]> git.lizzy.rs Git - rust.git/blobdiff - src/inline_asm.rs
Enable inline asm on macOS
[rust.git] / src / inline_asm.rs
index 07bb2622735d7ae49693d94775299dd38a894ddd..7b1a39c675cde67c37d17eee05b14cbb9e9237cf 100644 (file)
@@ -1,4 +1,4 @@
-//! Codegen of [`asm!`] invocations.
+//! Codegen of `asm!` invocations.
 
 use crate::prelude::*;
 
@@ -6,7 +6,7 @@
 
 use rustc_ast::ast::{InlineAsmOptions, InlineAsmTemplatePiece};
 use rustc_middle::mir::InlineAsmOperand;
-use rustc_span::Symbol;
+use rustc_span::sym;
 use rustc_target::asm::*;
 
 pub(crate) fn codegen_inline_asm<'tcx>(
@@ -15,152 +15,159 @@ pub(crate) fn codegen_inline_asm<'tcx>(
     template: &[InlineAsmTemplatePiece],
     operands: &[InlineAsmOperand<'tcx>],
     options: InlineAsmOptions,
+    destination: Option<mir::BasicBlock>,
 ) {
     // FIXME add .eh_frame unwind info directives
 
-    if template.is_empty() {
-        // Black box
-        return;
-    } else if template[0] == InlineAsmTemplatePiece::String("int $$0x29".to_string()) {
-        let true_ = fx.bcx.ins().iconst(types::I32, 1);
-        fx.bcx.ins().trapnz(true_, TrapCode::User(1));
-        return;
-    } else if template[0] == InlineAsmTemplatePiece::String("movq %rbx, ".to_string())
-        && matches!(
-            template[1],
-            InlineAsmTemplatePiece::Placeholder { operand_idx: 0, modifier: Some('r'), span: _ }
-        )
-        && template[2] == InlineAsmTemplatePiece::String("\n".to_string())
-        && template[3] == InlineAsmTemplatePiece::String("cpuid".to_string())
-        && template[4] == InlineAsmTemplatePiece::String("\n".to_string())
-        && template[5] == InlineAsmTemplatePiece::String("xchgq %rbx, ".to_string())
-        && matches!(
-            template[6],
-            InlineAsmTemplatePiece::Placeholder { operand_idx: 0, modifier: Some('r'), span: _ }
-        )
-    {
-        assert_eq!(operands.len(), 4);
-        let (leaf, eax_place) = match operands[1] {
-            InlineAsmOperand::InOut { reg, late: true, ref in_value, out_place } => {
-                let reg = expect_reg(reg);
-                assert_eq!(reg, InlineAsmReg::X86(X86InlineAsmReg::ax));
-                (
-                    crate::base::codegen_operand(fx, in_value).load_scalar(fx),
-                    crate::base::codegen_place(fx, out_place.unwrap()),
-                )
-            }
-            _ => unreachable!(),
-        };
-        let ebx_place = match operands[0] {
-            InlineAsmOperand::Out { reg, late: true, place } => {
-                assert_eq!(
-                    reg,
-                    InlineAsmRegOrRegClass::RegClass(InlineAsmRegClass::X86(
-                        X86InlineAsmRegClass::reg
-                    ))
-                );
-                crate::base::codegen_place(fx, place.unwrap())
-            }
-            _ => unreachable!(),
-        };
-        let (sub_leaf, ecx_place) = match operands[2] {
-            InlineAsmOperand::InOut { reg, late: true, ref in_value, out_place } => {
-                let reg = expect_reg(reg);
-                assert_eq!(reg, InlineAsmReg::X86(X86InlineAsmReg::cx));
-                (
-                    crate::base::codegen_operand(fx, in_value).load_scalar(fx),
-                    crate::base::codegen_place(fx, out_place.unwrap()),
-                )
-            }
-            _ => unreachable!(),
-        };
-        let edx_place = match operands[3] {
-            InlineAsmOperand::Out { reg, late: true, place } => {
-                let reg = expect_reg(reg);
-                assert_eq!(reg, InlineAsmReg::X86(X86InlineAsmReg::dx));
-                crate::base::codegen_place(fx, place.unwrap())
-            }
-            _ => unreachable!(),
-        };
-
-        let (eax, ebx, ecx, edx) = crate::intrinsics::codegen_cpuid_call(fx, leaf, sub_leaf);
-
-        eax_place.write_cvalue(fx, CValue::by_val(eax, fx.layout_of(fx.tcx.types.u32)));
-        ebx_place.write_cvalue(fx, CValue::by_val(ebx, fx.layout_of(fx.tcx.types.u32)));
-        ecx_place.write_cvalue(fx, CValue::by_val(ecx, fx.layout_of(fx.tcx.types.u32)));
-        edx_place.write_cvalue(fx, CValue::by_val(edx, fx.layout_of(fx.tcx.types.u32)));
-        return;
-    } else if fx.tcx.symbol_name(fx.instance).name.starts_with("___chkstk") {
-        // ___chkstk, ___chkstk_ms and __alloca are only used on Windows
-        crate::trap::trap_unimplemented(fx, "Stack probes are not supported");
-    } else if fx.tcx.symbol_name(fx.instance).name == "__alloca" {
