r257005 - [WebAssembly] Enable -ffunction-sections and -fdata-sections by default.

[JF Bastien via cfe-commits]

Hi Dan,

I think this change (or one of the surrounding ones) broken compiling C
code with WebAssembly.

Errors look like:  error at line 3: unknown section: .text.foobar

See:
https://build.chromium.org/p/client.wasm.llvm/builders/linux/builds/1507/steps/Link%20LLVM%20Torture%20with%20wasmate/logs/stdio

Could you look into it?

Thanks,

JF

On Wed, Jan 6, 2016 at 4:50 PM, Dan Gohman via cfe-commits <
cfe-commits at lists.llvm.org> wrote:

> Author: djg
> Date: Wed Jan  6 18:50:27 2016
> New Revision: 257005
>
> URL: http://llvm.org/viewvc/llvm-project?rev=257005&view=rev
> Log:
> [WebAssembly] Enable -ffunction-sections and -fdata-sections by default.
>
> These remain user-overridable with -fno-function-sections and
> -fno-data-sections.
>
> Modified:
>     cfe/trunk/lib/Driver/Tools.cpp
>     cfe/trunk/test/Driver/wasm-toolchain.c
>
> Modified: cfe/trunk/lib/Driver/Tools.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Driver/Tools.cpp?rev=257005&r1=257004&r2=257005&view=diff
>
> ==============================================================================
> --- cfe/trunk/lib/Driver/Tools.cpp (original)
> +++ cfe/trunk/lib/Driver/Tools.cpp Wed Jan  6 18:50:27 2016
> @@ -4176,8 +4176,11 @@ void Clang::ConstructJob(Compilation &C,
>      CmdArgs.push_back("-generate-type-units");
>    }
>
> -  // CloudABI uses -ffunction-sections and -fdata-sections by default.
> -  bool UseSeparateSections = Triple.getOS() == llvm::Triple::CloudABI;
> +  // CloudABI and WebAssembly use -ffunction-sections and -fdata-sections
> by
> +  // default.
> +  bool UseSeparateSections = Triple.getOS() == llvm::Triple::CloudABI ||
> +                             Triple.getArch() == llvm::Triple::wasm32 ||
> +                             Triple.getArch() == llvm::Triple::wasm64;
>
>    if (Args.hasFlag(options::OPT_ffunction_sections,
>                     options::OPT_fno_function_sections,
> UseSeparateSections)) {
> @@ -6536,7 +6539,9 @@ void wasm::Linker::ConstructJob(Compilat
>    CmdArgs.push_back("ld");
>
>    // Enable garbage collection of unused input sections by default, since
> code
> -  // size is of particular importance.
> +  // size is of particular importance. This is significantly facilitated
> by
> +  // the enabling of -ffunction-sections and -fdata-sections in
> +  // Clang::ConstructJob.
>    if (areOptimizationsEnabled(Args))
>      CmdArgs.push_back("--gc-sections");
>
>
> Modified: cfe/trunk/test/Driver/wasm-toolchain.c
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Driver/wasm-toolchain.c?rev=257005&r1=257004&r2=257005&view=diff
>
> ==============================================================================
> --- cfe/trunk/test/Driver/wasm-toolchain.c (original)
> +++ cfe/trunk/test/Driver/wasm-toolchain.c Wed Jan  6 18:50:27 2016
> @@ -1,7 +1,19 @@
>  // A basic clang -cc1 command-line.
>
>  // RUN: %clang %s -### -target wasm32-unknown-unknown 2>&1 | FileCheck
> -check-prefix=CC1 %s
> -// CC1: clang{{.*}} "-cc1" "-triple" "wasm32-unknown-unknown" {{.*}}
> +// CC1: clang{{.*}} "-cc1" "-triple" "wasm32-unknown-unknown" {{.*}}
> "-ffunction-sections" "-fdata-sections"
> +
> +// Ditto, but ensure that a user -fno-function-sections disables the
> +// default -ffunction-sections.
> +
> +// RUN: %clang %s -### -target wasm32-unknown-unknown
> -fno-function-sections 2>&1 | FileCheck -check-prefix=NO_FUNCTION_SECTIONS
> %s
> +// NO_FUNCTION_SECTIONS-NOT: function-sections
> +
> +// Ditto, but ensure that a user -fno-data-sections disables the
> +// default -fdata-sections.
> +
> +// RUN: %clang %s -### -target wasm32-unknown-unknown -fno-data-sections
> 2>&1 | FileCheck -check-prefix=NO_DATA_SECTIONS %s
> +// NO_DATA_SECTIONS-NOT: data-sections
>
>  // A basic C link command-line.
>
>
>
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