From 53e6d7a3102409f0f2a5a9ffbfbeaa62c135d991 Mon Sep 17 00:00:00 2001
From: Andrew MacLeod <amacleod@redhat.com>
Date: Tue, 18 Oct 2022 16:29:49 -0400
Subject: [PATCH] Add assume support to VRP.
This provides an assume_query class using rangers GORI module to
determine what ranges would be applied to any SSA NAMES in the function
if the return value were [1, 1]. Any parameter ranges are stored in
the SSA_NAME_RANGE_INFO field, and ranger's inferred range machinery is
then used to look these up and match them to assume call parameteres
in the bodies of other functions..
PR c++/106654
gcc/
* gimple-range-gori.h (compute_operand_range): Make public.
* gimple-range-infer.cc (gimple_infer_range::check_assume_func): New.
(gimple_infer_range::gimple_infer_range): Check for assume calls.
* gimple-range-infer.h (check_assume_func): Add prototype.
* gimple-range.cc (assume_query::assume_range_p): New.
(assume_query::range_of_expr): New.
(assume_query::assume_query): New.
(assume_query::calculate_op): New.
(assume_query::calculate_phi): New.
(assume_query::check_taken_edge): New.
(assume_query::calculate_stmt): New.
(assume_query::dump): New.
* gimple-range.h (class assume_query): New.
* tree-vrp.cc (pass_assumptions::execute): Add processing.
gcc/testsuite/
* g++.dg/cpp23/attr-assume-opt.C: New.
---
gcc/gimple-range-gori.h | 6 +-
gcc/gimple-range-infer.cc | 54 ++++++
gcc/gimple-range-infer.h | 1 +
gcc/gimple-range.cc | 190 +++++++++++++++++++
gcc/gimple-range.h | 18 ++
gcc/testsuite/g++.dg/cpp23/attr-assume-opt.C | 42 ++++
gcc/tree-vrp.cc | 34 ++++
7 files changed, 342 insertions(+), 3 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp23/attr-assume-opt.C
@@ -165,15 +165,15 @@ public:
bool has_edge_range_p (tree name, basic_block bb = NULL);
bool has_edge_range_p (tree name, edge e);
void dump (FILE *f);
+ bool compute_operand_range (vrange &r, gimple *stmt, const vrange &lhs,
+ tree name, class fur_source &src,
+ value_relation *rel = NULL);
private:
bool refine_using_relation (tree op1, vrange &op1_range,
tree op2, vrange &op2_range,
fur_source &src, relation_kind k);
bool may_recompute_p (tree name, edge e);
bool may_recompute_p (tree name, basic_block bb = NULL);
- bool compute_operand_range (vrange &r, gimple *stmt, const vrange &lhs,
- tree name, class fur_source &src,
- value_relation *rel = NULL);
bool compute_operand_range_switch (vrange &r, gswitch *s, const vrange &lhs,
tree name, fur_source &src);
bool compute_operand1_range (vrange &r, gimple_range_op_handler &handler,
@@ -35,6 +35,7 @@ along with GCC; see the file COPYING3. If not see
#include "gimple-iterator.h"
#include "gimple-walk.h"
#include "cfganal.h"
+#include "tree-dfa.h"
// Adapted from infer_nonnull_range_by_dereference and check_loadstore
// to process nonnull ssa_name OP in S. DATA contains a pointer to a
@@ -56,6 +57,54 @@ non_null_loadstore (gimple *, tree op, tree, void *data)
return false;
}
+// Process an ASSUME call to see if there are any inferred ranges available.
+
+void
+gimple_infer_range::check_assume_func (gcall *call)
+{
+ tree arg;
+ unsigned i;
+ tree assume_id = TREE_OPERAND (gimple_call_arg (call, 0), 0);
+ if (!assume_id)
+ return;
+ struct function *fun = DECL_STRUCT_FUNCTION (assume_id);
+ if (!fun)
+ return;
+ // Loop over arguments, matching them to the assume paramters.
+ for (arg = DECL_ARGUMENTS (assume_id), i = 1;
+ arg && i < gimple_call_num_args (call);
+ i++, arg = DECL_CHAIN (arg))
+ {
+ tree op = gimple_call_arg (call, i);
+ tree type = TREE_TYPE (op);
+ if (gimple_range_ssa_p (op) && Value_Range::supports_type_p (type))
+ {
+ tree default_def = ssa_default_def (fun, arg);
+ if (!default_def || type != TREE_TYPE (default_def))
+ continue;
+ // Query the global range of the default def in the assume function.
