Re: [patch] Scalar to vector widening

[Ken Werner <ken at linux dot vnet dot ibm dot com>]

On Friday, October 08, 2010 3:14:41 pm Ulrich Weigand wrote:
> I don't think these are quite right.  If, say, arg2 is a vector of
> different type, this may get simply cast away.  Likewise, if arg1
> is a very short integer type, the cast may actually remove valid
> bits in arg2 ...   I think the cast really should only be done if
> one side is a vector and the other a scalar.

Oh, I overlooked that - thanks.

> However, I don't quite like distributing the code between the various
> promotion routines.  In fact, I'm starting to think this shouldn't
> actually be though of as a promotion at all.  Instead, why not simply
> handle the case directly in vector_binop?  If only one side is a vector
> and the other is a scalar, cast it there.  This should simplify the
> patch even further.

Sounds good. Attached is a new version of the patch. Tested on i686-*-linux-
gnu, no regressions.

Regards
Ken

ChangeLog:

2010-10-08  Ken Werner  <ken.werner@de.ibm.com>

	* valops.c (value_cast): Handle vector types.
	* valarith.c (value_binop): Widen scalar to vector if appropriate.

testsuite/ChangeLog:

2010-10-08  Ken Werner  <ken.werner@de.ibm.com>

	* gdb.base/gnu_vector.c (ia, ib, fa, fb): New variables.
	* gdb.base/gnu_vector.exp: Add tests for scalar to vector widening.


Index: gdb/valarith.c
===================================================================
RCS file: /cvs/src/src/gdb/valarith.c,v
retrieving revision 1.86
diff -p -u -r1.86 valarith.c
--- gdb/valarith.c	11 Aug 2010 16:48:26 -0000	1.86
+++ gdb/valarith.c	8 Oct 2010 16:22:00 -0000
@@ -1435,14 +1435,34 @@ vector_binop (struct value *val1, struct
 struct value *
 value_binop (struct value *arg1, struct value *arg2, enum exp_opcode op)
 {
+  struct value *val;
   struct type *type1 = check_typedef (value_type (arg1));
   struct type *type2 = check_typedef (value_type (arg2));
-
-  if ((TYPE_CODE (type1) == TYPE_CODE_ARRAY && TYPE_VECTOR (type1))
-	  || (TYPE_CODE (type2) == TYPE_CODE_ARRAY && TYPE_VECTOR (type2)))
-    return vector_binop (arg1, arg2, op);
+  int t1_is_vec = (TYPE_CODE (type1) == TYPE_CODE_ARRAY
+		   && TYPE_VECTOR (type1));
+  int t2_is_vec = (TYPE_CODE (type2) == TYPE_CODE_ARRAY
+		   && TYPE_VECTOR (type2));
+
+  if (!t1_is_vec && !t2_is_vec)
+    val = scalar_binop (arg1, arg2, op);
+  else if (t1_is_vec && t2_is_vec)
+    val = vector_binop (arg1, arg2, op);
   else
-    return scalar_binop (arg1, arg2, op);
+    {
+      /* Widen the scalar operand to a vector.  */
+      struct value **v = t1_is_vec ? &arg2 : &arg1;
+      struct type *t = t1_is_vec ? type2 : type1;
+      
+      if (TYPE_CODE (t) != TYPE_CODE_FLT
+	  && TYPE_CODE (t) != TYPE_CODE_DECFLOAT
+	  && !is_integral_type (t))
+	error (_("Argument to operation not a number or boolean."));
+
+      *v = value_cast (t1_is_vec ? type1 : type2, *v);
+      val = vector_binop (arg1, arg2, op);
+    }
+
+  return val;
 }
 
