[lld] r266953 - [LTO] Discard names for Values that are not global.

[Rafael Espíndola via llvm-commits]

According to heaptrack this takes the peak memory consumption when
linking llvm-as from 185.14 MB to 159.89MB, so I would highly
recommend changing the default now :-)

Cheers,
Rafael


On 21 April 2016 at 00:46, Davide Italiano via llvm-commits
<llvm-commits at lists.llvm.org> wrote:
> Author: davide
> Date: Wed Apr 20 23:46:22 2016
> New Revision: 266953
>
> URL: http://llvm.org/viewvc/llvm-project?rev=266953&view=rev
> Log:
> [LTO] Discard names for Values that are not global.
>
> This is not on by default (but it might be in the future).
> The knob to enable the optimization is -lto-discard-value-names.
>
> Added:
>     lld/trunk/test/ELF/lto/discard-value-names.ll
> Modified:
>     lld/trunk/ELF/Config.h
>     lld/trunk/ELF/Driver.cpp
>     lld/trunk/ELF/LTO.h
>     lld/trunk/ELF/Options.td
>
> Modified: lld/trunk/ELF/Config.h
> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Config.h?rev=266953&r1=266952&r2=266953&view=diff
> ==============================================================================
> --- lld/trunk/ELF/Config.h (original)
> +++ lld/trunk/ELF/Config.h Wed Apr 20 23:46:22 2016
> @@ -58,6 +58,7 @@ struct Configuration {
>    bool Demangle = true;
>    bool DisableVerify;
>    bool DiscardAll;
> +  bool DiscardValueNames;
>    bool DiscardLocals;
>    bool DiscardNone;
>    bool EhFrameHdr;
>
> Modified: lld/trunk/ELF/Driver.cpp
> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Driver.cpp?rev=266953&r1=266952&r2=266953&view=diff
> ==============================================================================
> --- lld/trunk/ELF/Driver.cpp (original)
> +++ lld/trunk/ELF/Driver.cpp Wed Apr 20 23:46:22 2016
> @@ -289,6 +289,7 @@ void LinkerDriver::readConfigs(opt::Inpu
>    Config->Demangle = !Args.hasArg(OPT_no_demangle);
>    Config->DisableVerify = Args.hasArg(OPT_disable_verify);
>    Config->DiscardAll = Args.hasArg(OPT_discard_all);
> +  Config->DiscardValueNames = Args.hasArg(OPT_lto_discard_value_names);
>    Config->DiscardLocals = Args.hasArg(OPT_discard_locals);
>    Config->DiscardNone = Args.hasArg(OPT_discard_none);
>    Config->EhFrameHdr = Args.hasArg(OPT_eh_frame_hdr);
>
> Modified: lld/trunk/ELF/LTO.h
> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/LTO.h?rev=266953&r1=266952&r2=266953&view=diff
> ==============================================================================
> --- lld/trunk/ELF/LTO.h (original)
> +++ lld/trunk/ELF/LTO.h Wed Apr 20 23:46:22 2016
> @@ -21,6 +21,7 @@
>  #ifndef LLD_ELF_LTO_H
>  #define LLD_ELF_LTO_H
>
> +#include "Config.h"
>  #include "lld/Core/LLVM.h"
>  #include "llvm/ADT/SmallString.h"
>  #include "llvm/ADT/StringSet.h"
> @@ -41,6 +42,7 @@ public:
>
>    BitcodeCompiler()
>        : Combined(new llvm::Module("ld-temp.o", Context)), Mover(*Combined) {
> +    Context.setDiscardValueNames(Config->DiscardValueNames);
>      Context.enableDebugTypeODRUniquing();
>    }
>
>
> Modified: lld/trunk/ELF/Options.td
> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Options.td?rev=266953&r1=266952&r2=266953&view=diff
> ==============================================================================
> --- lld/trunk/ELF/Options.td (original)
> +++ lld/trunk/ELF/Options.td Wed Apr 20 23:46:22 2016
> @@ -238,6 +238,7 @@ def G : Separate<["-"], "G">;
>  def alias_version_script_version_script : Joined<["--"], "version-script=">, Alias<version_script>;
>
>  // LTO-related options.
> +def lto_discard_value_names : Flag<["-"], "lto-discard-value-names">;
>  def lto_jobs : Joined<["--"], "lto-jobs=">,
>    HelpText<"Number of threads to run codegen">;
>  def disable_verify : Flag<["-"], "disable-verify">;
>
> Added: lld/trunk/test/ELF/lto/discard-value-names.ll
> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/lto/discard-value-names.ll?rev=266953&view=auto
> ==============================================================================
> --- lld/trunk/test/ELF/lto/discard-value-names.ll (added)
> +++ lld/trunk/test/ELF/lto/discard-value-names.ll Wed Apr 20 23:46:22 2016
> @@ -0,0 +1,33 @@
> +; RUN: llvm-as %s -o %t.o
> +
> +; RUN: ld.lld -m elf_x86_64 -shared -save-temps %t.o -o %t2.o
> +; RUN: llvm-dis < %t2.o.lto.bc | FileCheck %s
> +
> +; RUN: ld.lld -m elf_x86_64 -lto-discard-value-names -shared -save-temps %t.o -o %t2.o
> +; RUN: llvm-dis < %t2.o.lto.bc | FileCheck --check-prefix=NONAME %s
> +
> +; CHECK: @GlobalValueName
> +; CHECK: @foo(i32 %in)
> +; CHECK: somelabel:
> +; CHECK:  %GV = load i32, i32* @GlobalValueName
> +; CHECK:  %add = add i32 %in, %GV
> +; CHECK:  ret i32 %add
> +
> +; NONAME: @GlobalValueName
> +; NONAME: @foo(i32)
> +; NONAME-NOT: somelabel:
> +; NONAME:  %2 = load i32, i32* @GlobalValueName
> +; NONAME:  %3 = add i32 %0, %2
> +; NONAME:  ret i32 %3
> +
> +target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
> +target triple = "x86_64-unknown-linux-gnu"
> +
> + at GlobalValueName = global i32 0
> +
> +define i32 @foo(i32 %in) {
> +somelabel:
> +  %GV = load i32, i32* @GlobalValueName
> +  %add = add i32 %in, %GV
> +  ret i32 %add
> +}
>
>
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits