Libgomp magic offset value self-documentation

2019-10-02  Julian Brown  <julian@codesourcery.com>
	    Cesar Philippidis  <cesar@codesourcery.com>

	libgomp/
	* libgomp.h (OFFSET_INLINED, OFFSET_POINTER, OFFSET_STRUCT): Define.
	* target.c (FIELD_TGT_EMPTY): Define.
	(gomp_map_val): Use OFFSET_* macros instead of magic constants.  Write
	as switch instead of list of ifs.
	(gomp_map_vars_internal): Use OFFSET_* and FIELD_TGT_EMPTY macros.

git-svn-id: https://gcc.gnu.org/svn/gcc/trunk@276519 138bc75d-0d04-0410-961f-82ee72b054a4

3 files changed, 41 insertions, 17 deletions

diff --git a/libgomp/ChangeLog b/libgomp/ChangeLog
index 3fe34c7c0b7..2059e053457 100644
--- a/libgomp/ChangeLog
+++ b/libgomp/ChangeLog
@@ -1,3 +1,12 @@
+2019-10-02  Julian Brown  <julian@codesourcery.com>
+	    Cesar Philippidis  <cesar@codesourcery.com>
+
+	* libgomp.h (OFFSET_INLINED, OFFSET_POINTER, OFFSET_STRUCT): Define.
+	* target.c (FIELD_TGT_EMPTY): Define.
+	(gomp_map_val): Use OFFSET_* macros instead of magic constants.  Write
+	as switch instead of list of ifs.
+	(gomp_map_vars_internal): Use OFFSET_* and FIELD_TGT_EMPTY macros.
+
 2019-10-02  Andreas Tobler  <andreast@gcc.gnu.org>
 
 	* testsuite/libgomp.oacc-c-c++-common/loop-default.h: Remove alloca.h
diff --git a/libgomp/libgomp.h b/libgomp/libgomp.h
index abb5c2263c4..178eb600ccd 100644
--- a/libgomp/libgomp.h
+++ b/libgomp/libgomp.h
@@ -903,6 +903,11 @@ struct target_mem_desc {
    artificial pointer to "omp declare target link" object.  */
 #define REFCOUNT_LINK (~(uintptr_t) 1)
 
+/* Special offset values.  */
+#define OFFSET_INLINED (~(uintptr_t) 0)
+#define OFFSET_POINTER (~(uintptr_t) 1)
+#define OFFSET_STRUCT (~(uintptr_t) 2)
+
 struct splay_tree_key_s {
   /* Address of the host object.  */
   uintptr_t host_start;
diff --git a/libgomp/target.c b/libgomp/target.c
index 1c9ca68ba10..a83cb48108a 100644
--- a/libgomp/target.c
+++ b/libgomp/target.c
@@ -44,6 +44,8 @@
 #include "plugin-suffix.h"
 #endif
 
+#define FIELD_TGT_EMPTY (~(size_t) 0)
+
 static void gomp_target_init (void);
 
 /* The whole initialization code for offloading plugins is only run one.  */
@@ -497,17 +499,25 @@ gomp_map_val (struct target_mem_desc *tgt, void **hostaddrs, size_t i)
     return tgt->list[i].key->tgt->tgt_start
 	   + tgt->list[i].key->tgt_offset
 	   + tgt->list[i].offset;
-  if (tgt->list[i].offset == ~(uintptr_t) 0)
-    return (uintptr_t) hostaddrs[i];
-  if (tgt->list[i].offset == ~(uintptr_t) 1)
-    return 0;
-  if (tgt->list[i].offset == ~(uintptr_t) 2)
-    return tgt->list[i + 1].key->tgt->tgt_start
-	   + tgt->list[i + 1].key->tgt_offset
-	   + tgt->list[i + 1].offset
-	   + (uintptr_t) hostaddrs[i]
-	   - (uintptr_t) hostaddrs[i + 1];
-  return tgt->tgt_start + tgt->list[i].offset;
+
+  switch (tgt->list[i].offset)
+    {
+    case OFFSET_INLINED:
+      return (uintptr_t) hostaddrs[i];
+
+    case OFFSET_POINTER:
+      return 0;
+
+    case OFFSET_STRUCT:
+      return tgt->list[i + 1].key->tgt->tgt_start
+	     + tgt->list[i + 1].key->tgt_offset
+	     + tgt->list[i + 1].offset
+	     + (uintptr_t) hostaddrs[i]
+	     - (uintptr_t) hostaddrs[i + 1];
+
+    default:
+      return tgt->tgt_start + tgt->list[i].offset;
+    }
 }
 
 static inline __attribute__((always_inline)) struct target_mem_desc *
@@ -575,7 +585,7 @@ gomp_map_vars_internal (struct gomp_device_descr *devicep,
 	  || (kind & typemask) == GOMP_MAP_FIRSTPRIVATE_INT)
 	{
 	  tgt->list[i].key = NULL;
-	  tgt->list[i].offset = ~(uintptr_t) 0;
+	  tgt->list[i].offset = OFFSET_INLINED;
 	  continue;
 	}
       else if ((kind & typemask) == GOMP_MAP_USE_DEVICE_PTR)
@@ -596,7 +606,7 @@ gomp_map_vars_internal (struct gomp_device_descr *devicep,
 	  cur_node.host_end = (uintptr_t) hostaddrs[last]
 			      + sizes[last];
 	  tgt->list[i].key = NULL;
-	  tgt->list[i].offset = ~(uintptr_t) 2;
+	  tgt->list[i].offset = OFFSET_STRUCT;
 	  splay_tree_key n = splay_tree_lookup (mem_map, &cur_node);
 	  if (n == NULL)
 	    {
@@ -629,7 +639,7 @@ gomp_map_vars_internal (struct gomp_device_descr *devicep,
       else if ((kind & typemask) == GOMP_MAP_ALWAYS_POINTER)
 	{
 	  tgt->list[i].key = NULL;
-	  tgt->list[i].offset = ~(uintptr_t) 1;
+	  tgt->list[i].offset = OFFSET_POINTER;
 	  has_firstprivate = true;
 	  continue;
 	}
@@ -659,7 +669,7 @@ gomp_map_vars_internal (struct gomp_device_descr *devicep,
 	  if (!n)
 	    {
 	      tgt->list[i].key = NULL;
-	      tgt->list[i].offset = ~(uintptr_t) 1;
+	      tgt->list[i].offset = OFFSET_POINTER;
 	      continue;
 	    }
 	}
@@ -884,12 +894,12 @@ gomp_map_vars_internal (struct gomp_device_descr *devicep,
 		size_t align = (size_t) 1 << (kind >> rshift);
 		tgt->list[i].key = k;
 		k->tgt = tgt;
-		if (field_tgt_clear != ~(size_t) 0)
+		if (field_tgt_clear != FIELD_TGT_EMPTY)
 		  {
 		    k->tgt_offset = k->host_start - field_tgt_base
 				    + field_tgt_offset;
 		    if (i == field_tgt_clear)
-		      field_tgt_clear = ~(size_t) 0;
+		      field_tgt_clear = FIELD_TGT_EMPTY;
 		  }
 		else
 		  {