Linphone-android在android6.0上X264

https://mailman.videolan.org/pipermail/x264-devel/2015-October/011479.html

linphone使用open264做编解码器时在很多机型上会有严重卡顿的问题，问题在于open264编解码效率较低，在编译时使用x264做编码可以解决由于效率低而造成卡顿的问题，但在android6.0以上使用x264编码时会出现问题。

linphone在android6.0以上机型上无法正常加载x264编码器，原因是Android 6不会将共享库与文本重定位链接起来。

需要对以下汇编文件做修改。实测改善了部分机型的体验，linphone使用h264编码坑比较多，推荐使用VP8编码。

---
 common/arm/asm.S     | 61 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 common/arm/mc-a.S    |  5 +++--
 common/arm/quant-a.S |  4 ++--
 3 files changed, 65 insertions(+), 5 deletions(-)

diff --git a/common/arm/asm.S b/common/arm/asm.S
index c363c38..a96e0a7 100644
--- a/common/arm/asm.S
+++ b/common/arm/asm.S
@@ -56,6 +56,12 @@
 #   define FUNC @
 #endif
 
+#if SYS_LINUX
+#define HAVE_SECTION_DATA_REL_RO 1
+#else
+#define HAVE_SECTION_DATA_REL_RO 0
+#endif
+
 .macro require8, val=1
 ELF     .eabi_attribute 24, \val
 .endm
@@ -85,8 +91,30 @@ FUNC    .func   \name
 .endif
 .endm
 
+.macro const name, align=2, relocate=0
+    .macro endconst
+ELF     .size   \name, . - \name
+        .purgem endconst
+    .endm
+.if HAVE_SECTION_DATA_REL_RO && \relocate
+        .section        .data.rel.ro
+.else
+        .section        .rodata
+.endif
+        .align          \align
+\name:
+.endm
+
 .macro movrel rd, val
-#if HAVE_ARMV6T2 && !defined(PIC)
+#if defined(PIC)
+        ldr             \rd,  1f
+        b               2f
+1:
+@ FIXME: thumb
+        .word           \val - (2f + 8)
+2:
+        add             \rd,  \rd,  pc
+#elif HAVE_ARMV6T2
         movw            \rd, #:lower16:\val
         movt            \rd, #:upper16:\val
 #else
@@ -94,6 +122,37 @@ FUNC    .func   \name
 #endif
 .endm
 
+.macro movrelx rd, val, got
+#if defined(PIC) && defined(__ELF__)
+        ldr             \got, 2f
+        ldr             \rd,  1f
+        b               3f
+1:
+@ FIXME: thumb
+        .word \val(GOT)
+2:
+        .word _GLOBAL_OFFSET_TABLE_ - (3f + 8)
+3:
+        add             \got, \got, pc
+        ldr             \rd, [\got, \rd]
+#elif defined(PIC) && defined(__APPLE__)
+        ldr             \rd,  1f
+        b               2f
+1:
+@ FIXME: thumb
+        .word           3f - (2f + 8)
+2:
+        ldr             \rd, [pc, \rd]
+        .non_lazy_symbol_pointer
+3:
+        .indirect_symbol \val
+        .word           0
+        .text
+#else
+        movrel          \rd, \val
+#endif
+.endm
+
 .macro movconst rd, val
 #if HAVE_ARMV6T2
     movw        \rd, #:lower16:\val
diff --git a/common/arm/mc-a.S b/common/arm/mc-a.S
index 30d1c1a..cee1b4a 100644
--- a/common/arm/mc-a.S
+++ b/common/arm/mc-a.S
@@ -140,12 +140,13 @@ MEMCPY_ALIGNED 16, 8
 MEMCPY_ALIGNED  8, 16
 MEMCPY_ALIGNED  8, 8
 
-.section .rodata
-memcpy_table:
+const memcpy_table align=2, relocate=1
 .word memcpy_aligned_16_16_neon
 .word memcpy_aligned_16_8_neon
 .word memcpy_aligned_8_16_neon
 .word memcpy_aligned_8_8_neon
+endconst
+
 .text
 
 .ltorg
diff --git a/common/arm/quant-a.S b/common/arm/quant-a.S
index 7a2667f..1a5aa03 100644
--- a/common/arm/quant-a.S
+++ b/common/arm/quant-a.S
@@ -346,7 +346,7 @@ function x264_decimate_score\size\()_neon
     lsr         r1,  r1,  #2
 .endif
     rbit        r1,  r1
-    movrel      r3,  X(x264_decimate_table4)
+    movrelx     r3,  X(x264_decimate_table4), r2
 1:
     clz         r2,  r1
     lsl         r1,  r1,  r2
@@ -415,7 +415,7 @@ function x264_decimate_score64_neon
     mvn         r12, r12
     mov         r0,  #0
     mov         lr,  #32
-    movrel      r3,  X(x264_decimate_table8)
+    movrelx     r3,  X(x264_decimate_table8), r2
     beq         2f
 1:
     clz         r2,  r1
-- 
2.6.1