compiler_rt: Import popcountdi2.c and popcountsi2.c files

Imported from the LLVM compiler_rt library on master branch as of
30 Oct 2018 (SVN revision: r345645).

This is to get the __popcountsi2(si_int a) and __popcountdi2(di_int a)
builtin which are required by a driver that uses a __builtin_popcount().

Change-Id: I8e0d97cebdd90d224690c8ce1b02e657acdddb25
Signed-off-by: Lionel Debieve <lionel.debieve@st.com>

lib/compiler-rt/builtins/popcountdi2.c

+/* ===-- popcountdi2.c - Implement __popcountdi2 ----------------------------===
+ *
+ *                     The LLVM Compiler Infrastructure
+ *
+ * This file is dual licensed under the MIT and the University of Illinois Open
+ * Source Licenses. See LICENSE.TXT for details.
+ *
+ * ===----------------------------------------------------------------------===
+ *
+ * This file implements __popcountdi2 for the compiler_rt library.
+ *
+ * ===----------------------------------------------------------------------===
+ */
+
+#include "int_lib.h"
+
+/* Returns: count of 1 bits */
+
+COMPILER_RT_ABI si_int
+__popcountdi2(di_int a)
+{
+    du_int x2 = (du_int)a;
+    x2 = x2 - ((x2 >> 1) & 0x5555555555555555uLL);
+    /* Every 2 bits holds the sum of every pair of bits (32) */
+    x2 = ((x2 >> 2) & 0x3333333333333333uLL) + (x2 & 0x3333333333333333uLL);
+    /* Every 4 bits holds the sum of every 4-set of bits (3 significant bits) (16) */
+    x2 = (x2 + (x2 >> 4)) & 0x0F0F0F0F0F0F0F0FuLL;
+    /* Every 8 bits holds the sum of every 8-set of bits (4 significant bits) (8) */
+    su_int x = (su_int)(x2 + (x2 >> 32));
+    /* The lower 32 bits hold four 16 bit sums (5 significant bits). */
+    /*   Upper 32 bits are garbage */
+    x = x + (x >> 16);
+    /* The lower 16 bits hold two 32 bit sums (6 significant bits). */
+    /*   Upper 16 bits are garbage */
+    return (x + (x >> 8)) & 0x0000007F;  /* (7 significant bits) */
+}

lib/compiler-rt/builtins/popcountsi2.c

+/* ===-- popcountsi2.c - Implement __popcountsi2 ---------------------------===
+ *
+ *                     The LLVM Compiler Infrastructure
+ *
+ * This file is dual licensed under the MIT and the University of Illinois Open
+ * Source Licenses. See LICENSE.TXT for details.
+ *
+ * ===----------------------------------------------------------------------===
+ *
+ * This file implements __popcountsi2 for the compiler_rt library.
+ *
+ * ===----------------------------------------------------------------------===
+ */
+
+#include "int_lib.h"
+
+/* Returns: count of 1 bits */
+
+COMPILER_RT_ABI si_int
+__popcountsi2(si_int a)
+{
+    su_int x = (su_int)a;
+    x = x - ((x >> 1) & 0x55555555);
+    /* Every 2 bits holds the sum of every pair of bits */
+    x = ((x >> 2) & 0x33333333) + (x & 0x33333333);
+    /* Every 4 bits holds the sum of every 4-set of bits (3 significant bits) */
+    x = (x + (x >> 4)) & 0x0F0F0F0F;
+    /* Every 8 bits holds the sum of every 8-set of bits (4 significant bits) */
+    x = (x + (x >> 16));
+    /* The lower 16 bits hold two 8 bit sums (5 significant bits).*/
+    /*    Upper 16 bits are garbage */
+    return (x + (x >> 8)) & 0x0000003F;  /* (6 significant bits) */
+}

lib/compiler-rt/compiler-rt.mk

@@ -28,8 +28,11 @@
 # POSSIBILITY OF SUCH DAMAGE.
 #
 
+COMPILER_RT_SRCS	:=	lib/compiler-rt/builtins/popcountdi2.c		\
+				lib/compiler-rt/builtins/popcountsi2.c
+
 ifeq (${ARCH},aarch32)
-COMPILER_RT_SRCS	:=	lib/compiler-rt/builtins/arm/aeabi_ldivmod.S	\
+COMPILER_RT_SRCS	+=	lib/compiler-rt/builtins/arm/aeabi_ldivmod.S	\
 				lib/compiler-rt/builtins/arm/aeabi_uldivmod.S	\
 				lib/compiler-rt/builtins/ctzdi2.c		\
 				lib/compiler-rt/builtins/divdi3.c		\