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flags.h (flag_wrapv): New flag controlling overflow semantics.

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* flags.h (flag_wrapv): New flag controlling overflow semantics.
	* toplev.c (flag_wrapv): Declare the variable with default false.
	(lang_independent_options): New option "-fwrapv" to set the above.

	* fold-const.c (extract_muldiv_1): Disable optimization of (2*x)/2
	as x, when signed arithmetic overflow wraps around.
	(fold): Optimize "-A - B" as "-B - A" if overflow wraps around.
	* loop.c (basic_induction_var): Ignore BIVs that rely on undefined
	overflow when flag_wrapv is true.

	* java/lang.c (java_init_options): Prescribe wrap-around two's
	complement arithmetic overflow by setting flag_wrapv.

	* doc/invoke.texi: Document new -fwrapv command line option.
	* doc/c-tree.texi: Mention that the overflow semantics of
	NEGATE_EXPR, PLUS_EXPR, MINUS_EXPR and MULT_EXPR is dependent
	upon both flag_wrapv and flag_trapv.

	* gcc.dg/fwrapv-1.c: New test case.
	* gcc.dg/fwrapv-2.c: New test case.

	* libjava.lang/Overflow.java: New test.
	* libjava.lang/Overflow.out: New file.

From-SVN: r67270
This commit is contained in:
Roger Sayle 2003-05-31 13:23:32 +00:00 • committed by Roger Sayle
parent 82a2669ea7
commit 4fa26a6079
15 changed files with 137 additions and 2 deletions
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16
libjava/testsuite/libjava.lang/Overflow.java Normal file
View file

@ -0,0 +1,16 @@
class Overflow
{
static int test(int x)
{
return (2*x)/2;
}
public static void main(String argv[])
{
int x = Integer.MAX_VALUE;
if (test(x) == x)
throw new RuntimeException ();
}
}