From eb8dffe0fbff242efc573fba9eff7a1da7eb893f Mon Sep 17 00:00:00 2001 From: Roger Sayle Date: Sat, 25 Feb 2006 22:27:54 +0000 Subject: re PR middle-end/23673 (fold does not fold (a^b) != 0 to a != b) PR middle-end/23673 * fold-const.c (fold_binary) : Fold (X^Y) == 0 as X == Y and (X^Y) != 0 as X != Y. Fold (X^Y) == Y as X == 0, and some symmetry related transformations. Fold (X^C1) == C2 as X == (C1^C2). * gcc.dg/fold-eqxor-1.c: New test case. * gcc.dg/fold-eqxor-2.c: Likewise. * gcc.dg/fold-eqxor-3.c: Likewise. From-SVN: r111442 --- gcc/ChangeLog | 8 ++++++++ gcc/fold-const.c | 26 ++++++++++++++++++++++++++ gcc/testsuite/ChangeLog | 7 +++++++ gcc/testsuite/gcc.dg/fold-eqxor-1.c | 28 ++++++++++++++++++++++++++++ gcc/testsuite/gcc.dg/fold-eqxor-2.c | 28 ++++++++++++++++++++++++++++ gcc/testsuite/gcc.dg/fold-eqxor-3.c | 28 ++++++++++++++++++++++++++++ 6 files changed, 125 insertions(+) create mode 100644 gcc/testsuite/gcc.dg/fold-eqxor-1.c create mode 100644 gcc/testsuite/gcc.dg/fold-eqxor-2.c create mode 100644 gcc/testsuite/gcc.dg/fold-eqxor-3.c (limited to 'gcc') diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 2c42abf..b2abdce 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,11 @@ +2006-02-25 Roger Sayle + + PR middle-end/23673 + * fold-const.c (fold_binary) : Fold (X^Y) == 0 as X == Y + and (X^Y) != 0 as X != Y. Fold (X^Y) == Y as X == 0, and some + symmetry related transformations. Fold (X^C1) == C2 as + X == (C1^C2). + 2006-02-25 Juergen Weigert Richard Guenther diff --git a/gcc/fold-const.c b/gcc/fold-const.c index 04a8fab..3c3852b 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -9767,6 +9767,32 @@ fold_binary (enum tree_code code, tree type, tree op0, tree op1) } } + /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */ + if (integer_zerop (arg1) + && TREE_CODE (arg0) == BIT_XOR_EXPR) + return fold_build2 (code, type, TREE_OPERAND (arg0, 0), + TREE_OPERAND (arg0, 1)); + + /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */ + if (TREE_CODE (arg0) == BIT_XOR_EXPR + && operand_equal_p (TREE_OPERAND (arg0, 1), arg1, 0)) + return fold_build2 (code, type, TREE_OPERAND (arg0, 0), + build_int_cst (TREE_TYPE (arg1), 0)); + /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */ + if (TREE_CODE (arg0) == BIT_XOR_EXPR + && operand_equal_p (TREE_OPERAND (arg0, 0), arg1, 0) + && reorder_operands_p (TREE_OPERAND (arg0, 1), arg1)) + return fold_build2 (code, type, TREE_OPERAND (arg0, 1), + build_int_cst (TREE_TYPE (arg1), 0)); + + /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */ + if (TREE_CODE (arg0) == BIT_XOR_EXPR + && TREE_CODE (arg1) == INTEGER_CST + && TREE_CODE (TREE_OPERAND (arg0, 1)) == INTEGER_CST) + return fold_build2 (code, type, TREE_OPERAND (arg0, 0), + fold_build2 (BIT_XOR_EXPR, TREE_TYPE (arg1), + TREE_OPERAND (arg0, 1), arg1)); + if (integer_zerop (arg1) && tree_expr_nonzero_p (arg0)) { diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 387e690..9656f4e 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,10 @@ +2006-02-25 Roger Sayle + + PR middle-end/23673 + * gcc.dg/fold-eqxor-1.c: New test case. + * gcc.dg/fold-eqxor-2.c: Likewise. + * gcc.dg/fold-eqxor-3.c: Likewise. + 2006-02-25 Thomas Koenig PR fortran/23092 diff --git a/gcc/testsuite/gcc.dg/fold-eqxor-1.c b/gcc/testsuite/gcc.dg/fold-eqxor-1.c new file mode 100644 index 0000000..d220e42 --- /dev/null +++ b/gcc/testsuite/gcc.dg/fold-eqxor-1.c @@ -0,0 +1,28 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-tree-original" } */ + +int test1(int a, int b) +{ + return (a ^ b) == 0; +} + +int test2(int c, int d) +{ + return (c ^ d) != 0; +} + +unsigned int test3(unsigned int e, unsigned int f) +{ + return (e ^ f) == 0; +} + +unsigned int test4(unsigned int g, unsigned int h) +{ + return (g ^ h) != 0; +} + +/* { dg-final { scan-tree-dump-times "a == b" 1 "original" } } */ +/* { dg-final { scan-tree-dump-times "c != d" 1 "original" } } */ +/* { dg-final { scan-tree-dump-times "e == f" 1 "original" } } */ +/* { dg-final { scan-tree-dump-times "g != h" 1 "original" } } */ +/* { dg-final { cleanup-tree-dump "original" } } */ diff --git a/gcc/testsuite/gcc.dg/fold-eqxor-2.c b/gcc/testsuite/gcc.dg/fold-eqxor-2.c new file mode 100644 index 0000000..ee5ec9fa --- /dev/null +++ b/gcc/testsuite/gcc.dg/fold-eqxor-2.c @@ -0,0 +1,28 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-tree-original" } */ + +int test1(int a, int b) +{ + return (a ^ b) == a; +} + +int test2(int c, int d) +{ + return (c ^ d) != c; +} + +int test3(int e, int f) +{ + return (e ^ f) == f; +} + +int test4(int g, int h) +{ + return (g ^ h) != h; +} + +/* { dg-final { scan-tree-dump-times "b == 0" 1 "original" } } */ +/* { dg-final { scan-tree-dump-times "d != 0" 1 "original" } } */ +/* { dg-final { scan-tree-dump-times "e == 0" 1 "original" } } */ +/* { dg-final { scan-tree-dump-times "g != 0" 1 "original" } } */ +/* { dg-final { cleanup-tree-dump "original" } } */ diff --git a/gcc/testsuite/gcc.dg/fold-eqxor-3.c b/gcc/testsuite/gcc.dg/fold-eqxor-3.c new file mode 100644 index 0000000..a087375 --- /dev/null +++ b/gcc/testsuite/gcc.dg/fold-eqxor-3.c @@ -0,0 +1,28 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-tree-original" } */ + +int test1(int a, int b) +{ + return (a ^ 2) == 2; +} + +int test2(int c, int d) +{ + return (c ^ 4) != 4; +} + +int test3(int e, int f) +{ + return (e ^ 2) == 6; +} + +int test4(int g, int h) +{ + return (g ^ 6) != 4; +} + +/* { dg-final { scan-tree-dump-times "a == 0" 1 "original" } } */ +/* { dg-final { scan-tree-dump-times "c != 0" 1 "original" } } */ +/* { dg-final { scan-tree-dump-times "e == 4" 1 "original" } } */ +/* { dg-final { scan-tree-dump-times "g != 2" 1 "original" } } */ +/* { dg-final { cleanup-tree-dump "original" } } */ -- cgit v1.1