Auto merge of #79608 - alessandrod:bpf, r=nagisa

BPF target support

This adds `bpfel-unknown-none` and `bpfeb-unknown-none`, two new no_std targets that generate little and big endian BPF. The approach taken is very similar to the cuda target, where `TargetOptions::obj_is_bitcode` is enabled and code generation is done by the linker.

I added the targets to `dist-various-2`. There are [some tests](https://github.com/alessandrod/bpf-linker/tree/main/tests/assembly) in bpf-linker and I'm planning to add more. Those are currently not ran as part of rust CI.

compiler/rustc_codegen_cranelift/src/toolchain.rs

@@ -67,6 +67,7 @@ fn infer_from(
                     LinkerFlavor::Msvc => "link.exe",
                     LinkerFlavor::Lld(_) => "lld",
                     LinkerFlavor::PtxLinker => "rust-ptx-linker",
+                    LinkerFlavor::BpfLinker => "bpf-linker",
                 }),
                 flavor,
             )),

compiler/rustc_codegen_llvm/src/asm.rs

@@ -288,6 +288,7 @@ fn codegen_inline_asm(
                 InlineAsmArch::Mips | InlineAsmArch::Mips64 => {}
                 InlineAsmArch::SpirV => {}
                 InlineAsmArch::Wasm32 => {}
+                InlineAsmArch::Bpf => {}
             }
         }
         if !options.contains(InlineAsmOptions::NOMEM) {
@@ -593,6 +594,8 @@ fn reg_to_llvm(reg: InlineAsmRegOrRegClass, layout: Option<&TyAndLayout<'tcx>>)
             InlineAsmRegClass::X86(X86InlineAsmRegClass::zmm_reg) => "v",
             InlineAsmRegClass::X86(X86InlineAsmRegClass::kreg) => "^Yk",
             InlineAsmRegClass::Wasm(WasmInlineAsmRegClass::local) => "r",
+            InlineAsmRegClass::Bpf(BpfInlineAsmRegClass::reg) => "r",
+            InlineAsmRegClass::Bpf(BpfInlineAsmRegClass::wreg) => "w",
             InlineAsmRegClass::SpirV(SpirVInlineAsmRegClass::reg) => {
                 bug!("LLVM backend does not support SPIR-V")
             }
@@ -661,6 +664,7 @@ fn modifier_to_llvm(
         },
         InlineAsmRegClass::X86(X86InlineAsmRegClass::kreg) => None,
         InlineAsmRegClass::Wasm(WasmInlineAsmRegClass::local) => None,
+        InlineAsmRegClass::Bpf(_) => None,
         InlineAsmRegClass::SpirV(SpirVInlineAsmRegClass::reg) => {
             bug!("LLVM backend does not support SPIR-V")
         }
@@ -708,6 +712,8 @@ fn dummy_output_type(cx: &CodegenCx<'ll, 'tcx>, reg: InlineAsmRegClass) -> &'ll
         | InlineAsmRegClass::X86(X86InlineAsmRegClass::zmm_reg) => cx.type_f32(),
         InlineAsmRegClass::X86(X86InlineAsmRegClass::kreg) => cx.type_i16(),
         InlineAsmRegClass::Wasm(WasmInlineAsmRegClass::local) => cx.type_i32(),
+        InlineAsmRegClass::Bpf(BpfInlineAsmRegClass::reg) => cx.type_i64(),
+        InlineAsmRegClass::Bpf(BpfInlineAsmRegClass::wreg) => cx.type_i32(),
         InlineAsmRegClass::SpirV(SpirVInlineAsmRegClass::reg) => {
             bug!("LLVM backend does not support SPIR-V")
         }

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -1124,6 +1124,7 @@ fn infer_from(
                     LinkerFlavor::Msvc => "link.exe",
                     LinkerFlavor::Lld(_) => "lld",
                     LinkerFlavor::PtxLinker => "rust-ptx-linker",
+                    LinkerFlavor::BpfLinker => "bpf-linker",
                 }),
                 flavor,
             )),

compiler/rustc_codegen_ssa/src/back/linker.rs

@@ -84,6 +84,10 @@ pub fn to_linker<'a>(
             LinkerFlavor::PtxLinker => {
                 Box::new(PtxLinker { cmd, sess, info: self }) as Box<dyn Linker>
             }
+
+            LinkerFlavor::BpfLinker => {
+                Box::new(BpfLinker { cmd, sess, info: self }) as Box<dyn Linker>
+            }
         }
     }
 }
@@ -1431,3 +1435,128 @@ fn group_end(&mut self) {}
 
