Support ofsetted parameters in local modref
Jan Hubicka
hubicka@ucw.cz
Tue Oct 13 09:18:52 GMT 2020
Hi,
this patch makes local modref to track parameters that are passed through with
and adjustment (via pointer_plus or addr_expr of mem_ref). I intended to re-use
logic in ipa-prop, but it turns out that it is weird:
if (TREE_CODE (op1) != ADDR_EXPR)
return;
op1 = TREE_OPERAND (op1, 0);
if (TREE_CODE (TREE_TYPE (op1)) != RECORD_TYPE)
return;
base = get_ref_base_and_extent_hwi (op1, &offset, &size, &reverse);
offset_int mem_offset;
if (!base
|| TREE_CODE (base) != MEM_REF
|| !mem_ref_offset (base).is_constant (&mem_offset))
return;
offset += mem_offset.to_short_addr () * BITS_PER_UNIT;
ssa = TREE_OPERAND (base, 0);
if (TREE_CODE (ssa) != SSA_NAME
|| !SSA_NAME_IS_DEFAULT_DEF (ssa)
|| offset < 0)
return;
/* Dynamic types are changed in constructors and destructors. */
index = ipa_get_param_decl_index (info, SSA_NAME_VAR (ssa));
if (index >= 0 && param_type && POINTER_TYPE_P (param_type))
ipa_set_ancestor_jf (jfunc, offset, index,
parm_ref_data_pass_through_p (fbi, index, call, ssa));
First it does not handle POINTER_PLUS that is quite common i.e. for
test (int *a)
{
test2 (a+1);
}
and also it restrict to access paths that starts by RECORD_TYPE. This seems
not to make sense since all ADDR_EXPRs of refs are just pointer adjustements.
I think it is leftover from time when ancestor was meant to track C++ type
hiearchy.
Next it also does refuse negative offset for not very apparent reason (this
happens in multiple inheritance in C++).
On tramp3d it is also common that the parameter ADDR_EXPR happens in
separate statement rather than call itself (i.e. no forward propagation
is done)
Finally it works on bits witout overflow check and uses HOST_WIDE_INT
instead of poly_int64 that I think would be right datatype to accumulate
offsets these days.
So I implemented my own pattern matching and I think we should switch ipa-prop
on it incrementally. It is based on similar logic in
ao_ref_init_from_ptr_and_size. I support chained statements since they happen
in tramp3d after early opts.
Bootstrapped/regtested x86_64-linux. Also ltobootstrapped and I am waiting
for cc1plus stats to finish. OK?
gcc/ChangeLog:
2020-10-13 Jan Hubicka <hubicka@ucw.cz>
* ipa-modref.c (merge_call_side_effects): Use
unadjusted_ptr_and_unit_offset.
* ipa-prop.c (unadjusted_ptr_and_unit_offset): Declare.
* ipa-prop.h (unadjusted_ptr_and_unit_offset): New function.
