Merge pull request madler#8 from traceon/apple-clang-linker-fix

Fix AppleClang linking

arch/arm/arm.h

@@ -7,10 +7,10 @@
 
 /*
  A hack that helps AppleClang linker to see arm_cpu_has_* flags.
- A single call to dummy_linker_glue() in the compilation unit that reads
+ A single call to dummy_linker_glue_y() in the compilation unit that reads
  arm_cpu_has_* flags will resolve "undefined symbol" link error.
 */
-void dummy_linker_glue();
+void dummy_linker_glue_y();
 
 extern int arm_cpu_has_neon;
 extern int arm_cpu_has_crc32;

arch/arm/armfeature.c

@@ -14,7 +14,7 @@
 #  include <winapifamily.h>
 #endif
 
-Z_INTERNAL void dummy_linker_glue(void) {}
+Z_INTERNAL void dummy_linker_glue_y(void) {}
 
 static int arm_has_crc32() {
 #if defined(__linux__) && defined(HWCAP2_CRC32)

arch/x86/x86.c

@@ -17,6 +17,8 @@
 #  include <cpuid.h>
 #endif
 
+Z_INTERNAL void dummy_linker_glue_y(void) {}
+
 Z_INTERNAL int x86_cpu_has_avx2;
 Z_INTERNAL int x86_cpu_has_sse2;
 Z_INTERNAL int x86_cpu_has_ssse3;

arch/x86/x86.h

@@ -6,6 +6,13 @@
 #ifndef CPU_H_
 #define CPU_H_
 
+/*
+ A hack that helps AppleClang linker to see x86_cpu_has_* flags.
+ A single call to dummy_linker_glue_y() in the compilation unit that reads
+ x86_cpu_has_* flags will resolve "undefined symbol" link error.
+*/
+void dummy_linker_glue_y();
+
 extern int x86_cpu_has_avx2;
 extern int x86_cpu_has_sse2;
 extern int x86_cpu_has_ssse3;

crc32.c

@@ -187,6 +187,11 @@ Z_INTERNAL void crc_reset(deflate_state *const s) {
     }
 #endif
     s->strm->adler = PREFIX(crc32)(0L, NULL, 0);
+
+#if defined(__APPLE__)
+    dummy_linker_glue_x();
+    dummy_linker_glue_y();
+#endif
 }
 
 Z_INTERNAL void copy_with_crc(PREFIX3(stream) *strm, unsigned char *dst, unsigned long size) {

functable.c

@@ -134,6 +134,8 @@ extern uint32_t longest_match_unaligned_avx2(deflate_state *const s, Pos cur_mat
 #endif
 #endif
 
+Z_INTERNAL void dummy_linker_glue_x(void) {}
+
 /* functable init */
 Z_INTERNAL struct functable_s functable;
 
@@ -288,10 +290,13 @@ static void __attribute__((constructor)) chunkunroll_stub_init() {
         functable.chunkunroll = &chunkunroll_avx;
 #endif
 #ifdef ARM_NEON_CHUNKSET
-    dummy_linker_glue();
     if (arm_cpu_has_neon)
         functable.chunkunroll = &chunkunroll_neon;
 #endif
+
+#if defined(__APPLE__)
+    dummy_linker_glue_y();
+#endif
 }
 
 static void __attribute__((constructor)) chunkmemset_stub_init() {

functable.h

@@ -8,6 +8,13 @@
 
 #include "deflate.h"
 
+/*
+ A hack that helps AppleClang linker to see functable.
+ A single call to dummy_linker_glue_x() in the compilation unit that reads
+ functable will resolve "undefined symbol" link error.
+*/
+void dummy_linker_glue_x();
+
 struct functable_s {
     void     (* insert_string)      (deflate_state *const s, const uint32_t str, uint32_t count);
     Pos      (* quick_insert_string)(deflate_state *const s, const uint32_t str);
@@ -24,6 +31,6 @@ struct functable_s {
     uint8_t* (* chunkmemset_safe)   (uint8_t *out, unsigned dist, unsigned len, unsigned left);
 };
 
-Z_INTERNAL extern struct functable_s functable;
+extern struct functable_s functable;
 
 #endif