diff --git a/gcc/ChangeLog b/gcc/ChangeLog index a140b83847b61a447e639d68693885bb0c741188..b71e988e1003a5681e8e2c17f59d774f78db2a98 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,8 @@ +2012-05-08 Richard Guenther <rguenther@suse.de> + + * fold-const.c (fold_binary_loc): Fold (X * CST1) & CST2 + to zero or to (X * CST1) & CST2' when CST1 has trailing zeros. + 2012-05-08 Georg-Johann Lay <avr@gjlay.de> * Makefile.in (TEXI_GCC_FILES): Add avr-mmcu.texi. diff --git a/gcc/fold-const.c b/gcc/fold-const.c index f8b31b7d1134d969dbb3d0beb58458cb7a54adfb..5bb75d490d9845e172c5c28a70d18c8fdf446817 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -11449,6 +11449,30 @@ fold_binary_loc (location_t loc, return fold_convert_loc (loc, type, arg0); } + /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero + bits from CST2. */ + if (TREE_CODE (arg1) == INTEGER_CST + && TREE_CODE (arg0) == MULT_EXPR + && TREE_CODE (TREE_OPERAND (arg0, 1)) == INTEGER_CST) + { + int arg1tz + = double_int_ctz (tree_to_double_int (TREE_OPERAND (arg0, 1))); + if (arg1tz > 0) + { + double_int arg1mask, masked; + arg1mask = double_int_not (double_int_mask (arg1tz)); + arg1mask = double_int_ext (arg1mask, TYPE_PRECISION (type), + TYPE_UNSIGNED (type)); + masked = double_int_and (arg1mask, tree_to_double_int (arg1)); + if (double_int_zero_p (masked)) + return omit_two_operands_loc (loc, type, build_zero_cst (type), + arg0, arg1); + else if (!double_int_equal_p (masked, tree_to_double_int (arg1))) + return fold_build2_loc (loc, code, type, op0, + double_int_to_tree (type, masked)); + } + } + /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M, ((A & N) + B) & M -> (A + B) & M Similarly if (N & M) == 0, diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index f9ef02a8278f045bf013c40a12c7b7da00962078..ca4bcf89c6e4ffacac5b35eb2ebb6689f959aa7c 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,7 @@ +2012-05-08 Richard Guenther <rguenther@suse.de> + + * gcc.dg/fold-bitand-4.c: New testcase. + 2012-05-08 Dehao Chen <dehao@google.com> * gcc.dg/predict-1.c: Check if LOOP_IV_COMPARE static predict diff --git a/gcc/testsuite/gcc.dg/fold-bitand-4.c b/gcc/testsuite/gcc.dg/fold-bitand-4.c new file mode 100644 index 0000000000000000000000000000000000000000..dba83615dfe73e8cc3d6cb78e6e1cade02bf81d8 --- /dev/null +++ b/gcc/testsuite/gcc.dg/fold-bitand-4.c @@ -0,0 +1,16 @@ +/* { dg-do compile } */ +/* { dg-options "-O -fdump-tree-original" } */ + +int foo (int i) +{ + return (i * 8) & 5; +} + +unsigned bar (unsigned i) +{ + return (i * 6) & 5; +} + +/* { dg-final { scan-tree-dump-times "\\\&" 1 "original" } } */ +/* { dg-final { scan-tree-dump-times "\\\& 4;" 1 "original" } } */ +/* { dg-final { cleanup-tree-dump "original" } } */