nixpkgs/pkgs/development/compilers/gcc/common/extra-target-flags.nix
Tobias Mayer 2be2b5328c
gcc: optimize cross-compiled libraries
`libstdc++` and a few other libraries are comiled with the options
set in `EXTRA_TARGET_FLAGS`. Normally, this is filled form
`EXTRA_FLAGS` inside of `builder.sh`, from which it inherits its
optimization option. For cross compilers `EXTRA_TARGET_FLAGS` is
set by a dedicated function that does not specify any optimization,
leading to sub-par runtime performance of many C++ programs.
2020-05-27 10:07:01 +02:00

34 lines
1.3 KiB
Nix

{ stdenv, crossStageStatic, langD ? false, libcCross, threadsCross }:
let
inherit (stdenv) lib hostPlatform targetPlatform;
in
{
# For non-cross builds these flags are currently assigned in builder.sh.
# It would be good to consolidate the generation of makeFlags
# ({C,CXX,LD}FLAGS_FOR_{BUILD,TARGET}, etc...) at some point.
EXTRA_TARGET_FLAGS = let
mkFlags = dep: langD: lib.optionals (targetPlatform != hostPlatform && dep != null && !langD) ([
"-O2 -idirafter ${lib.getDev dep}${dep.incdir or "/include"}"
] ++ stdenv.lib.optionals (! crossStageStatic) [
"-B${lib.getLib dep}${dep.libdir or "/lib"}"
]);
in mkFlags libcCross langD
++ lib.optionals (!crossStageStatic) (mkFlags threadsCross langD)
;
EXTRA_TARGET_LDFLAGS = let
mkFlags = dep: lib.optionals (targetPlatform != hostPlatform && dep != null) ([
"-Wl,-L${lib.getLib dep}${dep.libdir or "/lib"}"
] ++ (if crossStageStatic then [
"-B${lib.getLib dep}${dep.libdir or "/lib"}"
] else [
"-Wl,-rpath,${lib.getLib dep}${dep.libdir or "/lib"}"
"-Wl,-rpath-link,${lib.getLib dep}${dep.libdir or "/lib"}"
]));
in mkFlags libcCross
++ lib.optionals (!crossStageStatic) (mkFlags threadsCross)
;
}