re PR c/35701 (Quieten -Wconversion warnings)

2008-08-20  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>

	PR 35701
	* c-common.c (conversion_warning): Do not warn if applying bit-and
	operator to unsigned constant that fits in the target type.
	
testsuite/
	* gcc.dg/pr35701.c: New.
	* gcc.dg/Wconversion-real-integer.c: Add more tests.
	* gcc.dg/Wconversion-pr34389.c: Update.
	* g++.dg/warn/Wconversion-pr34389.C: Update.

From-SVN: r139329

8 files changed, 145 insertions, 8 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 9560a7b..956d401 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,11 @@
 2008-08-20  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>
 
+	PR 35701
+	* c-common.c (conversion_warning): Do not warn if applying bit-and
+	operator to unsigned constant that fits in the target type.
+
+2008-08-20  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>
+
 	PR c++/35602
 	* c-common.c (conversion_warning): Do not warn for artificial
 	expressions.
diff --git a/gcc/c-common.c b/gcc/c-common.c
index 92e58c9..bb420ba 100644
--- a/gcc/c-common.c
+++ b/gcc/c-common.c
@@ -1693,13 +1693,16 @@ conversion_warning (tree type, tree expr)
 					     TREE_OPERAND (expr, 1), 
 					     /* bitwise */1);
 
-	      /* If one of the operands is a non-negative constant
-		 that fits in the target type, then the type of the
-		 other operand does not matter. */
 	      if (TREE_CODE (expr) == BIT_AND_EXPR)
 		{
 		  tree op0 = TREE_OPERAND (expr, 0);
 		  tree op1 = TREE_OPERAND (expr, 1);
+		  bool unsigned0 = TYPE_UNSIGNED (TREE_TYPE (op0));
+		  bool unsigned1 = TYPE_UNSIGNED (TREE_TYPE (op1));
+
+		  /* If one of the operands is a non-negative constant
+		     that fits in the target type, then the type of the
+		     other operand does not matter. */
 		  if ((TREE_CODE (op0) == INTEGER_CST
 		       && int_fits_type_p (op0, c_common_signed_type (type))
 		       && int_fits_type_p (op0, c_common_unsigned_type (type)))
@@ -1708,6 +1711,15 @@ conversion_warning (tree type, tree expr)
 			  && int_fits_type_p (op1, 
 					      c_common_unsigned_type (type))))
 		    return;
+		  /* If constant is unsigned and fits in the target
+		     type, then the result will also fit.  */
+		  else if ((TREE_CODE (op0) == INTEGER_CST
+			    && unsigned0 
+			    && int_fits_type_p (op0, type))
+			   || (TREE_CODE (op1) == INTEGER_CST
+			       && unsigned1
+			       && int_fits_type_p (op1, type)))
+		    return;
 		}
 	    }
           /* Warn for integer types converted to smaller integer types.  */
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 2c87d83..2a6c60e 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,13 @@
 2008-08-20  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>
 
+	PR 35701
+	* gcc.dg/pr35701.c: New.
+	* gcc.dg/Wconversion-real-integer.c: Add more tests.
+	* gcc.dg/Wconversion-pr34389.c: Update.
+	* g++.dg/warn/Wconversion-pr34389.C: Update.
+
+2008-08-20  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>
+
 	PR c++/35602
 	* g++.dg/warn/pr35602.C: New.
 
