Rollup merge of #102293 - ecnelises:aix.initial, r=davidtwco

Add powerpc64-ibm-aix as Tier-3 target

This is part of the effort mentioned in https://github.com/rust-lang/compiler-team/issues/553.

A reference to these options are definitions from [clang](ad6fe32032/clang/lib/Basic/Targets/PPC.h (L414-L448)) and [llvm](https://github.com/llvm/llvm-project/blob/main/llvm/lib/Target/PowerPC/PPCTargetMachine.cpp).

AIX has a system `ld` but [its options and behaviors](https://www.ibm.com/docs/en/aix/7.3?topic=l-ld-command) are different from GNU ld. Thanks to ``@bzEq`` for contributing the linking args.

compiler/rustc_target/src/spec/aix_base.rs

@@ -0,0 +1,32 @@
+use crate::abi::Endian;
+use crate::spec::{crt_objects, cvs, Cc, CodeModel, LinkOutputKind, LinkerFlavor, TargetOptions};
+
+pub fn opts() -> TargetOptions {
+    TargetOptions {
+        abi: "vec-extabi".into(),
+        code_model: Some(CodeModel::Small),
+        cpu: "pwr7".into(),
+        os: "aix".into(),
+        vendor: "ibm".into(),
+        dynamic_linking: true,
+        endian: Endian::Big,
+        executables: true,
+        archive_format: "aix_big".into(),
+        families: cvs!["unix"],
+        has_rpath: false,
+        has_thread_local: true,
+        crt_static_respected: true,
+        linker_flavor: LinkerFlavor::Unix(Cc::No),
+        linker: Some("ld".into()),
+        eh_frame_header: false,
+        is_like_aix: true,
+        default_dwarf_version: 3,
+        function_sections: true,
+        pre_link_objects: crt_objects::new(&[
+            (LinkOutputKind::DynamicNoPicExe, &["/usr/lib/crt0_64.o", "/usr/lib/crti_64.o"]),
+            (LinkOutputKind::DynamicPicExe, &["/usr/lib/crt0_64.o", "/usr/lib/crti_64.o"]),
+        ]),
+        dll_suffix: ".a".into(),
+        ..Default::default()
+    }
+}

compiler/rustc_target/src/spec/mod.rs

@@ -58,6 +58,7 @@ use rustc_macros::HashStable_Generic;
 pub mod abi;
 pub mod crt_objects;
 
+mod aix_base;
 mod android_base;
 mod apple_base;
 mod avr_gnu_base;
@@ -1027,6 +1028,7 @@ supported_targets! {
     ("powerpc-unknown-linux-gnu", powerpc_unknown_linux_gnu),
     ("powerpc-unknown-linux-gnuspe", powerpc_unknown_linux_gnuspe),
     ("powerpc-unknown-linux-musl", powerpc_unknown_linux_musl),
+    ("powerpc64-ibm-aix", powerpc64_ibm_aix),
     ("powerpc64-unknown-linux-gnu", powerpc64_unknown_linux_gnu),
     ("powerpc64-unknown-linux-musl", powerpc64_unknown_linux_musl),
     ("powerpc64le-unknown-linux-gnu", powerpc64le_unknown_linux_gnu),
@@ -1454,6 +1456,9 @@ pub struct TargetOptions {
     pub families: StaticCow<[StaticCow<str>]>,
     /// Whether the target toolchain's ABI supports returning small structs as an integer.
     pub abi_return_struct_as_int: bool,
+    /// Whether the target toolchain is like AIX's. Linker options on AIX are special and it uses
+    /// XCOFF as binary format. Defaults to false.
+    pub is_like_aix: bool,
     /// Whether the target toolchain is like macOS's. Only useful for compiling against iOS/macOS,
     /// in particular running dsymutil and some other stuff like `-dead_strip`. Defaults to false.
     /// Also indiates whether to use Apple-specific ABI changes, such as extending function
@@ -1817,6 +1822,7 @@ impl Default for TargetOptions {
             staticlib_suffix: ".a".into(),
             families: cvs![],
             abi_return_struct_as_int: false,
+            is_like_aix: false,
             is_like_osx: false,
             is_like_solaris: false,
             is_like_windows: false,
@@ -2488,6 +2494,7 @@ impl Target {
         key!(staticlib_suffix);
         key!(families, TargetFamilies);
         key!(abi_return_struct_as_int, bool);
+        key!(is_like_aix, bool);
         key!(is_like_osx, bool);
         key!(is_like_solaris, bool);
         key!(is_like_windows, bool);
@@ -2741,6 +2748,7 @@ impl ToJson for Target {
         target_option_val!(staticlib_suffix);
         target_option_val!(families, "target-family");
         target_option_val!(abi_return_struct_as_int);
+        target_option_val!(is_like_aix);
         target_option_val!(is_like_osx);
         target_option_val!(is_like_solaris);
         target_option_val!(is_like_windows);

compiler/rustc_target/src/spec/powerpc64_ibm_aix.rs

@@ -0,0 +1,23 @@
+use crate::spec::{Cc, LinkerFlavor, Target};
+
+pub fn target() -> Target {
+    let mut base = super::aix_base::opts();
+    base.max_atomic_width = Some(64);
+    base.add_pre_link_args(
+        LinkerFlavor::Unix(Cc::No),
+        &[
+            "-b64".into(),
+            "-bpT:0x100000000".into(),
+            "-bpD:0x110000000".into(),
+            "-bcdtors:all:0:s".into(),
+        ],
+    );
+
+    Target {
+        llvm_target: "powerpc64-ibm-aix".into(),
+        pointer_width: 64,
+        data_layout: "E-m:a-i64:64-n32:64-S128-v256:256:256-v512:512:512".into(),
+        arch: "powerpc64".into(),
+        options: base,
+    }
+}