From bd3d919b58466a9837e423c1255b88215f89bc9d Mon Sep 17 00:00:00 2001 From: Richard Biener Date: Tue, 30 Mar 2021 11:22:52 +0200 Subject: [PATCH] tree-optimization/99824 - avoid excessive integer type precision in VN VN sometimes builds new integer types to handle accesss where precision of the access type does not match the access size. The way ao_ref_init_from_vn_reference is computing the access size ignores the access type in case the ref operands have an outermost COMPONENT_REF which, in case it is an array for example, can be way larger than the access size. This can cause us to try building an integer type with precision larger than WIDE_INT_MAX_PRECISION eventually leading to memory corruption. The following adjusts ao_ref_init_from_vn_reference to only lower access sizes via the outermost COMPONENT_REF but otherwise honor the access size as specified by the access type. It also places an assert in integer type building that we remain in the limits of WIDE_INT_MAX_PRECISION. I chose the shared code where we set TYPE_MIN/MAX_VALUE because that will immediately cross the wide_ints capacity otherwise. 2021-03-30 Richard Biener PR tree-optimization/99824 * stor-layout.c (set_min_and_max_values_for_integral_type): Assert the precision is within the bounds of WIDE_INT_MAX_PRECISION. * tree-ssa-sccvn.c (ao_ref_init_from_vn_reference): Use the outermost component ref only to lower the access size and initialize that from the access type. * gcc.dg/torture/pr99824.c: New testcase. --- gcc/stor-layout.c | 2 ++ gcc/testsuite/gcc.dg/torture/pr99824.c | 33 +++++++++++++++++++++++++++++++++ gcc/tree-ssa-sccvn.c | 24 ++++++++++++++---------- 3 files changed, 49 insertions(+), 10 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/torture/pr99824.c diff --git a/gcc/stor-layout.c b/gcc/stor-layout.c index 784f131..94b8b21 100644 --- a/gcc/stor-layout.c +++ b/gcc/stor-layout.c @@ -2838,6 +2838,8 @@ set_min_and_max_values_for_integral_type (tree type, if (precision < 1) return; + gcc_assert (precision <= WIDE_INT_MAX_PRECISION); + TYPE_MIN_VALUE (type) = wide_int_to_tree (type, wi::min_value (precision, sgn)); TYPE_MAX_VALUE (type) diff --git a/gcc/testsuite/gcc.dg/torture/pr99824.c b/gcc/testsuite/gcc.dg/torture/pr99824.c new file mode 100644 index 0000000..9022d4a --- /dev/null +++ b/gcc/testsuite/gcc.dg/torture/pr99824.c @@ -0,0 +1,33 @@ +/* { dg-do compile } */ + +unsigned int +strlenx(char *s) +{ + char *orig_s = s; + for (; *s; ++s) + ; + return s - orig_s; +} + +struct i2c_adapter { + char name[48]; +}; + +struct { + int instance; + struct i2c_adapter i2c_adap[]; +} * init_cx18_i2c_cx; + +const struct i2c_adapter cx18_i2c_adap_template = {""}; +int init_cx18_i2c___trans_tmp_1; + +void +init_cx18_i2c() +{ + int i = 0; + for (;; i++) { + init_cx18_i2c_cx->i2c_adap[i] = cx18_i2c_adap_template; + init_cx18_i2c___trans_tmp_1 + = strlenx(init_cx18_i2c_cx->i2c_adap[i].name); + } +} diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c index 1c0500c..0567a2e 100644 --- a/gcc/tree-ssa-sccvn.c +++ b/gcc/tree-ssa-sccvn.c @@ -1002,22 +1002,26 @@ ao_ref_init_from_vn_reference (ao_ref *ref, poly_offset_int size = -1; tree size_tree = NULL_TREE; - /* First get the final access size from just the outermost expression. */ + machine_mode mode = TYPE_MODE (type); + if (mode == BLKmode) + size_tree = TYPE_SIZE (type); + else + size = GET_MODE_BITSIZE (mode); + if (size_tree != NULL_TREE + && poly_int_tree_p (size_tree)) + size = wi::to_poly_offset (size_tree); + + /* Lower the final access size from the outermost expression. */ op = &ops[0]; + size_tree = NULL_TREE; if (op->opcode == COMPONENT_REF) size_tree = DECL_SIZE (op->op0); else if (op->opcode == BIT_FIELD_REF) size_tree = op->op0; - else - { - machine_mode mode = TYPE_MODE (type); - if (mode == BLKmode) - size_tree = TYPE_SIZE (type); - else - size = GET_MODE_BITSIZE (mode); - } if (size_tree != NULL_TREE - && poly_int_tree_p (size_tree)) + && poly_int_tree_p (size_tree) + && (!known_size_p (size) + || known_lt (wi::to_poly_offset (size_tree), size))) size = wi::to_poly_offset (size_tree); /* Initially, maxsize is the same as the accessed element size. -- 2.7.4