diff --git a/gcc/testsuite/g++.dg/warn/Wconversion-pr34389.C b/gcc/testsuite/g++.dg/warn/Wconversion-pr34389.C
index f3cd310..a6df403 100644
--- a/gcc/testsuite/g++.dg/warn/Wconversion-pr34389.C
+++ b/gcc/testsuite/g++.dg/warn/Wconversion-pr34389.C
@@ -1,7 +1,7 @@
 /* PR 34389 */
 /* { dg-do compile } */
 /* { dg-options "-Wconversion -Wsign-conversion" } */
-
+/* { dg-require-effective-target int32plus } */
 short  mask1(short x)
 {
   short y = 0x7fff;
@@ -32,7 +32,8 @@ short  mask3(int si, unsigned int ui)
   us = si & 0x7fff;
   us = si & 0xAAAA; /* { dg-warning "conversion" } */
   us = ui & 0x7fff;
-  us = ui & 0xAAAA; /* { dg-warning "conversion" } */
+  us = ui & 0xAAAA; /* 0xAAAA is zero-extended, thus it masks the
+		       upper bits of 'ui' making it fit in 'us'.  */
 
   return ss;
 }
diff --git a/gcc/testsuite/g++.dg/warn/Wconversion-real-integer.C b/gcc/testsuite/g++.dg/warn/Wconversion-real-integer.C
index 64d5199..282ac13 100644
--- a/gcc/testsuite/g++.dg/warn/Wconversion-real-integer.C
+++ b/gcc/testsuite/g++.dg/warn/Wconversion-real-integer.C
@@ -4,7 +4,7 @@
 
 /* { dg-do compile }
 /* { dg-options "-Wconversion" } */
-
+/* { dg-require-effective-target int32plus } */
 #include <limits.h>
 
 void fsi (signed int x);
@@ -71,3 +71,42 @@ void h (void)
 }
 
 
+void fss (signed short x);
+void fus (unsigned short x);
+void fsc (signed char x);
+void fuc (unsigned char x);
+
+void h2 (void)
+{
+  unsigned short int us;
+  short int   ss;
+  unsigned char uc;
+  signed char sc;
+  
+  fss (4294967294.0); /* { dg-warning "conversion" } */
+  ss = 4294967294.0; /* { dg-warning "conversion" } */
+  fss (-4294967294.0);  /* { dg-warning "conversion" } */
+  ss = -4294967294.0;  /* { dg-warning "conversion" } */
+  fus (4294967294.0); /* { dg-warning "conversion" } */
+  us = 4294967294.0; /* { dg-warning "conversion" } */
+  fus (-4294967294.0);  /* { dg-warning "conversion" } */
+  us = -4294967294.0;  /* { dg-warning "conversion" } */
+
+  fsc (500.0); /* { dg-warning "conversion" } */
+  sc = 500.0; /* { dg-warning "conversion" } */
+  fsc (-500.0);  /* { dg-warning "conversion" } */
+  sc = -500.0;  /* { dg-warning "conversion" } */
+  fuc (500.0); /* { dg-warning "conversion" } */
+  uc = 500.0; /* { dg-warning "conversion" } */
+  fuc (-500.0);  /* { dg-warning "conversion" } */
+  uc = -500.0;  /* { dg-warning "conversion" } */
+
+  fss (500.0);
+  ss = 500.0;
+  fss (-500.0);
+  ss = -500.0;
+  fus (500.0); 
+  us = 500.0; 
+  fus (-500.0);   /* { dg-warning "conversion" } */
+  us = -500.0;    /* { dg-warning "conversion" } */
+}
diff --git a/gcc/testsuite/gcc.dg/Wconversion-pr34389.c b/gcc/testsuite/gcc.dg/Wconversion-pr34389.c
index 45cdf19..1a43368 100644
--- a/gcc/testsuite/gcc.dg/Wconversion-pr34389.c
+++ b/gcc/testsuite/gcc.dg/Wconversion-pr34389.c
@@ -1,6 +1,7 @@
 /* PR 34389 */
 /* { dg-do compile } */
 /* { dg-options "-Wconversion -Wsign-conversion" } */
+/* { dg-require-effective-target int32plus } */
 
 short  mask1(short x)
 {
@@ -32,7 +33,8 @@ short  mask3(int si, unsigned int ui)
   us = si & 0x7fff;
   us = si & 0xAAAA; /* { dg-warning "conversion" } */
   us = ui & 0x7fff;
-  us = ui & 0xAAAA; /* { dg-warning "conversion" } */
+  us = ui & 0xAAAA; /* 0xAAAA is zero-extended, thus it masks the
+		       upper bits of 'ui' making it fit in 'us'.  */
 