-        crate::trap::trap_unimplemented(fx, "Alloca is not supported");
+    if !template.is_empty() {
+        if template[0] == InlineAsmTemplatePiece::String("int $$0x29".to_string()) {
+            fx.bcx.ins().trap(TrapCode::User(1));
+            return;
+        } else if template[0] == InlineAsmTemplatePiece::String("movq %rbx, ".to_string())
+            && matches!(
+                template[1],
+                InlineAsmTemplatePiece::Placeholder {
+                    operand_idx: 0,
+                    modifier: Some('r'),
+                    span: _
+                }
+            )
+            && template[2] == InlineAsmTemplatePiece::String("\n".to_string())
+            && template[3] == InlineAsmTemplatePiece::String("cpuid".to_string())
+            && template[4] == InlineAsmTemplatePiece::String("\n".to_string())
+            && template[5] == InlineAsmTemplatePiece::String("xchgq %rbx, ".to_string())
+            && matches!(
+                template[6],
+                InlineAsmTemplatePiece::Placeholder {
+                    operand_idx: 0,
+                    modifier: Some('r'),
+                    span: _
+                }
+            )
+        {
+            assert_eq!(operands.len(), 4);
+            let (leaf, eax_place) = match operands[1] {
+                InlineAsmOperand::InOut { reg, late: true, ref in_value, out_place } => {
+                    assert_eq!(
+                        reg,
+                        InlineAsmRegOrRegClass::Reg(InlineAsmReg::X86(X86InlineAsmReg::ax))
+                    );
+                    (
+                        crate::base::codegen_operand(fx, in_value).load_scalar(fx),
+                        crate::base::codegen_place(fx, out_place.unwrap()),
+                    )
+                }
+                _ => unreachable!(),
+            };
+            let ebx_place = match operands[0] {
+                InlineAsmOperand::Out { reg, late: true, place } => {
+                    assert_eq!(
+                        reg,
+                        InlineAsmRegOrRegClass::RegClass(InlineAsmRegClass::X86(
+                            X86InlineAsmRegClass::reg
+                        ))
+                    );
+                    crate::base::codegen_place(fx, place.unwrap())
+                }
+                _ => unreachable!(),
+            };
+            let (sub_leaf, ecx_place) = match operands[2] {
+                InlineAsmOperand::InOut { reg, late: true, ref in_value, out_place } => {
+                    assert_eq!(
+                        reg,
+                        InlineAsmRegOrRegClass::Reg(InlineAsmReg::X86(X86InlineAsmReg::cx))
+                    );
+                    (
+                        crate::base::codegen_operand(fx, in_value).load_scalar(fx),
+                        crate::base::codegen_place(fx, out_place.unwrap()),
+                    )
+                }
+                _ => unreachable!(),
+            };
+            let edx_place = match operands[3] {
+                InlineAsmOperand::Out { reg, late: true, place } => {
+                    assert_eq!(
+                        reg,
+                        InlineAsmRegOrRegClass::Reg(InlineAsmReg::X86(X86InlineAsmReg::dx))
+                    );
+                    crate::base::codegen_place(fx, place.unwrap())
+                }
+                _ => unreachable!(),
+            };
+
+            let (eax, ebx, ecx, edx) = crate::intrinsics::codegen_cpuid_call(fx, leaf, sub_leaf);
+
+            eax_place.write_cvalue(fx, CValue::by_val(eax, fx.layout_of(fx.tcx.types.u32)));
+            ebx_place.write_cvalue(fx, CValue::by_val(ebx, fx.layout_of(fx.tcx.types.u32)));
+            ecx_place.write_cvalue(fx, CValue::by_val(ecx, fx.layout_of(fx.tcx.types.u32)));
+            edx_place.write_cvalue(fx, CValue::by_val(edx, fx.layout_of(fx.tcx.types.u32)));
+            let destination_block = fx.get_block(destination.unwrap());
+            fx.bcx.ins().jump(destination_block, &[]);
+            return;
+        } else if fx.tcx.symbol_name(fx.instance).name.starts_with("___chkstk") {
+            // ___chkstk, ___chkstk_ms and __alloca are only used on Windows
+            crate::trap::trap_unimplemented(fx, "Stack probes are not supported");
+            return;
+        } else if fx.tcx.symbol_name(fx.instance).name == "__alloca" {
+            crate::trap::trap_unimplemented(fx, "Alloca is not supported");
+            return;
+        }
     }
 
