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c-typeck.c (pointer_diff): Try to eliminate common term before doing conversions.

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* c-typeck.c (pointer_diff): Try to eliminate common term before
	doing conversions.

From-SVN: r45285
This commit is contained in:
J"orn Rennecke 2001-08-30 12:46:52 +00:00 committed by Joern Rennecke
parent f232e4a500
commit 95602da11c
2 changed files with 42 additions and 1 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
Thu Aug 30 10:21:43 2001 J"orn Rennecke <amylaar@redhat.com>
* c-typeck.c (pointer_diff): Try to eliminate common term before
doing conversions.
2001-08-29 Geoffrey Keating <geoffk@redhat.com>
* reload1.c (move2add_note_store): Correct typo checking for

38
gcc/c-typeck.c
View File

@ -2684,6 +2684,8 @@ pointer_diff (op0, op1)
tree restype = ptrdiff_type_node;
tree target_type = TREE_TYPE (TREE_TYPE (op0));
tree con0, con1, lit0, lit1;
tree orig_op1 = op1;
if (pedantic || warn_pointer_arith)
{
@ -2693,6 +2695,40 @@ pointer_diff (op0, op1)
pedwarn ("pointer to a function used in subtraction");
}
/* If the conversion to ptrdiff_type does anything like widening or
converting a partial to an integral mode, we get a convert_expression
that is in the way to do any simplifications.
(fold-const.c doesn't know that the extra bits won't be needed.
split_tree uses STRIP_SIGN_NOPS, which leaves conversions to a
different mode in place.)
So first try to find a common term here 'by hand'; we want to cover
at least the cases that occur in legal static initializers. */
con0 = TREE_CODE (op0) == NOP_EXPR ? TREE_OPERAND (op0, 0) : op0;
con1 = TREE_CODE (op1) == NOP_EXPR ? TREE_OPERAND (op1, 0) : op1;
if (TREE_CODE (con0) == PLUS_EXPR)
{
lit0 = TREE_OPERAND (con0, 1);
con0 = TREE_OPERAND (con0, 0);
}
else
lit0 = integer_zero_node;
if (TREE_CODE (con1) == PLUS_EXPR)
{
lit1 = TREE_OPERAND (con1, 1);
con1 = TREE_OPERAND (con1, 0);
}
else
lit1 = integer_zero_node;
if (operand_equal_p (con0, con1, 0))
{
op0 = lit0;
op1 = lit1;
}
/* First do the subtraction as integers;
then drop through to build the divide operator.
Do not do default conversions on the minus operator
@ -2701,7 +2737,7 @@ pointer_diff (op0, op1)
op0 = build_binary_op (MINUS_EXPR, convert (restype, op0),
convert (restype, op1), 0);
/* This generates an error if op1 is pointer to incomplete type. */
if (!COMPLETE_OR_VOID_TYPE_P (TREE_TYPE (TREE_TYPE (op1))))
if (!COMPLETE_OR_VOID_TYPE_P (TREE_TYPE (TREE_TYPE (orig_op1))))
error ("arithmetic on pointer to an incomplete type");
/* This generates an error if op0 is pointer to incomplete type. */