diff --git a/gcc/ipa-modref.c b/gcc/ipa-modref.c
index 4f86b9ccea1..92119eb6fe3 100644
--- a/gcc/ipa-modref.c
+++ b/gcc/ipa-modref.c
@@ -531,6 +532,10 @@ merge_call_side_effects (modref_summary *cur_summary,
for (unsigned i = 0; i < gimple_call_num_args (stmt); i++)
{
tree op = gimple_call_arg (stmt, i);
+ bool offset_known;
+ poly_int64 offset;
+
+ offset_known = unadjusted_ptr_and_unit_offset (op, &op, &offset);
if (TREE_CODE (op) == SSA_NAME
&& SSA_NAME_IS_DEFAULT_DEF (op)
&& TREE_CODE (SSA_NAME_VAR (op)) == PARM_DECL)
@@ -547,15 +552,23 @@ merge_call_side_effects (modref_summary *cur_summary,
index++;
}
parm_map[i].parm_index = index;
- parm_map[i].parm_offset_known = true;
- parm_map[i].parm_offset = 0;
+ parm_map[i].parm_offset_known = offset_known;
+ parm_map[i].parm_offset = offset;
}
else if (points_to_local_or_readonly_memory_p (op))
parm_map[i].parm_index = -2;
else
parm_map[i].parm_index = -1;
if (dump_file)
- fprintf (dump_file, " %i", parm_map[i].parm_index);
+ {
+ fprintf (dump_file, " %i", parm_map[i].parm_index);
+ if (parm_map[i].parm_offset_known)
+ {
+ fprintf (dump_file, " offset:");
+ print_dec ((poly_int64_pod)parm_map[i].parm_offset,
+ dump_file, SIGNED);
+ }
+ }
}
if (dump_file)
fprintf (dump_file, "\n");
diff --git a/gcc/ipa-prop.c b/gcc/ipa-prop.c
index 2d09d913051..fe317f56e02 100644
--- a/gcc/ipa-prop.c
+++ b/gcc/ipa-prop.c
@@ -1222,6 +1222,72 @@ load_from_unmodified_param_or_agg (struct ipa_func_body_info *fbi,
return index;
}
+/* Walk pointer adjustemnts from OP (such as POINTER_PLUS and ADDR_EXPR)
+ to find original pointer. Initialize RET to the pointer which results from
+ the walk.
+ If offset is known return true and initialize OFFSET_RET. */
+
+bool
+unadjusted_ptr_and_unit_offset (tree op, tree *ret, poly_int64 *offset_ret)
+{
+ poly_int64 offset = 0;
+ bool offset_known = true;
+
+ while (true)
+ {
+ if (TREE_CODE (op) == ADDR_EXPR)
+ {
+ poly_int64 extra_offset = 0;
+ tree base = get_addr_base_and_unit_offset (TREE_OPERAND (op, 0),
+ &offset);
+ if (!base)
+ {
+ base = get_base_address (TREE_OPERAND (op, 0));
+ if (TREE_CODE (base) != MEM_REF)
+ break;
+ offset_known = false;
+ }
+ else
+ {
+ if (TREE_CODE (base) != MEM_REF)
+ break;
+ offset += extra_offset;
+ }
+ op = TREE_OPERAND (base, 0);
+ if (mem_ref_offset (base).to_shwi (&extra_offset))
+ offset += extra_offset;
+ else
+ offset_known = false;
+ }
+ else if (TREE_CODE (op) == SSA_NAME
+ && !SSA_NAME_IS_DEFAULT_DEF (op))
+ {
+ gimple *pstmt = SSA_NAME_DEF_STMT (op);
+
+ if (gimple_assign_single_p (pstmt))
+ op = gimple_assign_rhs1 (pstmt);
+ else if (is_gimple_assign (pstmt)
+ && gimple_assign_rhs_code (pstmt) == POINTER_PLUS_EXPR)
+ {
+ poly_int64 extra_offset = 0;
+ if (ptrdiff_tree_p (gimple_assign_rhs2 (pstmt),
+ &extra_offset))
+ offset += extra_offset;
+ else
+ offset_known = false;
+ op = gimple_assign_rhs1 (pstmt);
+ }
+ else
+ break;
+ }
+ else
+ break;
+ }
+ *ret = op;
+ *offset_ret = offset;
+ return offset_known;
+}
+
/* Given that an actual argument is an SSA_NAME (given in NAME) and is a result
of an assignment statement STMT, try to determine whether we are actually
handling any of the following cases and construct an appropriate jump
diff --git a/gcc/ipa-prop.h b/gcc/ipa-prop.h
index 8b2edf6300c..0bbbbf9bd9f 100644
--- a/gcc/ipa-prop.h
+++ b/gcc/ipa-prop.h
@@ -1144,6 +1144,8 @@ 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 *);
+bool unadjusted_ptr_and_unit_offset (tree op, tree *ret,
+ poly_int64 *offset_ret);
/* From tree-sra.c: */
tree build_ref_for_offset (location_t, tree, poly_int64, bool, tree,
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