From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1930) id 8F017385802B; Thu, 9 Dec 2021 16:52:15 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 8F017385802B MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="utf-8" From: Martin Sebor To: gcc-cvs@gcc.gnu.org Subject: [gcc r12-5864] Introduce access_ref::merge_ref. X-Act-Checkin: gcc X-Git-Author: Martin Sebor X-Git-Refname: refs/heads/master X-Git-Oldrev: 9354a7d70caef1c94b8d0a66bb2fd4d86c037e7d X-Git-Newrev: 10d185b9845ad96edf45d55ca066a0258d3c3f9a Message-Id: <20211209165215.8F017385802B@sourceware.org> Date: Thu, 9 Dec 2021 16:52:15 +0000 (GMT) X-BeenThere: gcc-cvs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-cvs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 09 Dec 2021 16:52:15 -0000 https://gcc.gnu.org/g:10d185b9845ad96edf45d55ca066a0258d3c3f9a commit r12-5864-g10d185b9845ad96edf45d55ca066a0258d3c3f9a Author: Martin Sebor Date: Mon Dec 6 09:23:22 2021 -0700 Introduce access_ref::merge_ref. gcc/ChangeLog: * pointer-query.cc (access_ref::merge_ref): Define new function. (access_ref::get_ref): Move code into merge_ref and call it. * pointer-query.h (access_ref::merge_ref): Declare new function. Diff: --- gcc/pointer-query.cc | 227 ++++++++++++++++++++++++++++++++------------------- gcc/pointer-query.h | 4 + 2 files changed, 147 insertions(+), 84 deletions(-) diff --git a/gcc/pointer-query.cc b/gcc/pointer-query.cc index c75c4da6b60..24fbac84ec4 100644 --- a/gcc/pointer-query.cc +++ b/gcc/pointer-query.cc @@ -624,6 +624,97 @@ access_ref::phi () const return as_a (def_stmt); } +/* Determine the size and offset for ARG, append it to ALL_REFS, and + merge the result with *THIS. Ignore ARG if SKIP_NULL is set and + ARG refers to the null pointer. Return true on success and false + on failure. */ + +bool +access_ref::merge_ref (vec *all_refs, tree arg, gimple *stmt, + int ostype, bool skip_null, + ssa_name_limit_t &snlim, pointer_query &qry) +{ + access_ref aref; + if (!compute_objsize_r (arg, stmt, ostype, &aref, snlim, &qry) + || aref.sizrng[0] < 0) + /* This may be a PHI with all null pointer arguments. */ + return false; + + if (all_refs) + { + access_ref dummy_ref; + aref.get_ref (all_refs, &dummy_ref, ostype, &snlim, &qry); + } + + if (TREE_CODE (arg) == SSA_NAME) + qry.put_ref (arg, aref, ostype); + + if (all_refs) + all_refs->safe_push (aref); + + aref.deref += deref; + + bool merged_parmarray = aref.parmarray; + + const bool nullp = skip_null && integer_zerop (arg); + const offset_int maxobjsize = wi::to_offset (max_object_size ()); + offset_int minsize = sizrng[0]; + + if (sizrng[0] < 0) + { + /* If *THIS doesn't contain a meaningful result yet set it to AREF + unless the argument is null and it's okay to ignore it. */ + if (!nullp) + *this = aref; + + /* Set if the current argument refers to one or more objects of + known size (or range of sizes), as opposed to referring to + one or more unknown object(s). */ + const bool arg_known_size = (aref.sizrng[0] != 0 + || aref.sizrng[1] != maxobjsize); + if (arg_known_size) + sizrng[0] = aref.sizrng[0]; + + return true; + } + + /* Disregard null pointers in PHIs with two or more arguments. + TODO: Handle this better! */ + if (nullp) + return true; + + const bool known_size = (sizrng[0] != 0 || sizrng[1] != maxobjsize); + + if (known_size && aref.sizrng[0] < minsize) + minsize = aref.sizrng[0]; + + /* Determine the amount of remaining space in the argument. */ + offset_int argrem[2]; + argrem[1] = aref.size_remaining (argrem); + + /* Determine the amount of remaining space computed so far and + if the remaining space in the argument is more use it instead. */ + offset_int merged_rem[2]; + merged_rem[1] = size_remaining (merged_rem); + + /* Reset the PHI's BASE0 flag if any of the nonnull arguments + refers to an object at an unknown offset. */ + if (!aref.base0) + base0 = false; + + if (merged_rem[1] < argrem[1] + || (merged_rem[1] == argrem[1] + && sizrng[1] < aref.sizrng[1])) + /* Use the argument with the most space remaining as the result, + or the larger one if the space is equal. */ + *this = aref; + + sizrng[0] = minsize; + parmarray = merged_parmarray; + + return true; +} + /* Determine and return the largest object to which *THIS refers. If *THIS refers to a PHI and PREF is nonnull, fill *PREF with the details of the object determined by compute_objsize(ARG, OSTYPE) for each PHI @@ -636,9 +727,8 @@ access_ref::get_ref (vec *all_refs, ssa_name_limit_t *psnlim /* = NULL */, pointer_query *qry /* = NULL */) const { - gphi *phi_stmt = this->phi (); - if (!phi_stmt) - return ref; + if (!ref || TREE_CODE (ref) != SSA_NAME) + return NULL; /* FIXME: Calling get_ref() with a null PSNLIM is dangerous and might cause unbounded recursion. */ @@ -646,13 +736,49 @@ access_ref::get_ref (vec *all_refs, if (!psnlim) psnlim = &snlim_buf; - if (!psnlim->visit_phi (ref)) - return NULL_TREE; - pointer_query empty_qry; if (!qry) qry = &empty_qry; + if (gimple *def_stmt = SSA_NAME_DEF_STMT (ref)) + { + if (is_gimple_assign (def_stmt)) + { + tree_code code = gimple_assign_rhs_code (def_stmt); + if (code != MIN_EXPR && code != MAX_EXPR) + return NULL_TREE; + + access_ref aref; + tree arg1 = gimple_assign_rhs1 (def_stmt); + if (!aref.merge_ref (all_refs, arg1, def_stmt, ostype, false, + *psnlim, *qry)) + return NULL_TREE; + + tree arg2 = gimple_assign_rhs2 (def_stmt); + if (!aref.merge_ref (all_refs, arg2, def_stmt, ostype, false, + *psnlim, *qry)) + return NULL_TREE; + + if (pref && pref != this) + { + tree ref = pref->ref; + *pref = aref; + pref->ref = ref; + } + + return aref.ref; + } + } + else + return NULL_TREE; + + gphi *phi_stmt = this->phi (); + if (!phi_stmt) + return ref; + + if (!psnlim->visit_phi (ref)) + return NULL_TREE; + /* The conservative result of the PHI reflecting the offset and size of the largest PHI argument, regardless of whether or not they all refer to the same object. */ @@ -670,91 +796,17 @@ access_ref::get_ref (vec *all_refs, phi_ref = *pref; } - /* Set if any argument is a function array (or VLA) parameter not - declared [static]. */ - bool parmarray = false; - /* The size of the smallest object referenced by the PHI arguments. */ - offset_int minsize = 0; - const offset_int maxobjsize = wi::to_offset (max_object_size ()); - const unsigned nargs = gimple_phi_num_args (phi_stmt); for (unsigned i = 0; i < nargs; ++i) { access_ref phi_arg_ref; + bool skip_null = i || i + 1 < nargs; tree arg = gimple_phi_arg_def (phi_stmt, i); - if (!compute_objsize_r (arg, phi_stmt, ostype, &phi_arg_ref, *psnlim, - qry) - || phi_arg_ref.sizrng[0] < 