     fn linker_plugin_lto(&mut self) {}
 }
+
+pub struct BpfLinker<'a> {
+    cmd: Command,
+    sess: &'a Session,
+    info: &'a LinkerInfo,
+}
+
+impl<'a> Linker for BpfLinker<'a> {
+    fn cmd(&mut self) -> &mut Command {
+        &mut self.cmd
+    }
+
+    fn set_output_kind(&mut self, _output_kind: LinkOutputKind, _out_filename: &Path) {}
+
+    fn link_rlib(&mut self, path: &Path) {
+        self.cmd.arg(path);
+    }
+
+    fn link_whole_rlib(&mut self, path: &Path) {
+        self.cmd.arg(path);
+    }
+
+    fn include_path(&mut self, path: &Path) {
+        self.cmd.arg("-L").arg(path);
+    }
+
+    fn debuginfo(&mut self, _strip: Strip) {
+        self.cmd.arg("--debug");
+    }
+
+    fn add_object(&mut self, path: &Path) {
+        self.cmd.arg(path);
+    }
+
+    fn optimize(&mut self) {
+        self.cmd.arg(match self.sess.opts.optimize {
+            OptLevel::No => "-O0",
+            OptLevel::Less => "-O1",
+            OptLevel::Default => "-O2",
+            OptLevel::Aggressive => "-O3",
+            OptLevel::Size => "-Os",
+            OptLevel::SizeMin => "-Oz",
+        });
+    }
+
+    fn output_filename(&mut self, path: &Path) {
+        self.cmd.arg("-o").arg(path);
+    }
+
+    fn finalize(&mut self) {
+        self.cmd.arg("--cpu").arg(match self.sess.opts.cg.target_cpu {
+            Some(ref s) => s,
+            None => &self.sess.target.options.cpu,
+        });
+        self.cmd.arg("--cpu-features").arg(match &self.sess.opts.cg.target_feature {
+            feat if !feat.is_empty() => feat,
+            _ => &self.sess.target.options.features,
+        });
+    }
+
+    fn link_dylib(&mut self, _lib: Symbol, _verbatim: bool, _as_needed: bool) {
+        panic!("external dylibs not supported")
+    }
+
+    fn link_rust_dylib(&mut self, _lib: Symbol, _path: &Path) {
+        panic!("external dylibs not supported")
+    }
+
+    fn link_staticlib(&mut self, _lib: Symbol, _verbatim: bool) {
+        panic!("staticlibs not supported")
+    }
+
+    fn link_whole_staticlib(&mut self, _lib: Symbol, _verbatim: bool, _search_path: &[PathBuf]) {
+        panic!("staticlibs not supported")
+    }
+
+    fn framework_path(&mut self, _path: &Path) {
+        panic!("frameworks not supported")
+    }
+
+    fn link_framework(&mut self, _framework: Symbol, _as_needed: bool) {
+        panic!("frameworks not supported")
+    }
+
+    fn full_relro(&mut self) {}
+
+    fn partial_relro(&mut self) {}
+
+    fn no_relro(&mut self) {}
+
+    fn gc_sections(&mut self, _keep_metadata: bool) {}
+
+    fn no_gc_sections(&mut self) {}
+
+    fn pgo_gen(&mut self) {}
+
+    fn no_crt_objects(&mut self) {}
+
+    fn no_default_libraries(&mut self) {}
+
+    fn control_flow_guard(&mut self) {}
+
+    fn export_symbols(&mut self, tmpdir: &Path, crate_type: CrateType) {
+        let path = tmpdir.join("symbols");
+        let res: io::Result<()> = try {
+            let mut f = BufWriter::new(File::create(&path)?);
+            for sym in self.info.exports[&crate_type].iter() {
+                writeln!(f, "{}", sym)?;
+            }
+        };
+        if let Err(e) = res {
+            self.sess.fatal(&format!("failed to write symbols file: {}", e));
+        } else {
+            self.cmd.arg("--export-symbols").arg(&path);
+        }
+    }
+
+    fn subsystem(&mut self, _subsystem: &str) {}
+
+    fn group_start(&mut self) {}
+
+    fn group_end(&mut self) {}
+
+    fn linker_plugin_lto(&mut self) {}
+}

compiler/rustc_codegen_ssa/src/target_features.rs

@@ -210,6 +210,8 @@
     ("nontrapping-fptoint", Some(sym::wasm_target_feature)),
 ];
 
+const BPF_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[("alu32", Some(sym::bpf_target_feature))];
+
 /// When rustdoc is running, provide a list of all known features so that all their respective
 /// primitives may be documented.
 ///
@@ -224,6 +226,7 @@ pub fn all_known_features() -> impl Iterator<Item = (&'static str, Option<Symbol
         .chain(MIPS_ALLOWED_FEATURES.iter())
         .chain(RISCV_ALLOWED_FEATURES.iter())
         .chain(WASM_ALLOWED_FEATURES.iter())
+        .chain(BPF_ALLOWED_FEATURES.iter())
         .cloned()
 }
 
@@ -237,6 +240,7 @@ pub fn supported_target_features(sess: &Session) -> &'static [(&'static str, Opt
         "powerpc" | "powerpc64" => POWERPC_ALLOWED_FEATURES,
         "riscv32" | "riscv64" => RISCV_ALLOWED_FEATURES,
         "wasm32" | "wasm64" => WASM_ALLOWED_FEATURES,
+        "bpf" => BPF_ALLOWED_FEATURES,
         _ => &[],
     }
 }

compiler/rustc_feature/src/active.rs

@@ -250,6 +250,7 @@ pub fn set(&self, features: &mut Features, span: Span) {
     (active, f16c_target_feature, "1.36.0", Some(44839), None),
     (active, riscv_target_feature, "1.45.0", Some(44839), None),
     (active, ermsb_target_feature, "1.49.0", Some(44839), None),
+    (active, bpf_target_feature, "1.54.0", Some(44839), None),
 
