reticulating codegen

oxidecomputer · Sep 15, 2024 · 85a1bc2 · 85a1bc2
1 parent b8c9f44
commit 85a1bc2
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Showing 4 changed files with 109 additions and 25 deletions.
diff --git a/codegen/htq/src/control.rs b/codegen/htq/src/control.rs
@@ -62,6 +62,11 @@ fn emit_control_apply(
     let mut ra = RegisterAllocator::default();
     let mut names = control.names();
     let mut statements = Vec::default();
+
+    for p in parameters {
+        ra.alloc(&p.reg.0);
+    }
+
     for s in &control.apply.statements {
         statements.extend(
             emit_statement(s, ast, hlir, &mut names, &mut ra)?.into_iter(),
@@ -94,6 +99,9 @@ fn emit_control_action(
         };
         parameters.push(p);
     }
+    for p in &parameters {
+        ra.alloc(&p.reg.0);
+    }
     for s in &action.statement_block.statements {
         statements.extend(
             emit_statement(s, ast, hlir, &mut names, &mut ra)?.into_iter(),

diff --git a/codegen/htq/src/expression.rs b/codegen/htq/src/expression.rs
@@ -1,15 +1,27 @@
-use htq::ast::{Register, Rset, Statement, Type, Value};
-use p4::ast::{Expression, ExpressionKind};
+use std::collections::HashMap;
+
+use htq::ast::{Fget, Load, Register, Rset, Statement, Type, Value};
+use p4::{
+    ast::{DeclarationInfo, Expression, ExpressionKind, Lvalue, NameInfo},
+    hlir::Hlir,
+};
 
 // Copyright 2024 Oxide Computer Company
-use crate::{error::CodegenError, VersionedRegister};
+use crate::{
+    error::CodegenError, p4_type_to_htq_type, statement::member_offsets,
+    RegisterAllocator, VersionedRegister,
+};
 
 // Builds a vector of statements that implement the expression. Returns the
 // statements and the register the result of the expression is held in.
 pub(crate) fn emit_expression(
     expr: &Expression,
+    hlir: &Hlir,
+    ast: &p4::ast::AST,
+    ra: &mut RegisterAllocator,
+    names: &HashMap<String, NameInfo>,
 ) -> Result<(Vec<Statement>, Register, Type), CodegenError> {
-    let r = VersionedRegister::for_expression(expr);
+    let r = VersionedRegister::for_token(&expr.token);
     match &expr.kind {
         ExpressionKind::BoolLit(value) => emit_bool_lit(*value, r),
         ExpressionKind::BitLit(width, value) => {
@@ -19,6 +31,7 @@ pub(crate) fn emit_expression(
         ExpressionKind::SignedLit(width, value) => {
             emit_signed_lit(*width, *value, r)
         }
+        ExpressionKind::Lvalue(lval) => emit_lval(lval, hlir, ast, ra, names),
         ExpressionKind::Call(_) => {
             //TODO
             Ok((
@@ -27,18 +40,74 @@ pub(crate) fn emit_expression(
                 Type::User("badtype".to_owned()),
             ))
         }
-        ExpressionKind::Lvalue(_) => {
-            //TODO
-            Ok((
-                Vec::default(),
-                Register::new("badreg"),
-                Type::User("badtype".to_owned()),
-            ))
-        }
         xpr => todo!("expression: {xpr:?}"),
     }
 }
 
