1 files changed, 40 insertions, 0 deletions
diff --git a/arch/arm/crc32_acle.c b/arch/arm/crc32_acle.c
index 37b1b98..0bcd3cf 100644
--- a/arch/arm/crc32_acle.c
+++ b/arch/arm/crc32_acle.c
@@ -11,6 +11,46 @@
 #endif
 #include "../../zutil.h"
 
+#if defined(__clang__)
+/* CRC32 intrinsics are #ifdef'ed out of arm_acle.h unless we build with an
+ * armv8 target, which is incompatible with ThinLTO optimizations on Android.
+ * (Namely, mixing and matching different module-level targets makes ThinLTO
+ * warn, and Android defaults to armv7-a. This restriction does not apply to
+ * function-level `target`s, however.)
+ *
+ * Since we only need four crc intrinsics, and since clang's implementation of
+ * those are just wrappers around compiler builtins, it's simplest to #define
+ * those builtins directly. If this #define list grows too much (or we depend on
+ * an intrinsic that isn't a trivial wrapper), we may have to find a better way
+ * to go about this.
+ *
+ * NOTE: clang currently complains that "'+soft-float-abi' is not a recognized
+ * feature for this target (ignoring feature)." This appears to be a harmless
+ * bug in clang.
+ */
+#define __crc32b __builtin_arm_crc32b
+#define __crc32d __builtin_arm_crc32d
+#define __crc32w __builtin_arm_crc32w
+#define __crc32cw __builtin_arm_crc32cw
+#define __crc32h __builtin_arm_crc32h
+
+#if defined(__aarch64__)
+#define TARGET_ARMV8_WITH_CRC __attribute__((target("crc")))
+#else  // !defined(__aarch64__)
+#define TARGET_ARMV8_WITH_CRC __attribute__((target("armv8-a,crc")))
+#endif  // defined(__aarch64__)
+
+#elif defined(__GNUC__)
+/* For GCC, we are setting CRC extensions at module level, so ThinLTO is not
+ * allowed. We can just include arm_acle.h.
+ */
+#include <arm_acle.h>
+#define TARGET_ARMV8_WITH_CRC
+#else  // !defined(__GNUC__) && !defined(_aarch64__)
+#error ARM CRC32 SIMD extensions only supported for Clang and GCC
+#endif
+
+TARGET_ARMV8_WITH_CRC
 uint32_t crc32_acle(uint32_t crc, const unsigned char *buf, uint64_t len) {
     Z_REGISTER uint32_t c;
     Z_REGISTER const uint16_t *buf2;