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fold-const.c (tree_expr_nonnegative_p): Detect more non-negative cases.

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* fold-const.c (tree_expr_nonnegative_p): Detect more
	non-negative cases.

testsuite:
	* g++.old-deja/g++.warn/compare1.C: New test.
	* gcc.dg/compare4.c: New test.

From-SVN: r42365
This commit is contained in:
Kaveh R. Ghazi 2001-05-21 01:21:23 +00:00 committed by Kaveh Ghazi
parent 4b40451753
commit 88e3805d76
5 changed files with 107 additions and 0 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
2001-05-20 Kaveh R. Ghazi <ghazi@caip.rutgers.edu>
* fold-const.c (tree_expr_nonnegative_p): Detect more non-negative
cases.
2001-05-21 Joseph S. Myers <jsm28@cam.ac.uk>
* extend.texi: Clarify documentation of extensions included in ISO

13
gcc/fold-const.c
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@ -7351,11 +7351,24 @@ tree_expr_nonnegative_p (t)
{
switch (TREE_CODE (t))
{
case ABS_EXPR:
case FFS_EXPR:
return 1;
case INTEGER_CST:
return tree_int_cst_sgn (t) >= 0;
case COND_EXPR:
return tree_expr_nonnegative_p (TREE_OPERAND (t, 1))
&& tree_expr_nonnegative_p (TREE_OPERAND (t, 2));
case COMPOUND_EXPR:
return tree_expr_nonnegative_p (TREE_OPERAND (t, 1));
case MIN_EXPR:
return tree_expr_nonnegative_p (TREE_OPERAND (t, 0))
&& tree_expr_nonnegative_p (TREE_OPERAND (t, 1));
case MAX_EXPR:
return tree_expr_nonnegative_p (TREE_OPERAND (t, 0))
|| tree_expr_nonnegative_p (TREE_OPERAND (t, 1));
case MODIFY_EXPR:
return tree_expr_nonnegative_p (TREE_OPERAND (t, 1));
case BIND_EXPR:
return tree_expr_nonnegative_p (TREE_OPERAND (t, 1));
case RTL_EXPR:

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2001-05-20 Kaveh R. Ghazi <ghazi@caip.rutgers.edu>
* g++.old-deja/g++.warn/compare1.C: New test.
* gcc.dg/compare4.c: New test.
2001-05-20 Nathan Sidwell <nathan@codesourcery.com>
* g++.old-deja/g++.other/optimize1.C: New test.

36
gcc/testsuite/g++.old-deja/g++.warn/compare1.C Normal file
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@ -0,0 +1,36 @@
// Build don't link:
// Special g++ Options: -ansi -pedantic-errors -Wsign-compare
// Copyright (C) 2001 Free Software Foundation, Inc.
// Contributed by Kaveh R. Ghazi <ghazi@caip.rutgers.edu> 5/13/2001
int foo(int x, int y, unsigned u)
{
/* A MAX_EXPR is non-negative if EITHER argument to the MAX_EXPR is
determined to be non-negative. */
if (u < (x >? -1)) // WARNING - signed and unsigned
return x;
if (u < (x >? 10))
return x;
if ((10 >? x) < u)
return x;
if (u < (x >? (y ? (x==y) : 10)))
return x;
if (((y ? 10 : (x==y)) >? x) < u)
return x;
/* A MIN_EXPR is non-negative if BOTH arguments to the MIN_EXPR are
determined to be non-negative. */
if (u < ((x?11:8) <? -1)) // WARNING - signed and unsigned
return x;
if (u < ((x?11:8) <? 10))
return x;
if ((10 <? (x?8:11)) < u)
return x;
if (u < ((x?11:(x==y)) <? 10))
return x;
if ((10 <? (x?(x==y):11)) < u)
return x;
return 0;
}

48
gcc/testsuite/gcc.dg/compare4.c Normal file
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@ -0,0 +1,48 @@
/* Test for a bogus warning on comparison between signed and unsigned.
Origin: Kaveh R. Ghazi <ghazi@caip.rutgers.edu> 5/13/2001. */
/* { dg-do compile } */
/* { dg-options "-Wsign-compare" } */
extern void bar(void);
int foo(int x, int y, unsigned u)
{
/* A COMPOUND_EXPR is non-negative if the last element is known to
be non-negative. */
if (u < (bar(), -1)) /*{ dg-warning "signed and unsigned" "COMPOUND_EXPR" }*/
return x;
if (u < (bar(), 10))
return x;
if ((bar(), 10) < u)
return x;
if (u < (x ? (bar(),bar(),bar(),bar(),x==y) : 10))
return x;
if ((x ? 10 : (bar(),bar(),bar(),bar(),x==y)) < u)
return x;
/* Test an ABS_EXPR, which is by definition non-negative. */
if (u < __builtin_abs(x))
return x;
if (__builtin_abs(x) < u)
return x;
if (u < (x ? __builtin_abs(x) : 10))
return x;
if ((x ? 10: __builtin_abs(x)) < u)
return x;
/* A MODIFY_EXPR is non-negative if the new value is known to be
non-negative. */
if (u < (x = -1)) /* { dg-warning "signed and unsigned" "MODIFY_EXPR" } */
return x;
if (u < (x = 10))
return x;
if ((x = 10) < u)
return x;
if (u < (x = (y ? (x==y) : 10)))
return x;
if ((x = (y ? 10 : (x==y))) < u)
return x;
return 0;
}