   return ss;
 }
diff --git a/gcc/testsuite/gcc.dg/Wconversion-real-integer.c b/gcc/testsuite/gcc.dg/Wconversion-real-integer.c
index 1c03ba4..1625fc0 100644
--- a/gcc/testsuite/gcc.dg/Wconversion-real-integer.c
+++ b/gcc/testsuite/gcc.dg/Wconversion-real-integer.c
@@ -4,7 +4,7 @@
 /* { dg-do compile }
 /* { dg-skip-if "doubles are floats,ints are 16bits" { "avr-*-*" } { "*" } { "" } } */
 /* { dg-options "-std=c99 -Wconversion" } */
-
+/* { dg-require-effective-target int32plus } */
 #include <limits.h>
 
 void fsi (signed int x);
@@ -71,4 +71,42 @@ void h (void)
 }
 
 
+void fss (signed short x);
+void fus (unsigned short x);
+void fsc (signed char x);
+void fuc (unsigned char x);
+
+void h2 (void)
+{
+  unsigned short int us;
+  short int   ss;
+  unsigned char uc;
+  signed char sc;
+  
+  fss (4294967294.0); /* { dg-warning "conversion" } */
+  ss = 4294967294.0; /* { dg-warning "conversion" } */
+  fss (-4294967294.0);  /* { dg-warning "conversion" } */
+  ss = -4294967294.0;  /* { dg-warning "conversion" } */
+  fus (4294967294.0); /* { dg-warning "conversion" } */
+  us = 4294967294.0; /* { dg-warning "conversion" } */
+  fus (-4294967294.0);  /* { dg-warning "conversion" } */
+  us = -4294967294.0;  /* { dg-warning "conversion" } */
 
+  fsc (500.0); /* { dg-warning "conversion" } */
+  sc = 500.0; /* { dg-warning "conversion" } */
+  fsc (-500.0);  /* { dg-warning "conversion" } */
+  sc = -500.0;  /* { dg-warning "conversion" } */
+  fuc (500.0); /* { dg-warning "conversion" } */
+  uc = 500.0; /* { dg-warning "conversion" } */
+  fuc (-500.0);  /* { dg-warning "conversion" } */
+  uc = -500.0;  /* { dg-warning "conversion" } */
+
+  fss (500.0);
+  ss = 500.0;
+  fss (-500.0);
+  ss = -500.0;
+  fus (500.0); 
+  us = 500.0; 
+  fus (-500.0);   /* { dg-warning "conversion" } */
+  us = -500.0;    /* { dg-warning "conversion" } */
+}
diff --git a/gcc/testsuite/gcc.dg/pr35701.c b/gcc/testsuite/gcc.dg/pr35701.c
new file mode 100644
index 0000000..4144430
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr35701.c
@@ -0,0 +1,31 @@
+/* PR 35701 */
+/* { dg-do compile } */
+/* { dg-options "-Wconversion -Wsign-conversion" } */
+/* { dg-require-effective-target int32plus } */
+
+typedef struct _my_struct_t {
+  unsigned int small:1;
+  unsigned int big:31;
+} my_struct_t, *my_struct_p_t;
+
+void
+my_func1(unsigned int sm, unsigned int bi, my_struct_p_t msp)
+{
+  msp->small = sm; /* { dg-warning "conversion" } */
+  msp->big = bi; /* { dg-warning "conversion" } */
+}
+
+void
+my_func2(unsigned int sm, unsigned int bi, my_struct_p_t msp)
+{
+  msp->small = sm & 1U;
+  msp->big = bi & 0x7fffffffU;
+}
+
+unsigned short
+my_func3(unsigned int sm)
+{
+  unsigned short res;
+  res = sm & 0xff20U;
+  return res;
+}