[PATCH] set_mem_attributes alignment and ARRAY_REF (PR middle-end/37774)
Jakub Jelinek
jakub@redhat.com
Wed Oct 8 20:56:00 GMT 2008
On Wed, Oct 08, 2008 at 05:03:37PM +0200, Richard Guenther wrote:
> I agree with your findings. Note that it may be worth factoring
> out bits to share code with builtins.c:get_pointer_alignment.
The attached patch which I've bootstrapped/regtested on x86_64-linux
does that factoring out.
2008-10-08 Jakub Jelinek <jakub@redhat.com>
PR middle-end/37774
* tree.h (get_object_alignment): Declare.
* emit-rtl.c (set_mem_attributes_minus_bitpos): Call
get_object_alignment if needed.
* builtins.c (get_pointer_alignment): Move ADDR_EXPR operand handling
to ...
(get_object_alignment): ... here. New function. Try harder to
determine alignment from get_inner_reference returned offset.
--- gcc/tree.h.jj 2008-10-07 20:09:54.000000000 +0200
+++ gcc/tree.h 2008-10-08 19:53:54.000000000 +0200
@@ -4864,6 +4864,7 @@ extern tree build_string_literal (int, c
extern bool validate_arglist (const_tree, ...);
extern rtx builtin_memset_read_str (void *, HOST_WIDE_INT, enum machine_mode);
extern int get_pointer_alignment (tree, unsigned int);
+extern int get_object_alignment (tree, unsigned int, unsigned int);
extern tree fold_call_stmt (gimple, bool);
extern tree gimple_fold_builtin_snprintf_chk (gimple, tree, enum built_in_function);
--- gcc/emit-rtl.c.jj 2008-09-15 09:36:26.000000000 +0200
+++ gcc/emit-rtl.c 2008-10-08 20:28:31.000000000 +0200
@@ -1564,6 +1564,7 @@ set_mem_attributes_minus_bitpos (rtx ref
if (! TYPE_P (t))
{
tree base;
+ bool align_computed = false;
if (TREE_THIS_VOLATILE (t))
MEM_VOLATILE_P (ref) = 1;
@@ -1620,6 +1621,7 @@ set_mem_attributes_minus_bitpos (rtx ref
&& host_integerp (DECL_SIZE_UNIT (t), 1)
? GEN_INT (tree_low_cst (DECL_SIZE_UNIT (t), 1)) : 0);
align = DECL_ALIGN (t);
+ align_computed = true;
}
/* If this is a constant, we know the alignment. */
@@ -1629,6 +1631,7 @@ set_mem_attributes_minus_bitpos (rtx ref
#ifdef CONSTANT_ALIGNMENT
align = CONSTANT_ALIGNMENT (t, align);
#endif
+ align_computed = true;
}
/* If this is a field reference and not a bit-field, record it. */
@@ -1688,6 +1691,7 @@ set_mem_attributes_minus_bitpos (rtx ref
align = DECL_ALIGN (t2);
if (aoff && (unsigned HOST_WIDE_INT) aoff < align)
align = aoff;
+ align_computed = true;
offset = GEN_INT (ioff);
apply_bitpos = bitpos;
}
@@ -1721,6 +1725,13 @@ set_mem_attributes_minus_bitpos (rtx ref
expr = t;
offset = NULL;
}
+
+ if (!align_computed && !INDIRECT_REF_P (t))
+ {
+ unsigned int obj_align
+ = get_object_alignment (t, align, BIGGEST_ALIGNMENT);
+ align = MAX (align, obj_align);
+ }
}
/* If we modified OFFSET based on T, then subtract the outstanding
--- gcc/builtins.c.jj 2008-10-04 11:24:36.000000000 +0200
+++ gcc/builtins.c 2008-10-08 20:16:56.000000000 +0200
@@ -253,6 +253,82 @@ static bool called_as_built_in (tree nod
return false;
}
+/* Return the alignment in bits of EXP, an object.