     // -------------------------------------------------------------------------
     // feature-group-end: actual feature gates (target features)

compiler/rustc_llvm/build.rs

@@ -86,6 +86,7 @@ fn main() {
         "nvptx",
         "hexagon",
         "riscv",
+        "bpf",
     ];
 
     let required_components = &[

compiler/rustc_llvm/src/lib.rs

@@ -167,4 +167,12 @@ fn init() { }
         LLVMInitializeWebAssemblyAsmPrinter,
         LLVMInitializeWebAssemblyAsmParser
     );
+    init_target!(
+        llvm_component = "bpf",
+        LLVMInitializeBPFTargetInfo,
+        LLVMInitializeBPFTarget,
+        LLVMInitializeBPFTargetMC,
+        LLVMInitializeBPFAsmPrinter,
+        LLVMInitializeBPFAsmParser
+    );
 }

compiler/rustc_span/src/symbol.rs

@@ -328,6 +328,7 @@
         box_free,
         box_patterns,
         box_syntax,
+        bpf_target_feature,
         braced_empty_structs,
         branch,
         breakpoint,
@@ -1332,6 +1333,7 @@
         wrapping_add,
         wrapping_mul,
         wrapping_sub,
+        wreg,
         write_bytes,
         xmm_reg,
         ymm_reg,

compiler/rustc_target/src/abi/call/bpf.rs

+// see https://github.com/llvm/llvm-project/blob/main/llvm/lib/Target/BPF/BPFCallingConv.td
+use crate::abi::call::{ArgAbi, FnAbi};
+
+fn classify_ret<Ty>(ret: &mut ArgAbi<'_, Ty>) {
+    if ret.layout.is_aggregate() || ret.layout.size.bits() > 64 {
+        ret.make_indirect();
+    } else {
+        ret.extend_integer_width_to(32);
+    }
+}
+
+fn classify_arg<Ty>(arg: &mut ArgAbi<'_, Ty>) {
+    if arg.layout.is_aggregate() || arg.layout.size.bits() > 64 {
+        arg.make_indirect();
+    } else {
+        arg.extend_integer_width_to(32);
+    }
+}
+
+pub fn compute_abi_info<Ty>(fn_abi: &mut FnAbi<'_, Ty>) {
+    if !fn_abi.ret.is_ignore() {
+        classify_ret(&mut fn_abi.ret);
+    }
+
+    for arg in &mut fn_abi.args {
+        if arg.is_ignore() {
+            continue;
+        }
+        classify_arg(arg);
+    }
+}

compiler/rustc_target/src/abi/call/mod.rs

@@ -6,6 +6,7 @@
 mod amdgpu;
 mod arm;
 mod avr;
+mod bpf;
 mod hexagon;
 mod mips;
 mod mips64;
@@ -654,6 +655,7 @@ pub fn adjust_for_cabi<C>(&mut self, cx: &C, abi: spec::abi::Abi) -> Result<(),
                 }
             }
             "asmjs" => wasm::compute_c_abi_info(cx, self),
+            "bpf" => bpf::compute_abi_info(self),
             a => return Err(format!("unrecognized arch \"{}\" in target specification", a)),
         }
 

compiler/rustc_target/src/asm/bpf.rs

+use super::{InlineAsmArch, InlineAsmType, Target};
+use rustc_macros::HashStable_Generic;
+use std::fmt;
+
+def_reg_class! {
+    Bpf BpfInlineAsmRegClass {
+        reg,
+        wreg,
+    }
+}
+
+impl BpfInlineAsmRegClass {
+    pub fn valid_modifiers(self, _arch: InlineAsmArch) -> &'static [char] {
+        &[]
+    }
+
+    pub fn suggest_class(self, _arch: InlineAsmArch, _ty: InlineAsmType) -> Option<Self> {
+        None
+    }
+
+    pub fn suggest_modifier(
+        self,
+        _arch: InlineAsmArch,
+        _ty: InlineAsmType,
+    ) -> Option<(char, &'static str)> {
+        None
+    }
+
+    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<(char, &'static str)> {
+        None
+    }
+
+    pub fn supported_types(
+        self,
+        _arch: InlineAsmArch,
+    ) -> &'static [(InlineAsmType, Option<&'static str>)] {
+        match self {
+            Self::reg => types! { _: I8, I16, I32, I64; },
+            Self::wreg => types! { "alu32": I8, I16, I32; },
+        }
+    }
+}
+
+fn only_alu32(
+    _arch: InlineAsmArch,
+    mut has_feature: impl FnMut(&str) -> bool,
+    _target: &Target,
+) -> Result<(), &'static str> {
+    if !has_feature("alu32") {
+        Err("register can't be used without the `alu32` target feature")
+    } else {
+        Ok(())
+    }
+}
+
+def_regs! {
+    Bpf BpfInlineAsmReg BpfInlineAsmRegClass {
+        r0: reg = ["r0"],
+        r1: reg = ["r1"],
+        r2: reg = ["r2"],
+        r3: reg = ["r3"],
+        r4: reg = ["r4"],
+        r5: reg = ["r5"],
+        r6: reg = ["r6"],
+        r7: reg = ["r7"],
+        r8: reg = ["r8"],
+        r9: reg = ["r9"],
+        w0: wreg = ["w0"] % only_alu32,
+        w1: wreg = ["w1"] % only_alu32,
+        w2: wreg = ["w2"] % only_alu32,
+        w3: wreg = ["w3"] % only_alu32,
+        w4: wreg = ["w4"] % only_alu32,
+        w5: wreg = ["w5"] % only_alu32,
+        w6: wreg = ["w6"] % only_alu32,
+        w7: wreg = ["w7"] % only_alu32,
+        w8: wreg = ["w8"] % only_alu32,
+        w9: wreg = ["w9"] % only_alu32,
+
+        #error = ["r10", "w10"] =>
+            "the stack pointer cannot be used as an operand for inline asm",
+    }
+}
+
+impl BpfInlineAsmReg {
+    pub fn emit(
+        self,
+        out: &mut dyn fmt::Write,
+        _arch: InlineAsmArch,
+        _modifier: Option<char>,
+    ) -> fmt::Result {
+        out.write_str(self.name())
+    }
+
+    pub fn overlapping_regs(self, mut cb: impl FnMut(BpfInlineAsmReg)) {
+        cb(self);
+
+        macro_rules! reg_conflicts {
+            (
+                $(
+                    $r:ident : $w:ident
+                ),*
+            ) => {
+                match self {
+                    $(
+                        Self::$r => {
+                            cb(Self::$w);
+                        }
+                        Self::$w => {
+                            cb(Self::$r);
+                        }
+                    )*
+                }
+            };
+        }
+
+        reg_conflicts! {
+            r0 : w0,
+            r1 : w1,
+            r2 : w2,
+            r3 : w3,
+            r4 : w4,
+            r5 : w5,
+            r6 : w6,
+            r7 : w7,
+            r8 : w8,
+            r9 : w9
+        }
+    }
+}

