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[Patch] bogus signed/unsigned warning
- From: Ansgar Esztermann <ansgar at thphy dot uni-duesseldorf dot de>
- To: gcc-patches at gcc dot gnu dot org
- Date: Wed, 28 Aug 2002 15:42:41 +0200 (CEST)
- Subject: [Patch] bogus signed/unsigned warning
Hello,
this is a resubmission of a patch I proposed a few days ago.
I have cleaned up the source code formatting and resolved a mix-up
of language-independent and language-specific files.
Description:
gcc used to issue bogus warnings with -Wsign-compare if one of the
operands was a statement expression. This caused testcases 10 and 12 in
gcc.dg/compare2.c to fail.
ChangeLog:
2002-08-28 Ansgar Esztermann <ansgar@thphy.uni-duesseldorf.de>
* c-typeck.c (c_tree_expr_nonnegative_p): New function.
(build_binary_op): Call c_tree_expr_nonnegative_p rather than
tree_expr_nonnegative_p.
(build_conditional_expr): Likewise.
* c-tree.h (c_tree_expr_nonnegative_p): Declare.
* gcc.dg/compare2.c: Remove xfail from cases 10 and 12.
Testing:
make bootstrap on i686-pc-linux-gnu succeeded.
make check yielded the same results as before, except for the two
testcases mentioned above.
Patch:
Index: c-tree.h
===================================================================
RCS file: /cvsroot/gcc/gcc/gcc/c-tree.h,v
retrieving revision 1.105
diff -c -3 -p -r1.105 c-tree.h
*** c-tree.h 15 Aug 2002 21:16:23 -0000 1.105
--- c-tree.h 28 Aug 2002 08:46:50 -0000
*************** extern tree build_array_ref
*** 268,273 ****
--- 268,274 ----
extern tree build_external_ref PARAMS ((tree, int));
extern tree parser_build_binary_op PARAMS ((enum tree_code,
tree, tree));
+ extern int c_tree_expr_nonnegative_p PARAMS ((tree));
extern void readonly_warning PARAMS ((tree, const char *));
extern tree build_conditional_expr PARAMS ((tree, tree, tree));
extern tree build_compound_expr PARAMS ((tree));
Index: c-typeck.c
===================================================================
RCS file: /cvsroot/gcc/gcc/gcc/c-typeck.c,v
retrieving revision 1.203
diff -c -3 -p -r1.203 c-typeck.c
*** c-typeck.c 15 Aug 2002 21:16:23 -0000 1.203
--- c-typeck.c 28 Aug 2002 08:46:53 -0000
*************** build_binary_op (code, orig_op0, orig_op
*** 2463,2469 ****
constant expression involving such literals or a
conditional expression involving such literals)
and it is non-negative. */
! if (tree_expr_nonnegative_p (sop))
/* OK */;
/* Do not warn if the comparison is an equality operation,
the unsigned quantity is an integral constant, and it
--- 2463,2469 ----
constant expression involving such literals or a
conditional expression involving such literals)
and it is non-negative. */
! if (c_tree_expr_nonnegative_p (sop))
/* OK */;
/* Do not warn if the comparison is an equality operation,
the unsigned quantity is an integral constant, and it
*************** build_binary_op (code, orig_op0, orig_op
*** 2579,2584 ****
--- 2579,2605 ----
}
}
+
+ /* Return true if `t' is known to be non-negative. */
+
+ int
+ c_tree_expr_nonnegative_p (t)
+ tree t;
+ {
+ if (TREE_CODE (t) == STMT_EXPR)
+ {
+ t=COMPOUND_BODY (STMT_EXPR_STMT (t));
+
+ /* Find the last statement in the chain, ignoring the final
+ * scope statement */
+ while (TREE_CHAIN (t) != NULL_TREE
+ && TREE_CODE (TREE_CHAIN (t)) != SCOPE_STMT)
+ t=TREE_CHAIN (t);
+ return tree_expr_nonnegative_p (TREE_OPERAND (t, 0));
+ }
+ return tree_expr_nonnegative_p (t);
+ }
+
/* Return a tree for the difference of pointers OP0 and OP1.
The resulting tree has type int. */
*************** build_conditional_expr (ifexp, op1, op2)
*** 3406,3413 ****
/* Do not warn if the signed quantity is an unsuffixed
integer literal (or some static constant expression
involving such literals) and it is non-negative. */
! else if ((unsigned_op2 && tree_expr_nonnegative_p (op1))
! || (unsigned_op1 && tree_expr_nonnegative_p (op2)))
/* OK */;
else
warning ("signed and unsigned type in conditional expression");
--- 3427,3434 ----
/* Do not warn if the signed quantity is an unsuffixed
integer literal (or some static constant expression
involving such literals) and it is non-negative. */
! else if ((unsigned_op2 && c_tree_expr_nonnegative_p (op1))
! || (unsigned_op1 && c_tree_expr_nonnegative_p (op2)))
/* OK */;
else
warning ("signed and unsigned type in conditional expression");
Index: testsuite/gcc.dg/compare2.c
===================================================================
RCS file: /cvsroot/gcc/gcc/gcc/testsuite/gcc.dg/compare2.c,v
retrieving revision 1.5
diff -c -3 -p -r1.5 compare2.c
*** testsuite/gcc.dg/compare2.c 19 Sep 2000 07:33:44 -0000 1.5
--- testsuite/gcc.dg/compare2.c 28 Aug 2002 08:47:05 -0000
*************** void f(int x, unsigned int y)
*** 26,36 ****
/* Statement expression. */
x > ({tf; 64;}); /* { dg-bogus "signed and unsigned" "case 9" } */
! y > ({tf; 64;}); /* { dg-bogus "signed and unsigned" "case 10" { xfail *-*-* } } */
/* Statement expression with recursive ?: . */
x > ({tf; tf?64:(tf?128:256);}); /* { dg-bogus "signed and unsigned" "case 11" } */
! y > ({tf; tf?64:(tf?128:256);}); /* { dg-bogus "signed and unsigned" "case 12" { xfail *-*-* } } */
/* Statement expression with signed ?:. */
x > ({tf; tf?64:-1;}); /* { dg-bogus "signed and unsigned" "case 13" } */
--- 26,36 ----
/* Statement expression. */
x > ({tf; 64;}); /* { dg-bogus "signed and unsigned" "case 9" } */
! y > ({tf; 64;}); /* { dg-bogus "signed and unsigned" "case 10" } */
/* Statement expression with recursive ?: . */
x > ({tf; tf?64:(tf?128:256);}); /* { dg-bogus "signed and unsigned" "case 11" } */
! y > ({tf; tf?64:(tf?128:256);}); /* { dg-bogus "signed and unsigned" "case 12" } */
/* Statement expression with signed ?:. */
x > ({tf; tf?64:-1;}); /* { dg-bogus "signed and unsigned" "case 13" } */
Ansgar
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