add generic x86_32 support (#52634)

* add generic x86_32 support

- Add support for i386-i586.
- Add `isx86_32` predicate that can replace most uses of `isi686`.
- `isi686` is reinterpreted to mean "exactly i686 arch, and not say i585 or i386".
- This branch was used to build working i586 kernel running on i586 hardware.

* revert `isi[345]86`, remove dead code

- Remove changes to dead code in `doubles.nix` and `for-meta.nix`.
- Remove `isi[345]86` predicates since other cpu families don't have specific model predicates.

* remove i386-linux since linux not supported on that cpu

lib/systems/inspect.nix

@@ -9,7 +9,8 @@ let abis = lib.mapAttrs (_: abi: builtins.removeAttrs abi [ "assertions" ]) abis
 rec {
   patterns = rec {
     isi686         = { cpu = cpuTypes.i686; };
-    isx86_64       = { cpu = cpuTypes.x86_64; };
+    isx86_32       = { cpu = { family = "x86"; bits = 32; }; };
+    isx86_64       = { cpu = { family = "x86"; bits = 64; }; };
     isPowerPC      = { cpu = cpuTypes.powerpc; };
     isPower = { cpu = { family = "power"; }; };
     isx86          = { cpu = { family = "x86"; }; };

lib/systems/platforms.nix

@@ -467,6 +467,8 @@ rec {
   };
 
   selectBySystem = system: {
+      "i486-linux" = pc32;
+      "i586-linux" = pc32;
       "i686-linux" = pc32;
       "x86_64-linux" = pc64;
       "armv5tel-linux" = sheevaplug;

pkgs/build-support/bintools-wrapper/default.nix

@@ -177,7 +177,7 @@ stdenv.mkDerivation {
       /**/ if targetPlatform.isAarch64 then endianPrefix + "aarch64"
       else if targetPlatform.isAarch32     then endianPrefix + "arm"
       else if targetPlatform.isx86_64  then "x86-64"
-      else if targetPlatform.isx86     then "i386"
+      else if targetPlatform.isx86_32  then "i386"
       else if targetPlatform.isMips    then {
           "mips"     = "btsmipn32"; # n32 variant
           "mipsel"   = "ltsmipn32"; # n32 variant

pkgs/development/compilers/gcc/4.8/default.nix

@@ -312,7 +312,7 @@ stdenv.mkDerivation ({
     optional (!bootstrap) "--disable-bootstrap" ++
 
     # Platform-specific flags
-    optional (targetPlatform == hostPlatform && targetPlatform.isi686) "--with-arch=i686" ++
+    optional (targetPlatform == hostPlatform && targetPlatform.isx86_32) "--with-arch=${stdenv.hostPlatform.parsed.cpu.name}" ++
     optionals hostPlatform.isSunOS [
       "--enable-long-long" "--enable-libssp" "--enable-threads=posix" "--disable-nls" "--enable-__cxa_atexit"
       # On Illumos/Solaris GNU as is preferred

pkgs/development/compilers/gcc/4.9/default.nix

@@ -325,7 +325,7 @@ stdenv.mkDerivation ({
     optional (!bootstrap) "--disable-bootstrap" ++
 
     # Platform-specific flags
-    optional (targetPlatform == hostPlatform && targetPlatform.isi686) "--with-arch=i686" ++
+    optional (targetPlatform == hostPlatform && targetPlatform.isx86_32) "--with-arch=${stdenv.hostPlatform.parsed.cpu.name}" ++
     optionals hostPlatform.isSunOS [
       "--enable-long-long" "--enable-libssp" "--enable-threads=posix" "--disable-nls" "--enable-__cxa_atexit"
       # On Illumos/Solaris GNU as is preferred

pkgs/development/compilers/gcc/5/default.nix

@@ -324,7 +324,7 @@ stdenv.mkDerivation ({
     optional (!bootstrap) "--disable-bootstrap" ++
 
