stage2: Move BlockData out of ir.Inst.Block

src/codegen/c.zig

@@ -33,6 +33,11 @@ pub const CValue = union(enum) {
     decl_ref: *Decl,
 };
 
+const BlockData = struct {
+    block_id: usize,
+    result: CValue,
+};
+
 pub const CValueMap = std.AutoHashMap(*Inst, CValue);
 pub const TypedefMap = std.HashMap(Type, struct { name: []const u8, rendered: []u8 }, Type.hash, Type.eql, std.hash_map.default_max_load_percentage);
 
@@ -83,6 +88,7 @@ pub const Object = struct {
     gpa: *mem.Allocator,
     code: std.ArrayList(u8),
     value_map: CValueMap,
+    blocks: std.AutoHashMapUnmanaged(*ir.Inst.Block, BlockData) = .{},
     next_arg_index: usize = 0,
     next_local_index: usize = 0,
     next_block_index: usize = 0,
@@ -939,8 +945,6 @@ fn genBlock(o: *Object, inst: *Inst.Block) !CValue {
     o.next_block_index += 1;
     const writer = o.writer();
 
-    // store the block id in relocs.capacity as it is not  used for anything else in the C backend.
-    inst.codegen.relocs.capacity = block_id;
     const result = if (inst.base.ty.tag() != .void and !inst.base.isUnused()) blk: {
         // allocate a location for the result
         const local = try o.allocLocal(inst.base.ty, .Mut);
@@ -948,7 +952,11 @@ fn genBlock(o: *Object, inst: *Inst.Block) !CValue {
         break :blk local;
     } else CValue{ .none = {} };
 
-    inst.codegen.mcv = @bitCast(@import("../codegen.zig").AnyMCValue, result);
+    try o.blocks.putNoClobber(o.gpa, inst, .{
+        .block_id = block_id,
+        .result = result,
+    });
+
     try genBody(o, inst.body);
     try o.indent_writer.insertNewline();
     // label must be followed by an expression, add an empty one.
@@ -957,7 +965,7 @@ fn genBlock(o: *Object, inst: *Inst.Block) !CValue {
 }
 
 fn genBr(o: *Object, inst: *Inst.Br) !CValue {
-    const result = @bitCast(CValue, inst.block.codegen.mcv);
+    const result = o.blocks.get(inst.block).?.result;
     const writer = o.writer();
 
     // If result is .none then the value of the block is unused.
@@ -973,7 +981,7 @@ fn genBr(o: *Object, inst: *Inst.Br) !CValue {
 }
 
 fn genBrVoid(o: *Object, block: *Inst.Block) !CValue {
-    try o.writer().print("goto zig_block_{d};\n", .{block.codegen.relocs.capacity});
+    try o.writer().print("goto zig_block_{d};\n", .{o.blocks.get(block).?.block_id});
     return CValue.none;
 }
 

src/codegen/wasm.zig

@@ -14,7 +14,6 @@ const Inst = ir.Inst;
 const Type = @import("../type.zig").Type;
 const Value = @import("../value.zig").Value;
 const Compilation = @import("../Compilation.zig");
-const AnyMCValue = @import("../codegen.zig").AnyMCValue;
 const LazySrcLoc = Module.LazySrcLoc;
 const link = @import("../link.zig");
 const TypedValue = @import("../TypedValue.zig");
@@ -29,8 +28,6 @@ const WValue = union(enum) {
     constant: *Inst,
     /// Offset position in the list of bytecode instructions
     code_offset: usize,
-    /// The label of the block, used by breaks to find its relative distance
-    block_idx: u32,
     /// Used for variables that create multiple locals on the stack when allocated
     /// such as structs and optionals.
     multi_value: u32,
@@ -492,6 +489,8 @@ pub const Context = struct {
     gpa: *mem.Allocator,
     /// Table to save `WValue`'s generated by an `Inst`
     values: ValueTable,
+    /// Mapping from *Inst.Block to block ids
+    blocks: std.AutoArrayHashMapUnmanaged(*Inst.Block, u32) = .{},
     /// `bytes` contains the wasm bytecode belonging to the 'code' section.
     code: ArrayList(u8),
     /// Contains the generated function type bytecode for the current function
@@ -521,6 +520,7 @@ pub const Context = struct {
 
     pub fn deinit(self: *Context) void {
         self.values.deinit(self.gpa);
+        self.blocks.deinit(self.gpa);
         self.locals.deinit(self.gpa);
         self.* = undefined;
     }
@@ -590,7 +590,6 @@ pub const Context = struct {
     fn emitWValue(self: *Context, val: WValue) InnerError!void {
         const writer = self.code.writer();
         switch (val) {
-            .block_idx => unreachable, // block_idx cannot be referenced
             .multi_value => unreachable, // multi_value can never be written directly, and must be accessed individually
             .none, .code_offset => {}, // no-op
             .local => |idx| {
@@ -968,13 +967,9 @@ pub const Context = struct {
         const block_ty = try self.genBlockType(block.base.src, block.base.ty);
 
         try self.startBlock(.block, block_ty, null);
-        block.codegen = .{
-            // we don't use relocs, so using `relocs` is illegal behaviour.
-            .relocs = undefined,
-            // Here we set the current block idx, so breaks know the depth to jump
-            // to when breaking out.
-            .mcv = @bitCast(AnyMCValue, WValue{ .block_idx = self.block_depth }),
-        };
+        // Here we set the current block idx, so breaks know the depth to jump
+        // to when breaking out.
+        try self.blocks.putNoClobber(self.gpa, block, self.block_depth);
         try self.genBody(block.body);
         try self.endBlock();
 
@@ -1091,10 +1086,9 @@ pub const Context = struct {
             try self.emitWValue(operand);
         }
 
-        // every block contains a `WValue` with its block index.
+        // We map every block to its block index.
         // We then determine how far we have to jump to it by substracting it from current block depth
-        const wvalue = @bitCast(WValue, br.block.codegen.mcv);
-        const idx: u32 = self.block_depth - wvalue.block_idx;
+        const idx: u32 = self.block_depth - self.blocks.get(br.block).?;
         const writer = self.code.writer();
         try writer.writeByte(wasm.opcode(.br));
         try leb.writeULEB128(writer, idx);