diff options
Diffstat (limited to 'instrumentation/afl-gcc-pass.so.cc')
| -rw-r--r-- | instrumentation/afl-gcc-pass.so.cc | 30 |
1 files changed, 26 insertions, 4 deletions
diff --git a/instrumentation/afl-gcc-pass.so.cc b/instrumentation/afl-gcc-pass.so.cc index f8d5fd9e..e19c67df 100644 --- a/instrumentation/afl-gcc-pass.so.cc +++ b/instrumentation/afl-gcc-pass.so.cc @@ -278,6 +278,10 @@ struct afl_pass : gimple_opt_pass { } + /* .map_ptr is initialized at the function entry point, if we + instrument any blocks, see below. */ + + /* .entry = &map_ptr[.index]; */ gimple *idx_map = gimple_build_assign(ntry, POINTER_PLUS_EXPR, map_ptr, indx); gimple_seq_add_stmt(&seq, idx_map); @@ -288,10 +292,11 @@ struct afl_pass : gimple_opt_pass { if (blocks == 0) cntr = create_tmp_var(TREE_TYPE(memref), ".afl_edge_count"); + /* Load the count from the entry. */ gimple *load_cntr = gimple_build_assign(cntr, memref); gimple_seq_add_stmt(&seq, load_cntr); - tree cntrb = cntr; + /* Prepare to add constant 1 to it. */ tree incrv = build_one_cst(TREE_TYPE(cntr)); if (neverZero) { @@ -306,6 +311,10 @@ struct afl_pass : gimple_opt_pass { } + /* Call the ADD_OVERFLOW builtin, to add 1 (in incrv) to + count. The builtin yields a complex pair: the result of + the add in the real part, and the overflow flag in the + imaginary part, */ auto_vec<tree> vargs(2); vargs.quick_push(cntr); vargs.quick_push(incrv); @@ -314,14 +323,27 @@ struct afl_pass : gimple_opt_pass { gimple_call_set_lhs(add1_cntr, xaddc); gimple_seq_add_stmt(&seq, add1_cntr); - cntrb = build1(REALPART_EXPR, TREE_TYPE(cntr), xaddc); - incrv = build1(IMAGPART_EXPR, TREE_TYPE(xincr), xaddc); + /* Extract the real part into count. */ + tree cntrb = build1(REALPART_EXPR, TREE_TYPE(cntr), xaddc); + gimple *xtrct_cntr = gimple_build_assign(cntr, cntrb); + gimple_seq_add_stmt(&seq, xtrct_cntr); + + /* Extract the imaginary part into xincr. */ + tree incrb = build1(IMAGPART_EXPR, TREE_TYPE(xincr), xaddc); + gimple *xtrct_xincr = gimple_build_assign(xincr, incrb); + gimple_seq_add_stmt(&seq, xtrct_xincr); + + /* Arrange for the add below to use the overflow flag stored + in xincr. */ + incrv = xincr; } - gimple *incr_cntr = gimple_build_assign(cntr, PLUS_EXPR, cntrb, incrv); + /* Add the increment (1 or the overflow bit) to count. */ + gimple *incr_cntr = gimple_build_assign(cntr, PLUS_EXPR, cntr, incrv); gimple_seq_add_stmt(&seq, incr_cntr); + /* Store count in the map entry. */ gimple *store_cntr = gimple_build_assign(unshare_expr(memref), cntr); gimple_seq_add_stmt(&seq, store_cntr); |