stage2: rework Value Payload layout

This is the same as the previous commit but for Value instead of Type.

Add `Value.castTag` and note that it is preferable to call than
`Value.cast`. This matches other abstractions in the codebase.

Added a convenience function `Value.Tag.create` which really cleans up
the callsites of creating `Value` objects.

`Value` tags can now share payload types. This is in preparation for
another improvement that I want to do.

1 files changed, 26 insertions, 26 deletions

diff --git a/src/codegen.zig b/src/codegen.zig
index d98a87a440..f978115ebc 100644
--- a/src/codegen.zig
+++ b/src/codegen.zig
@@ -137,7 +137,7 @@ pub fn generateSymbol(
         },
         .Array => {
             // TODO populate .debug_info for the array
-            if (typed_value.val.cast(Value.Payload.Bytes)) |payload| {
+            if (typed_value.val.castTag(.bytes)) |payload| {
                 if (typed_value.ty.sentinel()) |sentinel| {
                     try code.ensureCapacity(code.items.len + payload.data.len + 1);
                     code.appendSliceAssumeCapacity(payload.data);
@@ -168,8 +168,8 @@ pub fn generateSymbol(
         },
         .Pointer => {
             // TODO populate .debug_info for the pointer
-            if (typed_value.val.cast(Value.Payload.DeclRef)) |payload| {
-                const decl = payload.decl;
+            if (typed_value.val.castTag(.decl_ref)) |payload| {
+                const decl = payload.data;
                 if (decl.analysis != .complete) return error.AnalysisFail;
                 // TODO handle the dependency of this symbol on the decl's vaddr.
                 // If the decl changes vaddr, then this symbol needs to get regenerated.
@@ -432,7 +432,7 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
                 @panic("Attempted to compile for architecture that was disabled by build configuration");
             }
 
-            const module_fn = typed_value.val.cast(Value.Payload.Function).?.func;
+            const module_fn = typed_value.val.castTag(.function).?.data;
 
             const fn_type = module_fn.owner_decl.typed_value.most_recent.typed_value.ty;
 
@@ -1579,9 +1579,9 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
                             }
                         }
 
-                        if (inst.func.cast(ir.Inst.Constant)) |func_inst| {
-                            if (func_inst.val.cast(Value.Payload.Function)) |func_val| {
-                                const func = func_val.func;
+                        if (inst.func.value()) |func_value| {
+                            if (func_value.castTag(.function)) |func_payload| {
+                                const func = func_payload.data;
 
                                 const ptr_bits = self.target.cpu.arch.ptrBitWidth();
                                 const ptr_bytes: u64 = @divExact(ptr_bits, 8);
@@ -1607,9 +1607,9 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
                     .riscv64 => {
                         if (info.args.len > 0) return self.fail(inst.base.src, "TODO implement fn args for {}", .{self.target.cpu.arch});
 
-                        if (inst.func.cast(ir.Inst.Constant)) |func_inst| {
-                            if (func_inst.val.cast(Value.Payload.Function)) |func_val| {
-                                const func = func_val.func;
+                        if (inst.func.value()) |func_value| {
+                            if (func_value.castTag(.function)) |func_payload| {
+                                const func = func_payload.data;
 
                                 const ptr_bits = self.target.cpu.arch.ptrBitWidth();
                                 const ptr_bytes: u64 = @divExact(ptr_bits, 8);
@@ -1631,12 +1631,12 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
                         }
                     },
                     .spu_2 => {
-                        if (inst.func.cast(ir.Inst.Constant)) |func_inst| {
+                        if (inst.func.value()) |func_value| {
                             if (info.args.len != 0) {
                                 return self.fail(inst.base.src, "TODO implement call with more than 0 parameters", .{});
                             }
-                            if (func_inst.val.cast(Value.Payload.Function)) |func_val| {
-                                const func = func_val.func;
+                            if (func_value.castTag(.function)) |func_payload| {
+                                const func = func_payload.data;
                                 const got_addr = if (self.bin_file.cast(link.File.Elf)) |elf_file| blk: {
                                     const got = &elf_file.program_headers.items[elf_file.phdr_got_index.?];
                                     break :blk @intCast(u16, got.p_vaddr + func.owner_decl.link.elf.offset_table_index * 2);
@@ -1705,9 +1705,9 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
                             }
                         }
 
