From 50bebb9e21c7e131522bec467b477ed7f55feb91 Mon Sep 17 00:00:00 2001
From: Andrew Kelley <andrew@ziglang.org>
Date: Wed, 10 May 2023 20:47:33 -0700
Subject: InternPool: ability to encode enums

This introduces a string table into InternPool as well as a curious new
field called `maps` which is an array list of array hash maps with
void/void key/value.

Some types such as enums, structs, and unions need to store mappings
from field names to field index, or value to field index. In such cases,
they will store the underlying field names and values directly, relying
on one of these maps, stored separately, to provide lookup.

This allows the InternPool to be serialized via simple array copies,
omitting all the maps, which are only used for optimizing lookup based
on field name or field value.

When the InternPool is deserialized it can be loaded via simple array
copies, and then as a post-processing step the field name maps can be
generated as extra metadata that is tacked on.

This commit provides two encodings for enums - one when the integer tag
type is explicitly provided and one when it is not. This is simpler than
the previous setup, which has three encodings.

Previous sizes:
 * EnumSimple: 40 bytes + 16 bytes per field
 * EnumNumbered: 80 bytes + 24 bytes per field
 * EnumFull: 184 bytes + 24 bytes per field

Sizes after this commit:
 * type_enum_explicit: 24 bytes + 8 bytes per field
 * type_enum_auto: 16 bytes + 4 bytes per field
---
 src/Sema.zig | 4 ++++
 1 file changed, 4 insertions(+)

(limited to 'src/Sema.zig')

diff --git a/src/Sema.zig b/src/Sema.zig
index 76ac887c06..e9bf66565e 100644
--- a/src/Sema.zig
+++ b/src/Sema.zig
@@ -31760,6 +31760,8 @@ pub fn resolveTypeRequiresComptime(sema: *Sema, ty: Type) CompileError!bool {
 
             .opaque_type => false,
 
+            .enum_type => @panic("TODO"),
+
             // values, not types
             .un => unreachable,
             .simple_value => unreachable,
@@ -33293,6 +33295,7 @@ pub fn typeHasOnePossibleValue(sema: *Sema, ty: Type) CompileError!?Value {
                 return only.toValue();
             },
             .opaque_type => null,
+            .enum_type => @panic("TODO"),
 
             // values, not types
             .un => unreachable,
@@ -33862,6 +33865,7 @@ pub fn typeRequiresComptime(sema: *Sema, ty: Type) CompileError!bool {
             },
 
             .opaque_type => false,
+            .enum_type => @panic("TODO"),
 
             // values, not types
             .un => unreachable,
-- 
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