fold-const.c (extract_array_ref): Remove.
2007-10-15 Richard Guenther <rguenther@suse.de> * fold-const.c (extract_array_ref): Remove. (fold_comparison): Handle POINTER_PLUS_EXPR with the generic address expression comparison folding. Remove the folding that used extract_array_ref. From-SVN: r129347
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Richard Guenther
Richard Biener
parent
eb64c8e52f
commit
3e0de2559e
@ -1,3 +1,10 @@
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2007-10-15 Richard Guenther <rguenther@suse.de>
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* fold-const.c (extract_array_ref): Remove.
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(fold_comparison): Handle POINTER_PLUS_EXPR with the
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generic address expression comparison folding. Remove
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the folding that used extract_array_ref.
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2007-10-15 Maxim Kuvyrkov <maxim@codesourcery.com>
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PR target/33133
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129
gcc/fold-const.c
129
gcc/fold-const.c
@ -6322,76 +6322,6 @@ constant_boolean_node (int value, tree type)
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}
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/* Return true if expr looks like an ARRAY_REF and set base and
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offset to the appropriate trees. If there is no offset,
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offset is set to NULL_TREE. Base will be canonicalized to
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something you can get the element type from using
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TREE_TYPE (TREE_TYPE (base)). Offset will be the offset
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in bytes to the base in sizetype. */
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static bool
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extract_array_ref (tree expr, tree *base, tree *offset)
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{
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/* One canonical form is a PLUS_EXPR with the first
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argument being an ADDR_EXPR with a possible NOP_EXPR
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attached. */
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if (TREE_CODE (expr) == POINTER_PLUS_EXPR)
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{
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tree op0 = TREE_OPERAND (expr, 0);
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tree inner_base, dummy1;
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/* Strip NOP_EXPRs here because the C frontends and/or
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folders present us (int *)&x.a p+ 4 possibly. */
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STRIP_NOPS (op0);
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if (extract_array_ref (op0, &inner_base, &dummy1))
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{
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*base = inner_base;
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*offset = fold_convert (sizetype, TREE_OPERAND (expr, 1));
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if (dummy1 != NULL_TREE)
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*offset = fold_build2 (PLUS_EXPR, sizetype,
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dummy1, *offset);
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return true;
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}
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}
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/* Other canonical form is an ADDR_EXPR of an ARRAY_REF,
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which we transform into an ADDR_EXPR with appropriate
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offset. For other arguments to the ADDR_EXPR we assume
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zero offset and as such do not care about the ADDR_EXPR
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type and strip possible nops from it. */
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else if (TREE_CODE (expr) == ADDR_EXPR)
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{
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tree op0 = TREE_OPERAND (expr, 0);
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if (TREE_CODE (op0) == ARRAY_REF)
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{
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tree idx = TREE_OPERAND (op0, 1);
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*base = TREE_OPERAND (op0, 0);
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*offset = fold_build2 (MULT_EXPR, TREE_TYPE (idx), idx,
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array_ref_element_size (op0));
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*offset = fold_convert (sizetype, *offset);
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}
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else
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{
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/* Handle array-to-pointer decay as &a. */
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if (TREE_CODE (TREE_TYPE (op0)) == ARRAY_TYPE)
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*base = TREE_OPERAND (expr, 0);
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else
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*base = expr;
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*offset = NULL_TREE;
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}
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return true;
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}
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/* The next canonical form is a VAR_DECL with POINTER_TYPE. */
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else if (SSA_VAR_P (expr)
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&& TREE_CODE (TREE_TYPE (expr)) == POINTER_TYPE)
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{
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*base = expr;
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*offset = NULL_TREE;
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return true;
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}
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return false;
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}
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/* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
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Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
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CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
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@ -8802,11 +8732,13 @@ fold_comparison (enum tree_code code, tree type, tree op0, tree op1)
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/* For comparisons of pointers we can decompose it to a compile time
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comparison of the base objects and the offsets into the object.
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This requires at least one operand being an ADDR_EXPR to do more
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than the operand_equal_p test below. */
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This requires at least one operand being an ADDR_EXPR or a
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POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
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if (POINTER_TYPE_P (TREE_TYPE (arg0))
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&& (TREE_CODE (arg0) == ADDR_EXPR
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|| TREE_CODE (arg1) == ADDR_EXPR))
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|| TREE_CODE (arg1) == ADDR_EXPR
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|| TREE_CODE (arg0) == POINTER_PLUS_EXPR
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|| TREE_CODE (arg1) == POINTER_PLUS_EXPR))
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{
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tree base0, base1, offset0 = NULL_TREE, offset1 = NULL_TREE;
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HOST_WIDE_INT bitsize, bitpos0 = 0, bitpos1 = 0;
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@ -8828,6 +8760,11 @@ fold_comparison (enum tree_code code, tree type, tree op0, tree op1)
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else
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indirect_base0 = true;
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}
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else if (TREE_CODE (arg0) == POINTER_PLUS_EXPR)
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{
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base0 = TREE_OPERAND (arg0, 0);
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offset0 = TREE_OPERAND (arg0, 1);
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}
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base1 = arg1;
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if (TREE_CODE (arg1) == ADDR_EXPR)
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@ -8843,6 +8780,11 @@ fold_comparison (enum tree_code code, tree type, tree op0, tree op1)
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else if (!indirect_base0)
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base1 = NULL_TREE;
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}
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else if (TREE_CODE (arg1) == POINTER_PLUS_EXPR)
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{
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base1 = TREE_OPERAND (arg1, 0);
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offset1 = TREE_OPERAND (arg1, 1);
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}
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else if (indirect_base0)
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base1 = NULL_TREE;
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@ -8904,47 +8846,6 @@ fold_comparison (enum tree_code code, tree type, tree op0, tree op1)
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}
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}
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/* If this is a comparison of two exprs that look like an ARRAY_REF of the
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same object, then we can fold this to a comparison of the two offsets in
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signed size type. This is possible because pointer arithmetic is
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restricted to retain within an object and overflow on pointer differences
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is undefined as of 6.5.6/8 and /9 with respect to the signed ptrdiff_t.
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We check flag_wrapv directly because pointers types are unsigned,
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and therefore TYPE_OVERFLOW_WRAPS returns true for them. That is
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normally what we want to avoid certain odd overflow cases, but
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not here. */
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if (POINTER_TYPE_P (TREE_TYPE (arg0))
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&& !flag_wrapv
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&& !TYPE_OVERFLOW_TRAPS (TREE_TYPE (arg0)))
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{
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tree base0, offset0, base1, offset1;
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if (extract_array_ref (arg0, &base0, &offset0)
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&& extract_array_ref (arg1, &base1, &offset1)
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&& operand_equal_p (base0, base1, 0))
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{
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tree signed_size_type_node;
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signed_size_type_node = signed_type_for (size_type_node);
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/* By converting to signed size type we cover middle-end pointer
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arithmetic which operates on unsigned pointer types of size
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type size and ARRAY_REF offsets which are properly sign or
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zero extended from their type in case it is narrower than
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size type. */
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if (offset0 == NULL_TREE)
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offset0 = build_int_cst (signed_size_type_node, 0);
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else
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offset0 = fold_convert (signed_size_type_node, offset0);
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if (offset1 == NULL_TREE)
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offset1 = build_int_cst (signed_size_type_node, 0);
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else
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offset1 = fold_convert (signed_size_type_node, offset1);
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return fold_build2 (code, type, offset0, offset1);
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}
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}
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/* Transform comparisons of the form X +- C1 CMP Y +- C2 to
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X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
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the resulting offset is smaller in absolute value than the
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