-                        if (inst.func.cast(ir.Inst.Constant)) |func_inst| {
-                            if (func_inst.val.cast(Value.Payload.Function)) |func_val| {
-                                const func = func_val.func;
+                        if (inst.func.value()) |func_value| {
+                            if (func_value.castTag(.function)) |func_payload| {
+                                const func = func_payload.data;
                                 const ptr_bits = self.target.cpu.arch.ptrBitWidth();
                                 const ptr_bytes: u64 = @divExact(ptr_bits, 8);
                                 const got_addr = if (self.bin_file.cast(link.File.Elf)) |elf_file| blk: {
@@ -1766,9 +1766,9 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
                             }
                         }
 
-                        if (inst.func.cast(ir.Inst.Constant)) |func_inst| {
-                            if (func_inst.val.cast(Value.Payload.Function)) |func_val| {
-                                const func = func_val.func;
+                        if (inst.func.value()) |func_value| {
+                            if (func_value.castTag(.function)) |func_payload| {
+                                const func = func_payload.data;
                                 const ptr_bits = self.target.cpu.arch.ptrBitWidth();
                                 const ptr_bytes: u64 = @divExact(ptr_bits, 8);
                                 const got_addr = if (self.bin_file.cast(link.File.Elf)) |elf_file| blk: {
@@ -1825,9 +1825,9 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
                     }
                 }
 
-                if (inst.func.cast(ir.Inst.Constant)) |func_inst| {
-                    if (func_inst.val.cast(Value.Payload.Function)) |func_val| {
-                        const func = func_val.func;
+                if (inst.func.value()) |func_value| {
+                    if (func_value.castTag(.function)) |func_payload| {
+                        const func = func_payload.data;
                         const text_segment = &macho_file.load_commands.items[macho_file.text_segment_cmd_index.?].Segment;
                         const got = &text_segment.sections.items[macho_file.got_section_index.?];
                         const got_addr = got.addr + func.owner_decl.link.macho.offset_table_index * @sizeOf(u64);
@@ -3223,20 +3223,20 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
             const ptr_bytes: u64 = @divExact(ptr_bits, 8);
             switch (typed_value.ty.zigTypeTag()) {
                 .Pointer => {
-                    if (typed_value.val.cast(Value.Payload.DeclRef)) |payload| {
+                    if (typed_value.val.castTag(.decl_ref)) |payload| {
                         if (self.bin_file.cast(link.File.Elf)) |elf_file| {
-                            const decl = payload.decl;
+                            const decl = payload.data;
                             const got = &elf_file.program_headers.items[elf_file.phdr_got_index.?];
                             const got_addr = got.p_vaddr + decl.link.elf.offset_table_index * ptr_bytes;
                             return MCValue{ .memory = got_addr };
                         } else if (self.bin_file.cast(link.File.MachO)) |macho_file| {
-                            const decl = payload.decl;
+                            const decl = payload.data;
                             const text_segment = &macho_file.load_commands.items[macho_file.text_segment_cmd_index.?].Segment;
                             const got = &text_segment.sections.items[macho_file.got_section_index.?];
                             const got_addr = got.addr + decl.link.macho.offset_table_index * ptr_bytes;
                             return MCValue{ .memory = got_addr };
                         } else if (self.bin_file.cast(link.File.Coff)) |coff_file| {
-                            const decl = payload.decl;
+                            const decl = payload.data;
                             const got_addr = coff_file.offset_table_virtual_address + decl.link.coff.offset_table_index * ptr_bytes;
                             return MCValue{ .memory = got_addr };
                         } else {