compiler/rustc_target/src/asm/mod.rs

@@ -148,6 +148,7 @@ pub(super) fn fill_reg_map(
 
 mod aarch64;
 mod arm;
+mod bpf;
 mod hexagon;
 mod mips;
 mod nvptx;
@@ -159,6 +160,7 @@ pub(super) fn fill_reg_map(
 
 pub use aarch64::{AArch64InlineAsmReg, AArch64InlineAsmRegClass};
 pub use arm::{ArmInlineAsmReg, ArmInlineAsmRegClass};
+pub use bpf::{BpfInlineAsmReg, BpfInlineAsmRegClass};
 pub use hexagon::{HexagonInlineAsmReg, HexagonInlineAsmRegClass};
 pub use mips::{MipsInlineAsmReg, MipsInlineAsmRegClass};
 pub use nvptx::{NvptxInlineAsmReg, NvptxInlineAsmRegClass};
@@ -184,6 +186,7 @@ pub enum InlineAsmArch {
     PowerPC64,
     SpirV,
     Wasm32,
+    Bpf,
 }
 
 impl FromStr for InlineAsmArch {
@@ -205,6 +208,7 @@ fn from_str(s: &str) -> Result<InlineAsmArch, ()> {
             "mips64" => Ok(Self::Mips64),
             "spirv" => Ok(Self::SpirV),
             "wasm32" => Ok(Self::Wasm32),
+            "bpf" => Ok(Self::Bpf),
             _ => Err(()),
         }
     }
@@ -233,6 +237,7 @@ pub enum InlineAsmReg {
     Mips(MipsInlineAsmReg),
     SpirV(SpirVInlineAsmReg),
     Wasm(WasmInlineAsmReg),
+    Bpf(BpfInlineAsmReg),
     // Placeholder for invalid register constraints for the current target
     Err,
 }
@@ -247,6 +252,7 @@ pub fn name(self) -> &'static str {
             Self::PowerPC(r) => r.name(),
             Self::Hexagon(r) => r.name(),
             Self::Mips(r) => r.name(),
+            Self::Bpf(r) => r.name(),
             Self::Err => "<reg>",
         }
     }
@@ -260,6 +266,7 @@ pub fn reg_class(self) -> InlineAsmRegClass {
             Self::PowerPC(r) => InlineAsmRegClass::PowerPC(r.reg_class()),
             Self::Hexagon(r) => InlineAsmRegClass::Hexagon(r.reg_class()),
             Self::Mips(r) => InlineAsmRegClass::Mips(r.reg_class()),
+            Self::Bpf(r) => InlineAsmRegClass::Bpf(r.reg_class()),
             Self::Err => InlineAsmRegClass::Err,
         }
     }
@@ -304,6 +311,9 @@ pub fn parse(
             InlineAsmArch::Wasm32 => {
                 Self::Wasm(WasmInlineAsmReg::parse(arch, has_feature, target, &name)?)
             }
+            InlineAsmArch::Bpf => {
+                Self::Bpf(BpfInlineAsmReg::parse(arch, has_feature, target, &name)?)
+            }
         })
     }
 