+ Don't return more than MAX_ALIGN no matter what, ALIGN is the inital
+ guessed alignment e.g. from type alignment. */
+
+int
+get_object_alignment (tree exp, unsigned int align, unsigned int max_align)
+{
+ unsigned int inner;
+
+ inner = max_align;
+ if (handled_component_p (exp))
+ {
+ HOST_WIDE_INT bitsize, bitpos;
+ tree offset;
+ enum machine_mode mode;
+ int unsignedp, volatilep;
+
+ exp = get_inner_reference (exp, &bitsize, &bitpos, &offset,
+ &mode, &unsignedp, &volatilep, true);
+ if (bitpos)
+ inner = MIN (inner, (unsigned) (bitpos & -bitpos));
+ while (offset)
+ {
+ tree next_offset;
+
+ if (TREE_CODE (offset) == PLUS_EXPR)
+ {
+ next_offset = TREE_OPERAND (offset, 0);
+ offset = TREE_OPERAND (offset, 1);
+ }
+ else
+ next_offset = NULL;
+ if (host_integerp (offset, 1))
+ {
+ /* Any overflow in calculating offset_bits won't change
+ the alignment. */
+ unsigned offset_bits
+ = ((unsigned) tree_low_cst (offset, 1) * BITS_PER_UNIT);
+
+ if (offset_bits)
+ inner = MIN (inner, (offset_bits & -offset_bits));
+ }
+ else if (TREE_CODE (offset) == MULT_EXPR
+ && host_integerp (TREE_OPERAND (offset, 1), 1))
+ {
+ /* Any overflow in calculating offset_factor won't change
+ the alignment. */
+ unsigned offset_factor
+ = ((unsigned) tree_low_cst (TREE_OPERAND (offset, 1), 1)
+ * BITS_PER_UNIT);
+
+ if (offset_factor)
+ inner = MIN (inner, (offset_factor & -offset_factor));
+ }
+ else
+ {
+ inner = MIN (inner, BITS_PER_UNIT);
+ break;
+ }
+ offset = next_offset;
+ }
+ }
+ if (DECL_P (exp))
+ align = MIN (inner, DECL_ALIGN (exp));
+#ifdef CONSTANT_ALIGNMENT
+ else if (CONSTANT_CLASS_P (exp))
+ align = MIN (inner, (unsigned)CONSTANT_ALIGNMENT (exp, align));
+#endif
+ else if (TREE_CODE (exp) == VIEW_CONVERT_EXPR
+ || TREE_CODE (exp) == INDIRECT_REF)
+ align = MIN (TYPE_ALIGN (TREE_TYPE (exp)), inner);
+ else
+ align = MIN (align, inner);
+ return MIN (align, max_align);
+}
+
/* Return the alignment in bits of EXP, a pointer valued expression.
But don't return more than MAX_ALIGN no matter what.
The alignment returned is, by default, the alignment of the thing that
@@ -306,59 +382,7 @@ get_pointer_alignment (tree exp, unsigne
case ADDR_EXPR:
/* See what we are pointing at and look at its alignment. */
- exp = TREE_OPERAND (exp, 0);
- inner = max_align;
- if (handled_component_p (exp))
- {
- HOST_WIDE_INT bitsize, bitpos;
- tree offset;
- enum machine_mode mode;
- int unsignedp, volatilep;
-
- exp = get_inner_reference (exp, &bitsize, &bitpos, &offset,
- &mode, &unsignedp, &volatilep, true);
- if (bitpos)
- inner = MIN (inner, (unsigned) (bitpos & -bitpos));
- if (offset && TREE_CODE (offset) == PLUS_EXPR
- && host_integerp (TREE_OPERAND (offset, 1), 1))
- {
- /* Any overflow in calculating offset_bits won't change
- the alignment. */
- unsigned offset_bits
- = ((unsigned) tree_low_cst (TREE_OPERAND (offset, 1), 1)
- * BITS_PER_UNIT);
-
- if (offset_bits)
- inner = MIN (inner, (offset_bits & -offset_bits));
- offset = TREE_OPERAND (offset, 0);
- }
- if (offset && TREE_CODE (offset) == MULT_EXPR
- && host_integerp (TREE_OPERAND (offset, 1), 1))
- {
- /* Any overflow in calculating offset_factor won't change
- the alignment. */
- unsigned offset_factor
- = ((unsigned) tree_low_cst (TREE_OPERAND (offset, 1), 1)
- * BITS_PER_UNIT);
-
- if (offset_factor)
- inner = MIN (inner, (offset_factor & -offset_factor));
- }
- else if (offset)
- inner = MIN (inner, BITS_PER_UNIT);
- }
- if (DECL_P (exp))
- align = MIN (inner, DECL_ALIGN (exp));
-#ifdef CONSTANT_ALIGNMENT
- else if (CONSTANT_CLASS_P (exp))
- align = MIN (inner, (unsigned)CONSTANT_ALIGNMENT (exp, align));
-#endif
- else if (TREE_CODE (exp) == VIEW_CONVERT_EXPR
- || TREE_CODE (exp) == INDIRECT_REF)
- align = MIN (TYPE_ALIGN (TREE_TYPE (exp)), inner);
- else
- align = MIN (align, inner);
- return MIN (align, max_align);
+ return get_object_alignment (TREE_OPERAND (exp, 0), align, max_align);
default:
return align;
Jakub
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