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201e2935ed
selfpatch-slr/playground/spslr_pinpoint.cpp

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#include <iostream>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <map>
#include <list>
#include <gcc-plugin.h>
#include <plugin-version.h>
#include <tree.h>
#include <langhooks.h>
#include <gimple.h>
#include <gimplify.h>
#include <tree-pass.h>
#include <gimple-iterator.h>
#include <gimple-pretty-print.h>
#include <tree-pretty-print.h>
#include <tree-dump.h>
#include <print-tree.h>
#include <tree-iterator.h>
int plugin_is_GPL_compatible;
#define SPSLR_OFFSETOF "__spslr_offsetof"
// Recognize __attribute__((spslr)) on structures and track their layout
struct Member {
using OFF = unsigned long;
using SIZE = unsigned long;
static constexpr int FLAG_DANGERZONE = 1;
OFF offset = 0;
SIZE size = 0;
int flags = 0;
};
struct Target {
using UID = unsigned long;
UID uid;
std::map<Member::OFF, Member> members;
void log_member(const Member& member);
const Member* get_member(Member::OFF offset) const;
};
struct TargetTree {
tree t;
Target::UID uid;
};
static Target::UID next_target_uid = 0;
static std::unordered_map<Target::UID, Target> targets;
static std::list<TargetTree> target_trees;
static std::unordered_set<tree> target_markings;
static bool find_target_log(tree t, Target::UID& uid) {
for (const TargetTree& tt : target_trees) {
if (lang_hooks.types_compatible_p(tt.t, t)) {
uid = tt.uid;
return true;
}
}
return false;
}
void Target::log_member(const Member& member) {
Member tmp_member;
tmp_member.offset = member.offset;
tmp_member.size = (member.size == 0 ? 1 : member.size);
tmp_member.flags = (member.size == 0 ? Member::FLAG_DANGERZONE : 0) | member.flags;
// Overlaps are dangerous -> remove and integrate into member
auto overlap_end = members.lower_bound(tmp_member.offset + tmp_member.size);
for (auto it = std::make_reverse_iterator(overlap_end); it != members.rend();) {
const Member& existing_member = it->second;
if (existing_member.offset + existing_member.size <= tmp_member.offset)
break;
Member::OFF combined_end = std::max<Member::OFF>(tmp_member.offset + tmp_member.size,
existing_member.offset + existing_member.size);
Member::OFF combined_offset = std::min<Member::OFF>(tmp_member.offset, existing_member.offset);
Member::SIZE combined_size = combined_end - combined_offset;
tmp_member.flags |= (existing_member.flags | Member::FLAG_DANGERZONE);
tmp_member.offset = combined_offset;
tmp_member.size = combined_size;
// Erase overlapping member
auto tmp_forward = std::prev(it.base());
tmp_forward = members.erase(tmp_forward);
it = std::make_reverse_iterator(tmp_forward);
}
members.emplace(tmp_member.offset, tmp_member);
}
const Member* Target::get_member(Member::OFF offset) const {
auto it = members.find(offset);
if (it == members.end())
return nullptr;
return &it->second;
}
static void log_target(tree node) {
node = TYPE_MAIN_VARIANT(node);
if (!node)
return;
if (TREE_CODE(node) != RECORD_TYPE)
return;
auto marking = target_markings.find(node);
if (marking == target_markings.end())
return;
Target::UID existing_target;