+fn emit_lval(
+    lval: &Lvalue,
+    hlir: &Hlir,
+    ast: &p4::ast::AST,
+    ra: &mut RegisterAllocator,
+    names: &HashMap<String, NameInfo>,
+) -> Result<(Vec<Statement>, Register, Type), CodegenError> {
+    let mut result: Vec<Statement> = Vec::default();
+
+    let info = hlir
+        .lvalue_decls
+        .get(lval)
+        .ok_or(CodegenError::UndefinedLvalue(lval.clone()))?;
+
+    let typ = p4_type_to_htq_type(&info.ty)?;
+
+    match &info.decl {
+        DeclarationInfo::Parameter(_) => {
+            let treg = VersionedRegister::for_token(&lval.token);
+            result.push(Statement::Load(Load {
+                target: treg.to_reg(),
+                typ: typ.clone(),
+                source: Register::new(lval.root()),
+                offset: Value::number(0),
+            }));
+            Ok((result, treg.to_reg(), typ))
+        }
+        DeclarationInfo::ActionParameter(_) => {
+            let treg = VersionedRegister::for_token(&lval.token);
+            result.push(Statement::Load(Load {
+                target: treg.to_reg(),
+                typ: typ.clone(),
+                source: Register::new(lval.root()),
+                offset: Value::number(0),
+            }));
+            Ok((result, treg.to_reg(), typ))
+        }
+        DeclarationInfo::StructMember | DeclarationInfo::HeaderMember => {
+            let offsets = member_offsets(ast, names, lval)?;
+            let treg = VersionedRegister::for_token(&lval.token);
+
+            let src_root = lval.root();
+            let source = ra
+                .get(src_root)
+                .ok_or(CodegenError::UndefinedLvalue(lval.clone()))?;
+
+            result.push(Statement::Fget(Fget {
+                target: treg.to_reg(),
+                typ: typ.clone(),
+                source,
+                offsets,
+            }));
+            Ok((result, treg.to_reg(), typ))
+        }
+        DeclarationInfo::Local => {
+            let reg = ra
+                .get(&lval.name)
+                .ok_or(CodegenError::UndefinedLvalue(lval.clone()))?;
+            Ok((result, reg, typ))
+        }
+        other => todo!("emit lval for \n{other:#?}"),
+    }
+}
+
 pub(crate) fn emit_bool_lit(
     value: bool,
     ra: VersionedRegister,

diff --git a/codegen/htq/src/lib.rs b/codegen/htq/src/lib.rs
@@ -6,7 +6,7 @@ use control::emit_control_functions;
 use error::CodegenError;
 use header::{p4_header_to_htq_header, p4_struct_to_htq_header};
 use htq::{ast::Register, emit::Emit};
-use p4::{ast::Expression, hlir::Hlir};
+use p4::{hlir::Hlir, lexer::Token};
 use parser::emit_parser_functions;
 use table::p4_table_to_htq_table;
 
@@ -136,6 +136,12 @@ impl RegisterAllocator {
             }
         }
     }
+
+    pub(crate) fn get(&self, name: &str) -> Option<htq::ast::Register> {
+        self.data
+            .get(name)
+            .map(|rev| htq::ast::Register::new(&format!("{}.{}", name, rev)))
+    }
 }
 
 #[derive(Debug, Clone)]
@@ -145,12 +151,9 @@ pub(crate) struct VersionedRegister {
 }
 
 impl VersionedRegister {
-    pub(crate) fn for_expression(expr: &Expression) -> Self {
+    pub(crate) fn for_token(tk: &Token) -> Self {
         Self {
-            reg: Register::new(&format!(
-                "tmp{}_{}",
-                expr.token.line, expr.token.col
-            )),
+            reg: Register::new(&format!("tmp{}_{}", tk.line, tk.col)),
             version: 0,
         }
     }
@@ -164,6 +167,10 @@ impl VersionedRegister {
     }
 
     pub(crate) fn to_reg(&self) -> Register {
-        Register::new(&format!("{}.{}", self.reg.0, self.version))
+        if self.version == 0 {
+            Register::new(&self.reg.0)
+        } else {
+            Register::new(&format!("{}.{}", self.reg.0, self.version))
+        }
     }
 }
diff --git a/codegen/htq/src/statement.rs b/codegen/htq/src/statement.rs
@@ -83,12 +83,12 @@ fn emit_assignment(
     // - list
     //
 
-    let target_info = match hlir.lvalue_decls.get(target) {
-        Some(info) => info,
-        None => return Err(CodegenError::UndefinedLvalue(target.clone())),
-    };
+    let target_info = hlir
+        .lvalue_decls
+        .get(target)
+        .ok_or(CodegenError::UndefinedLvalue(target.clone()))?;
 
-    let (mut instrs, reg, typ) = emit_expression(source)?;
+    let (mut instrs, reg, typ) = emit_expression(source, hlir, ast, ra, names)?;
 
     match &target_info.decl {
         DeclarationInfo::Parameter(Direction::Out)
@@ -143,7 +143,7 @@ fn emit_assignment(
     Ok(instrs)
 }
 
-fn member_offsets(
+pub(crate) fn member_offsets(
     ast: &p4::ast::AST,
     names: &HashMap<String, NameInfo>,
     lval: &Lvalue,