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authorupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
committerupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
commit554fd8c5195424bdbcabf5de30fdc183aba391bd (patch)
tree976dc5ab7fddf506dadce60ae936f43f58787092 /gcc/testsuite/gcc.c-torture/execute/bitfld-1.c
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Diffstat (limited to 'gcc/testsuite/gcc.c-torture/execute/bitfld-1.c')
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diff --git a/gcc/testsuite/gcc.c-torture/execute/bitfld-1.c b/gcc/testsuite/gcc.c-torture/execute/bitfld-1.c
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+/* Copyright 2002 Free Software Foundation, Inc.
+
+ Tests correct signedness of operations on bitfields; in particular
+ that integer promotions are done correctly, including the case when
+ casts are present.
+
+ The C front end was eliding the cast of an unsigned bitfield to
+ unsigned as a no-op, when in fact it forces a conversion to a
+ full-width unsigned int. (At the time of writing, the C++ front end
+ has a different bug; it erroneously promotes the uncast unsigned
+ bitfield to an unsigned int).
+
+ Source: Neil Booth, 25 Jan 2002, based on PR 3325 (and 3326, which
+ is a different manifestation of the same bug).
+*/
+
+extern void abort ();
+
+int
+main(int argc, char *argv[])
+{
+ struct x { signed int i : 7; unsigned int u : 7; } bit;
+
+ unsigned int u;
+ int i;
+ unsigned int unsigned_result = -13U % 61;
+ int signed_result = -13 % 61;
+
+ bit.u = 61, u = 61;
+ bit.i = -13, i = -13;
+
+ if (i % u != unsigned_result)
+ abort ();
+ if (i % (unsigned int) u != unsigned_result)
+ abort ();
+
+ /* Somewhat counter-intuitively, bit.u is promoted to an int, making
+ the operands and result an int. */
+ if (i % bit.u != signed_result)
+ abort ();
+
+ if (bit.i % bit.u != signed_result)
+ abort ();
+
+ /* But with a cast to unsigned int, the unsigned int is promoted to
+ itself as a no-op, and the operands and result are unsigned. */
+ if (i % (unsigned int) bit.u != unsigned_result)
+ abort ();
+
+ if (bit.i % (unsigned int) bit.u != unsigned_result)
+ abort ();
+
+ return 0;
+}