if (find_target_log(node, existing_target))
return;
Target::UID tuid = next_target_uid++;
TargetTree new_tt;
new_tt.t = node;
new_tt.uid = tuid;
target_trees.push_back(new_tt);
targets.emplace(tuid, Target{});
Target& target = targets.at(tuid);
target.uid = tuid;
// Log all members
for (tree field = TYPE_FIELDS(node); field; field = DECL_CHAIN(field)) {
if (TREE_CODE(field) != FIELD_DECL)
continue;
HOST_WIDE_INT field_byte_offset = 0;
if (TREE_CODE(DECL_FIELD_OFFSET(field)) == INTEGER_CST)
field_byte_offset = tree_to_uhwi(DECL_FIELD_OFFSET(field));
HOST_WIDE_INT field_bit_offset = 0;
if (TREE_CODE(DECL_FIELD_BIT_OFFSET(field)) == INTEGER_CST)
field_bit_offset = tree_to_uhwi(DECL_FIELD_BIT_OFFSET(field));
HOST_WIDE_INT field_bit_offset_bytes = field_bit_offset / 8;
field_byte_offset += field_bit_offset_bytes;
field_bit_offset -= field_bit_offset_bytes * 8;
HOST_WIDE_INT field_bit_size = 0;
if (TREE_CODE(DECL_SIZE(field)) == INTEGER_CST)
field_bit_size = tree_to_uhwi(DECL_SIZE(field));
bool is_bitfield = (DECL_BIT_FIELD_TYPE(field) != NULL_TREE);
bool is_multibyte = (field_bit_size % 8 == 0 && field_bit_offset == 0);
bool is_dangerous = (is_bitfield || !is_multibyte);
HOST_WIDE_INT field_offset_bit_size = field_bit_offset + field_bit_size;
HOST_WIDE_INT effective_field_size = field_offset_bit_size / 8;
if (field_offset_bit_size % 8 != 0)
effective_field_size += 1;
Member member;
member.offset = (Member::OFF)field_byte_offset;
member.size = (Member::SIZE)effective_field_size;
member.flags = (is_dangerous ? Member::FLAG_DANGERZONE : 0);
target.log_member(member);
}
}
static tree log_target_attribute(tree* node, tree name, tree args, int flags, bool* no_add_attrs) {
if (!node)
return NULL_TREE;
if (TREE_CODE(*node) != RECORD_TYPE)
return NULL_TREE;
tree type_main_variant = TYPE_MAIN_VARIANT(*node);
if (!type_main_variant)
return NULL_TREE;
target_markings.insert(type_main_variant);
return NULL_TREE;
}
static struct attribute_spec spslr_attribute = {
"spslr", 0, 0, false, false, false, false, log_target_attribute, NULL
};
void on_register_attributes(void* event_data, void* data) {
register_attribute(&spslr_attribute);
}
static void on_type_complete(void* event_data, void* user_data) {
tree type = (tree)event_data;
log_target(type);
}
// Early hook to make COMPONENT_REF nodes survice front end
struct SPSLROffsetofCallData {
using UID = unsigned long;
UID uid;
Target::UID target;
Member::OFF member;
};
static tree spslr_offsetof_decl = NULL_TREE;
static SPSLROffsetofCallData::UID spslr_offsetof_next_uid = 0;
static std::unordered_map<SPSLROffsetofCallData::UID, SPSLROffsetofCallData> spslr_offsetof_calls;
static bool require_spslr_offsetof_decl() {
if (spslr_offsetof_decl)
return true;
tree param_types = tree_cons(NULL_TREE, long_unsigned_type_node, NULL_TREE);
tree fntype = build_function_type(sizetype, param_types);
spslr_offsetof_decl = build_fn_decl(SPSLR_OFFSETOF, fntype);
if (!spslr_offsetof_decl)
return false;
DECL_EXTERNAL (spslr_offsetof_decl) = 1;
TREE_PUBLIC (spslr_offsetof_decl) = 1;
DECL_ARTIFICIAL (spslr_offsetof_decl) = 1;
// Prevent VOP problems later when removing calls