0) - /* A PHI with all null pointer arguments. */ + if (!phi_ref.merge_ref (all_refs, arg, phi_stmt, ostype, skip_null, + *psnlim, *qry)) return NULL_TREE; - - if (TREE_CODE (arg) == SSA_NAME) - qry->put_ref (arg, phi_arg_ref); - - if (all_refs) - all_refs->safe_push (phi_arg_ref); - - parmarray |= phi_arg_ref.parmarray; - - const bool nullp = integer_zerop (arg) && (i || i + 1 < nargs); - - if (phi_ref.sizrng[0] < 0) - { - /* If PHI_REF doesn't contain a meaningful result yet set it - to the result for the first argument. */ - if (!nullp) - phi_ref = phi_arg_ref; - - /* Set if the current argument refers to one or more objects of - known size (or range of sizes), as opposed to referring to - one or more unknown object(s). */ - const bool arg_known_size = (phi_arg_ref.sizrng[0] != 0 - || phi_arg_ref.sizrng[1] != maxobjsize); - if (arg_known_size) - minsize = phi_arg_ref.sizrng[0]; - - continue; - } - - const bool phi_known_size = (phi_ref.sizrng[0] != 0 - || phi_ref.sizrng[1] != maxobjsize); - - if (phi_known_size && phi_arg_ref.sizrng[0] < minsize) - minsize = phi_arg_ref.sizrng[0]; - - /* Disregard null pointers in PHIs with two or more arguments. - TODO: Handle this better! */ - if (nullp) - continue; - - /* Determine the amount of remaining space in the argument. */ - offset_int argrem[2]; - argrem[1] = phi_arg_ref.size_remaining (argrem); - - /* Determine the amount of remaining space computed so far and - if the remaining space in the argument is more use it instead. */ - offset_int phirem[2]; - phirem[1] = phi_ref.size_remaining (phirem); - - /* Reset the PHI's BASE0 flag if any of the nonnull arguments - refers to an object at an unknown offset. */ - if (!phi_arg_ref.base0) - phi_ref.base0 = false; - - if (phirem[1] < argrem[1] - || (phirem[1] == argrem[1] - && phi_ref.sizrng[1] < phi_arg_ref.sizrng[1])) - /* Use the argument with the most space remaining as the result, - or the larger one if the space is equal. */ - phi_ref = phi_arg_ref; } - /* Replace the lower bound of the largest argument with the size - of the smallest argument, and set PARMARRAY if any argument - was one. */ - phi_ref.sizrng[0] = minsize; - phi_ref.parmarray = parmarray; - if (phi_ref.sizrng[0] < 0) { /* Fail if none of the PHI's arguments resulted in updating PHI_REF @@ -766,7 +818,14 @@ access_ref::get_ref (vec *all_refs, /* Avoid changing *THIS. */ if (pref && pref != this) - *pref = phi_ref; + { + /* Keep the SSA_NAME of the PHI unchanged so that all PHI arguments + can be referred to later if necessary. This is useful even if + they all refer to the same object. */ + tree ref = pref->ref; + *pref = phi_ref; + pref->ref = ref; + } psnlim->leave_phi (ref); diff --git a/gcc/pointer-query.h b/gcc/pointer-query.h index cbc87c86ed3..fe46f711e96 100644 --- a/gcc/pointer-query.h +++ b/gcc/pointer-query.h @@ -66,6 +66,10 @@ struct access_ref /* Return the PHI node REF refers to or null if it doesn't. */ gphi *phi () const; + /* Merge the result for a pointer with *THIS. */ + bool merge_ref (vec *all_refs, tree, gimple *, int, bool, + ssa_name_limit_t &, pointer_query &); + /* Return the object to which REF refers. */ tree get_ref (vec *, access_ref * = nullptr, int = 1, ssa_name_limit_t * = nullptr, pointer_query * = nullptr) const;