From 2f75d6ebf81833cac96596108c2d56d0c6cdb2a0 Mon Sep 17 00:00:00 2001 From: Martin Liska Date: Tue, 13 Dec 2016 16:35:14 +0100 Subject: [PATCH] Add sanopt for ASAN_MARK poison and unpoison. * sanopt.c (sanopt_optimize_walker): Set contains_asan_mark. (sanopt_optimize): Add new argument. (sanitize_asan_mark_unpoison): New function. (maybe_contains_asan_check): Likewise. (sanitize_asan_mark_poison): Likewise. (pass_sanopt::execute): Call the new functions. From-SVN: r243611 --- gcc/ChangeLog | 9 +++ gcc/sanopt.c | 206 +++++++++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 211 insertions(+), 4 deletions(-) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index aa816d95d24..d3c9a9fd2b9 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,12 @@ +2016-12-13 Martin Liska + + * sanopt.c (sanopt_optimize_walker): Set contains_asan_mark. + (sanopt_optimize): Add new argument. + (sanitize_asan_mark_unpoison): New function. + (maybe_contains_asan_check): Likewise. + (sanitize_asan_mark_poison): Likewise. + (pass_sanopt::execute): Call the new functions. + 2016-12-13 Martin Liska PR tree-optimization/78428 diff --git a/gcc/sanopt.c b/gcc/sanopt.c index 320e14e9421..7fe8d32e39a 100644 --- a/gcc/sanopt.c +++ b/gcc/sanopt.c @@ -24,6 +24,7 @@ along with GCC; see the file COPYING3. If not see #include "backend.h" #include "tree.h" #include "gimple.h" +#include "ssa.h" #include "tree-pass.h" #include "tree-ssa-operands.h" #include "gimple-pretty-print.h" @@ -37,7 +38,6 @@ along with GCC; see the file COPYING3. If not see #include "tree-phinodes.h" #include "ssa-iterators.h" - /* This is used to carry information about basic blocks. It is attached to the AUX field of the standard CFG block. */ @@ -160,8 +160,10 @@ struct sanopt_ctx /* Number of IFN_ASAN_CHECK statements. */ int asan_num_accesses; -}; + /* True when the current functions constains an ASAN_MARK. */ + bool contains_asan_mark; +}; /* Return true if there might be any call to free/munmap operation on any path in between DOM (which should be imm(BB)) and BB. */ @@ -582,6 +584,9 @@ sanopt_optimize_walker (basic_block bb, struct sanopt_ctx *ctx) if (!remove) ctx->asan_num_accesses++; break; + case IFN_ASAN_MARK: + ctx->contains_asan_mark = true; + break; default: break; } @@ -620,10 +625,11 @@ sanopt_optimize_walker (basic_block bb, struct sanopt_ctx *ctx) /* Try to remove redundant sanitizer checks in function FUN. */ static int -sanopt_optimize (function *fun) +sanopt_optimize (function *fun, bool *contains_asan_mark) { struct sanopt_ctx ctx; ctx.asan_num_accesses = 0; + ctx.contains_asan_mark = false; /* Set up block info for each basic block. */ alloc_aux_for_blocks (sizeof (sanopt_info)); @@ -638,6 +644,7 @@ sanopt_optimize (function *fun) free_aux_for_blocks (); + *contains_asan_mark = ctx.contains_asan_mark; return ctx.asan_num_accesses; } @@ -671,18 +678,201 @@ public: }; // class pass_sanopt +/* Sanitize all ASAN_MARK unpoison calls that are not reachable by a BB + that contains an ASAN_MARK poison. All these ASAN_MARK unpoison call + can be removed as all variables are unpoisoned in a function prologue. */ + +static void +sanitize_asan_mark_unpoison (void) +{ + /* 1) Find all BBs that contain an ASAN_MARK poison call. */ + auto_sbitmap with_poison (last_basic_block_for_fn (cfun) + 1); + bitmap_clear (with_poison); + basic_block bb; + + FOR_EACH_BB_FN (bb, cfun) + { + if (bitmap_bit_p (with_poison, bb->index)) + continue; + + gimple_stmt_iterator gsi; + for (gsi = gsi_last_bb (bb); !gsi_end_p (gsi); gsi_prev (&gsi)) + { + gimple *stmt = gsi_stmt (gsi); + if (asan_mark_p (stmt, ASAN_MARK_POISON)) + { + bitmap_set_bit (with_poison, bb->index); + break; + } + } + } + + auto_sbitmap poisoned (last_basic_block_for_fn (cfun) + 1); + bitmap_clear (poisoned); + auto_sbitmap worklist (last_basic_block_for_fn (cfun) + 1); + bitmap_copy (worklist, with_poison); + + /* 2) Propagate the information to all reachable blocks. */ + while (!bitmap_empty_p (worklist)) + { + unsigned i = bitmap_first_set_bit (worklist); + bitmap_clear_bit (worklist, i); + basic_block bb = BASIC_BLOCK_FOR_FN (cfun, i); + gcc_assert (bb); + + edge e; + edge_iterator ei; + FOR_EACH_EDGE (e, ei, bb->succs) + if (!bitmap_bit_p (poisoned, e->dest->index)) + { + bitmap_set_bit (poisoned, e->dest->index); + bitmap_set_bit (worklist, e->dest->index); + } + } + + /* 3) Iterate all BBs not included in POISONED BBs and remove unpoison + ASAN_MARK preceding an ASAN_MARK poison (which can still happen). */ + FOR_EACH_BB_FN (bb, cfun) + { + if (bitmap_bit_p (poisoned, bb->index)) + continue; + + gimple_stmt_iterator gsi; + for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi);) + { + bool next = true; + gimple *stmt = gsi_stmt (gsi); + if (gimple_call_internal_p (stmt, IFN_ASAN_MARK)) + { + if (asan_mark_p (stmt, ASAN_MARK_POISON)) + break; + else + { + if (dump_file) + fprintf (dump_file, "Removing ASAN_MARK unpoison\n"); + unlink_stmt_vdef (stmt); + release_defs (stmt); + gsi_remove (&gsi, true); + next = false; + } + } + + if (next) + gsi_next (&gsi); + } + } +} + +/* Return true when STMT is either ASAN_CHECK call or a call of a function + that can contain an ASAN_CHECK. */ + +static bool +maybe_contains_asan_check (gimple *stmt) +{ + if (is_gimple_call (stmt)) + { + if (gimple_call_internal_p (stmt, IFN_ASAN_MARK)) + return false; + else + return !(gimple_call_flags (stmt) & ECF_CONST); + } + else if (is_a (stmt)) + return true; + + return false; +} + +/* Sanitize all ASAN_MARK poison calls that are not followed by an ASAN_CHECK + call. These calls can be removed. */ + +static void +sanitize_asan_mark_poison (void) +{ + /* 1) Find all BBs that possibly contain an ASAN_CHECK. */ + auto_sbitmap with_check (last_basic_block_for_fn (cfun) + 1); + bitmap_clear (with_check); + basic_block bb; + + FOR_EACH_BB_FN (bb, cfun) + { + gimple_stmt_iterator gsi; + for (gsi = gsi_last_bb (bb); !gsi_end_p (gsi); gsi_prev (&gsi)) + { + gimple *stmt = gsi_stmt (gsi); + if (maybe_contains_asan_check (stmt)) + { + bitmap_set_bit (with_check, bb->index); + break; + } + } + } + + auto_sbitmap can_reach_check (last_basic_block_for_fn (cfun) + 1); + bitmap_clear (can_reach_check); + auto_sbitmap worklist (last_basic_block_for_fn (cfun) + 1); + bitmap_copy (worklist, with_check); + + /* 2) Propagate the information to all definitions blocks. */ + while (!bitmap_empty_p (worklist)) + { + unsigned i = bitmap_first_set_bit (worklist); + bitmap_clear_bit (worklist, i); + basic_block bb = BASIC_BLOCK_FOR_FN (cfun, i); + gcc_assert (bb); + + edge e; + edge_iterator ei; + FOR_EACH_EDGE (e, ei, bb->preds) + if (!bitmap_bit_p (can_reach_check, e->src->index)) + { + bitmap_set_bit (can_reach_check, e->src->index); + bitmap_set_bit (worklist, e->src->index); + } + } + + /* 3) Iterate all BBs not included in CAN_REACH_CHECK BBs and remove poison + ASAN_MARK not followed by a call to function having an ASAN_CHECK. */ + FOR_EACH_BB_FN (bb, cfun) + { + if (bitmap_bit_p (can_reach_check, bb->index)) + continue; + + gimple_stmt_iterator gsi; + for (gsi = gsi_last_bb (bb); !gsi_end_p (gsi);) + { + bool prev = true; + gimple *stmt = gsi_stmt (gsi); + if (maybe_contains_asan_check (stmt)) + break; + else if (asan_mark_p (stmt, ASAN_MARK_POISON)) + { + if (dump_file) + fprintf (dump_file, "Removing ASAN_MARK poison\n"); + unlink_stmt_vdef (stmt); + release_defs (stmt); + gsi_remove (&gsi, true); + prev = false; + } + + if (prev) + gsi_prev (&gsi); + } + } +} + unsigned int pass_sanopt::execute (function *fun) { basic_block bb; int asan_num_accesses = 0; + bool contains_asan_mark = false; /* Try to remove redundant checks. */ if (optimize && (flag_sanitize & (SANITIZE_NULL | SANITIZE_ALIGNMENT | SANITIZE_ADDRESS | SANITIZE_VPTR))) - asan_num_accesses = sanopt_optimize (fun); + asan_num_accesses = sanopt_optimize (fun, &contains_asan_mark); else if (flag_sanitize & SANITIZE_ADDRESS) { gimple_stmt_iterator gsi; @@ -692,9 +882,17 @@ pass_sanopt::execute (function *fun) gimple *stmt = gsi_stmt (gsi); if (gimple_call_internal_p (stmt, IFN_ASAN_CHECK)) ++asan_num_accesses; + else if (gimple_call_internal_p (stmt, IFN_ASAN_MARK)) + contains_asan_mark = true; } } + if (contains_asan_mark) + { + sanitize_asan_mark_unpoison (); + sanitize_asan_mark_poison (); + } + bool use_calls = ASAN_INSTRUMENTATION_WITH_CALL_THRESHOLD < INT_MAX && asan_num_accesses >= ASAN_INSTRUMENTATION_WITH_CALL_THRESHOLD; -- 2.30.2