+ Value_Range assume_range (type);
+ global_ranges.range_of_expr (assume_range, default_def);
+ // If there is a non-varying result, add it as an inferred range.
+ if (!assume_range.varying_p ())
+ {
+ add_range (op, assume_range);
+ if (dump_file)
+ {
+ print_generic_expr (dump_file, assume_id, TDF_SLIM);
+ fprintf (dump_file, " assume inferred range of ");
+ print_generic_expr (dump_file, op, TDF_SLIM);
+ fprintf (dump_file, " (param ");
+ print_generic_expr (dump_file, arg, TDF_SLIM);
+ fprintf (dump_file, ") = ");
+ assume_range.dump (dump_file);
+ fputc ('\n', dump_file);
+ }
+ }
+ }
+ }
+}
+
// Add NAME and RANGE to the range inference summary.
void
@@ -111,6 +160,11 @@ gimple_infer_range::gimple_infer_range (gimple *s)
// Fallthru and walk load/store ops now.
}
+ // Check for inferred ranges from ASSUME calls.
+ if (is_a<gcall *> (s) && gimple_call_internal_p (s)
+ && gimple_call_internal_fn (s) == IFN_ASSUME)
+ check_assume_func (as_a<gcall *> (s));
+
// Look for possible non-null values.
if (flag_delete_null_pointer_checks && gimple_code (s) != GIMPLE_ASM
&& !gimple_clobber_p (s))
@@ -40,6 +40,7 @@ public:
void add_range (tree name, vrange &range);
void add_nonzero (tree name);
private:
+ void check_assume_func (gcall *call);
unsigned num_args;
static const int size_limit = 10;
tree m_names[size_limit];
@@ -645,3 +645,193 @@ disable_ranger (struct function *fun)
delete fun->x_range_query;
fun->x_range_query = NULL;
}
+
+// ------------------------------------------------------------------------
+
+// If there is a non-varying value associated with NAME, return true and the
+// range in R.
+
+bool
+assume_query::assume_range_p (vrange &r, tree name)
+{
+ if (global.get_global_range (r, name))
+ return !r.varying_p ();
+ return false;
+}
+
+// Query used by GORI to pick up any known value on entry to a block.
+
+bool
+assume_query::range_of_expr (vrange &r, tree expr, gimple *stmt)
+{
+ if (!gimple_range_ssa_p (expr))
+ return get_tree_range (r, expr, stmt);
+
+ if (!global.get_global_range (r, expr))
+ r.set_varying (TREE_TYPE (expr));
+ return true;
+}
+
+// If the current function returns an integral value, and has a single return
+// statement, it will calculate any SSA_NAMES is can determine ranges forr
+// assuming the function returns 1.
+
+assume_query::assume_query ()
+{
+ basic_block exit_bb = EXIT_BLOCK_PTR_FOR_FN (cfun);
+ if (single_pred_p (exit_bb))
+ {
+ basic_block bb = single_pred (exit_bb);
+ gimple_stmt_iterator gsi = gsi_last_nondebug_bb (bb);
+ if (gsi_end_p (gsi))
+ return;
+ gimple *s = gsi_stmt (gsi);
+ if (!is_a<greturn *> (s))
+ return;
+ greturn *gret = as_a<greturn *> (s);
+ tree op = gimple_return_retval (gret);
+ if (!gimple_range_ssa_p (op))
+ return;
+ tree lhs_type = TREE_TYPE (op);
+ if (!irange::supports_p (lhs_type))
+ return;
+
+ unsigned prec = TYPE_PRECISION (lhs_type);
+ int_range<2> lhs_range (lhs_type, wi::one (prec), wi::one (prec));
+ global.set_global_range (op, lhs_range);
+
+ gimple *def = SSA_NAME_DEF_STMT (op);
+ if (!def || gimple_get_lhs (def) != op)
+ return;
+ fur_stmt src (gret, this);
+ calculate_stmt (def, lhs_range, src);
+ }
+}
+
+// Evaluate operand OP on statement S, using the provided LHS range.
+// If successful, set the range in the global table, then visit OP's def stmt.
