add mapper for strlen()

[r16818]

diff --git a/include/libfirm/lowering.h b/include/libfirm/lowering.h
index 47bede5..d583d3e 100644 (file)
--- a/include/libfirm/lowering.h
+++ b/include/libfirm/lowering.h
@@ -410,12 +410,19 @@ int i_mapper_tanh(ir_node *call, void *ctx);
 int i_mapper_strcmp(ir_node *call, void *ctx);
 
 /**
- * A mapper for the strcmp-Function: inttype strncmp(char pointer a, char pointer b, inttype len);
+ * A mapper for the strncmp-Function: inttype strncmp(char pointer a, char pointer b, inttype len);
  *
  * @return 0 if the strncmp call was removed, 0 else.
  */
 int i_mapper_strncmp(ir_node *call, void *ctx);
 
+/**
+ * A mapper for the strlen-Function: inttype strlen(char pointer a);
+ *
+ * @return 0 if the strlen call was removed, 0 else.
+ */
+int i_mapper_strlen(ir_node *call, void *ctx);
+
 /**
  * A mapper for the memcpy-Function: void pointer memcpy(void pointer d, void pointer s, inttype c);
  *

diff --git a/ir/lower/lower_intrinsics.c b/ir/lower/lower_intrinsics.c
index d7e746e..555a739 100644 (file)
--- a/ir/lower/lower_intrinsics.c
+++ b/ir/lower/lower_intrinsics.c
@@ -536,6 +536,74 @@ int i_mapper_strncmp(ir_node *call, void *ctx) {
        return 0;
 }  /* i_mapper_strncmp */
 
+/**
+ * Calculate the value of strlen if possible.
+ *
+ * @param ent     the entity
+ * @param res_tp  the result type
+ */
+static ir_node *eval_strlen(ir_entity *ent, ir_type *res_tp) {
+       ir_type *tp = get_entity_type(ent);
+       ir_mode *mode;
+       int     i, n, len = -1;
+
+       if (! is_Array_type(tp))
+               return NULL;
+       tp = get_array_element_type(tp);
+       if (! is_Primitive_type(tp))
+               return NULL;
+       mode = get_type_mode(tp);
+
+       /* FIXME: This is too restrict, as the type char might be more the 8bits */
+       if (!mode_is_int(mode) || get_mode_size_bits(mode) != get_mode_size_bits(mode_Bs))
+               return NULL;
+
+       n = get_compound_ent_n_values(ent);
+       for (i = 0; i < n; ++i) {
+               ir_node *irn = get_compound_ent_value(ent, i);
+
+               if (! is_Const(irn))
+                       return NULL;
+
+               if (is_Const_null(irn)) {
+                       /* found the length */
+                       len = i;
+                       break;
+               }
+       }
+       if (len >= 0) {
+               tarval *tv = new_tarval_from_long(len, get_type_mode(res_tp));
+               return new_Const_type(tv, res_tp);
+       }
+       return NULL;
+}  /* eval_strlen */
+
+/* A mapper for strlen */
+int i_mapper_strlen(ir_node *call, void *ctx) {
+       ir_node *s   = get_Call_param(call, 0);
+       ir_node *irn = NULL;
+
+       /* FIXME: this cannot handle constant strings inside struct initializers yet */
+       if (is_SymConst(s) && get_SymConst_kind(s) == symconst_addr_ent) {
+               ir_entity *ent = get_SymConst_entity(s);
+
+               if (get_entity_variability(ent) == variability_constant) {
+                       /* a constant entity */
+                       ir_type *tp = get_Call_type(call);
+
+                       tp  = get_method_res_type(tp, 0);
+                       irn = eval_strlen(ent, tp);
+
+                       if (irn) {
+                               ir_node *mem = get_Call_mem(call);
+                               DBG_OPT_ALGSIM0(call, irn, FS_OPT_RTS_STRLEN);
+                               replace_call(irn, call, mem, NULL, NULL);
+                       }
+               }
+       }
+       return 0;
+}  /* i_mapper_strlen */
+
 /* A mapper for memcpy */
 int i_mapper_memcpy(ir_node *call, void *ctx) {
        ir_node *len = get_Call_param(call, 2);