Add support for BPF inline assembly

2 files changed, 154 insertions, 0 deletions

diff --git a/compiler/rustc_target/src/asm/bpf.rs b/compiler/rustc_target/src/asm/bpf.rs
new file mode 100644
index 00000000000..ecb6bdc95ce
--- /dev/null
+++ b/compiler/rustc_target/src/asm/bpf.rs
@@ -0,0 +1,129 @@
+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
+        }
+    }
+}
diff --git a/compiler/rustc_target/src/asm/mod.rs b/compiler/rustc_target/src/asm/mod.rs
index c17c2961434..305ea7d50e6 100644
--- a/compiler/rustc_target/src/asm/mod.rs
+++ b/compiler/rustc_target/src/asm/mod.rs
@@ -148,6 +148,7 @@ macro_rules! types {
 
 mod aarch64;
 mod arm;
+mod bpf;
 mod hexagon;
 mod mips;
 mod nvptx;
@@ -159,6 +160,7 @@ mod x86;
 
 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 @@ impl FromStr for 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 @@ impl InlineAsmReg {
             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 @@ impl InlineAsmReg {
             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 @@ impl InlineAsmReg {
             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 @@ impl InlineAsmReg {
             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 @@ impl 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 @@ impl InlineAsmRegClass {
             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 @@ impl InlineAsmRegClass {
             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 @@ impl InlineAsmRegClass {
             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 @@ impl InlineAsmRegClass {
             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 @@ impl InlineAsmRegClass {
             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 @@ impl InlineAsmRegClass {
             }
             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 @@ impl InlineAsmRegClass {
             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
+        }
     }
 }