Add i686-unknown-redox target

Co-Authored-By: Jeremy Soller <jackpot51@gmail.com>

Author: bjorn3

compiler/rustc_target/src/spec/mod.rs

@@ -1647,6 +1647,7 @@ supported_targets! {
     ("x86_64-unknown-l4re-uclibc", x86_64_unknown_l4re_uclibc),
 
     ("aarch64-unknown-redox", aarch64_unknown_redox),
+    ("i686-unknown-redox", i686_unknown_redox),
     ("x86_64-unknown-redox", x86_64_unknown_redox),
 
     ("i386-apple-ios", i386_apple_ios),

compiler/rustc_target/src/spec/targets/i686_unknown_redox.rs

@@ -0,0 +1,27 @@
+use crate::spec::{base, Cc, LinkerFlavor, Lld, StackProbeType, Target};
+
+pub fn target() -> Target {
+    let mut base = base::redox::opts();
+    base.cpu = "pentiumpro".into();
+    base.plt_by_default = false;
+    base.max_atomic_width = Some(64);
+    base.add_pre_link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &["-m32"]);
+    // don't use probe-stack=inline-asm until rust#83139 and rust#84667 are resolved
+    base.stack_probes = StackProbeType::Call;
+
+    Target {
+        llvm_target: "i686-unknown-redox".into(),
+        metadata: crate::spec::TargetMetadata {
+            description: None,
+            tier: None,
+            host_tools: None,
+            std: None,
+        },
+        pointer_width: 32,
+        data_layout:
+            "e-m:e-p:32:32-p270:32:32-p271:32:32-p272:64:64-i128:128-f64:32:64-f80:32-n8:16:32-S128"
+                .into(),
+        arch: "x86".into(),
+        options: base,
+    }
+}

src/bootstrap/src/core/sanity.rs

@@ -40,6 +40,7 @@ pub struct Finder {
 #[cfg(not(feature = "bootstrap-self-test"))]
 const STAGE0_MISSING_TARGETS: &[&str] = &[
     // just a dummy comment so the list doesn't get onelined
+    "i686-unknown-redox",
 ];
 
 /// Minimum version threshold for libstdc++ required when using prebuilt LLVM

src/doc/rustc/src/platform-support.md

@@ -300,6 +300,7 @@ target | std | host | notes
 [`i686-unknown-hurd-gnu`](platform-support/hurd.md) | ✓ | ✓ | 32-bit GNU/Hurd [^x86_32-floats-return-ABI]
 [`i686-unknown-netbsd`](platform-support/netbsd.md) | ✓ | ✓ | NetBSD/i386 with SSE2 [^x86_32-floats-return-ABI]
 [`i686-unknown-openbsd`](platform-support/openbsd.md) | ✓ | ✓ | 32-bit OpenBSD [^x86_32-floats-return-ABI]
+`i686-unknown-redox` | ? |  | i686 Redox OS
 `i686-uwp-windows-gnu` | ✓ |  | [^x86_32-floats-return-ABI]
 `i686-uwp-windows-msvc` | ✓ |  | [^x86_32-floats-return-ABI]
 [`i686-win7-windows-msvc`](platform-support/win7-windows-msvc.md) | ✓ |   | 32-bit Windows 7 support [^x86_32-floats-return-ABI]

src/tools/build-manifest/src/main.rs

@@ -103,6 +103,7 @@ static TARGETS: &[&str] = &[
     "i686-unknown-freebsd",
     "i686-unknown-linux-gnu",
     "i686-unknown-linux-musl",
+    "i686-unknown-redox",
     "i686-unknown-uefi",
     "loongarch64-unknown-linux-gnu",
     "loongarch64-unknown-none",

tests/assembly/targets/targets-elf.rs

@@ -228,6 +228,9 @@
 //@ revisions: i686_unknown_openbsd
 //@ [i686_unknown_openbsd] compile-flags: --target i686-unknown-openbsd
 //@ [i686_unknown_openbsd] needs-llvm-components: x86
+//@ revisions: i686_unknown_redox
+//@ [i686_unknown_redox] compile-flags: --target i686-unknown-redox
+//@ [i686_unknown_redox] needs-llvm-components: x86
 //@ revisions: i686_wrs_vxworks
 //@ [i686_wrs_vxworks] compile-flags: --target i686-wrs-vxworks
 //@ [i686_wrs_vxworks] needs-llvm-components: x86