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| -rw-r--r-- | gcc/ChangeLog | 7 | ||||
| -rw-r--r-- | gcc/expr.c | 31 |
2 files changed, 38 insertions, 0 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 94a82fa..330db3e 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,10 @@ +2005-08-31 Richard Guenther <rguenther@suse.de> + + PR middle-end/23477 + * expr.c (all_zeros_p): New function. + (expand_expr_real_1): Handle the case of an all-zero + non-addressable constructor separately. + 2005-08-31 Adrian Straetling <straetling@de.ibm.com> * builtins.c: (expand_builtin_strcpy, expand_builtin_strcat): Change @@ -4645,6 +4645,24 @@ mostly_zeros_p (tree exp) return initializer_zerop (exp); } + +/* Return 1 if EXP contains all zeros. */ + +static int +all_zeros_p (tree exp) +{ + if (TREE_CODE (exp) == CONSTRUCTOR) + + { + HOST_WIDE_INT nz_elts, nc_elts, count; + bool must_clear; + + categorize_ctor_elements (exp, &nz_elts, &nc_elts, &count, &must_clear); + return nz_elts == 0; + } + + return initializer_zerop (exp); +} /* Helper function for store_constructor. TARGET, BITSIZE, BITPOS, MODE, EXP are as for store_field. @@ -6843,6 +6861,19 @@ expand_expr_real_1 (tree exp, rtx target, enum machine_mode tmode, return const0_rtx; } + /* Try to avoid creating a temporary at all. This is possible + if all of the initializer is zero. + FIXME: try to handle all [0..255] initializers we can handle + with memset. */ + else if (TREE_STATIC (exp) + && !TREE_ADDRESSABLE (exp) + && target != 0 && mode == BLKmode + && all_zeros_p (exp)) + { + clear_storage (target, expr_size (exp), BLOCK_OP_NORMAL); + return target; + } + /* All elts simple constants => refer to a constant in memory. But if this is a non-BLKmode mode, let it store a field at a time since that should make a CONST_INT or CONST_DOUBLE when we |