+
+void
+assume_query::calculate_op (tree op, gimple *s, vrange &lhs, fur_source &src)
+{
+ Value_Range op_range (TREE_TYPE (op));
+ if (m_gori.compute_operand_range (op_range, s, lhs, op, src)
+ && !op_range.varying_p ())
+ {
+ Value_Range range (TREE_TYPE (op));
+ if (global.get_global_range (range, op))
+ op_range.intersect (range);
+ global.set_global_range (op, op_range);
+ gimple *def_stmt = SSA_NAME_DEF_STMT (op);
+ if (def_stmt && gimple_get_lhs (def_stmt) == op)
+ calculate_stmt (def_stmt, op_range, src);
+ }
+}
+
+// Evaluate PHI statement, using the provided LHS range.
+// Check each constant argument predecessor if it can be taken
+// provide LHS to any symbolic argmeuents, and process their def statements.
+
+void
+assume_query::calculate_phi (gphi *phi, vrange &lhs_range, fur_source &src)
+{
+ for (unsigned x= 0; x < gimple_phi_num_args (phi); x++)
+ {
+ tree arg = gimple_phi_arg_def (phi, x);
+ Value_Range arg_range (TREE_TYPE (arg));
+ if (gimple_range_ssa_p (arg))
+ {
+ // A symbol arg will be the LHS value.
+ arg_range = lhs_range;
+ range_cast (arg_range, TREE_TYPE (arg));
+ if (!global.get_global_range (arg_range, arg))
+ {
+ global.set_global_range (arg, arg_range);
+ gimple *def_stmt = SSA_NAME_DEF_STMT (arg);
+ if (def_stmt && gimple_get_lhs (def_stmt) == arg)
+ calculate_stmt (def_stmt, arg_range, src);
+ }
+ }
+ else if (get_tree_range (arg_range, arg, NULL))
+ {
+ // If this is a constant value that differs from LHS, this
+ // edge cannot be taken.
+ arg_range.intersect (lhs_range);
+ if (arg_range.undefined_p ())
+ continue;
+ // Otherwise check the condition feeding this edge.
+ edge e = gimple_phi_arg_edge (phi, x);
+ check_taken_edge (e, src);
+ }
+ }
+}
+
+// If an edge is known to be taken, examine the outgoing edge to see
+// if it carries any range information that can also be evaluated.
+
+void
+assume_query::check_taken_edge (edge e, fur_source &src)
+{
+ gimple *stmt = gimple_outgoing_range_stmt_p (e->src);
+ if (stmt && is_a<gcond *> (stmt))
+ {
+ int_range<2> cond;
+ gcond_edge_range (cond, e);
+ calculate_stmt (stmt, cond, src);
+ }
+}
+
+// Evaluate statement S which produces range LHS_RANGE.
+
+void
+assume_query::calculate_stmt (gimple *s, vrange &lhs_range, fur_source &src)
+{
+ gimple_range_op_handler handler (s);
+ if (handler)
+ {
+ tree op = gimple_range_ssa_p (handler.operand1 ());
+ if (op)
+ calculate_op (op, s, lhs_range, src);
+ op = gimple_range_ssa_p (handler.operand2 ());
+ if (op)
+ calculate_op (op, s, lhs_range, src);
+ }
+ else if (is_a<gphi *> (s))
+ {
+ calculate_phi (as_a<gphi *> (s), lhs_range, src);
+ // Don't further check predecessors of blocks with PHIs.
+ return;
+ }
+
+ // Even if the walk back terminates before the top, if this is a single
+ // predecessor block, see if the predecessor provided any ranges to get here.
+ if (single_pred_p (gimple_bb (s)))
+ check_taken_edge (single_pred_edge (gimple_bb (s)), src);
+}
+
+// Show everything that was calculated.
