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| author | Eric Botcazou <ebotcazou@libertysurf.fr> | 2003-07-02 09:41:07 +0200 |
|---|---|---|
| committer | Eric Botcazou <ebotcazou@gcc.gnu.org> | 2003-07-02 07:41:07 +0000 |
| commit | 1a8c4ca62da430aa2d8920b70f1614ab0755059b (patch) | |
| tree | 2f0ff7e67c577a96205f1a538d682dfa6c362eb3 /gcc | |
| parent | 23cdfcf71f295697ac4322f0a0e8128e22e834b4 (diff) | |
| download | gcc-1a8c4ca62da430aa2d8920b70f1614ab0755059b.zip gcc-1a8c4ca62da430aa2d8920b70f1614ab0755059b.tar.gz gcc-1a8c4ca62da430aa2d8920b70f1614ab0755059b.tar.bz2 | |
re PR rtl-optimization/11210 (optimizer drops conditional with typecast from signed to unsigned char)
PR optimization/11210
* expr.c (handled_component_p) [NOP_EXPR]: Add ??? note
about the behaviour with regard to bitfields.
* fold-const (decode_field_reference): Record outermost type in
case the expression is a NOP. Strip all NOPs. Set the signedness
to that of the outermost type (if any) when the bitsize is equal
to the size of the type.
From-SVN: r68823
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/ChangeLog | 10 | ||||
| -rw-r--r-- | gcc/expr.c | 3 | ||||
| -rw-r--r-- | gcc/fold-const.c | 14 |
3 files changed, 27 insertions, 0 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 1162a58..edc420b 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,13 @@ +2003-07-02 Eric Botcazou <ebotcazou@libertysurf.fr> + + PR optimization/11210 + * expr.c (handled_component_p) [NOP_EXPR]: Add ??? note + about the behaviour with regard to bitfields. + * fold-const (decode_field_reference): Record outermost type in + case the expression is a NOP. Strip all NOPs. Set the signedness + to that of the outermost type (if any) when the bitsize is equal + to the size of the type. + 2003-07-02 Richard Sandiford <rsandifo@redhat.com> * config/mips/mips.md (addsi3): Remove workaround for adds of -32768. @@ -5903,6 +5903,9 @@ handled_component_p (tree t) case VIEW_CONVERT_EXPR: return 1; + /* ??? Sure they are handled, but get_inner_reference may return + a different PBITSIZE, depending upon whether the expression is + wrapped up in a NOP_EXPR or not, e.g. for bitfields. */ case NOP_EXPR: case CONVERT_EXPR: return (TYPE_MODE (TREE_TYPE (t)) diff --git a/gcc/fold-const.c b/gcc/fold-const.c index 25069c5..3cc01ea 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -2625,6 +2625,7 @@ decode_field_reference (tree exp, HOST_WIDE_INT *pbitsize, HOST_WIDE_INT *pbitpo enum machine_mode *pmode, int *punsignedp, int *pvolatilep, tree *pmask, tree *pand_mask) { + tree outer_type = 0; tree and_mask = 0; tree mask, inner, offset; tree unsigned_type; @@ -2636,6 +2637,13 @@ decode_field_reference (tree exp, HOST_WIDE_INT *pbitsize, HOST_WIDE_INT *pbitpo if (! INTEGRAL_TYPE_P (TREE_TYPE (exp))) return 0; + /* We are interested in the bare arrangement of bits, so strip everything + that doesn't affect the machine mode. However, record the type of the + outermost expression if it may matter below. */ + if (TREE_CODE (exp) == NOP_EXPR + || TREE_CODE (exp) == CONVERT_EXPR + || TREE_CODE (exp) == NON_LVALUE_EXPR) + outer_type = TREE_TYPE (exp); STRIP_NOPS (exp); if (TREE_CODE (exp) == BIT_AND_EXPR) @@ -2654,6 +2662,12 @@ decode_field_reference (tree exp, HOST_WIDE_INT *pbitsize, HOST_WIDE_INT *pbitpo || TREE_CODE (inner) == PLACEHOLDER_EXPR) return 0; + /* If the number of bits in the reference is the same as the bitsize of + the outer type, then the outer type gives the signedness. Otherwise + (in case of a small bitfield) the signedness is unchanged. */ + if (outer_type && *pbitsize == tree_low_cst (TYPE_SIZE (outer_type), 1)) + *punsignedp = TREE_UNSIGNED (outer_type); + /* Compute the mask to access the bitfield. */ unsigned_type = (*lang_hooks.types.type_for_size) (*pbitsize, 1); precision = TYPE_PRECISION (unsigned_type); |