-    let mut slot_size = Size::from_bytes(0);
-    let mut clobbered_regs = Vec::new();
     let mut inputs = Vec::new();
     let mut outputs = Vec::new();
 
-    let mut new_slot = |reg_class: InlineAsmRegClass| {
-        let reg_size = reg_class
-            .supported_types(InlineAsmArch::X86_64)
-            .iter()
-            .map(|(ty, _)| ty.size())
-            .max()
-            .unwrap();
-        let align = rustc_target::abi::Align::from_bytes(reg_size.bytes()).unwrap();
-        slot_size = slot_size.align_to(align);
-        let offset = slot_size;
-        slot_size += reg_size;
-        offset
-    };
-
     let mut asm_gen = InlineAssemblyGenerator {
         tcx: fx.tcx,
-        arch: InlineAsmArch::X86_64,
+        arch: fx.tcx.sess.asm_arch.unwrap(),
+        enclosing_def_id: fx.instance.def_id(),
         template,
         operands,
         options,
         registers: Vec::new(),
+        stack_slots_clobber: Vec::new(),
+        stack_slots_input: Vec::new(),
+        stack_slots_output: Vec::new(),
+        stack_slot_size: Size::from_bytes(0),
     };
     asm_gen.allocate_registers();
+    asm_gen.allocate_stack_slots();
+
+    let inline_asm_index = fx.cx.inline_asm_index.get();
+    fx.cx.inline_asm_index.set(inline_asm_index + 1);
+    let asm_name = format!(
+        "__inline_asm_{}_n{}",
+        fx.cx.cgu_name.as_str().replace('.', "__").replace('-', "_"),
+        inline_asm_index
+    );
+
+    let generated_asm = asm_gen.generate_asm_wrapper(&asm_name);
+    fx.cx.global_asm.push_str(&generated_asm);
 