@@ -323,6 +333,7 @@ pub fn emit(
             Self::PowerPC(r) => r.emit(out, arch, modifier),
             Self::Hexagon(r) => r.emit(out, arch, modifier),
             Self::Mips(r) => r.emit(out, arch, modifier),
+            Self::Bpf(r) => r.emit(out, arch, modifier),
             Self::Err => unreachable!("Use of InlineAsmReg::Err"),
         }
     }
@@ -336,6 +347,7 @@ pub fn overlapping_regs(self, mut cb: impl FnMut(InlineAsmReg)) {
             Self::PowerPC(_) => cb(self),
             Self::Hexagon(r) => r.overlapping_regs(|r| cb(Self::Hexagon(r))),
             Self::Mips(_) => cb(self),
+            Self::Bpf(r) => r.overlapping_regs(|r| cb(Self::Bpf(r))),
             Self::Err => unreachable!("Use of InlineAsmReg::Err"),
         }
     }
@@ -364,6 +376,7 @@ pub enum InlineAsmRegClass {
     Mips(MipsInlineAsmRegClass),
     SpirV(SpirVInlineAsmRegClass),
     Wasm(WasmInlineAsmRegClass),
+    Bpf(BpfInlineAsmRegClass),
     // Placeholder for invalid register constraints for the current target
     Err,
 }
@@ -381,6 +394,7 @@ pub fn name(self) -> Symbol {
             Self::Mips(r) => r.name(),
             Self::SpirV(r) => r.name(),
             Self::Wasm(r) => r.name(),
+            Self::Bpf(r) => r.name(),
             Self::Err => rustc_span::symbol::sym::reg,
         }
     }
@@ -400,6 +414,7 @@ pub fn suggest_class(self, arch: InlineAsmArch, ty: InlineAsmType) -> Option<Sel
             Self::Mips(r) => r.suggest_class(arch, ty).map(InlineAsmRegClass::Mips),
             Self::SpirV(r) => r.suggest_class(arch, ty).map(InlineAsmRegClass::SpirV),
             Self::Wasm(r) => r.suggest_class(arch, ty).map(InlineAsmRegClass::Wasm),
+            Self::Bpf(r) => r.suggest_class(arch, ty).map(InlineAsmRegClass::Bpf),
             Self::Err => unreachable!("Use of InlineAsmRegClass::Err"),
         }
     }
@@ -426,6 +441,7 @@ pub fn suggest_modifier(
             Self::Mips(r) => r.suggest_modifier(arch, ty),
             Self::SpirV(r) => r.suggest_modifier(arch, ty),
             Self::Wasm(r) => r.suggest_modifier(arch, ty),
+            Self::Bpf(r) => r.suggest_modifier(arch, ty),
             Self::Err => unreachable!("Use of InlineAsmRegClass::Err"),
         }
     }
@@ -448,6 +464,7 @@ pub fn default_modifier(self, arch: InlineAsmArch) -> Option<(char, &'static str
             Self::Mips(r) => r.default_modifier(arch),
             Self::SpirV(r) => r.default_modifier(arch),
             Self::Wasm(r) => r.default_modifier(arch),
+            Self::Bpf(r) => r.default_modifier(arch),
             Self::Err => unreachable!("Use of InlineAsmRegClass::Err"),
         }
     }
@@ -469,6 +486,7 @@ pub fn supported_types(
             Self::Mips(r) => r.supported_types(arch),
             Self::SpirV(r) => r.supported_types(arch),
             Self::Wasm(r) => r.supported_types(arch),
+            Self::Bpf(r) => r.supported_types(arch),
             Self::Err => unreachable!("Use of InlineAsmRegClass::Err"),
         }
     }
@@ -493,6 +511,7 @@ pub fn parse(arch: InlineAsmArch, name: Symbol) -> Result<Self, &'static str> {
             }
             InlineAsmArch::SpirV => Self::SpirV(SpirVInlineAsmRegClass::parse(arch, name)?),
             InlineAsmArch::Wasm32 => Self::Wasm(WasmInlineAsmRegClass::parse(arch, name)?),
+            InlineAsmArch::Bpf => Self::Bpf(BpfInlineAsmRegClass::parse(arch, name)?),
         })
     }
 
@@ -510,6 +529,7 @@ pub fn valid_modifiers(self, arch: InlineAsmArch) -> &'static [char] {
             Self::Mips(r) => r.valid_modifiers(arch),
             Self::SpirV(r) => r.valid_modifiers(arch),
             Self::Wasm(r) => r.valid_modifiers(arch),
+            Self::Bpf(r) => r.valid_modifiers(arch),
             Self::Err => unreachable!("Use of InlineAsmRegClass::Err"),
         }
     }
@@ -679,5 +699,10 @@ pub fn allocatable_registers(
             wasm::fill_reg_map(arch, has_feature, target, &mut map);
             map
         }
+        InlineAsmArch::Bpf => {
+            let mut map = bpf::regclass_map();
+            bpf::fill_reg_map(arch, has_feature, target, &mut map);
+            map
+        }
     }
 }

compiler/rustc_target/src/spec/bpf_base.rs

+use crate::spec::{LinkerFlavor, MergeFunctions, PanicStrategy, TargetOptions};
+use crate::{abi::Endian, spec::abi::Abi};
+
+pub fn opts(endian: Endian) -> TargetOptions {
+    TargetOptions {
+        allow_asm: true,
+        endian,
+        linker_flavor: LinkerFlavor::BpfLinker,
+        atomic_cas: false,
+        executables: true,
+        dynamic_linking: true,
+        no_builtins: true,
+        panic_strategy: PanicStrategy::Abort,
+        position_independent_executables: true,
+        // Disable MergeFunctions since:
+        // - older kernels don't support bpf-to-bpf calls
+        // - on newer kernels, userspace still needs to relocate before calling
+        //   BPF_PROG_LOAD and not all BPF libraries do that yet
+        merge_functions: MergeFunctions::Disabled,
+        obj_is_bitcode: true,
+        requires_lto: false,
+        singlethread: true,
+        max_atomic_width: Some(64),
+        unsupported_abis: vec![
+            Abi::Cdecl,
+            Abi::Stdcall { unwind: false },
+            Abi::Stdcall { unwind: true },
+            Abi::Fastcall,
+            Abi::Vectorcall,
+            Abi::Thiscall { unwind: false },
+            Abi::Thiscall { unwind: true },
+            Abi::Aapcs,
+            Abi::Win64,
+            Abi::SysV64,
+            Abi::PtxKernel,
+            Abi::Msp430Interrupt,
+            Abi::X86Interrupt,
+            Abi::AmdGpuKernel,
+        ],
+        ..Default::default()
+    }
+}

