn) + else if ((insn_extra_memory_constraint (cn) + || insn_extra_relaxed_memory_constraint (cn)) /* Every memory operand can be reloaded to fit. */ && ((strict < 0 && MEM_P (op)) /* Before reload, accept what reload can turn