 /* Simulate the C operator ! -- return 1 if ARG1 contains zero.  */
Index: gdb/valops.c
===================================================================
RCS file: /cvs/src/src/gdb/valops.c,v
retrieving revision 1.251
diff -p -u -r1.251 valops.c
--- gdb/valops.c	24 Sep 2010 14:47:53 -0000	1.251
+++ gdb/valops.c	8 Oct 2010 16:22:01 -0000
@@ -421,7 +421,8 @@ value_cast (struct type *type, struct va
     }
 
   if (current_language->c_style_arrays
-      && TYPE_CODE (type2) == TYPE_CODE_ARRAY)
+      && TYPE_CODE (type2) == TYPE_CODE_ARRAY
+      && !TYPE_VECTOR (type2))
     arg2 = value_coerce_array (arg2);
 
   if (TYPE_CODE (type2) == TYPE_CODE_FUNC)
@@ -537,6 +538,26 @@ value_cast (struct type *type, struct va
 	 minus one, instead of biasing the normal case.  */
       return value_from_longest (type, -1);
     }
+  else if (code1 == TYPE_CODE_ARRAY && TYPE_VECTOR (type) && scalar)
+    {
+      /* Widen the scalar to a vector.  */
+      struct type *eltype;
+      struct value *val;
+      int i, n;
+
+      eltype = check_typedef (TYPE_TARGET_TYPE (type));
+      arg2 = value_cast (eltype, arg2);
+      val = allocate_value (type);
+      n = TYPE_LENGTH (type) / TYPE_LENGTH (eltype);
+
+      for (i = 0; i < n; i++)
+	{
+	  /* Duplicate the contents of arg2 into the destination vector.  */
+	  memcpy (value_contents_writeable (val) + (i * TYPE_LENGTH (eltype)),
+		  value_contents_all (arg2), TYPE_LENGTH (eltype));
+	}
+      return val;
+    }
   else if (TYPE_LENGTH (type) == TYPE_LENGTH (type2))
     {
       if (code1 == TYPE_CODE_PTR && code2 == TYPE_CODE_PTR)
Index: gdb/testsuite/gdb.base/gnu_vector.c
===================================================================
RCS file: /cvs/src/src/gdb/testsuite/gdb.base/gnu_vector.c,v
retrieving revision 1.2
diff -p -u -r1.2 gnu_vector.c
--- gdb/testsuite/gdb.base/gnu_vector.c	6 Oct 2010 08:44:15 -0000	1.2
+++ gdb/testsuite/gdb.base/gnu_vector.c	8 Oct 2010 16:22:01 -0000
@@ -17,16 +17,30 @@
 
    Contributed by Ken Werner <ken.werner@de.ibm.com>  */
 
-char __attribute__ ((vector_size (4 * sizeof(char)))) c4 = {1, 2, 3, 4};
-int __attribute__ ((vector_size (4 * sizeof(int)))) i4a = {2, 4, 8, 16};
-int __attribute__ ((vector_size (4 * sizeof(int)))) i4b = {1, 2, 8, 4};
-float __attribute__ ((vector_size (4 * sizeof(float)))) f4a = {2, 4, 8, 16};
-float __attribute__ ((vector_size (4 * sizeof(float)))) f4b = {1, 2, 8, 4};
-unsigned int __attribute__ ((vector_size (4 * sizeof(unsigned int)))) ui4 = {2, 4, 8, 16};
-int __attribute__ ((vector_size (2 * sizeof(int)))) i2 = {1, 2};
-long long __attribute__ ((vector_size (2 * sizeof(long long)))) ll2 = {1, 2};
-float __attribute__ ((vector_size (2 * sizeof(float)))) f2 = {1, 2};
-double __attribute__ ((vector_size (2 * sizeof(double)))) d2 = {1, 2};
+typedef int __attribute__ ((vector_size (4 * sizeof(int)))) int4;
+typedef unsigned int __attribute__ ((vector_size (4 * sizeof(unsigned int)))) uint4;
+typedef char __attribute__ ((vector_size (4 * sizeof(char)))) char4;
+typedef float __attribute__ ((vector_size (4 * sizeof(float)))) float4;
+
+typedef int __attribute__ ((vector_size (2 * sizeof(int)))) int2;
+typedef long long __attribute__ ((vector_size (2 * sizeof(long long)))) longlong2;
+typedef float __attribute__ ((vector_size (2 * sizeof(float)))) float2;
+typedef double __attribute__ ((vector_size (2 * sizeof(double)))) double2;
+
+int ia = 2;
+int ib = 1;
+float fa = 2;
+float fb = 1;
+char4 c4 = {1, 2, 3, 4};
+int4 i4a = {2, 4, 8, 16};
+int4 i4b = {1, 2, 8, 4};
+float4 f4a = {2, 4, 8, 16};
+float4 f4b = {1, 2, 8, 4};
+uint4 ui4 = {2, 4, 8, 16};
+int2 i2 = {1, 2};
+longlong2 ll2 = {1, 2};
+float2 f2 = {1, 2};
+double2 d2 = {1, 2};
 
