erts: Add fallback for builtin clz

* __builtin_clz may not exist
* fix bitcount fallback

2 files changed, 31 insertions, 13 deletions

diff --git a/erts/emulator/beam/erl_hashmap.c b/erts/emulator/beam/erl_hashmap.c
index 6bca2f1665..3da2a53333 100644
--- a/erts/emulator/beam/erl_hashmap.c
+++ b/erts/emulator/beam/erl_hashmap.c
@@ -1273,3 +1273,30 @@ BIF_RETTYPE hashmap_info_1(BIF_ALIST_1) {
     }
     BIF_ERROR(BIF_P, BADARG);
 }
+
+/* implementation of builtin emulations */
+
+#if !defined(__GNUC__)
+/* Count leading zeros emulation */
+Uint32 hashmap_clz(Uint32 x) {
+    Uint32 y;
+    int n = 32;
+    y = x >>16;  if (y != 0) {n = n -16;  x = y;}
+    y = x >> 8;  if (y != 0) {n = n - 8;  x = y;}
+    y = x >> 4;  if (y != 0) {n = n - 4;  x = y;}
+    y = x >> 2;  if (y != 0) {n = n - 2;  x = y;}
+    y = x >> 1;  if (y != 0) return n - 2;
+    return n - x;
+}
+const Uint32 SK5 = 0x55555555, SK3 = 0x33333333;
+const Uint32 SKF0 = 0xF0F0F0F, SKFF = 0xFF00FF;
+
+/* CTPOP emulation */
+Uint32 hashmap_bitcount(Uint32 x) {
+    x -= ((x >> 1  ) & SK5);
+    x  =  (x & SK3 ) + ((x >> 2 ) & SK3 );
+    x  =  (x & SKF0) + ((x >> 4 ) & SKF0);
+    x +=   x >> 8;
+    return (x + (x >> 16)) & 0x3F;
+}
+#endif
diff --git a/erts/emulator/beam/erl_hashmap.h b/erts/emulator/beam/erl_hashmap.h
index 8ba249b053..1964787218 100644
--- a/erts/emulator/beam/erl_hashmap.h
+++ b/erts/emulator/beam/erl_hashmap.h
@@ -40,21 +40,12 @@ int hashmap_key_hash_cmp(Eterm* ap, Eterm* bp);
 
 /* HASH */
 
-
 #if defined(__GNUC__)
-#define hashmap_bitcount(x) 	(Uint32) __builtin_popcount((unsigned int) (x))
+#define hashmap_clz(x)       ((Uint32) __builtin_clz((unsigned int)(x)))
+#define hashmap_bitcount(x)  ((Uint32) __builtin_popcount((unsigned int) (x)))
 #else
-const Uint32 SK5 = 0x55555555, SK3 = 0x33333333;
-const Uint32 SKF0 = 0xF0F0F0F, SKFF = 0xFF00FF;
-
-/* CTPOP emulation */
-Uint32 hashmap_bitcount(Uint32 map) {
-    map -= (( map >> 1  ) & SK5 );
-    map  = ( map & SK3  ) + (( map >> 2 ) & SK3 );
-    map  = ( map & SKF0 ) + (( map >> 4 ) & SKF0);
-    map +=   map >> 8;
-    return ( map + ( map >> 16)) & 0x3F;
-}
+Uint32 hashmap_clz(Uint32 x);
+Uint32 hashmap_bitcount(Uint32 x);
 #endif
 
 /* hamt nodes v2.0