-    // FIXME overlap input and output slots to save stack space
     for (i, operand) in operands.iter().enumerate() {
         match *operand {
-            InlineAsmOperand::In { reg, ref value } => {
-                let reg = asm_gen.registers[i].unwrap();
-                clobbered_regs.push((reg, new_slot(reg.reg_class())));
+            InlineAsmOperand::In { reg: _, ref value } => {
                 inputs.push((
-                    reg,
-                    new_slot(reg.reg_class()),
+                    asm_gen.stack_slots_input[i].unwrap(),
                     crate::base::codegen_operand(fx, value).load_scalar(fx),
                 ));
             }
-            InlineAsmOperand::Out { reg, late: _, place } => {
-                let reg = asm_gen.registers[i].unwrap();
-                clobbered_regs.push((reg, new_slot(reg.reg_class())));
+            InlineAsmOperand::Out { reg: _, late: _, place } => {
                 if let Some(place) = place {
                     outputs.push((
-                        reg,
-                        new_slot(reg.reg_class()),
+                        asm_gen.stack_slots_output[i].unwrap(),
                         crate::base::codegen_place(fx, place),
                     ));
                 }
             }
-            InlineAsmOperand::InOut { reg, late: _, ref in_value, out_place } => {
-                let reg = asm_gen.registers[i].unwrap();
-                clobbered_regs.push((reg, new_slot(reg.reg_class())));
+            InlineAsmOperand::InOut { reg: _, late: _, ref in_value, out_place } => {
                 inputs.push((
-                    reg,
-                    new_slot(reg.reg_class()),
+                    asm_gen.stack_slots_input[i].unwrap(),
                     crate::base::codegen_operand(fx, in_value).load_scalar(fx),
                 ));
                 if let Some(out_place) = out_place {
                     outputs.push((
-                        reg,
-                        new_slot(reg.reg_class()),
+                        asm_gen.stack_slots_output[i].unwrap(),
                         crate::base::codegen_place(fx, out_place),
                     ));
                 }
@@ -171,23 +178,31 @@ pub(crate) fn codegen_inline_asm<'tcx>(
         }
     }
 
-    let inline_asm_index = fx.inline_asm_index;
-    fx.inline_asm_index += 1;
-    let asm_name = format!("{}__inline_asm_{}", fx.symbol_name, inline_asm_index);
+    call_inline_asm(fx, &asm_name, asm_gen.stack_slot_size, inputs, outputs);
 
-    let generated_asm = asm_gen.generate_asm_wrapper(&asm_name, clobbered_regs, &inputs, &outputs);
-    fx.cx.global_asm.push_str(&generated_asm);
-
-    call_inline_asm(fx, &asm_name, slot_size, inputs, outputs);
+    match destination {
+        Some(destination) => {
+            let destination_block = fx.get_block(destination);
+            fx.bcx.ins().jump(destination_block, &[]);
+        }
+        None => {
+            fx.bcx.ins().trap(TrapCode::UnreachableCodeReached);
+        }
+    }
 }
 
 struct InlineAssemblyGenerator<'a, 'tcx> {
     tcx: TyCtxt<'tcx>,
     arch: InlineAsmArch,
+    enclosing_def_id: DefId,
     template: &'a [InlineAsmTemplatePiece],
     operands: &'a [InlineAsmOperand<'tcx>],
     options: InlineAsmOptions,
     registers: Vec<Option<InlineAsmReg>>,
+    stack_slots_clobber: Vec<Option<Size>>,
+    stack_slots_input: Vec<Option<Size>>,
+    stack_slots_output: Vec<Option<Size>>,
+    stack_slot_size: Size,
 }
 
 impl<'tcx> InlineAssemblyGenerator<'_, 'tcx> {
@@ -195,7 +210,8 @@ fn allocate_registers(&mut self) {
         let sess = self.tcx.sess;
         let map = allocatable_registers(
             self.arch,
-            |feature| sess.target_features.contains(&Symbol::intern(feature)),
+            sess.relocation_model(),
+            self.tcx.asm_target_features(self.enclosing_def_id),
             &sess.target,
         );
         let mut allocated = FxHashMap::<_, (bool, bool)>::default();
@@ -311,37 +327,134 @@ fn allocate_registers(&mut self) {
         self.registers = regs;
     }
 