 int
 main ()
Index: gdb/testsuite/gdb.base/gnu_vector.exp
===================================================================
RCS file: /cvs/src/src/gdb/testsuite/gdb.base/gnu_vector.exp,v
retrieving revision 1.2
diff -p -u -r1.2 gnu_vector.exp
--- gdb/testsuite/gdb.base/gnu_vector.exp	6 Oct 2010 08:44:15 -0000	1.2
+++ gdb/testsuite/gdb.base/gnu_vector.exp	8 Oct 2010 16:22:01 -0000
@@ -76,9 +76,37 @@ gdb_test "print f4a - f4b" "\\\$$decimal
 gdb_test "print f4a * f4b" "\\\$$decimal = \\{2, 8, 64, 64\\}"
 gdb_test "print f4a / f4b" "\\\$$decimal = \\{2, 2, 1, 4\\}"
 
-# Test error conditions
-gdb_test "print i4a + 1" "Vector operations are only supported among vectors"
-gdb_test "print 1 + f4a" "Vector operations are only supported among vectors"
+# Test scalar to vector widening
+gdb_test "print (int2) 1" "\\\$$decimal = \\{1, 1\\}"
+gdb_test "print (longlong2) 2" "\\\$$decimal = \\{2, 2\\}"
+gdb_test "print (float2) 3" "\\\$$decimal = \\{3, 3\\}"
+gdb_test "print (double2) 4" "\\\$$decimal = \\{4, 4\\}"
+gdb_test "print (char4) 12" "\\\$$decimal = \\{12, 12, 12, 12\\}"
+gdb_test "print (uint4) ia" "\\\$$decimal = \\{2, 2, 2, 2\\}"
+gdb_test "print (int4) -3" "\\\$$decimal = \\{-3, -3, -3, -3\\}"
+gdb_test "print (float4) 4" "\\\$$decimal = \\{4, 4, 4, 4\\}"
+
+gdb_test "print i4a + ib" "\\\$$decimal = \\{3, 5, 9, 17\\}"
+gdb_test "print fa - f4b" "\\\$$decimal = \\{1, 0, -6, -2\\}"
+gdb_test "print f4a * fb" "\\\$$decimal = \\{2, 4, 8, 16\\}"
+gdb_test "print ia / i4b" "\\\$$decimal = \\{2, 1, 0, 0\\}"
+gdb_test "print i4a % ib" "\\\$$decimal = \\{0, 0, 0, 0\\}"
+
+gdb_test "print ia & i4b" "\\\$$decimal = \\{0, 2, 0, 0\\}"
+gdb_test "print i4a | ib" "\\\$$decimal = \\{3, 5, 9, 17\\}"
+gdb_test "print ia ^ i4b" "\\\$$decimal = \\{3, 0, 10, 6\\}"
+gdb_test "print i4a << ib" "\\\$$decimal = \\{4, 8, 16, 32\\}"
+gdb_test "print i4a >> ib" "\\\$$decimal = \\{1, 2, 4, 8\\}"
+
+gdb_test "print i4b = ia" "\\\$$decimal = \\{2, 2, 2, 2\\}"
+gdb_test "print i4a = 3" "\\\$$decimal = \\{3, 3, 3, 3\\}"
+gdb_test "print f4a = fb" "\\\$$decimal = \\{1, 1, 1, 1\\}"
+gdb_test "print f4b = 2" "\\\$$decimal = \\{2, 2, 2, 2\\}"
+
+gdb_test "print i4a = \{2, 4, 8, 16\}" "\\\$$decimal = \\{2, 4, 8, 16\\}"
+gdb_test "print i4a <<= ib" "\\\$$decimal = \\{4, 8, 16, 32\\}"
+
+# Test some error scenarios
 gdb_test "print i4a + d2" "Cannot perform operation on vectors with different types"
 gdb_test "print d2 + i4a" "Cannot perform operation on vectors with different types"
 gdb_test "print f4a + ll2" "Cannot perform operation on vectors with different types"