compiler/rustc_target/src/spec/bpfeb_unknown_none.rs

+use crate::spec::Target;
+use crate::{abi::Endian, spec::bpf_base};
+
+pub fn target() -> Target {
+    Target {
+        llvm_target: "bpfeb".to_string(),
+        data_layout: "E-m:e-p:64:64-i64:64-i128:128-n32:64-S128".to_string(),
+        pointer_width: 64,
+        arch: "bpf".to_string(),
+        options: bpf_base::opts(Endian::Big),
+    }
+}

compiler/rustc_target/src/spec/bpfel_unknown_none.rs

+use crate::spec::Target;
+use crate::{abi::Endian, spec::bpf_base};
+
+pub fn target() -> Target {
+    Target {
+        llvm_target: "bpfel".to_string(),
+        data_layout: "e-m:e-p:64:64-i64:64-i128:128-n32:64-S128".to_string(),
+        pointer_width: 64,
+        arch: "bpf".to_string(),
+        options: bpf_base::opts(Endian::Little),
+    }
+}

compiler/rustc_target/src/spec/mod.rs

@@ -57,6 +57,7 @@
 mod apple_sdk_base;
 mod arm_base;
 mod avr_gnu_base;
+mod bpf_base;
 mod dragonfly_base;
 mod freebsd_base;
 mod fuchsia_base;
@@ -93,6 +94,7 @@ pub enum LinkerFlavor {
     Msvc,
     Lld(LldFlavor),
     PtxLinker,
+    BpfLinker,
 }
 
 #[derive(Clone, Copy, Debug, Eq, Ord, PartialEq, PartialOrd)]
@@ -161,6 +163,7 @@ pub fn desc(&self) -> &str {
     ((LinkerFlavor::Ld), "ld"),
     ((LinkerFlavor::Msvc), "msvc"),
     ((LinkerFlavor::PtxLinker), "ptx-linker"),
+    ((LinkerFlavor::BpfLinker), "bpf-linker"),
     ((LinkerFlavor::Lld(LldFlavor::Wasm)), "wasm-ld"),
     ((LinkerFlavor::Lld(LldFlavor::Ld64)), "ld64.lld"),
     ((LinkerFlavor::Lld(LldFlavor::Ld)), "ld.lld"),
@@ -897,6 +900,9 @@ fn $module() {
     ("aarch64_be-unknown-linux-gnu", aarch64_be_unknown_linux_gnu),
     ("aarch64-unknown-linux-gnu_ilp32", aarch64_unknown_linux_gnu_ilp32),
     ("aarch64_be-unknown-linux-gnu_ilp32", aarch64_be_unknown_linux_gnu_ilp32),
+
+    ("bpfeb-unknown-none", bpfeb_unknown_none),
+    ("bpfel-unknown-none", bpfel_unknown_none),
 }
 
 /// Everything `rustc` knows about how to compile for a specific target.

compiler/rustc_typeck/src/collect.rs

@@ -2597,6 +2597,7 @@ fn from_target_feature(
                 Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
                 Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
                 Some(sym::ermsb_target_feature) => rust_features.ermsb_target_feature,
+                Some(sym::bpf_target_feature) => rust_features.bpf_target_feature,
                 Some(name) => bug!("unknown target feature gate {}", name),
                 None => true,
             };

config.toml.example

@@ -94,7 +94,7 @@ changelog-seen = 2
 # support. You'll need to write a target specification at least, and most
 # likely, teach rustc about the C ABI of the target. Get in touch with the
 # Rust team and file an issue if you need assistance in porting!
-#targets = "AArch64;ARM;Hexagon;MSP430;Mips;NVPTX;PowerPC;RISCV;Sparc;SystemZ;WebAssembly;X86"
+#targets = "AArch64;ARM;BPF;Hexagon;MSP430;Mips;NVPTX;PowerPC;RISCV;Sparc;SystemZ;WebAssembly;X86"
 
 # LLVM experimental targets to build support for. These targets are specified in
 # the same format as above, but since these targets are experimental, they are

src/bootstrap/compile.rs

@@ -269,7 +269,9 @@ pub fn std_cargo(builder: &Builder<'_>, target: TargetSelection, stage: u32, car
 
     if builder.no_std(target) == Some(true) {
         let mut features = "compiler-builtins-mem".to_string();
-        features.push_str(compiler_builtins_c_feature);
+        if !target.starts_with("bpf") {
+            features.push_str(compiler_builtins_c_feature);
+        }
 
         // for no-std targets we only compile a few no_std crates
         cargo

src/bootstrap/native.rs

@@ -153,7 +153,7 @@ fn run(self, builder: &Builder<'_>) -> PathBuf {
         let llvm_targets = match &builder.config.llvm_targets {
             Some(s) => s,
             None => {
-                "AArch64;ARM;Hexagon;MSP430;Mips;NVPTX;PowerPC;RISCV;\
+                "AArch64;ARM;BPF;Hexagon;MSP430;Mips;NVPTX;PowerPC;RISCV;\
                      Sparc;SystemZ;WebAssembly;X86"
             }
         };

src/bootstrap/util.rs

@@ -307,5 +307,6 @@ pub fn use_host_linker(target: TargetSelection) -> bool {
         || target.contains("wasm32")
         || target.contains("nvptx")
         || target.contains("fortanix")
-        || target.contains("fuchsia"))
+        || target.contains("fuchsia")
+        || target.contains("bpf"))
 }

src/doc/rustc/src/codegen-options/index.md

@@ -234,6 +234,8 @@ flavor. Valid options are:
 * `ptx-linker`: use
   [`rust-ptx-linker`](https://github.com/denzp/rust-ptx-linker) for Nvidia
   NVPTX GPGPU support.
+* `bpf-linker`: use
+  [`bpf-linker`](https://github.com/alessandrod/bpf-linker) for eBPF support.
 * `wasm-ld`: use the [`wasm-ld`](https://lld.llvm.org/WebAssembly.html)
   executable, a port of LLVM `lld` for WebAssembly.
 * `ld64.lld`: use the LLVM `lld` executable with the [`-flavor darwin`

