Implement __gnu_[u]ldivmod_helper methods in libc

These symbols were previously provided by Android's out-dated libgcc,
but they're removed/deprecated in upstream libgcc, and also won't be
available in libclang_rt.builtins. We need to provide these methods in
libc itself for compatiblity.

Test: build with these symbols stripped in libgcc
Bug: 29275768
Change-Id: Ie1ccdb711872bf3fc317cb908fed67c9a8955e42
Merged-In: I04a05258c6c06b5a22ead41e148b02792ffbc941
(cherry picked from commit b410d0e69ef6f545c7652ee0e4cf7b4dd4d2c38a)

2 files changed, 46 insertions, 2 deletions

diff --git a/libc/Android.bp b/libc/Android.bp
index 23ccbe3e9..720156255 100644
--- a/libc/Android.bp
+++ b/libc/Android.bp
@@ -762,12 +762,13 @@ cc_library_static {
                 "arch-arm/generic/bionic/strlen.c",
 
                 "arch-arm/bionic/__aeabi_read_tp.S",
-                "arch-arm/bionic/atomics_arm.c",
                 "arch-arm/bionic/__bionic_clone.S",
+                "arch-arm/bionic/__restore.S",
                 "arch-arm/bionic/_exit_with_stack_teardown.S",
+                "arch-arm/bionic/atomics_arm.c",
+                "arch-arm/bionic/bpabi.c",
                 "arch-arm/bionic/libcrt_compat.c",
                 "arch-arm/bionic/popcount_tab.c",
-                "arch-arm/bionic/__restore.S",
                 "arch-arm/bionic/setjmp.S",
                 "arch-arm/bionic/syscall.S",
                 "arch-arm/bionic/vfork.S",
diff --git a/libc/arch-arm/bionic/bpabi.c b/libc/arch-arm/bionic/bpabi.c
new file mode 100644
index 000000000..5c9cd99c6
--- /dev/null
+++ b/libc/arch-arm/bionic/bpabi.c
@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+extern long long __divdi3(long long, long long);
+extern unsigned long long __udivdi3(unsigned long long, unsigned long long);
+
+long long __gnu_ldivmod_helper(long long a, long long b, long long* remainder) {
+  long long quotient = __divdi3(a, b);
+  *remainder = a - b * quotient;
+  return quotient;
+}
+
+unsigned long long __gnu_uldivmod_helper(unsigned long long a, unsigned long long b,
+                                         unsigned long long* remainder) {
+  unsigned long long quotient = __udivdi3(a, b);
+  *remainder = a - b * quotient;
+  return quotient;
+}