compiler: eliminate Decl.value_arena and Sema.perm_arena

The main motivation for this commit is eliminating Decl.value_arena.
Everything else is dominoes.

Decl.name used to be stored in the GPA, now it is stored in InternPool.
It ended up being simpler to migrate other strings to be interned as
well, such as struct field names, union field names, and a few others.
This ended up requiring a big diff, sorry about that. But the changes
are pretty nice, we finally start to take advantage of InternPool's
existence.

global_error_set and error_name_list are simplified. Now it is a single
ArrayHashMap(NullTerminatedString, void) and the index is the error tag
value.

Module.tmp_hack_arena is re-introduced (it was removed in
eeff407941560ce8eb5b737b2436dfa93cfd3a0c) in order to deal with
comptime_args, optimized_order, and struct and union fields. After
structs and unions get moved into InternPool properly, tmp_hack_arena
can be deleted again.

1 files changed, 11 insertions, 10 deletions

diff --git a/src/Compilation.zig b/src/Compilation.zig
index 0ee916c446..64f947c3c3 100644
--- a/src/Compilation.zig
+++ b/src/Compilation.zig
@@ -1317,7 +1317,7 @@ pub fn create(gpa: Allocator, options: InitOptions) !*Compilation {
                 .global_zir_cache = global_zir_cache,
                 .local_zir_cache = local_zir_cache,
                 .emit_h = emit_h,
-                .error_name_list = .{},
+                .tmp_hack_arena = std.heap.ArenaAllocator.init(gpa),
             };
             try module.init();
 
@@ -2627,7 +2627,7 @@ pub fn getAllErrorsAlloc(self: *Compilation) !ErrorBundle {
             var it = module.failed_files.iterator();
             while (it.next()) |entry| {
                 if (entry.value_ptr.*) |msg| {
-                    try addModuleErrorMsg(&bundle, msg.*);
+                    try addModuleErrorMsg(module, &bundle, msg.*);
                 } else {
                     // Must be ZIR errors. Note that this may include AST errors.
                     // addZirErrorMessages asserts that the tree is loaded.
@@ -2640,7 +2640,7 @@ pub fn getAllErrorsAlloc(self: *Compilation) !ErrorBundle {
             var it = module.failed_embed_files.iterator();
             while (it.next()) |entry| {
                 const msg = entry.value_ptr.*;
-                try addModuleErrorMsg(&bundle, msg.*);
+                try addModuleErrorMsg(module, &bundle, msg.*);
             }
         }
         {
@@ -2650,7 +2650,7 @@ pub fn getAllErrorsAlloc(self: *Compilation) !ErrorBundle {
                 // Skip errors for Decls within files that had a parse failure.
                 // We'll try again once parsing succeeds.
                 if (module.declFileScope(decl_index).okToReportErrors()) {
-                    try addModuleErrorMsg(&bundle, entry.value_ptr.*.*);
+                    try addModuleErrorMsg(module, &bundle, entry.value_ptr.*.*);
                     if (module.cimport_errors.get(entry.key_ptr.*)) |cimport_errors| for (cimport_errors) |c_error| {
                         try bundle.addRootErrorMessage(.{
                             .msg = try bundle.addString(std.mem.span(c_error.msg)),
@@ -2675,12 +2675,12 @@ pub fn getAllErrorsAlloc(self: *Compilation) !ErrorBundle {
                 // Skip errors for Decls within files that had a parse failure.
                 // We'll try again once parsing succeeds.
                 if (module.declFileScope(decl_index).okToReportErrors()) {
-                    try addModuleErrorMsg(&bundle, entry.value_ptr.*.*);
+                    try addModuleErrorMsg(module, &bundle, entry.value_ptr.*.*);
                 }
             }
         }
         for (module.failed_exports.values()) |value| {
-            try addModuleErrorMsg(&bundle, value.*);
+            try addModuleErrorMsg(module, &bundle, value.*);
         }
     }
 
@@ -2728,7 +2728,7 @@ pub fn getAllErrorsAlloc(self: *Compilation) !ErrorBundle {
                 };
             }
 
-            try addModuleErrorMsg(&bundle, err_msg);
+            try addModuleErrorMsg(module, &bundle, err_msg);
         }
     }
 
@@ -2784,8 +2784,9 @@ pub const ErrorNoteHashContext = struct {
     }
 };
 
-pub fn addModuleErrorMsg(eb: *ErrorBundle.Wip, module_err_msg: Module.ErrorMsg) !void {
+pub fn addModuleErrorMsg(mod: *Module, eb: *ErrorBundle.Wip, module_err_msg: Module.ErrorMsg) !void {
     const gpa = eb.gpa;
+    const ip = &mod.intern_pool;
     const err_source = module_err_msg.src_loc.file_scope.getSource(gpa) catch |err| {
         const file_path = try module_err_msg.src_loc.file_scope.fullPath(gpa);
         defer gpa.free(file_path);
@@ -2811,7 +2812,7 @@ pub fn addModuleErrorMsg(eb: *ErrorBundle.Wip, module_err_msg: Module.ErrorMsg)
                 .src_loc = .none,
             });
             break;
-        } else if (module_reference.decl == null) {
+        } else if (module_reference.decl == .none) {
             try ref_traces.append(gpa, .{
                 .decl_name = 0,
                 .src_loc = .none,
@@ -2824,7 +2825,7 @@ pub fn addModuleErrorMsg(eb: *ErrorBundle.Wip, module_err_msg: Module.ErrorMsg)
         const rt_file_path = try module_reference.src_loc.file_scope.fullPath(gpa);
         defer gpa.free(rt_file_path);
         try ref_traces.append(gpa, .{
-            .decl_name = try eb.addString(std.mem.sliceTo(module_reference.decl.?, 0)),
+            .decl_name = try eb.addString(ip.stringToSliceUnwrap(module_reference.decl).?),
             .src_loc = try eb.addSourceLocation(.{
                 .src_path = try eb.addString(rt_file_path),
                 .span_start = span.start,