// Explanation -> VOPs mark memory side-effects, which these calls have none of anyways
DECL_PURE_P(spslr_offsetof_decl) = 1;
DECL_IS_NOVOPS(spslr_offsetof_decl) = 1;
return true;
}
static bool is_relevant_offsetof(tree ref, Target::UID& tuid, Member::OFF& moff) {
if (!ref || TREE_CODE(ref) != COMPONENT_REF)
return false;
tree base = TREE_OPERAND(ref, 0);
if (!base)
return false;
tree base_type = TREE_TYPE(base);
if (!base_type)
return false;
if (!find_target_log(base_type, tuid))
return false;
auto target_it = targets.find(tuid);
if (target_it == targets.end())
return false;
const Target& t = target_it->second;
tree field = TREE_OPERAND(ref, 1);
HOST_WIDE_INT field_byte_offset = 0;
if (TREE_CODE(DECL_FIELD_OFFSET(field)) == INTEGER_CST)
field_byte_offset = tree_to_uhwi(DECL_FIELD_OFFSET(field));
HOST_WIDE_INT field_bit_offset = 0;
if (TREE_CODE(DECL_FIELD_BIT_OFFSET(field)) == INTEGER_CST)
field_bit_offset = tree_to_uhwi(DECL_FIELD_BIT_OFFSET(field));
Member::OFF effective_field_offset = (field_byte_offset + (field_bit_offset / 8));
moff = effective_field_offset;
const Member* m = t.get_member(effective_field_offset);
if (!m)
return false;
return !(m->flags & Member::FLAG_DANGERZONE);
}
static tree instrument_offsetof_maybe(tree ref) {
SPSLROffsetofCallData call_data;
if (!is_relevant_offsetof(ref, call_data.target, call_data.member))
return NULL_TREE;
location_t loc = EXPR_LOCATION(ref);
tree result_type = TREE_TYPE(ref);
if (!require_spslr_offsetof_decl()) {
std::cerr << "spslr_pinpoint -> failed to instrument COMPONENT_REF (" << SPSLR_OFFSETOF << " unavailable)" << std::endl;
return NULL_TREE;
}
call_data.uid = spslr_offsetof_next_uid++;
spslr_offsetof_calls.emplace(call_data.uid, call_data);
tree call_uid_tree = build_int_cst(long_unsigned_type_node, call_data.uid);
tree call_tree = build_call_expr_loc(loc, spslr_offsetof_decl, 1, call_uid_tree);
// Get base as char*
tree base = TREE_OPERAND(ref, 0);
tree base_addr;
if (TREE_CODE(base) == ADDR_EXPR) {
// base_addr = base;
std::cerr << "spslr_pinpoint -> unexpected ADDR_EXPR as COMPONENT_REF base!" << std::endl;
return NULL_TREE;
} else {
base_addr = build_fold_addr_expr(base);
}
tree char_ptr_type = build_pointer_type(char_type_node);
tree base_char_ptr = fold_convert(char_ptr_type, base_addr);
// Add __spslr_offsetof, cast back to field pointer, then dereference
tree plus = build2_loc(loc, POINTER_PLUS_EXPR, char_ptr_type, base_char_ptr, call_tree);
tree field_ptr_type = build_pointer_type(result_type);
tree cast_back = build1_loc(loc, NOP_EXPR, field_ptr_type, plus);
tree new_ref = build1_loc(loc, INDIRECT_REF, result_type, cast_back);
return new_ref;
}
static void on_build_component_ref(void* event_data, void* user_data) {
tree* component_ref_node = (tree*)event_data;
if (!component_ref_node)
return;
tree repl = instrument_offsetof_maybe(*component_ref_node);
if (repl)
*component_ref_node = repl;
}
// Identify any missing COMPONENT_REFs (e.g. from CONSTRUCTOR trees)
static const pass_data log_component_refs_pass_data = {
GIMPLE_PASS,
"log_component_refs",
OPTGROUP_NONE,
TV_NONE,
0,0,0,0,
TODO_update_ssa
};
struct log_component_refs_pass : gimple_opt_pass {