-    fn generate_asm_wrapper(
-        &self,
-        asm_name: &str,
-        clobbered_regs: Vec<(InlineAsmReg, Size)>,
-        inputs: &[(InlineAsmReg, Size, Value)],
-        outputs: &[(InlineAsmReg, Size, CPlace<'_>)],
-    ) -> String {
+    fn allocate_stack_slots(&mut self) {
+        let mut slot_size = Size::from_bytes(0);
+        let mut slots_clobber = vec![None; self.operands.len()];
+        let mut slots_input = vec![None; self.operands.len()];
+        let mut slots_output = vec![None; self.operands.len()];
+
+        let new_slot_fn = |slot_size: &mut Size, reg_class: InlineAsmRegClass| {
+            let reg_size =
+                reg_class.supported_types(self.arch).iter().map(|(ty, _)| ty.size()).max().unwrap();
+            let align = rustc_target::abi::Align::from_bytes(reg_size.bytes()).unwrap();
+            let offset = slot_size.align_to(align);
+            *slot_size = offset + reg_size;
+            offset
+        };
+        let mut new_slot = |x| new_slot_fn(&mut slot_size, x);
+
+        // Allocate stack slots for saving clobbered registers
+        let abi_clobber = InlineAsmClobberAbi::parse(self.arch, &self.tcx.sess.target, sym::C)
+            .unwrap()
+            .clobbered_regs();
+        for (i, reg) in self.registers.iter().enumerate().filter_map(|(i, r)| r.map(|r| (i, r))) {
+            let mut need_save = true;
+            // If the register overlaps with a register clobbered by function call, then
+            // we don't need to save it.
+            for r in abi_clobber {
+                r.overlapping_regs(|r| {
+                    if r == reg {
+                        need_save = false;
+                    }
+                });
+
+                if !need_save {
+                    break;
+                }
+            }
+
+            if need_save {
+                slots_clobber[i] = Some(new_slot(reg.reg_class()));
+            }
+        }
+
+        // Allocate stack slots for inout
+        for (i, operand) in self.operands.iter().enumerate() {
+            match *operand {
+                InlineAsmOperand::InOut { reg, out_place: Some(_), .. } => {
+                    let slot = new_slot(reg.reg_class());
+                    slots_input[i] = Some(slot);
+                    slots_output[i] = Some(slot);
+                }
+                _ => (),
+            }
+        }
+
+        let slot_size_before_input = slot_size;
+        let mut new_slot = |x| new_slot_fn(&mut slot_size, x);
+
+        // Allocate stack slots for input
+        for (i, operand) in self.operands.iter().enumerate() {
+            match *operand {
+                InlineAsmOperand::In { reg, .. }
+                | InlineAsmOperand::InOut { reg, out_place: None, .. } => {
+                    slots_input[i] = Some(new_slot(reg.reg_class()));
+                }
+                _ => (),
+            }
+        }
+
+        // Reset slot size to before input so that input and output operands can overlap
+        // and save some memory.
+        let slot_size_after_input = slot_size;
+        slot_size = slot_size_before_input;
+        let mut new_slot = |x| new_slot_fn(&mut slot_size, x);
+
+        // Allocate stack slots for output
+        for (i, operand) in self.operands.iter().enumerate() {
+            match *operand {
+                InlineAsmOperand::Out { reg, place: Some(_), .. } => {
+                    slots_output[i] = Some(new_slot(reg.reg_class()));
+                }
+                _ => (),
+            }
+        }
+
+        slot_size = slot_size.max(slot_size_after_input);
+
+        self.stack_slots_clobber = slots_clobber;
+        self.stack_slots_input = slots_input;
+        self.stack_slots_output = slots_output;
+        self.stack_slot_size = slot_size;
+    }
+
+    fn generate_asm_wrapper(&self, asm_name: &str) -> String {
         let mut generated_asm = String::new();
         writeln!(generated_asm, ".globl {}", asm_name).unwrap();
         writeln!(generated_asm, ".type {},@function", asm_name).unwrap();
         writeln!(generated_asm, ".section .text.{},\"ax\",@progbits", asm_name).unwrap();
         writeln!(generated_asm, "{}:", asm_name).unwrap();
 
-        generated_asm.push_str(".intel_syntax noprefix\n");
-        generated_asm.push_str("    push rbp\n");
-        generated_asm.push_str("    mov rbp,rdi\n");
+        let is_x86 = matches!(self.arch, InlineAsmArch::X86 | InlineAsmArch::X86_64);
+
+        if is_x86 {
+            generated_asm.push_str(".intel_syntax noprefix\n");
+        }
+        Self::prologue(&mut generated_asm, self.arch);
 