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

@@ -219,6 +219,8 @@ target | std | host | notes
 `armv7a-none-eabihf` | * | | ARM Cortex-A, hardfloat
 `armv7s-apple-ios` | ✓ |  |
 `avr-unknown-gnu-atmega328` | * |  | AVR. Requires `-Z build-std=core`
+`bpfeb-unknown-none` | * |  | BPF (big endian)
+`bpfel-unknown-none` | * |  | BPF (little endian)
 `hexagon-unknown-linux-musl` | ? |  |
 `i386-apple-ios` | ✓ |  | 32-bit x86 iOS
 `i686-apple-darwin` | ✓ | ✓ | 32-bit macOS (10.7+, Lion+)

src/doc/unstable-book/src/library-features/asm.md

@@ -30,6 +30,7 @@ Inline assembly is currently supported on the following architectures:
 - Hexagon
 - MIPS32r2 and MIPS64r2
 - wasm32
+- BPF
 
 ## Basic usage
 
@@ -570,6 +571,8 @@ Here is the list of currently supported register classes:
 | PowerPC | `reg_nonzero` | | `r[1-31]` | `b` |
 | PowerPC | `freg` | `f[0-31]` | `f` |
 | wasm32 | `local` | None\* | `r` |
+| BPF | `reg` | `r[0-10]` | `r` |
+| BPF | `wreg` | `w[0-10]` | `w` |
 
 > **Note**: On x86 we treat `reg_byte` differently from `reg` because the compiler can allocate `al` and `ah` separately whereas `reg` reserves the whole register.
 >
@@ -615,6 +618,8 @@ Each register class has constraints on which value types they can be used with.
 | PowerPC | `reg_nonzero` | None | `i8`, `i16`, `i32` |
 | PowerPC | `freg` | None | `f32`, `f64` |
 | wasm32 | `local` | None | `i8` `i16` `i32` `i64` `f32` `f64` |
+| BPF | `reg` | None | `i8` `i16` `i32` `i64` |
+| BPF | `wreg` | `alu32` | `i8` `i16` `i32` |
 
 > **Note**: For the purposes of the above table pointers, function pointers and `isize`/`usize` are treated as the equivalent integer type (`i16`/`i32`/`i64` depending on the target).
 
@@ -674,6 +679,7 @@ Some registers have multiple names. These are all treated by the compiler as ide
 | Hexagon | `r29` | `sp` |
 | Hexagon | `r30` | `fr` |
 | Hexagon | `r31` | `lr` |
+| BPF | `r[0-10]` | `w[0-10]` |
 
 Some registers cannot be used for input or output operands:
 

llvm-project @ 39c55558

-Subproject commit 5f67a5715771b7d29e4713e8d68338602d216dcf
+Subproject commit 39c5555872cc5d379cc3535a31dc0cdac969466f