log_component_refs_pass(gcc::context *ctxt);
unsigned int execute(function* fun) override;
};
log_component_refs_pass::log_component_refs_pass(gcc::context *ctxt) : gimple_opt_pass(log_component_refs_pass_data, ctxt) {}
struct GCRChain {
struct Link {
tree t = NULL_TREE;
bool relevant = false;
SPSLROffsetofCallData call_data;
};
bool relevant = false;
std::list<Link> links;
tree base = NULL_TREE;
};
static tree walk_tree_contains_component_ref(tree* tp, int* walk_subtrees, void* data) {
int* found_flag = (int*)data;
if (!tp || !*tp)
return NULL_TREE;
if (TREE_CODE(*tp) == COMPONENT_REF)
*found_flag = 1;
return NULL_TREE;
}
static bool contains_component_ref(tree ref) {
int found_flag = 0;
walk_tree(&ref, walk_tree_contains_component_ref, &found_flag, NULL);
return found_flag != 0;
}
static bool gimple_component_ref_chain(tree ref, GCRChain& chain) {
if (!ref)
return false;
if (TREE_CODE(ref) != COMPONENT_REF) {
if (chain.links.empty())
return false;
if (contains_component_ref(ref))
return false;
chain.base = ref;
return true;
}
GCRChain::Link link;
link.t = ref;
link.relevant = is_relevant_offsetof(ref, link.call_data.target, link.call_data.member);
if (link.relevant) {
link.call_data.uid = spslr_offsetof_next_uid++;
chain.relevant = true;
}
chain.links.push_front(link);
return gimple_component_ref_chain(TREE_OPERAND(ref, 0), chain);
}
static HOST_WIDE_INT get_field_offset_bits(tree field)
{
gcc_assert(TREE_CODE(field) == FIELD_DECL);
// Get the offset expression (may not be a constant early in compilation)
tree offset_tree = DECL_FIELD_OFFSET(field);
HOST_WIDE_INT bitpos_within_unit = tree_to_uhwi(DECL_FIELD_BIT_OFFSET(field));
// Convert the byte offset to bits
HOST_WIDE_INT bit_offset = bitpos_within_unit;
if (offset_tree && TREE_CODE(offset_tree) == INTEGER_CST)
bit_offset += tree_to_shwi(offset_tree) * BITS_PER_UNIT;
return bit_offset;
}
static bool get_field_offset(tree field, Member::OFF& off) {
if (!field || TREE_CODE(field) != FIELD_DECL)
return false;
if (DECL_BIT_FIELD(field))
return false;
tree byte_offset_tree = DECL_FIELD_OFFSET(field);
tree bit_offset_tree = DECL_FIELD_BIT_OFFSET(field);
if (!byte_offset_tree || !bit_offset_tree)
return false;
if (TREE_CODE(byte_offset_tree) != INTEGER_CST || TREE_CODE(bit_offset_tree) != INTEGER_CST)
return false;
HOST_WIDE_INT byte_offset = tree_to_uhwi(byte_offset_tree);
HOST_WIDE_INT bit_offset = tree_to_uhwi(bit_offset_tree);
if (bit_offset % 8 != 0)
return false;
off = (Member::OFF)byte_offset + (Member::OFF)bit_offset / 8;
return true;
}
static tree gimple_instrument_offsetof_maybe(tree ref, gimple_stmt_iterator* gsi) {
GCRChain gcrc;
if (!gimple_component_ref_chain(ref, gcrc)) {
std::cerr << "spslr_pinpoint -> failed to parse COMPONENT_REF chain" << std::endl;
return NULL_TREE;
}
if (!gcrc.relevant)
return NULL_TREE;
// Store base pointer in a temporary variable (as char*)
tree char_ptr_type = build_pointer_type(char_type_node);
tree base_tmp = NULL_TREE;
{
tree base_ptr;
if (TREE_CODE(gcrc.base) == ADDR_EXPR) {
std::cerr << "spslr_pinpoint -> unexpected ADDR_EXPR as COMPONENT_REF base!" << std::endl;
return NULL_TREE;
} else {
