* fold-const.c (tree_expr_nonnegative_p): Treat truth values as

	non-negative.

testsuite:
	* gcc.dg/compare3.c: New test.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@38374 138bc75d-0d04-0410-961f-82ee72b054a4

4 files changed, 74 insertions, 2 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 6932876158b..23c0eb5f38e 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2000-12-18  Kaveh R. Ghazi  <ghazi@caip.rutgers.edu>
+
+	* fold-const.c (tree_expr_nonnegative_p): Treat truth values as
+	non-negative.
+
 Tue Dec 19 00:37:08 2000  J"orn Rennecke <amylaar@redhat.com>
 
 	* reload.c (push_reload): When using a dying register for the reload
diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index d8131faf226..a0a76b2d491 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -7299,8 +7299,12 @@ tree_expr_nonnegative_p (t)
       return rtl_expr_nonnegative_p (RTL_EXPR_RTL (t));
       
     default:
-      /* We don't know sign of `t', so be safe and return false.  */
-      return 0;
+      if (truth_value_p (TREE_CODE (t)))
+	/* Truth values evaluate to 0 or 1, which is nonnegative.  */
+	return 1;
+      else
+	/* We don't know sign of `t', so be conservative and return false.  */
+	return 0;
     }
 }
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index b60cda7515e..06c54bc3d1f 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2000-12-18  Kaveh R. Ghazi  <ghazi@caip.rutgers.edu>
+
+	* gcc.dg/compare3.c: New test.
+
 2000-12-18  Joseph S. Myers  <jsm28@cam.ac.uk>
 
 	* gcc.dg/format-warnll-1.c: New test.
diff --git a/gcc/testsuite/gcc.dg/compare3.c b/gcc/testsuite/gcc.dg/compare3.c
new file mode 100644
index 00000000000..eda3faf2754
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/compare3.c
@@ -0,0 +1,59 @@
+/* Test for a bogus warning on comparison between signed and unsigned.
+   This was inspired by code in gcc. */
+
+/* { dg-do compile } */
+/* { dg-options "-Wsign-compare" } */
+
+int tf = 1;
+
+void f(int x, unsigned int y)
+{
+  /* Test comparing conditional expressions containing truth values.
+     This can occur explicitly, or e.g. when (foo?2:(bar?1:0)) is
+     optimized into (foo?2:(bar!=0)).  */
+  x > (tf?64:(tf!=x)); /* { dg-bogus "signed and unsigned" "case 1" } */
+  y > (tf?64:(tf!=x)); /* { dg-bogus "signed and unsigned" "case 2" } */
+  x > (tf?(tf!=x):64); /* { dg-bogus "signed and unsigned" "case 3" } */
+  y > (tf?(tf!=x):64); /* { dg-bogus "signed and unsigned" "case 4" } */
+
+  x > (tf?64:(tf==x)); /* { dg-bogus "signed and unsigned" "case 5" } */
+  y > (tf?64:(tf==x)); /* { dg-bogus "signed and unsigned" "case 6" } */
+  x > (tf?(tf==x):64); /* { dg-bogus "signed and unsigned" "case 7" } */
+  y > (tf?(tf==x):64); /* { dg-bogus "signed and unsigned" "case 8" } */
+
+  x > (tf?64:(tf>x)); /* { dg-bogus "signed and unsigned" "case 9" } */
+  y > (tf?64:(tf>x)); /* { dg-bogus "signed and unsigned" "case 10" } */
+  x > (tf?(tf>x):64); /* { dg-bogus "signed and unsigned" "case 11" } */
+  y > (tf?(tf>x):64); /* { dg-bogus "signed and unsigned" "case 12" } */
+
+  x < (tf?64:(tf<x)); /* { dg-bogus "signed and unsigned" "case 13" } */
+  y < (tf?64:(tf<x)); /* { dg-bogus "signed and unsigned" "case 14" } */
+  x < (tf?(tf<x):64); /* { dg-bogus "signed and unsigned" "case 15" } */
+  y < (tf?(tf<x):64); /* { dg-bogus "signed and unsigned" "case 16" } */
+
+  x > (tf?64:(tf>=x)); /* { dg-bogus "signed and unsigned" "case 17" } */
+  y > (tf?64:(tf>=x)); /* { dg-bogus "signed and unsigned" "case 18" } */
+  x > (tf?(tf>=x):64); /* { dg-bogus "signed and unsigned" "case 19" } */
+  y > (tf?(tf>=x):64); /* { dg-bogus "signed and unsigned" "case 20" } */
+
+  x > (tf?64:(tf<=x)); /* { dg-bogus "signed and unsigned" "case 21" } */
+  y > (tf?64:(tf<=x)); /* { dg-bogus "signed and unsigned" "case 22" } */
+  x > (tf?(tf<=x):64); /* { dg-bogus "signed and unsigned" "case 23" } */
+  y > (tf?(tf<=x):64); /* { dg-bogus "signed and unsigned" "case 24" } */
+
+  x > (tf?64:(tf&&x)); /* { dg-bogus "signed and unsigned" "case 25" } */
+  y > (tf?64:(tf&&x)); /* { dg-bogus "signed and unsigned" "case 26" } */
+  x > (tf?(tf&&x):64); /* { dg-bogus "signed and unsigned" "case 27" } */
+  y > (tf?(tf&&x):64); /* { dg-bogus "signed and unsigned" "case 28" } */
+
+  x > (tf?64:(tf||x)); /* { dg-bogus "signed and unsigned" "case 29" } */
+  y > (tf?64:(tf||x)); /* { dg-bogus "signed and unsigned" "case 30" } */
+  x > (tf?(tf||x):64); /* { dg-bogus "signed and unsigned" "case 31" } */
+  y > (tf?(tf||x):64); /* { dg-bogus "signed and unsigned" "case 32" } */
+
+  x > (tf?64:(!tf)); /* { dg-bogus "signed and unsigned" "case 33" } */
+  y > (tf?64:(!tf)); /* { dg-bogus "signed and unsigned" "case 34" } */
+  x > (tf?(!tf):64); /* { dg-bogus "signed and unsigned" "case 35" } */
+  y > (tf?(!tf):64); /* { dg-bogus "signed and unsigned" "case 36" } */
+
+}