Build with -Bsymbolic to prevent symbol preemption

The CMake build was already using -fvisibility=protected, which has the
same effect but uses duplicate symbol entries for internal/external use.

Bug: b/148240133
Change-Id: I8069a1b293a6ec0604be32179ed591ffaa645ed7
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/41648
Presubmit-Ready: Nicolas Capens <nicolascapens@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>

CMakeLists.txt

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1c3a63a..538d360 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -293,8 +293,9 @@
         set_property(TARGET ${TARGET} APPEND_STRING PROPERTY LINK_FLAGS " -Wl,--version-script=${DIR}/${TARGET}.lds")
         set_property(TARGET ${TARGET} APPEND_STRING PROPERTY LINK_DEPENDS "${DIR}/${TARGET}.lds;")
 
-        # Don't allow symbols to be overridden by another module.
-        set_property(TARGET ${TARGET} APPEND_STRING PROPERTY COMPILE_FLAGS " -fvisibility=protected")
+        # -Bsymbolic binds symbol references to their global definitions within
+        # a shared object, thereby preventing symbol preemption.
+        set_property(TARGET ${TARGET} APPEND_STRING PROPERTY COMPILE_FLAGS "  -Wl,-Bsymbolic")
 
         if(ARCH STREQUAL "mipsel" OR ARCH STREQUAL "mips64el")
           # MIPS supports sysv hash-style only.

src/Android.bp

diff --git a/src/Android.bp b/src/Android.bp
index 06d3fa7..65debb5 100644
--- a/src/Android.bp
+++ b/src/Android.bp
@@ -555,6 +555,12 @@
         "-Wno-non-virtual-dtor",
     ],
 
+    ldflags: [
+        // -Bsymbolic binds symbol references to their global definitions within
+        // a shared object, thereby preventing symbol preemption.
+        "-Wl,-Bsymbolic",
+    ],
+
     local_include_dirs: [ "Vulkan" ],
 
     version_script: "Vulkan/android_vk_swiftshader.lds",

src/Vulkan/BUILD.gn

diff --git a/src/Vulkan/BUILD.gn b/src/Vulkan/BUILD.gn
index ce7b87a..063704e 100644
--- a/src/Vulkan/BUILD.gn
+++ b/src/Vulkan/BUILD.gn
@@ -158,8 +158,12 @@
     inputs = [
       "vk_swiftshader.lds",
     ]
-    ldflags = [ "-Wl,--version-script=" +
-                rebase_path("vk_swiftshader.lds", root_build_dir) ]
+    ldflags = [
+      # -Bsymbolic binds symbol references to their global definitions within
+      # a shared object, thereby preventing symbol preemption.
+      "-Wl,-Bsymbolic",
+      "-Wl,--version-script=" +
+          rebase_path("vk_swiftshader.lds", root_build_dir) ]
   }
 
   deps = [