diff options
Diffstat (limited to 'gcc/gimple-fold.c')
| -rw-r--r-- | gcc/gimple-fold.c | 45 |
1 files changed, 42 insertions, 3 deletions
diff --git a/gcc/gimple-fold.c b/gcc/gimple-fold.c index ed22592..fa7a396 100644 --- a/gcc/gimple-fold.c +++ b/gcc/gimple-fold.c @@ -65,6 +65,7 @@ along with GCC; see the file COPYING3. If not see #include "calls.h" #include "tree-vector-builder.h" #include "tree-ssa-strlen.h" +#include "varasm.h" enum strlen_range_kind { /* Compute the exact constant string length. */ @@ -1280,7 +1281,7 @@ get_range_strlen_tree (tree arg, bitmap *visited, strlen_range_kind rkind, c_strlen_data *pdata, unsigned eltsize) { gcc_assert (TREE_CODE (arg) != SSA_NAME); - + /* The length computed by this invocation of the function. */ tree val = NULL_TREE; @@ -1422,7 +1423,44 @@ get_range_strlen_tree (tree arg, bitmap *visited, strlen_range_kind rkind, type about the length here. */ tight_bound = true; } - else if (VAR_P (arg)) + else if (TREE_CODE (arg) == MEM_REF + && TREE_CODE (TREE_TYPE (arg)) == ARRAY_TYPE + && TREE_CODE (TREE_TYPE (TREE_TYPE (arg))) == INTEGER_TYPE + && TREE_CODE (TREE_OPERAND (arg, 0)) == ADDR_EXPR) + { + /* Handle a MEM_REF into a DECL accessing an array of integers, + being conservative about references to extern structures with + flexible array members that can be initialized to arbitrary + numbers of elements as an extension (static structs are okay). + FIXME: Make this less conservative -- see + component_ref_size in tree.c. */ + tree ref = TREE_OPERAND (TREE_OPERAND (arg, 0), 0); + if ((TREE_CODE (ref) == PARM_DECL || VAR_P (ref)) + && (decl_binds_to_current_def_p (ref) + || !array_at_struct_end_p (arg))) + { + /* Fail if the offset is out of bounds. Such accesses + should be diagnosed at some point. */ + val = DECL_SIZE_UNIT (ref); + if (!val || integer_zerop (val)) + return false; + + poly_offset_int psiz = wi::to_offset (val); + poly_offset_int poff = mem_ref_offset (arg); + if (known_le (psiz, poff)) + return false; + + pdata->minlen = ssize_int (0); + + /* Subtract the offset and one for the terminating nul. */ + psiz -= poff; + psiz -= 1; + val = wide_int_to_tree (TREE_TYPE (val), psiz); + /* Since VAL reflects the size of a declared object + rather the type of the access it is not a tight bound. */ + } + } + else if (TREE_CODE (arg) == PARM_DECL || VAR_P (arg)) { /* Avoid handling pointers to arrays. GCC might misuse a pointer to an array of one bound to point to an array @@ -1500,7 +1538,8 @@ get_range_strlen_tree (tree arg, bitmap *visited, strlen_range_kind rkind, the referenced subobject minus 1 (for the terminating nul). */ tree type = TREE_TYPE (base); if (TREE_CODE (type) == POINTER_TYPE - || !VAR_P (base) || !(val = DECL_SIZE_UNIT (base))) + || (TREE_CODE (base) != PARM_DECL && !VAR_P (base)) + || !(val = DECL_SIZE_UNIT (base))) val = build_all_ones_cst (size_type_node); else { |