From d073e2d75d9ed492de9a8dc6970e5b69fae20e5a Mon Sep 17 00:00:00 2001 From: Martin Jambor Date: Tue, 15 Aug 2023 17:26:13 +0200 Subject: [PATCH] Feed results of IPA-CP into tree value numbering PRs 68930 and 92497 show that when IPA-CP figures out constants in aggregate parameters or when passed by reference but the loads happen in an inlined function the information is lost. This happens even when the inlined function itself was known to have - or even cloned to have - such constants in incoming parameters because the transform phase of IPA passes is not run on them. See discussion in the bugs for reasons why. Honza suggested that we can plug the results of IPA-CP analysis into value numbering, so that FRE can figure out that some loads fetch known constants. This is what this patch attempts to do. The patch does not attempt to populate partial_defs with information from IPA-CP, this can be hopefully added as a follow-up. gcc/ChangeLog: 2023-08-11 Martin Jambor PR ipa/68930 PR ipa/92497 * ipa-prop.h (ipcp_get_aggregate_const): Declare. * ipa-prop.cc (ipcp_get_aggregate_const): New function. (ipcp_transform_function): Do not deallocate transformation info. * tree-ssa-sccvn.cc: Include alloc-pool.h, symbol-summary.h and ipa-prop.h. (vn_reference_lookup_2): When hitting default-def vuse, query IPA-CP transformation info for any known constants. gcc/testsuite/ChangeLog: 2023-06-07 Martin Jambor PR ipa/68930 PR ipa/92497 * gcc.dg/ipa/pr92497-1.c: New test. * gcc.dg/ipa/pr92497-2.c: Likewise. --- gcc/ipa-prop.cc | 33 +++++++++++++++++++++++---- gcc/ipa-prop.h | 3 +++ gcc/testsuite/gcc.dg/ipa/pr92497-1.c | 26 +++++++++++++++++++++ gcc/testsuite/gcc.dg/ipa/pr92497-2.c | 26 +++++++++++++++++++++ gcc/tree-ssa-sccvn.cc | 34 +++++++++++++++++++++++++++- 5 files changed, 116 insertions(+), 6 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/ipa/pr92497-1.c create mode 100644 gcc/testsuite/gcc.dg/ipa/pr92497-2.c diff --git a/gcc/ipa-prop.cc b/gcc/ipa-prop.cc index 4f6ed7b89bd7..9efaa5cb8489 100644 --- a/gcc/ipa-prop.cc +++ b/gcc/ipa-prop.cc @@ -5760,6 +5760,34 @@ ipcp_modif_dom_walker::before_dom_children (basic_block bb) return NULL; } +/* If IPA-CP discovered a constant in parameter PARM at OFFSET of a given SIZE + - whether passed by reference or not is given by BY_REF - return that + constant. Otherwise return NULL_TREE. */ + +tree +ipcp_get_aggregate_const (struct function *func, tree parm, bool by_ref, + HOST_WIDE_INT bit_offset, HOST_WIDE_INT bit_size) +{ + cgraph_node *node = cgraph_node::get (func->decl); + ipcp_transformation *ts = ipcp_get_transformation_summary (node); + + if (!ts || !ts->m_agg_values) + return NULL_TREE; + + int index = ts->get_param_index (func->decl, parm); + if (index < 0) + return NULL_TREE; + + ipa_argagg_value_list avl (ts); + unsigned unit_offset = bit_offset / BITS_PER_UNIT; + tree v = avl.get_value (index, unit_offset, by_ref); + if (!v + || maybe_ne (tree_to_poly_int64 (TYPE_SIZE (TREE_TYPE (v))), bit_size)) + return NULL_TREE; + + return v; +} + /* Return true if we have recorded VALUE and MASK about PARM. Set VALUE and MASk accordingly. */ @@ -6031,11 +6059,6 @@ ipcp_transform_function (struct cgraph_node *node) free_ipa_bb_info (bi); fbi.bb_infos.release (); - ipcp_transformation *s = ipcp_transformation_sum->get (node); - s->m_agg_values = NULL; - s->bits = NULL; - s->m_vr = NULL; - vec_free (descriptors); if (cfg_changed) delete_unreachable_blocks_update_callgraph (node, false); diff --git a/gcc/ipa-prop.h b/gcc/ipa-prop.h index 410c951a2564..7e033d2a7b83 100644 --- a/gcc/ipa-prop.h +++ b/gcc/ipa-prop.h @@ -1235,6 +1235,9 @@ void ipa_dump_param (FILE *, class ipa_node_params *info, int i); void ipa_release_body_info (struct ipa_func_body_info *); tree ipa_get_callee_param_type (struct cgraph_edge *e, int i); bool ipcp_get_parm_bits (tree, tree *, widest_int *); +tree ipcp_get_aggregate_const (struct function *func, tree parm, bool by_ref, + HOST_WIDE_INT bit_offset, + HOST_WIDE_INT bit_size); bool unadjusted_ptr_and_unit_offset (tree op, tree *ret, poly_int64 *offset_ret); diff --git a/gcc/testsuite/gcc.dg/ipa/pr92497-1.c b/gcc/testsuite/gcc.dg/ipa/pr92497-1.c new file mode 100644 index 000000000000..dcece15963ce --- /dev/null +++ b/gcc/testsuite/gcc.dg/ipa/pr92497-1.c @@ -0,0 +1,26 @@ +/* { dg-do run } */ +/* { dg-options "-O2 -fno-early-inlining" } */ + +struct a {int a;}; +static int +foo (struct a a) +{ + if (!__builtin_constant_p (a.a)) + __builtin_abort (); + return a.a; +} + +static int __attribute__ ((noinline)) +bar (struct a a) +{ + return foo(a); +} + +volatile int r; + +int main() +{ + struct a a={1}; + r = bar (a); + return 0; +} diff --git a/gcc/testsuite/gcc.dg/ipa/pr92497-2.c b/gcc/testsuite/gcc.dg/ipa/pr92497-2.c new file mode 100644 index 000000000000..c64090d1a7ab --- /dev/null +++ b/gcc/testsuite/gcc.dg/ipa/pr92497-2.c @@ -0,0 +1,26 @@ +/* { dg-do run } */ +/* { dg-options "-O2 -fno-early-inlining -fno-ipa-sra" } */ + +struct a {int a;}; +static int +foo (struct a *a) +{ + if (!__builtin_constant_p (a->a)) + __builtin_abort (); + return a->a; +} + +static int __attribute__ ((noinline)) +bar (struct a *a) +{ + return foo(a); +} + +volatile int r; + +int main() +{ + struct a a={1}; + r = bar (&a); + return 0; +} diff --git a/gcc/tree-ssa-sccvn.cc b/gcc/tree-ssa-sccvn.cc index 32e06fae3b9f..b1678911671e 100644 --- a/gcc/tree-ssa-sccvn.cc +++ b/gcc/tree-ssa-sccvn.cc @@ -74,6 +74,9 @@ along with GCC; see the file COPYING3. If not see #include "ipa-modref-tree.h" #include "ipa-modref.h" #include "tree-ssa-sccvn.h" +#include "alloc-pool.h" +#include "symbol-summary.h" +#include "ipa-prop.h" /* This algorithm is based on the SCC algorithm presented by Keith Cooper and L. Taylor Simpson in "SCC-Based Value numbering" @@ -2327,7 +2330,7 @@ vn_walk_cb_data::push_partial_def (pd_data pd, with the current VUSE and performs the expression lookup. */ static void * -vn_reference_lookup_2 (ao_ref *op ATTRIBUTE_UNUSED, tree vuse, void *data_) +vn_reference_lookup_2 (ao_ref *op, tree vuse, void *data_) { vn_walk_cb_data *data = (vn_walk_cb_data *)data_; vn_reference_t vr = data->vr; @@ -2361,6 +2364,35 @@ vn_reference_lookup_2 (ao_ref *op ATTRIBUTE_UNUSED, tree vuse, void *data_) return *slot; } + if (SSA_NAME_IS_DEFAULT_DEF (vuse)) + { + HOST_WIDE_INT op_offset, op_size; + tree v = NULL_TREE; + tree base = ao_ref_base (op); + + if (base + && op->offset.is_constant (&op_offset) + && op->size.is_constant (&op_size) + && op->max_size_known_p () + && known_eq (op->size, op->max_size)) + { + if (TREE_CODE (base) == PARM_DECL) + v = ipcp_get_aggregate_const (cfun, base, false, op_offset, + op_size); + else if (TREE_CODE (base) == MEM_REF + && integer_zerop (TREE_OPERAND (base, 1)) + && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME + && SSA_NAME_IS_DEFAULT_DEF (TREE_OPERAND (base, 0)) + && (TREE_CODE (SSA_NAME_VAR (TREE_OPERAND (base, 0))) + == PARM_DECL)) + v = ipcp_get_aggregate_const (cfun, + SSA_NAME_VAR (TREE_OPERAND (base, 0)), + true, op_offset, op_size); + } + if (v) + return data->finish (vr->set, vr->base_set, v); + } + return NULL; } -- 2.47.2