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| author | Richard Guenther <rguenth@gcc.gnu.org> | 2005-04-23 21:34:40 +0000 |
|---|---|---|
| committer | Richard Biener <rguenth@gcc.gnu.org> | 2005-04-23 21:34:40 +0000 |
| commit | 75cf42ccffa6a661cce421e0d9eb0e0689d75aae (patch) | |
| tree | ad181a15c3fa2379b1bb6a0ffc0864bace316ee0 /gcc/fold-const.c | |
| parent | be1b5cba3527dececdb66c6c356260500a040345 (diff) | |
| download | gcc-75cf42ccffa6a661cce421e0d9eb0e0689d75aae.zip gcc-75cf42ccffa6a661cce421e0d9eb0e0689d75aae.tar.gz gcc-75cf42ccffa6a661cce421e0d9eb0e0689d75aae.tar.bz2 | |
re PR middle-end/21082 (&a[b] - &a[c] is not folded to b - c)
2005-04-23 Richard Guenther <rguenth@gcc.gnu.org>
PR middle-end/21082
* fold-const.c: Fold &a[i]-&a[j] to i-j.
* g++.dg/tree-ssa/pr21082.C: New testcase.
From-SVN: r98636
Diffstat (limited to 'gcc/fold-const.c')
| -rw-r--r-- | gcc/fold-const.c | 23 |
1 files changed, 22 insertions, 1 deletions
diff --git a/gcc/fold-const.c b/gcc/fold-const.c index e928025..a75d1a2 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -7841,7 +7841,28 @@ fold_binary (enum tree_code code, tree type, tree op0, tree op1) && ptr_difference_const (arg0, arg1, &diff)) return build_int_cst_type (type, diff); } - + + /* Fold &a[i] - &a[j] to i-j. */ + if (TREE_CODE (arg0) == ADDR_EXPR + && TREE_CODE (TREE_OPERAND (arg0, 0)) == ARRAY_REF + && TREE_CODE (arg1) == ADDR_EXPR + && TREE_CODE (TREE_OPERAND (arg1, 0)) == ARRAY_REF) + { + tree aref0 = TREE_OPERAND (arg0, 0); + tree aref1 = TREE_OPERAND (arg1, 0); + if (operand_equal_p (TREE_OPERAND (aref0, 0), + TREE_OPERAND (aref1, 0), 0)) + { + tree op0 = fold_convert (type, TREE_OPERAND (aref0, 1)); + tree op1 = fold_convert (type, TREE_OPERAND (aref1, 1)); + tree esz = array_ref_element_size (aref0); + tree diff = build2 (MINUS_EXPR, type, op0, op1); + return fold_build2 (MULT_EXPR, type, diff, + fold_convert (type, esz)); + + } + } + /* Try replacing &a[i1] - c * i2 with &a[i1 - i2], if c is step of the array. Loop optimizer sometimes produce this type of expressions. */ |