         // Save clobbered registers
         if !self.options.contains(InlineAsmOptions::NORETURN) {
-            // FIXME skip registers saved by the calling convention
-            for &(reg, offset) in &clobbered_regs {
-                save_register(&mut generated_asm, self.arch, reg, offset);
+            for (reg, slot) in self
+                .registers
+                .iter()
+                .zip(self.stack_slots_clobber.iter().copied())
+                .filter_map(|(r, s)| r.zip(s))
+            {
+                Self::save_register(&mut generated_asm, self.arch, reg, slot);
             }
         }
 
         // Write input registers
-        for &(reg, offset, _value) in inputs {
-            restore_register(&mut generated_asm, self.arch, reg, offset);
+        for (reg, slot) in self
+            .registers
+            .iter()
+            .zip(self.stack_slots_input.iter().copied())
+            .filter_map(|(r, s)| r.zip(s))
+        {
+            Self::restore_register(&mut generated_asm, self.arch, reg, slot);
         }
 
-        if self.options.contains(InlineAsmOptions::ATT_SYNTAX) {
+        if is_x86 && self.options.contains(InlineAsmOptions::ATT_SYNTAX) {
             generated_asm.push_str(".att_syntax\n");
         }
 
@@ -352,6 +465,9 @@ fn generate_asm_wrapper(
                     generated_asm.push_str(s);
                 }
                 InlineAsmTemplatePiece::Placeholder { operand_idx, modifier, span: _ } => {
+                    if self.options.contains(InlineAsmOptions::ATT_SYNTAX) {
+                        generated_asm.push('%');
+                    }
                     self.registers[*operand_idx]
                         .unwrap()
                         .emit(&mut generated_asm, self.arch, *modifier)
@@ -361,42 +477,179 @@ fn generate_asm_wrapper(
         }
         generated_asm.push('\n');
 
-        if self.options.contains(InlineAsmOptions::ATT_SYNTAX) {
+        if is_x86 && self.options.contains(InlineAsmOptions::ATT_SYNTAX) {
             generated_asm.push_str(".intel_syntax noprefix\n");
         }
 
         if !self.options.contains(InlineAsmOptions::NORETURN) {
             // Read output registers
-            for &(reg, offset, _place) in outputs {
-                save_register(&mut generated_asm, self.arch, reg, offset);
+            for (reg, slot) in self
+                .registers
+                .iter()
+                .zip(self.stack_slots_output.iter().copied())
+                .filter_map(|(r, s)| r.zip(s))
+            {
+                Self::save_register(&mut generated_asm, self.arch, reg, slot);
             }
 
             // Restore clobbered registers
-            for &(reg, offset) in clobbered_regs.iter().rev() {
-                restore_register(&mut generated_asm, self.arch, reg, offset);
+            for (reg, slot) in self
+                .registers
+                .iter()
+                .zip(self.stack_slots_clobber.iter().copied())
+                .filter_map(|(r, s)| r.zip(s))
+            {
+                Self::restore_register(&mut generated_asm, self.arch, reg, slot);
             }
 
-            generated_asm.push_str("    pop rbp\n");
-            generated_asm.push_str("    ret\n");
+            Self::epilogue(&mut generated_asm, self.arch);
         } else {
-            generated_asm.push_str("    ud2\n");
+            Self::epilogue_noreturn(&mut generated_asm, self.arch);
         }
 
-        generated_asm.push_str(".att_syntax\n");
+        if is_x86 {
+            generated_asm.push_str(".att_syntax\n");
+        }
         writeln!(generated_asm, ".size {name}, .-{name}", name = asm_name).unwrap();
         generated_asm.push_str(".text\n");
         generated_asm.push_str("\n\n");
 
