isl_pw_*_add_disjoint: try and extend one of the pws instead of copying pieces

This is especially useful when isl_pw_*_add_disjoint is used
to repeatedly add a single piece.

Signed-off-by: Sven Verdoolaege <skimo@kotnet.org>

diff --git a/isl_pw_templ.c b/isl_pw_templ.c
index 858ae8a..55d5903 100644 (file)
--- a/isl_pw_templ.c
+++ b/isl_pw_templ.c
@@ -377,16 +377,57 @@ __isl_give PW *FN(PW,add)(__isl_take PW *pw1, __isl_take PW *pw2)
        return align_params_pw_pw_and(pw1, pw2, &FN(PW,add_aligned));
 }
 
+/* Make sure "pw" has room for at least "n" more pieces.
+ *
+ * If there is only one reference to pw, we extend it in place.
+ * Otherwise, we create a new PW and copy the pieces.
+ */
+static __isl_give PW *FN(PW,grow)(__isl_take PW *pw, int n)
+{
+       int i;
+       isl_ctx *ctx;
+       PW *res;
+
+       if (!pw)
+               return NULL;
+       if (pw->n + n <= pw->size)
+               return pw;
+       ctx = FN(PW,get_ctx)(pw);
+       n += pw->n;
+       if (pw->ref == 1) {
+               res = isl_realloc(ctx, pw, struct PW,
+                           sizeof(struct PW) + (n - 1) * sizeof(S(PW,piece)));
+               if (!res)
+                       return FN(PW,free)(pw);
+               res->size = n;
+               return res;
+       }
+#ifdef HAS_TYPE
+       res = FN(PW,alloc_)(isl_space_copy(pw->dim), pw->type, n);
+#else
+       res = FN(PW,alloc_)(isl_space_copy(pw->dim), n);
+#endif
+       if (!res)
+               return FN(PW,free)(pw);
+       for (i = 0; i < pw->n; ++i)
+               res = FN(PW,add_piece)(res, isl_set_copy(pw->p[i].set),
+                                           FN(EL,copy)(pw->p[i].FIELD));
+       FN(PW,free)(pw);
+       return res;
+}
+
 static __isl_give PW *FN(PW,add_disjoint_aligned)(__isl_take PW *pw1,
        __isl_take PW *pw2)
 {
        int i;
        isl_ctx *ctx;
-       PW *res;
 
        if (!pw1 || !pw2)
                goto error;
 
+       if (pw1->size < pw1->n + pw2->n && pw1->n < pw2->n)
+               return FN(PW,add_disjoint_aligned)(pw2, pw1);
+
        ctx = isl_space_get_ctx(pw1->dim);
 #ifdef HAS_TYPE
        if (pw1->type != pw2->type)
@@ -405,26 +446,18 @@ static __isl_give PW *FN(PW,add_disjoint_aligned)(__isl_take PW *pw1,
                return pw1;
        }
 
-#ifdef HAS_TYPE
-       res = FN(PW,alloc_)(isl_space_copy(pw1->dim), pw1->type, pw1->n + pw2->n);
-#else
-       res = FN(PW,alloc_)(isl_space_copy(pw1->dim), pw1->n + pw2->n);
-#endif
-
-       for (i = 0; i < pw1->n; ++i)
-               res = FN(PW,add_piece)(res,
-                               isl_set_copy(pw1->p[i].set),
-                               FN(EL,copy)(pw1->p[i].FIELD));
+       pw1 = FN(PW,grow)(pw1, pw2->n);
+       if (!pw1)
+               goto error;
 
        for (i = 0; i < pw2->n; ++i)
-               res = FN(PW,add_piece)(res,
+               pw1 = FN(PW,add_piece)(pw1,
                                isl_set_copy(pw2->p[i].set),
                                FN(EL,copy)(pw2->p[i].FIELD));
 
-       FN(PW,free)(pw1);
        FN(PW,free)(pw2);
 
-       return res;
+       return pw1;
 error:
        FN(PW,free)(pw1);
        FN(PW,free)(pw2);