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| author | Richard Kenner <kenner@gcc.gnu.org> | 1993-12-08 05:46:16 -0500 |
|---|---|---|
| committer | Richard Kenner <kenner@gcc.gnu.org> | 1993-12-08 05:46:16 -0500 |
| commit | aae678414b17b8ec35ee8479c4909a7cb43d4195 (patch) | |
| tree | ba89090bcb9c210bd0f6fdde273dcad88d9409d0 | |
| parent | a03f67cb3ca5a46627fd3af24a3f3cc33c8557ba (diff) | |
| download | gcc-aae678414b17b8ec35ee8479c4909a7cb43d4195.zip gcc-aae678414b17b8ec35ee8479c4909a7cb43d4195.tar.gz gcc-aae678414b17b8ec35ee8479c4909a7cb43d4195.tar.bz2 | |
(fold, case *_{DIV,MOD}_EXPR): When using distributive law, take care
when C2 is negative.
From-SVN: r6194
| -rw-r--r-- | gcc/fold-const.c | 18 |
1 files changed, 13 insertions, 5 deletions
diff --git a/gcc/fold-const.c b/gcc/fold-const.c index 27f6bab..6821c06 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -3922,7 +3922,7 @@ fold (expr) where C1 % C3 == 0 or C3 % C1 == 0. We can simplify these expressions, which often appear in the offsets or sizes of objects with a varying size. Only deal with positive divisors - and multiplicands. + and multiplicands. If C2 is negative, we must have C2 % C3 == 0. Look for NOPs and SAVE_EXPRs inside. */ @@ -3942,7 +3942,10 @@ fold (expr) && TREE_CODE (TREE_OPERAND (xarg0, 1)) == INTEGER_CST) c2 = TREE_OPERAND (xarg0, 1), xarg0 = TREE_OPERAND (xarg0, 0); else if (TREE_CODE (xarg0) == MINUS_EXPR - && TREE_CODE (TREE_OPERAND (xarg0, 1)) == INTEGER_CST) + && TREE_CODE (TREE_OPERAND (xarg0, 1)) == INTEGER_CST + /* If we are doing this computation unsigned, the negate + is incorrect. */ + && ! TREE_UNSIGNED (type)) { c2 = fold (build1 (NEGATE_EXPR, type, TREE_OPERAND (xarg0, 1))); xarg0 = TREE_OPERAND (xarg0, 0); @@ -3959,7 +3962,10 @@ fold (expr) && (integer_zerop (const_binop (TRUNC_MOD_EXPR, TREE_OPERAND (xarg0, 1), arg1, 1)) || integer_zerop (const_binop (TRUNC_MOD_EXPR, arg1, - TREE_OPERAND (xarg0, 1), 1)))) + TREE_OPERAND (xarg0, 1), 1))) + && (tree_int_cst_lt (integer_zero_node, c2) + || integer_zerop (const_binop (TRUNC_MOD_EXPR, c2, + arg1, 1)))) { tree outer_div = integer_one_node; tree c1 = TREE_OPERAND (xarg0, 1); @@ -4020,7 +4026,8 @@ fold (expr) && TREE_CODE (TREE_OPERAND (xarg0, 1)) == INTEGER_CST) c2 = TREE_OPERAND (xarg0, 1), xarg0 = TREE_OPERAND (xarg0, 0); else if (TREE_CODE (xarg0) == MINUS_EXPR - && TREE_CODE (TREE_OPERAND (xarg0, 1)) == INTEGER_CST) + && TREE_CODE (TREE_OPERAND (xarg0, 1)) == INTEGER_CST + && ! TREE_UNSIGNED (type)) { c2 = fold (build1 (NEGATE_EXPR, type, TREE_OPERAND (xarg0, 1))); xarg0 = TREE_OPERAND (xarg0, 0); @@ -4032,7 +4039,8 @@ fold (expr) && TREE_CODE (TREE_OPERAND (xarg0, 1)) == INTEGER_CST && integer_zerop (const_binop (TRUNC_MOD_EXPR, TREE_OPERAND (xarg0, 1), - arg1, 1))) + arg1, 1)) + && tree_int_cst_lt (integer_zero_node, c2)) /* The result is (C2%C3). */ return omit_one_operand (type, const_binop (code, c2, arg1, 1), TREE_OPERAND (xarg0, 0)); |