From 62634158b7cd39ad1e330a87153a97bf3dc6f8de Mon Sep 17 00:00:00 2001
From: Mans Rullgard <mans@mansr.com>
Date: Fri, 29 Jun 2012 13:35:08 +0100
Subject: ARM: generate position independent code to access data symbols

This creates proper position independent code when accessing
data symbols if CONFIG_PIC is set.

References to external symbols should now use the movrelx macro.
Some additional code changes are required since this macro may
need a register to hold the GOT pointer.

Signed-off-by: Mans Rullgard <mans@mansr.com>
---
 libavutil/arm/asm.S | 73 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 72 insertions(+), 1 deletion(-)

(limited to 'libavutil/arm')

diff --git a/libavutil/arm/asm.S b/libavutil/arm/asm.S
index 6038a63a27..15081802c6 100644
--- a/libavutil/arm/asm.S
+++ b/libavutil/arm/asm.S
@@ -62,7 +62,14 @@ ELF     .eabi_attribute 25, \val
 .endm
 
 .macro  function name, export=0
+        .set            .Lpic_idx, 0
+        .set            .Lpic_gp, 0
     .macro endfunc
+      .if .Lpic_idx
+        .altmacro
+        put_pic         %(.Lpic_idx - 1)
+        .noaltmacro
+      .endif
 ELF     .size   \name, . - \name
         .endfunc
         .purgem endfunc
@@ -106,8 +113,44 @@ ELF     .size   \name, . - \name
 #endif
 .endm
 
+.macro  put_pic         num
+        put_pic_\num
+.endm
+
+.macro  do_def_pic      num, val, label
+    .macro put_pic_\num
+      .if \num
+        .altmacro
+        put_pic         %(\num - 1)
+        .noaltmacro
+      .endif
+\label: .word           \val
+        .purgem         put_pic_\num
+    .endm
+.endm
+
+.macro  def_pic         val, label
+        .altmacro
+        do_def_pic      %.Lpic_idx, \val, \label
+        .noaltmacro
+        .set            .Lpic_idx, .Lpic_idx + 1
+.endm
+
+.macro  ldpic           rd,  val, indir=0
+        ldr             \rd, .Lpicoff\@
+.Lpic\@:
+    .if \indir
+        ldr             \rd, [pc, \rd]
+    .else
+        add             \rd, pc,  \rd
+    .endif
+        def_pic         \val - (.Lpic\@ + (8 >> CONFIG_THUMB)), .Lpicoff\@
+.endm
+
 .macro  movrel rd, val
-#if HAVE_ARMV6T2 && !CONFIG_PIC && !defined(__APPLE__)
+#if CONFIG_PIC
+        ldpic           \rd, \val
+#elif HAVE_ARMV6T2 && !defined(__APPLE__)
         movw            \rd, #:lower16:\val
         movt            \rd, #:upper16:\val
 #else
@@ -115,6 +158,34 @@ ELF     .size   \name, . - \name
 #endif
 .endm
 
+.macro  movrelx         rd,  val, gp
+#if CONFIG_PIC && defined(__ELF__)
+    .ifnb \gp
+      .if .Lpic_gp
+        .unreq          gp
+      .endif
+        gp      .req    \gp
+        ldpic           gp,  _GLOBAL_OFFSET_TABLE_
+    .elseif !.Lpic_gp
+        gp      .req    r12
+        ldpic           gp,  _GLOBAL_OFFSET_TABLE_
+    .endif
+        .set            .Lpic_gp, 1
+        ldr             \rd, .Lpicoff\@
+        ldr             \rd, [gp, \rd]
+        def_pic         \val(GOT), .Lpicoff\@
+#elif CONFIG_PIC && defined(__APPLE__)
+        ldpic           \rd, .Lpic\@, indir=1
+        .non_lazy_symbol_pointer
+.Lpic\@:
+        .indirect_symbol \val
+        .word           0
+        .text
+#else
+        movrel          \rd, \val
+#endif
+.endm
+
 .macro  ldr_pre         rt,  rn,  rm:vararg
 A       ldr             \rt, [\rn, \rm]!
 T       add             \rn, \rn, \rm
-- 
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