+
+void
+assume_query::dump (FILE *f)
+{
+ fprintf (f, "Assumption details calculated:\n");
+ for (unsigned i = 0; i < num_ssa_names; i++)
+ {
+ tree name = ssa_name (i);
+ if (!name || !gimple_range_ssa_p (name))
+ continue;
+ tree type = TREE_TYPE (name);
+ if (!Value_Range::supports_type_p (type))
+ continue;
+
+ Value_Range assume_range (type);
+ if (assume_range_p (assume_range, name))
+ {
+ print_generic_expr (f, name, TDF_SLIM);
+ fprintf (f, " -> ");
+ assume_range.dump (f);
+ fputc ('\n', f);
+ }
+ }
+ fprintf (f, "------------------------------\n");
+}
@@ -80,4 +80,22 @@ extern gimple_ranger *enable_ranger (struct function *m,
bool use_imm_uses = true);
extern void disable_ranger (struct function *);
+class assume_query : public range_query
+{
+public:
+ assume_query ();
+ bool assume_range_p (vrange &r, tree name);
+ virtual bool range_of_expr (vrange &r, tree expr, gimple * = NULL);
+ void dump (FILE *f);
+protected:
+ void calculate_stmt (gimple *s, vrange &lhs_range, fur_source &src);
+ void calculate_op (tree op, gimple *s, vrange &lhs, fur_source &src);
+ void calculate_phi (gphi *phi, vrange &lhs_range, fur_source &src);
+ void check_taken_edge (edge e, fur_source &src);
+
+ ssa_global_cache global;
+ gori_compute m_gori;
+};
+
+
#endif // GCC_GIMPLE_RANGE_H
new file mode 100644
@@ -0,0 +1,42 @@
+// P1774R8 - Portable assumptions
+// { dg-do compile { target c++11 } }
+// { dg-options "-O2 -fdump-tree-vrp2" }
+// Test the we can optimize based on conditions in assume.
+
+int
+f1 (unsigned x, unsigned y, unsigned z)
+{
+ [[assume (x == 2 && y < 3 && z < 20)]];
+ unsigned q = x + y + z;
+ if (q > 23)
+ return 0;
+ return 1;
+}
+
+
+int
+f2 (int x, int y, int z)
+{
+ [[assume (x+12 == 14 && y >= 0 && y + 10 < 13 && z + 4 >= 4 && z - 2 < 18)]];
+ unsigned q = x + y + z;
+ if (q*2 > 46)
+ return 0;
+ return 1;
+}
+
+int
+f3 (int x, int y, int z)
+{
+ [[assume (x + 12 == 14 && z / 2 > 0)]];
+ [[assume (y >= 0 && z - 2 < 18)]];
+ [[assume (y + 10 < 13 && z + 4 >= 2)]];
+ int q = x + y + z;
+ if (q * 2 > 46)
+ return 0;
+ if (z < 0)
+ return 0;
+ return 1;
+}
+
+/* { dg-final { scan-tree-dump-times "return 0" 0 "vrp2" } } */
+/* { dg-final { scan-tree-dump-times "return 1" 3 "vrp2" } } */
@@ -50,6 +50,7 @@ along with GCC; see the file COPYING3. If not see
#include "gimple-range-path.h"
#include "value-pointer-equiv.h"
#include "gimple-fold.h"
+#include "tree-dfa.h"
/* Set of SSA names found live during the RPO traversal of the function
for still active basic-blocks. */
@@ -4465,6 +4466,39 @@ public:
bool gate (function *fun) final override { return fun->assume_function; }
unsigned int execute (function *) final override
{
+ assume_query query;
+ if (dump_file)
+ fprintf (dump_file, "Assumptions :\n--------------\n");
+
+ for (tree arg = DECL_ARGUMENTS (cfun->decl); arg; arg = DECL_CHAIN (arg))
+ {
+ tree name = ssa_default_def (cfun, arg);
+ if (!name || !gimple_range_ssa_p (name))
+ continue;
+ tree type = TREE_TYPE (name);
+ if (!Value_Range::supports_type_p (type))
+ continue;
+ Value_Range assume_range (type);
+ if (query.assume_range_p (assume_range, name))
+ {
+ // Set the global range of NAME to anything calculated.
+ set_range_info (name, assume_range);
+ if (dump_file)
+ {
+ print_generic_expr (dump_file, name, TDF_SLIM);
+ fprintf (dump_file, " -> ");
+ assume_range.dump (dump_file);
+ fputc ('\n', dump_file);
+ }
+ }
+ }
+ if (dump_file)
+ {
+ fputc ('\n', dump_file);
+ gimple_dump_cfg (dump_file, dump_flags & ~TDF_DETAILS);
+ if (dump_flags & TDF_DETAILS)
+ query.dump (dump_file);
+ }
return TODO_discard_function;
}
--
2.37.3