[Mesa-dev] [PATCH] Android: Fix LLVM duplicated symbols linking for N and M

[Rob Herring]

On Fri, Aug 18, 2017 at 7:27 PM, Emil Velikov <emil.l.velikov at gmail.com> wrote:
> On 18 August 2017 at 20:46, Rob Herring <robh at kernel.org> wrote:
>> Both statically linking libLLVMCore and dynamically linking libLLVM causes
>> duplicated symbols in gallium_dri.so and it fails to dlopen. We don't
>> really need to link libLLVMCore, but just need generated headers to be
>> built first. Dynamically linking to libLLVM instead is enough to do
>> that. Thanks to Qiang Yu for finding the root cause.
>>
> Nice find indeed, thanks.
>
> This reminds me - a small task for a rainy day.
> - Wire the version script files into the Android build - see the
> autoconf snippet below.
> It will hide the hundreds of symbols when static linking LLVM (aka
> sidestep the current issue) and make the binary noticeably smaller.
>
> gallium_dri_la_LDFLAGS += \
>        -Wl,--version-script=$(top_srcdir)/src/gallium/targets/dri/dri.sym

About 60K smaller out of 12MB. Is that inline with what you'd expect?

before:
   text    data     bss     dec     hex filename
12164054         420384  352476 12936914         c566d2
out/target/product/linaro_x86_64/system/lib64/dri/gallium_dri.so

after:
   text    data     bss     dec     hex filename
12104616         419816  352476 12876908         c47c6c
out/target/product/linaro_x86_64/system/lib64/dri/gallium_dri.so


The change is trivial, though I'm not sure if there's any downside to
setting --undefined-version (The Android build system turns this off).

diff --git a/src/gallium/targets/dri/Android.mk
b/src/gallium/targets/dri/Android.mk
index 150b2e368e51..440dded0cebe 100644
--- a/src/gallium/targets/dri/Android.mk
+++ b/src/gallium/targets/dri/Android.mk
@@ -32,6 +32,8 @@ LOCAL_SRC_FILES := target.c

 LOCAL_CFLAGS :=

+LOCAL_LDFLAGS := -Wl,--version-script=$(LOCAL_PATH)/dri.sym
-Wl,--undefined-version
+
 LOCAL_SHARED_LIBRARIES := \
        libdl \
        liblog \