         generated_asm
     }
+
+    fn prologue(generated_asm: &mut String, arch: InlineAsmArch) {
+        match arch {
+            InlineAsmArch::X86 => {
+                generated_asm.push_str("    push ebp\n");
+                generated_asm.push_str("    mov ebp,[esp+8]\n");
+            }
+            InlineAsmArch::X86_64 => {
+                generated_asm.push_str("    push rbp\n");
+                generated_asm.push_str("    mov rbp,rdi\n");
+            }
+            InlineAsmArch::RiscV32 => {
+                generated_asm.push_str("    addi sp, sp, -8\n");
+                generated_asm.push_str("    sw ra, 4(sp)\n");
+                generated_asm.push_str("    sw s0, 0(sp)\n");
+                generated_asm.push_str("    mv s0, a0\n");
+            }
+            InlineAsmArch::RiscV64 => {
+                generated_asm.push_str("    addi sp, sp, -16\n");
+                generated_asm.push_str("    sd ra, 8(sp)\n");
+                generated_asm.push_str("    sd s0, 0(sp)\n");
+                generated_asm.push_str("    mv s0, a0\n");
+            }
+            _ => unimplemented!("prologue for {:?}", arch),
+        }
+    }
+
+    fn epilogue(generated_asm: &mut String, arch: InlineAsmArch) {
+        match arch {
+            InlineAsmArch::X86 => {
+                generated_asm.push_str("    pop ebp\n");
+                generated_asm.push_str("    ret\n");
+            }
+            InlineAsmArch::X86_64 => {
+                generated_asm.push_str("    pop rbp\n");
+                generated_asm.push_str("    ret\n");
+            }
+            InlineAsmArch::RiscV32 => {
+                generated_asm.push_str("    lw s0, 0(sp)\n");
+                generated_asm.push_str("    lw ra, 4(sp)\n");
+                generated_asm.push_str("    addi sp, sp, 8\n");
+                generated_asm.push_str("    ret\n");
+            }
+            InlineAsmArch::RiscV64 => {
+                generated_asm.push_str("    ld s0, 0(sp)\n");
+                generated_asm.push_str("    ld ra, 8(sp)\n");
+                generated_asm.push_str("    addi sp, sp, 16\n");
+                generated_asm.push_str("    ret\n");
+            }
+            _ => unimplemented!("epilogue for {:?}", arch),
+        }
+    }
+
+    fn epilogue_noreturn(generated_asm: &mut String, arch: InlineAsmArch) {
+        match arch {
+            InlineAsmArch::X86 | InlineAsmArch::X86_64 => {
+                generated_asm.push_str("    ud2\n");
+            }
+            InlineAsmArch::RiscV32 | InlineAsmArch::RiscV64 => {
+                generated_asm.push_str("    ebreak\n");
+            }
+            _ => unimplemented!("epilogue_noreturn for {:?}", arch),
+        }
+    }
+
+    fn save_register(
+        generated_asm: &mut String,
+        arch: InlineAsmArch,
+        reg: InlineAsmReg,
+        offset: Size,
+    ) {
+        match arch {
+            InlineAsmArch::X86 => {
+                write!(generated_asm, "    mov [ebp+0x{:x}], ", offset.bytes()).unwrap();
+                reg.emit(generated_asm, InlineAsmArch::X86, None).unwrap();
+                generated_asm.push('\n');
+            }
+            InlineAsmArch::X86_64 => {
+                write!(generated_asm, "    mov [rbp+0x{:x}], ", offset.bytes()).unwrap();
+                reg.emit(generated_asm, InlineAsmArch::X86_64, None).unwrap();
+                generated_asm.push('\n');
+            }
+            InlineAsmArch::RiscV32 => {
+                generated_asm.push_str("    sw ");
+                reg.emit(generated_asm, InlineAsmArch::RiscV32, None).unwrap();
+                writeln!(generated_asm, ", 0x{:x}(s0)", offset.bytes()).unwrap();
+            }
+            InlineAsmArch::RiscV64 => {
+                generated_asm.push_str("    sd ");
+                reg.emit(generated_asm, InlineAsmArch::RiscV64, None).unwrap();
+                writeln!(generated_asm, ", 0x{:x}(s0)", offset.bytes()).unwrap();
+            }
+            _ => unimplemented!("save_register for {:?}", arch),
+        }
+    }
+
+    fn restore_register(
+        generated_asm: &mut String,
+        arch: InlineAsmArch,
+        reg: InlineAsmReg,
+        offset: Size,
+    ) {
+        match arch {
+            InlineAsmArch::X86 => {
+                generated_asm.push_str("    mov ");
+                reg.emit(generated_asm, InlineAsmArch::X86, None).unwrap();
+                writeln!(generated_asm, ", [ebp+0x{:x}]", offset.bytes()).unwrap();
+            }
+            InlineAsmArch::X86_64 => {
+                generated_asm.push_str("    mov ");
+                reg.emit(generated_asm, InlineAsmArch::X86_64, None).unwrap();
+                writeln!(generated_asm, ", [rbp+0x{:x}]", offset.bytes()).unwrap();
+            }
+            InlineAsmArch::RiscV32 => {
+                generated_asm.push_str("    lw ");
+                reg.emit(generated_asm, InlineAsmArch::RiscV32, None).unwrap();
+                writeln!(generated_asm, ", 0x{:x}(s0)", offset.bytes()).unwrap();
+            }
+            InlineAsmArch::RiscV64 => {
+                generated_asm.push_str("    ld ");
+                reg.emit(generated_asm, InlineAsmArch::RiscV64, None).unwrap();
+                writeln!(generated_asm, ", 0x{:x}(s0)", offset.bytes()).unwrap();
+            }
+            _ => unimplemented!("restore_register for {:?}", arch),
+        }
+    }
 }
 
