diff options
Diffstat (limited to 'gcc/builtins.c')
| -rw-r--r-- | gcc/builtins.c | 27 |
1 files changed, 24 insertions, 3 deletions
diff --git a/gcc/builtins.c b/gcc/builtins.c index 0747e04a3af..1ee8cf80001 100644 --- a/gcc/builtins.c +++ b/gcc/builtins.c @@ -264,8 +264,15 @@ called_as_built_in (tree node) return is_builtin_name (name); } -/* Return the alignment in bits of EXP, an object. - Don't return more than MAX_ALIGN no matter what. */ +/* Compute values M and N such that M divides (address of EXP - N) and + such that N < M. Store N in *BITPOSP and return M. + + Note that the address (and thus the alignment) computed here is based + on the address to which a symbol resolves, whereas DECL_ALIGN is based + on the address at which an object is actually located. These two + addresses are not always the same. For example, on ARM targets, + the address &foo of a Thumb function foo() has the lowest bit set, + whereas foo() itself starts on an even address. */ unsigned int get_object_alignment_1 (tree exp, unsigned HOST_WIDE_INT *bitposp) @@ -287,7 +294,21 @@ get_object_alignment_1 (tree exp, unsigned HOST_WIDE_INT *bitposp) exp = DECL_INITIAL (exp); if (DECL_P (exp) && TREE_CODE (exp) != LABEL_DECL) - align = DECL_ALIGN (exp); + { + if (TREE_CODE (exp) == FUNCTION_DECL) + { + /* Function addresses can encode extra information besides their + alignment. However, if TARGET_PTRMEMFUNC_VBIT_LOCATION + allows the low bit to be used as a virtual bit, we know + that the address itself must be 2-byte aligned. */ + if (TARGET_PTRMEMFUNC_VBIT_LOCATION == ptrmemfunc_vbit_in_pfn) + align = 2 * BITS_PER_UNIT; + else + align = BITS_PER_UNIT; + } + else + align = DECL_ALIGN (exp); + } else if (CONSTANT_CLASS_P (exp)) { align = TYPE_ALIGN (TREE_TYPE (exp)); |