x86_64: clean up

src/arch/x86_64/Emit.zig

@@ -177,12 +177,12 @@ fn encode(emit: *Emit, mnemonic: Instruction.Mnemonic, ops: struct {
     op3: Instruction.Operand = .none,
     op4: Instruction.Operand = .none,
 }) InnerError!void {
-    const inst = Instruction.new(mnemonic, .{
+    const inst = try Instruction.new(mnemonic, .{
         .op1 = ops.op1,
         .op2 = ops.op2,
         .op3 = ops.op3,
         .op4 = ops.op4,
-    }) catch unreachable;
+    });
     return inst.encode(emit.code.writer());
 }
 

src/arch/x86_64/Encoding.zig

@@ -121,7 +121,7 @@ pub fn findByMnemonic(mnemonic: Mnemonic, args: struct {
                 .encoding = encoding,
             };
             var cwriter = std.io.countingWriter(std.io.null_writer);
-            inst.encode(cwriter.writer()) catch unreachable;
+            inst.encode(cwriter.writer()) catch unreachable; // Not allowed to fail here unless OOM.
             return cwriter.bytes_written;
         }
     };

src/arch/x86_64/Mir.zig

@@ -24,9 +24,6 @@ instructions: std.MultiArrayList(Inst).Slice,
 /// The meaning of this data is determined by `Inst.Tag` value.
 extra: []const u32,
 
-pub const Mnemonic = encoder.Instruction.Mnemonic;
-pub const Operand = encoder.Instruction.Operand;
-
 pub const Inst = struct {
     tag: Tag,
     ops: Ops,
@@ -69,8 +66,6 @@ pub const Inst = struct {
         imul,
         ///
         int3,
-        /// Conditional jump
-        jcc,
         /// Jump
         jmp,
         /// Load effective address
@@ -99,8 +94,6 @@ pub const Inst = struct {
         sar,
         /// Integer subtraction with borrow
         sbb,
-        /// Set byte on condition
-        setcc,
         /// Logical shift left
         shl,
         /// Logical shift right
@@ -135,6 +128,10 @@ pub const Inst = struct {
 
         /// Conditional move
         cmovcc,
+        /// Conditional jump
+        jcc,
+        /// Set byte on condition
+        setcc,
 
         /// Mov absolute to/from memory wrt segment register to/from rax
         mov_moffs,

src/arch/x86_64/bits.zig

@@ -242,13 +242,6 @@ pub const Register = enum(u7) {
         };
     }
 
-    pub fn isRexInvalid(reg: Register) bool {
-        return switch (@enumToInt(reg)) {
-            @enumToInt(Register.ah)...@enumToInt(Register.bh) => true,
-            else => false,
-        };
-    }
-
     pub fn enc(reg: Register) u4 {
         const base = switch (@enumToInt(reg)) {
             // zig fmt: off

src/arch/x86_64/encoder.zig

@@ -1,5 +1,6 @@
 const std = @import("std");
 const assert = std.debug.assert;
+const log = std.log.scoped(.x86_64_encoder);
 const math = std.math;
 
 const bits = @import("bits.zig");
@@ -106,7 +107,7 @@ pub const Instruction = struct {
             .op3 = args.op3,
             .op4 = args.op4,
         })) orelse {
-            std.log.warn("{s} {s} {s} {s} {s}", .{
+            log.debug("no encoding found for: {s} {s} {s} {s} {s}", .{
                 @tagName(mnemonic),
                 @tagName(Encoding.Op.fromOperand(args.op1)),
                 @tagName(Encoding.Op.fromOperand(args.op2)),
@@ -115,7 +116,7 @@ pub const Instruction = struct {
             });
             return error.InvalidInstruction;
         };
-        std.log.debug("{}", .{encoding});
+        log.debug("selected encoding: {}", .{encoding});
         return .{
             .op1 = args.op1,
             .op2 = args.op2,