 fn call_inline_asm<'tcx>(
     fx: &mut FunctionCx<'_, '_, 'tcx>,
     asm_name: &str,
     slot_size: Size,
-    inputs: Vec<(InlineAsmReg, Size, Value)>,
-    outputs: Vec<(InlineAsmReg, Size, CPlace<'tcx>)>,
+    inputs: Vec<(Size, Value)>,
+    outputs: Vec<(Size, CPlace<'tcx>)>,
 ) {
     let stack_slot = fx.bcx.func.create_stack_slot(StackSlotData {
         kind: StackSlotKind::ExplicitSlot,
@@ -423,50 +676,16 @@ fn call_inline_asm<'tcx>(
         fx.add_comment(inline_asm_func, asm_name);
     }
 
-    for (_reg, offset, value) in inputs {
+    for (offset, value) in inputs {
         fx.bcx.ins().stack_store(value, stack_slot, i32::try_from(offset.bytes()).unwrap());
     }
 
     let stack_slot_addr = fx.bcx.ins().stack_addr(fx.pointer_type, stack_slot, 0);
     fx.bcx.ins().call(inline_asm_func, &[stack_slot_addr]);
 
-    for (_reg, offset, place) in outputs {
+    for (offset, place) in outputs {
         let ty = fx.clif_type(place.layout().ty).unwrap();
         let value = fx.bcx.ins().stack_load(ty, stack_slot, i32::try_from(offset.bytes()).unwrap());
         place.write_cvalue(fx, CValue::by_val(value, place.layout()));
     }
 }
-
-fn expect_reg(reg_or_class: InlineAsmRegOrRegClass) -> InlineAsmReg {
-    match reg_or_class {
-        InlineAsmRegOrRegClass::Reg(reg) => reg,
-        InlineAsmRegOrRegClass::RegClass(class) => unimplemented!("{:?}", class),
-    }
-}
-
-fn save_register(generated_asm: &mut String, arch: InlineAsmArch, reg: InlineAsmReg, offset: Size) {
-    match arch {
-        InlineAsmArch::X86_64 => {
-            write!(generated_asm, "    mov [rbp+0x{:x}], ", offset.bytes()).unwrap();
-            reg.emit(generated_asm, InlineAsmArch::X86_64, None).unwrap();
-            generated_asm.push('\n');
-        }
-        _ => unimplemented!("save_register for {:?}", arch),
-    }
-}
-
-fn restore_register(
-    generated_asm: &mut String,
-    arch: InlineAsmArch,
-    reg: InlineAsmReg,
-    offset: Size,
-) {
-    match arch {
-        InlineAsmArch::X86_64 => {
-            generated_asm.push_str("    mov ");
-            reg.emit(generated_asm, InlineAsmArch::X86_64, None).unwrap();
-            writeln!(generated_asm, ", [rbp+0x{:x}]", offset.bytes()).unwrap();
-        }
-        _ => unimplemented!("restore_register for {:?}", arch),
-    }
-}