From 1f7a8dccd4056be197e8f79fe7bbf2b8bd89c53b Mon Sep 17 00:00:00 2001 From: Roger Sayle Date: Mon, 31 May 2004 17:01:17 +0000 Subject: [PATCH] re PR c++/15069 (a bit test on a variable of enum type is miscompiled) PR middle-end/15069 * fold-const.c (fold_single_bit_test): Only perform "(X & C) != 0" into "X < 0" (where C is the signbit) if X's type is a full mode. * g++.dg/opt/fold3.C: New test case. From-SVN: r82490 --- gcc/ChangeLog | 6 ++++++ gcc/fold-const.c | 10 +++++----- gcc/testsuite/ChangeLog | 5 +++++ gcc/testsuite/g++.dg/opt/fold3.C | 21 +++++++++++++++++++++ 4 files changed, 37 insertions(+), 5 deletions(-) create mode 100644 gcc/testsuite/g++.dg/opt/fold3.C diff --git a/gcc/ChangeLog b/gcc/ChangeLog index c639b56d066..cea33d1852c 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2004-05-31 Roger Sayle + + PR middle-end/15069 + * fold-const.c (fold_single_bit_test): Only perform "(X & C) != 0" + into "X < 0" (where C is the signbit) if X's type is a full mode. + 2004-05-31 John David Anglin * pa.md: Disable the peephole2 patterns that generate indexed diff --git a/gcc/fold-const.c b/gcc/fold-const.c index d2e333e0d42..b0d1db29237 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -5413,7 +5413,11 @@ fold_single_bit_test (enum tree_code code, tree arg0, tree arg1, /* If we have (A & C) != 0 where C is the sign bit of A, convert this into A < 0. Similarly for (A & C) == 0 into A >= 0. */ arg00 = sign_bit_p (TREE_OPERAND (arg0, 0), TREE_OPERAND (arg0, 1)); - if (arg00 != NULL_TREE) + if (arg00 != NULL_TREE + /* This is only a win if casting to a signed type is cheap, + i.e. when arg00's type is not a partial mode. */ + && TYPE_PRECISION (TREE_TYPE (arg00)) + == GET_MODE_BITSIZE (TYPE_MODE (TREE_TYPE (arg00)))) { tree stype = lang_hooks.types.signed_type (TREE_TYPE (arg00)); return fold (build2 (code == EQ_EXPR ? GE_EXPR : LT_EXPR, @@ -5421,10 +5425,6 @@ fold_single_bit_test (enum tree_code code, tree arg0, tree arg1, fold_convert (stype, integer_zero_node))); } - /* At this point, we know that arg0 is not testing the sign bit. */ - if (TYPE_PRECISION (type) - 1 == bitnum) - abort (); - /* Otherwise we have (A & C) != 0 where C is a single bit, convert that into ((A >> C2) & 1). Where C2 = log2(C). Similarly for (A & C) == 0. */ diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 6d5e0a563eb..47ed126ef8b 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2004-05-31 Roger Sayle + + PR middle-end/15069 + * g++.dg/opt/fold3.C: New test case. + 2004-05-30 Graham Stott * lib/target-supports.exp (check_iconv_available): Fix fallout diff --git a/gcc/testsuite/g++.dg/opt/fold3.C b/gcc/testsuite/g++.dg/opt/fold3.C new file mode 100644 index 00000000000..87a36b9ad49 --- /dev/null +++ b/gcc/testsuite/g++.dg/opt/fold3.C @@ -0,0 +1,21 @@ +// PR middle-end/15069 +// { dg-do run } +// { dg-options "-O2" } + +extern "C" void abort (void); + +typedef enum { + FOUR = 4, + FIVE = 5 +} direction_t; + +int main () +{ + direction_t four = FOUR; + int flags = (four & 4L) ? (32L | 128L) : 0; + flags &= 32L; + + if (flags == 0) + abort (); +} + -- 2.30.2