While trawling through old bugs I came across one from 2005: PR 21433
- The COMPONENT_REF case of expand_expr_real_1 is probably wrong.
The report looks correct in that argument 0 in COMPONENT_REF cannot
be a CONSTRUCTOR. In my tests it's only been one of the following
codes:
array_ref
component_ref
mem_ref
parm_decl
result_decl
var_decl
The attached patch removes the CONSTRUCTOR code and replaces it with
an assert verifying it doesn't come up there. Besides testing on
x86_64-linux, the change is supported by comments in code and also
in the internals manual (although that looks incorrect and should
be changed to avoid suggesting the first operand is a decl).
tree.def:
/* Value is structure or union component.
Operand 0 is the structure or union (an expression).
Operand 1 is the field (a node of type FIELD_DECL).
Operand 2, if present, is the value of DECL_FIELD_OFFSET, measured
in units of DECL_OFFSET_ALIGN / BITS_PER_UNIT. */
DEFTREECODE (COMPONENT_REF, "component_ref", tcc_reference, 3)
generic.texi:
@item COMPONENT_REF
These nodes represent non-static data member accesses. The first
operand is the object (rather than a pointer to it); the second operand
is the @code{FIELD_DECL} for the data member. The third operand represents
the byte offset of the field, but should not be used directly; call
@code{component_ref_field_offset} instead.
PR middle-end/21433 - The COMPONENT_REF case of expand_expr_real_1 is probably wrong
gcc/ChangeLog:
PR middle-end/21433
* expr.c (expand_expr_real_1): Replace unreachable code with an assert.
diff --git a/gcc/expr.c b/gcc/expr.c
index 86dc1b6c973..7d5efe5722a 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -10767,61 +10767,8 @@ expand_expr_real_1 (tree exp, rtx target, machine_mode tmode,
goto normal_inner_ref;
case COMPONENT_REF:
- /* If the operand is a CONSTRUCTOR, we can just extract the
- appropriate field if it is present. */
- if (TREE_CODE (treeop0) == CONSTRUCTOR)
- {
- unsigned HOST_WIDE_INT idx;
- tree field, value;
- scalar_int_mode field_mode;
-
- FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (treeop0),
- idx, field, value)
- if (field == treeop1
- /* We can normally use the value of the field in the
- CONSTRUCTOR. However, if this is a bitfield in
- an integral mode that we can fit in a HOST_WIDE_INT,
- we must mask only the number of bits in the bitfield,
- since this is done implicitly by the constructor. If
- the bitfield does not meet either of those conditions,
- we can't do this optimization. */
- && (! DECL_BIT_FIELD (field)
- || (is_int_mode (DECL_MODE (field), &field_mode)
- && (GET_MODE_PRECISION (field_mode)
- <= HOST_BITS_PER_WIDE_INT))))
- {
- if (DECL_BIT_FIELD (field)
- && modifier == EXPAND_STACK_PARM)
- target = 0;
- op0 = expand_expr (value, target, tmode, modifier);
- if (DECL_BIT_FIELD (field))
- {
- HOST_WIDE_INT bitsize = TREE_INT_CST_LOW (DECL_SIZE (field));
- scalar_int_mode imode
- = SCALAR_INT_TYPE_MODE (TREE_TYPE (field));
-
- if (TYPE_UNSIGNED (TREE_TYPE (field)))
- {
- op1 = gen_int_mode ((HOST_WIDE_INT_1 << bitsize) - 1,
- imode);
- op0 = expand_and (imode, op0, op1, target);
- }
- else
- {
- int count = GET_MODE_PRECISION (imode) - bitsize;
-
- op0 = expand_shift (LSHIFT_EXPR, imode, op0, count,
- target, 0);
- op0 = expand_shift (RSHIFT_EXPR, imode, op0, count,
- target, 0);
- }
- }
-
- return op0;
- }
- }
- goto normal_inner_ref;
-
+ gcc_assert (TREE_CODE (treeop0) != CONSTRUCTOR);
+ /* Fall through. */
case BIT_FIELD_REF:
case ARRAY_RANGE_REF:
normal_inner_ref:
