Add isl_pw_aff_val_from_si

This function constructs a new piecewise affine expression defined over
a zero-dimensional parameter space. The value of the piecewise affine
expression is the constant value passed to this function.

This function simplifies the construction of parameter expressions.
Specifically, there is no need to talk about set dimensions or even set
spaces in case parameter only expressions are constructed. Constant
piecewise expressions with zero parameter dimensions can be combined
with other parameter-space only dimensions thanks to isl auto-alignment
of parameter dimensions.

Signed-off-by: Tobias Grosser <[email protected]>

doc/user.pod

@@ -3109,6 +3109,8 @@ value is constructed.
 	#include <isl/aff.h>
 	__isl_give isl_pw_aff *isl_pw_aff_param_from_id(__isl_take isl_id *id);
 	__isl_give isl_pw_aff *isl_pw_aff_val_from_val(__isl_take isl_val *val);
+	__isl_give isl_pw_aff *isl_pw_aff_val_from_si(__isl_keep isl_ctx *ctx,
+		int val);
 
 The following convenience functions first create a base expression and
 then create a piecewise expression over a given domain.

include/isl/aff.h

@@ -201,6 +201,7 @@ __isl_give isl_pw_aff *isl_pw_aff_var_on_domain(__isl_take isl_local_space *ls,
 
 __isl_give isl_pw_aff *isl_pw_aff_param_from_id(__isl_take isl_id *id);
 __isl_give isl_pw_aff *isl_pw_aff_val_from_val(__isl_take isl_val *val);
+__isl_give isl_pw_aff *isl_pw_aff_val_from_si(__isl_keep isl_ctx *ctx, int val);
 
 __isl_give isl_pw_aff *isl_pw_aff_nan_on_domain(__isl_take isl_local_space *ls);
 __isl_give isl_pw_aff *isl_pw_aff_val_on_domain(__isl_take isl_set *domain,

isl_aff.c

@@ -251,6 +251,21 @@ __isl_give isl_pw_aff *isl_pw_aff_val_from_val(__isl_take isl_val *val)
 	return isl_pw_aff_val_on_domain(isl_set_universe(space), val);
 }
 
+/* Return a piecewise affine expression defined over a zero dimensional
+ * parameter space. The value of the affine expression is "val".
+ */
+__isl_give isl_pw_aff *isl_pw_aff_val_from_si(__isl_keep isl_ctx *ctx, int val)
+{
+	isl_val *v;
+
+	if (!ctx)
+		return NULL;
+
+	v = isl_val_int_from_si(ctx, v);
+
+	return isl_pw_aff_val_from_val(v);
+}
+
 /* Return a piecewise affine expression that is equal to
  * the specified dimension in "ls".
  */

isl_test.c

@@ -4765,8 +4765,8 @@ static isl_bool union_pw_aff_plain_is_equal(__isl_keep isl_union_pw_aff *upa,
 
 /* Basic tests on isl_pw_aff.
  *
- * In particular test the construction of a single-parameter pw_aff from an id
- * or an isl val.
+ * In particular test the construction of a single-parameter pw_aff from an id,
+ * an isl val, or a signed integer.
  */
 static isl_stat test_pa(isl_ctx *ctx) {
 	isl_id *id;
@@ -4805,6 +4805,19 @@ static isl_stat test_pa(isl_ctx *ctx) {
 		isl_die(ctx, isl_error_unknown, "can not construct pw from val",
 			return isl_stat_error);
 
+	pwa = isl_pw_aff_val_from_si(ctx, 10);
+	pwa2 = isl_pw_aff_read_from_str(ctx, "{ [(10)] }");
+
+	equal = isl_pw_aff_plain_is_equal(pwa, pwa2);
+
+	isl_pw_aff_free(pwa);
+	isl_pw_aff_free(pwa2);
+
+	if (equal < 0)
+		return isl_stat_error;
+	if (!equal)
+		isl_die(ctx, isl_error_unknown, "can not construct pw from val",
+			return isl_stat_error);
 
 	return isl_stat_ok;
 }