     # Platform-specific flags
-    optional (targetPlatform == hostPlatform && targetPlatform.isi686) "--with-arch=i686" ++
+    optional (targetPlatform == hostPlatform && targetPlatform.isx86_32) "--with-arch=${stdenv.hostPlatform.parsed.cpu.name}" ++
     optionals hostPlatform.isSunOS [
       "--enable-long-long" "--enable-libssp" "--enable-threads=posix" "--disable-nls" "--enable-__cxa_atexit"
       # On Illumos/Solaris GNU as is preferred

pkgs/development/compilers/gcc/6/default.nix

@@ -326,7 +326,7 @@ stdenv.mkDerivation ({
     optional (!bootstrap) "--disable-bootstrap" ++
 
     # Platform-specific flags
-    optional (targetPlatform == hostPlatform && targetPlatform.isi686) "--with-arch=i686" ++
+    optional (targetPlatform == hostPlatform && targetPlatform.isx86_32) "--with-arch=${stdenv.hostPlatform.parsed.cpu.name}" ++
     optionals hostPlatform.isSunOS [
       "--enable-long-long" "--enable-libssp" "--enable-threads=posix" "--disable-nls" "--enable-__cxa_atexit"
       # On Illumos/Solaris GNU as is preferred

pkgs/development/compilers/gcc/7/default.nix

@@ -289,7 +289,7 @@ stdenv.mkDerivation ({
     optional (!bootstrap) "--disable-bootstrap" ++
 
     # Platform-specific flags
-    optional (targetPlatform == hostPlatform && targetPlatform.isi686) "--with-arch=i686" ++
+    optional (targetPlatform == hostPlatform && targetPlatform.isx86_32) "--with-arch=${stdenv.hostPlatform.parsed.cpu.name}" ++
     optionals hostPlatform.isSunOS [
       "--enable-long-long" "--enable-libssp" "--enable-threads=posix" "--disable-nls" "--enable-__cxa_atexit"
       # On Illumos/Solaris GNU as is preferred

pkgs/development/compilers/gcc/8/default.nix

@@ -277,7 +277,7 @@ stdenv.mkDerivation ({
     optional (!bootstrap) "--disable-bootstrap" ++
 
     # Platform-specific flags
-    optional (targetPlatform == hostPlatform && targetPlatform.isi686) "--with-arch=i686" ++
+    optional (targetPlatform == hostPlatform && targetPlatform.isx86_32) "--with-arch=${stdenv.hostPlatform.parsed.cpu.name}" ++
     optionals hostPlatform.isSunOS [
       "--enable-long-long" "--enable-libssp" "--enable-threads=posix" "--disable-nls" "--enable-__cxa_atexit"
       # On Illumos/Solaris GNU as is preferred

pkgs/development/compilers/llvm/7/llvm.nix

@@ -134,7 +134,7 @@ in stdenv.mkDerivation (rec {
     ln -s $lib/lib/libLLVM.dylib $lib/lib/libLLVM-${release_version}.dylib
   '';
 
-  doCheck = stdenv.isLinux && (!stdenv.isi686);
+  doCheck = stdenv.isLinux && (!stdenv.isx86_32);
 
   checkTarget = "check-all";
 

pkgs/stdenv/generic/default.nix

@@ -122,7 +122,9 @@ let
       # Utility flags to test the type of platform.
       inherit (hostPlatform)
         isDarwin isLinux isSunOS isCygwin isFreeBSD isOpenBSD
-        isi686 isx86_64 is64bit isAarch32 isAarch64 isMips isBigEndian;
+        isi686 isx86_32 isx86_64
+        is32bit is64bit
+        isAarch32 isAarch64 isMips isBigEndian;
       isArm = lib.warn
         "`stdenv.isArm` is deprecated after 18.03. Please use `stdenv.isAarch32` instead"
         hostPlatform.isAarch32;