stop freeing vregs twice when they are used twice in an instr

2 files changed, 5 insertions, 4 deletions

diff --git a/src/compile.zig b/src/compile.zig
index c352994..acae7ff 100644
--- a/src/compile.zig
+++ b/src/compile.zig
@@ -84,10 +84,11 @@ pub const Block = struct {
     fn init(allocator: Allocator, instrs: []Instr) !Block {
         var vreg_last_use: std.AutoHashMap(usize, std.ArrayList(VReg)) = .init(allocator);
         for (0.., instrs) |i, instr| {
+            const kv = try vreg_last_use.getOrPut(i);
+            if (!kv.found_existing) kv.value_ptr.* = .init(allocator);
             for (instr.sources().slice()) |src| {
-                const kv = try vreg_last_use.getOrPut(i);
-                if (!kv.found_existing) kv.value_ptr.* = .init(allocator);
-                try kv.value_ptr.append(src);
+                if (std.mem.indexOfScalar(VReg, kv.value_ptr.items, src) == null)
+                    try kv.value_ptr.append(src);
             }
         }
         return .{
diff --git a/src/main.zig b/src/main.zig
index 918c52d..7e0794a 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -39,7 +39,7 @@ pub fn main() !void {
     const source =
         \\let x = 1;
         \\print(18446744073709551615);
-        \\print(print(0 - x));
+        \\print(x + x);
     ;
     var lexer: Lexer = .{ .source = source };
     std.debug.print("Tokens:\n", .{});