base_ptr = build_fold_addr_expr(gcrc.base);
}
tree base_char_ptr = fold_convert(char_ptr_type, base_ptr);
base_tmp = create_tmp_var(char_ptr_type, NULL);
gimple* base_tmp_assignment = gimple_build_assign(base_tmp, base_char_ptr);
gsi_insert_before(gsi, base_tmp_assignment, GSI_SAME_STMT);
}
// For each component ref in chain, add the member offset to the pointer
for (const GCRChain::Link& cr : gcrc.links) {
// NOTE -> Could fold into single call here (needs to track what offsets contribute, +irrelevant combined)
if (cr.relevant) {
// Add offsetof call
if (!require_spslr_offsetof_decl()) {
std::cerr << "spslr_pinpoint -> failed to instrument COMPONENT_REF ("
<< SPSLR_OFFSETOF << " unavailable)" << std::endl;
return NULL_TREE;
}
spslr_offsetof_calls.emplace(cr.call_data.uid, cr.call_data);
// Call to __spslr_offsetof is a separate statement
tree call_uid_arg = build_int_cst(long_unsigned_type_node, cr.call_data.uid);
gimple* call_stmt = gimple_build_call(spslr_offsetof_decl, 1, call_uid_arg);
tree offset_tmp = create_tmp_var(size_type_node, NULL);
gimple_call_set_lhs(call_stmt, offset_tmp);
gsi_insert_before(gsi, call_stmt, GSI_SAME_STMT);
// Add call return value to current base pointer
tree addition = build2(POINTER_PLUS_EXPR, char_ptr_type, base_tmp, offset_tmp);
base_tmp = create_tmp_var(char_ptr_type, NULL);
gimple* addition_assignment = gimple_build_assign(base_tmp, addition);
gsi_insert_before(gsi, addition_assignment, GSI_SAME_STMT);
} else {
// Add offsetof contant
tree field = TREE_OPERAND(cr.t, 1);
Member::OFF offset = 0;
if (!get_field_offset(field, offset)) {
std::cerr << "spslr_pinpoint -> failed to get offset of an irrelevant member "
<< "in a relevant COMPONENT_REF chain" << std::endl;
return NULL_TREE;
}
// Add constant offset to current base pointer
tree addition = build2(POINTER_PLUS_EXPR, char_ptr_type, base_tmp, build_int_cst(sizetype, offset));
base_tmp = create_tmp_var(char_ptr_type, NULL);
gimple* addition_assignment = gimple_build_assign(base_tmp, addition);
gsi_insert_before(gsi, addition_assignment, GSI_SAME_STMT);
}
}
// Cast char pointer back to field pointer and dereference
tree field_ptr_type = build_pointer_type(TREE_TYPE(ref));
tree field_ptr = fold_convert(field_ptr_type, base_tmp);
tree field_ptr_tmp = create_tmp_var(field_ptr_type, NULL);
gimple* field_ptr_tmp_assignment = gimple_build_assign(field_ptr_tmp, field_ptr);
gsi_insert_before(gsi, field_ptr_tmp_assignment, GSI_SAME_STMT);
tree offset0 = fold_convert(field_ptr_type, build_int_cst(sizetype, 0));
tree result_ref = build2(MEM_REF, TREE_TYPE(ref), field_ptr_tmp, offset0);
return result_ref;
}
static void instrument_tree(const std::list<tree*>& path, gimple_stmt_iterator* gsi, unsigned& cancel_levels) {
if (path.empty() || !gsi)
return;
tree ref = *path.back();
if (!ref || TREE_CODE(ref) != COMPONENT_REF)
return;
cancel_levels = 1;
tree instrumented_ref = gimple_instrument_offsetof_maybe(ref, gsi);
if (!instrumented_ref)
return;
gimple_set_modified(gsi_stmt(*gsi), true);
*path.back() = instrumented_ref;
// At this point, instrumented_ref is a MEM_REF node (off=0). A wrapping ADDR_EXPR cancels it out.
