From 891fc5e9f1b6a88f9147b68e670f0cc172acfe21 Mon Sep 17 00:00:00 2001 From: Richard Guenther Date: Fri, 27 Apr 2007 11:42:43 +0000 Subject: [PATCH] re PR tree-optimization/31715 (Array calculation done incorrectly) 2007-04-27 Richard Guenther PR tree-optimization/31715 * tree-ssa-ccp.c (maybe_fold_offset_to_array_ref): Make sure to do computation on the offset in an appropriate signed type. * gcc.dg/Warray-bounds-4.c: New testcase. From-SVN: r124216 --- gcc/ChangeLog | 7 +++++ gcc/testsuite/ChangeLog | 5 ++++ gcc/testsuite/gcc.dg/Warray-bounds-4.c | 17 ++++++++++++ gcc/tree-ssa-ccp.c | 37 +++++++++++++++++--------- 4 files changed, 53 insertions(+), 13 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/Warray-bounds-4.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index d56233977f6..0e4f9873190 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,10 @@ +2007-04-27 Richard Guenther + + PR tree-optimization/31715 + * tree-ssa-ccp.c (maybe_fold_offset_to_array_ref): Make + sure to do computation on the offset in an appropriate + signed type. + 2007-04-27 Richard Sandiford * reload.h (elimination_target_reg_p): Declare. diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 40c811bb7aa..c9e601eb57d 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2007-04-27 Richard Guenther + + PR tree-optimization/31715 + * gcc.dg/Warray-bounds-4.c: New testcase. + 2007-04-26 Ian Lance Taylor PR target/28675 diff --git a/gcc/testsuite/gcc.dg/Warray-bounds-4.c b/gcc/testsuite/gcc.dg/Warray-bounds-4.c new file mode 100644 index 00000000000..71526f27ffd --- /dev/null +++ b/gcc/testsuite/gcc.dg/Warray-bounds-4.c @@ -0,0 +1,17 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -Wall" } */ + +typedef unsigned int DWORD; + +static void g(DWORD * p, int n) +{ + int i; + + for (i = 0; i < n && !p[n - 1]; i++); /* { dg-bogus "subscript is above array bounds" } */ +} + +void f() { + DWORD arr[8]; + + g(arr, 4); +} diff --git a/gcc/tree-ssa-ccp.c b/gcc/tree-ssa-ccp.c index 530dee01a09..9c9d847eed6 100644 --- a/gcc/tree-ssa-ccp.c +++ b/gcc/tree-ssa-ccp.c @@ -1550,7 +1550,7 @@ widen_bitfield (tree val, tree field, tree var) static tree maybe_fold_offset_to_array_ref (tree base, tree offset, tree orig_type) { - tree min_idx, idx, elt_offset = integer_zero_node; + tree min_idx, idx, idx_type, elt_offset = integer_zero_node; tree array_type, elt_type, elt_size; /* If BASE is an ARRAY_REF, we can pick up another offset (this time @@ -1578,7 +1578,10 @@ maybe_fold_offset_to_array_ref (tree base, tree offset, tree orig_type) elt_type = TREE_TYPE (array_type); if (!lang_hooks.types_compatible_p (orig_type, elt_type)) return NULL_TREE; - + + /* Use signed size type for intermediate computation on the index. */ + idx_type = signed_type_for (size_type_node); + /* If OFFSET and ELT_OFFSET are zero, we don't care about the size of the element type (so we can use the alignment if it's not constant). Otherwise, compute the offset as an index by using a division. If the @@ -1589,42 +1592,47 @@ maybe_fold_offset_to_array_ref (tree base, tree offset, tree orig_type) if (TREE_CODE (elt_size) != INTEGER_CST) elt_size = size_int (TYPE_ALIGN (elt_type)); - idx = integer_zero_node; + idx = build_int_cst (idx_type, 0); } else { unsigned HOST_WIDE_INT lquo, lrem; HOST_WIDE_INT hquo, hrem; + double_int soffset; + /* The final array offset should be signed, so we need + to sign-extend the (possibly pointer) offset here + and use signed division. */ + soffset = double_int_sext (tree_to_double_int (offset), + TYPE_PRECISION (TREE_TYPE (offset))); if (TREE_CODE (elt_size) != INTEGER_CST - || div_and_round_double (TRUNC_DIV_EXPR, 1, - TREE_INT_CST_LOW (offset), - TREE_INT_CST_HIGH (offset), + || div_and_round_double (TRUNC_DIV_EXPR, 0, + soffset.low, soffset.high, TREE_INT_CST_LOW (elt_size), TREE_INT_CST_HIGH (elt_size), &lquo, &hquo, &lrem, &hrem) || lrem || hrem) return NULL_TREE; - idx = build_int_cst_wide (TREE_TYPE (offset), lquo, hquo); + idx = build_int_cst_wide (idx_type, lquo, hquo); } /* Assume the low bound is zero. If there is a domain type, get the low bound, if any, convert the index into that type, and add the low bound. */ - min_idx = integer_zero_node; + min_idx = build_int_cst (idx_type, 0); if (TYPE_DOMAIN (array_type)) { - if (TYPE_MIN_VALUE (TYPE_DOMAIN (array_type))) - min_idx = TYPE_MIN_VALUE (TYPE_DOMAIN (array_type)); + idx_type = TYPE_DOMAIN (array_type); + if (TYPE_MIN_VALUE (idx_type)) + min_idx = TYPE_MIN_VALUE (idx_type); else - min_idx = fold_convert (TYPE_DOMAIN (array_type), min_idx); + min_idx = fold_convert (idx_type, min_idx); if (TREE_CODE (min_idx) != INTEGER_CST) return NULL_TREE; - idx = fold_convert (TYPE_DOMAIN (array_type), idx); - elt_offset = fold_convert (TYPE_DOMAIN (array_type), elt_offset); + elt_offset = fold_convert (idx_type, elt_offset); } if (!integer_zerop (min_idx)) @@ -1632,6 +1640,9 @@ maybe_fold_offset_to_array_ref (tree base, tree offset, tree orig_type) if (!integer_zerop (elt_offset)) idx = int_const_binop (PLUS_EXPR, idx, elt_offset, 0); + /* Make sure to possibly truncate late after offsetting. */ + idx = fold_convert (idx_type, idx); + return build4 (ARRAY_REF, orig_type, base, idx, NULL_TREE, NULL_TREE); } -- 2.30.2