src/test/assembly/asm/bpf-types.rs

+// min-llvm-version: 10.0.1
+// assembly-output: emit-asm
+// compile-flags: --target bpfel-unknown-none -C target_feature=+alu32
+// needs-llvm-components: bpf
+
+#![feature(no_core, lang_items, rustc_attrs, repr_simd)]
+#![crate_type = "rlib"]
+#![no_core]
+#![allow(asm_sub_register, non_camel_case_types)]
+
+#[rustc_builtin_macro]
+macro_rules! asm {
+    () => {};
+}
+#[rustc_builtin_macro]
+macro_rules! concat {
+    () => {};
+}
+#[rustc_builtin_macro]
+macro_rules! stringify {
+    () => {};
+}
+
+#[lang = "sized"]
+trait Sized {}
+#[lang = "copy"]
+trait Copy {}
+
+type ptr = *const u64;
+
+impl Copy for i8 {}
+impl Copy for i16 {}
+impl Copy for i32 {}
+impl Copy for i64 {}
+impl Copy for ptr {}
+
+macro_rules! check {
+    ($func:ident $ty:ident $class:ident) => {
+        #[no_mangle]
+        pub unsafe fn $func(x: $ty) -> $ty {
+            let y;
+            asm!("{} = {}", out($class) y, in($class) x);
+            y
+        }
+    };
+}
+
+macro_rules! check_reg {
+    ($func:ident $ty:ident $reg:tt) => {
+        #[no_mangle]
+        pub unsafe fn $func(x: $ty) -> $ty {
+            let y;
+            asm!(concat!($reg, " = ", $reg), lateout($reg) y, in($reg) x);
+            y
+        }
+    };
+}
+
+extern "C" {
+    fn extern_func();
+}
+
+// CHECK-LABEL: sym_fn
+// CHECK: #APP
+// CHECK: call extern_func
+// CHECK: #NO_APP
+#[no_mangle]
+pub unsafe fn sym_fn() {
+    asm!("call {}", sym extern_func);
+}
+
+// CHECK-LABEL: reg_i8:
+// CHECK: #APP
+// CHECK: r{{[0-9]+}} = r{{[0-9]+}}
+// CHECK: #NO_APP
+check!(reg_i8 i8 reg);
+
+// CHECK-LABEL: reg_i16:
+// CHECK: #APP
+// CHECK: r{{[0-9]+}} = r{{[0-9]+}}
+// CHECK: #NO_APP
+check!(reg_i16 i16 reg);
+
+// CHECK-LABEL: reg_i32:
+// CHECK: #APP
+// CHECK: r{{[0-9]+}} = r{{[0-9]+}}
+// CHECK: #NO_APP
+check!(reg_i32 i32 reg);
+
+// CHECK-LABEL: reg_i64:
+// CHECK: #APP
+// CHECK: r{{[0-9]+}} = r{{[0-9]+}}
+// CHECK: #NO_APP
+check!(reg_i64 i64 reg);
+
+// CHECK-LABEL: wreg_i8:
+// CHECK: #APP
+// CHECK: w{{[0-9]+}} = w{{[0-9]+}}
+// CHECK: #NO_APP
+check!(wreg_i8 i8 wreg);
+
+// CHECK-LABEL: wreg_i16:
+// CHECK: #APP
+// CHECK: w{{[0-9]+}} = w{{[0-9]+}}
+// CHECK: #NO_APP
+check!(wreg_i16 i16 wreg);
+
+// CHECK-LABEL: wreg_i32:
+// CHECK: #APP
+// CHECK: w{{[0-9]+}} = w{{[0-9]+}}
+// CHECK: #NO_APP
+check!(wreg_i32 i32 wreg);
+
+// CHECK-LABEL: r0_i8:
+// CHECK: #APP
+// CHECK: r0 = r0
+// CHECK: #NO_APP
+check_reg!(r0_i8 i8 "r0");
+
+// CHECK-LABEL: r0_i16:
+// CHECK: #APP
+// CHECK: r0 = r0
+// CHECK: #NO_APP
+check_reg!(r0_i16 i16 "r0");
+
+// CHECK-LABEL: r0_i32:
+// CHECK: #APP
+// CHECK: r0 = r0
+// CHECK: #NO_APP
+check_reg!(r0_i32 i32 "r0");
+
+// CHECK-LABEL: r0_i64:
+// CHECK: #APP
+// CHECK: r0 = r0
+// CHECK: #NO_APP
+check_reg!(r0_i64 i64 "r0");
+
+// CHECK-LABEL: w0_i8:
+// CHECK: #APP
+// CHECK: w0 = w0
+// CHECK: #NO_APP
+check_reg!(w0_i8 i8 "w0");
+
+// CHECK-LABEL: w0_i16:
+// CHECK: #APP
+// CHECK: w0 = w0
+// CHECK: #NO_APP
+check_reg!(w0_i16 i16 "w0");
+
+// CHECK-LABEL: w0_i32:
+// CHECK: #APP
+// CHECK: w0 = w0
+// CHECK: #NO_APP
+check_reg!(w0_i32 i32 "w0");

src/test/codegen/bpf-alu32.rs

+// only-bpf
+#![crate_type = "lib"]
+#![feature(bpf_target_feature)]
+#![no_std]
+
+#[no_mangle]
+#[target_feature(enable = "alu32")]
+// CHECK: define i8 @foo(i8 returned %arg) unnamed_addr #0 {
+pub unsafe fn foo(arg: u8) -> u8 {
+    arg
+}

src/test/ui/target-feature/gate.rs

@@ -27,6 +27,7 @@
 // gate-test-f16c_target_feature
 // gate-test-riscv_target_feature
 // gate-test-ermsb_target_feature
+// gate-test-bpf_target_feature
 
 #[target_feature(enable = "avx512bw")]
 //~^ ERROR: currently unstable

src/test/ui/target-feature/gate.stderr

 error[E0658]: the target feature `avx512bw` is currently unstable
-  --> $DIR/gate.rs:31:18
+  --> $DIR/gate.rs:32:18
    |
 LL | #[target_feature(enable = "avx512bw")]
    |                  ^^^^^^^^^^^^^^^^^^^

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

@@ -85,6 +85,8 @@
     "armv7r-none-eabihf",
     "armv7s-apple-ios",
     "asmjs-unknown-emscripten",
+    "bpfeb-unknown-none",
+    "bpfel-unknown-none",
     "i386-apple-ios",
     "i586-pc-windows-msvc",
     "i586-unknown-linux-gnu",

src/tools/compiletest/src/runtest.rs

@@ -1835,6 +1835,7 @@ fn build_auxiliary(&self, source_path: &str, aux_dir: &Path) -> bool {
             || self.config.target.contains("nvptx")
             || self.is_vxworks_pure_static()
             || self.config.target.contains("sgx")
+            || self.config.target.contains("bpf")
         {
             // We primarily compile all auxiliary libraries as dynamic libraries
             // to avoid code size bloat and large binaries as much as possible

src/tools/compiletest/src/util.rs

@@ -48,6 +48,8 @@
     ("armv7s", "arm"),
     ("asmjs", "asmjs"),
     ("avr", "avr"),
+    ("bpfeb", "bpf"),
+    ("bpfel", "bpf"),
     ("hexagon", "hexagon"),
     ("i386", "x86"),
     ("i586", "x86"),