if (path.size() < 2)
return;
tree* parent = *(++path.rbegin());
if (TREE_CODE(*parent) == ADDR_EXPR) {
// Note -> the base of the MEM_REF is expected to have the same type as the ADDR_EXPR
*parent = TREE_OPERAND(instrumented_ref, 0);
cancel_levels++;
}
}
struct TreeWalkData {
std::list<tree*> path;
gimple_stmt_iterator* gsi;
unsigned cancel_levels;
};
static tree walk_tree_level(tree* tp, int* walk_subtrees, void* data) {
TreeWalkData* twd = (TreeWalkData*)data;
if (!twd)
return NULL_TREE;
if (!twd->path.empty() && twd->path.back() == tp)
return NULL_TREE; // root of this level
if (walk_subtrees)
*walk_subtrees = 0;
twd->cancel_levels = 0;
twd->path.push_back(tp);
instrument_tree(twd->path, twd->gsi, twd->cancel_levels);
if (twd->cancel_levels == 0)
walk_tree(tp, walk_tree_level, data, NULL);
twd->path.pop_back();
if (twd->cancel_levels > 0)
twd->cancel_levels--;
// Cancel current level if there are still cancel_levels due
return twd->cancel_levels == 0 ? NULL_TREE : *tp;
}
static bool walk_gimple_stmt(gimple_stmt_iterator* gsi) {
if (!gsi || gsi_end_p(*gsi))
return false;
gimple* stmt = gsi_stmt(*gsi);
for (int i = 0; i < gimple_num_ops(stmt); i++) {
tree* op = gimple_op_ptr(stmt, i);
if (!op || !*op)
continue;
TreeWalkData twd;
twd.gsi = gsi;
walk_tree_level(op, NULL, &twd);
}
return true;
}
unsigned int log_component_refs_pass::execute(function* fun) {
const char* funcname = fun->decl && DECL_NAME(fun->decl)
? IDENTIFIER_POINTER(DECL_NAME(fun->decl))
: "<anonymous>";
tree fndecl = fun->decl;
if (!fndecl)
return 0;
gimple_seq body = gimple_body(fndecl);
for (gimple_stmt_iterator gsi = gsi_start(body); walk_gimple_stmt(&gsi); gsi_next(&gsi));
// print_gimple_seq(stderr, gimple_body(fun->decl), 0, TDF_NONE);
return 0;
}
// Gimple print pass for debugging
static const pass_data print_pass_data = {
GIMPLE_PASS,
"gimple_print",
OPTGROUP_NONE,
TV_NONE,
0,0,0,0, 0
};
struct print_pass : gimple_opt_pass {
print_pass(gcc::context *ctxt);
unsigned int execute(function* fun) override;
};
print_pass::print_pass(gcc::context *ctxt) : gimple_opt_pass(print_pass_data, ctxt) {}
unsigned int print_pass::execute(function* fun) {
const char* funcname = fun->decl && DECL_NAME(fun->decl)
? IDENTIFIER_POINTER(DECL_NAME(fun->decl))
: "<anonymous>";
fprintf(stderr, "[spslr_pinpoint] Function: %s\n", funcname);
basic_block bb;
FOR_EACH_BB_FN(bb, fun) {
for (gimple_stmt_iterator gsi = gsi_start_bb(bb); !gsi_end_p(gsi); gsi_next(&gsi)) {
gimple* stmt = gsi_stmt(gsi);
print_gimple_stmt(stderr, stmt, 0, TDF_SLIM);
}
}
fprintf(stderr, "\n");
return 0;
}
// Hook everything up in plugin_init
int plugin_init (struct plugin_name_args *plugin_info, struct plugin_gcc_version *version) {
if (!plugin_default_version_check(version, &gcc_version)) {
fprintf(stderr, "GCC version mismatch!\n");
std::cerr << "spslr_pinpoint -> GCC version mismatch" << std::endl;
return 1;
}
register_callback(plugin_info->base_name, PLUGIN_ATTRIBUTES, on_register_attributes, NULL);
register_callback(plugin_info->base_name, PLUGIN_FINISH_TYPE, on_type_complete, NULL);
// TODO register_callback(plugin_info->base_name, PLUGIN_BUILD_COMPONENT_REF, on_build_component_ref, NULL);
struct register_pass_info log_component_refs_pass_info;
log_component_refs_pass_info.pass = new log_component_refs_pass(nullptr);
log_component_refs_pass_info.ref_pass_instance_number = 1;
log_component_refs_pass_info.reference_pass_name = "cfg";
log_component_refs_pass_info.pos_op = PASS_POS_INSERT_BEFORE;
register_callback(plugin_info->base_name, PLUGIN_PASS_MANAGER_SETUP, nullptr, &log_component_refs_pass_info);
struct register_pass_info print_pass_info;
print_pass_info.pass = new print_pass(nullptr);
print_pass_info.ref_pass_instance_number = 1;
print_pass_info.reference_pass_name = "cfg";
print_pass_info.pos_op = PASS_POS_INSERT_AFTER;
register_callback(plugin_info->base_name, PLUGIN_PASS_MANAGER_SETUP, nullptr, &print_pass_info);
return 0;
}
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