From 237d9a105d5eec82aefc63da8e844c47d8990eea Mon Sep 17 00:00:00 2001
From: Andrew Kelley <andrew@ziglang.org>
Date: Tue, 25 Aug 2020 21:31:03 -0700
Subject: [PATCH] stage2: support debug dumping zir as a build option

So that it's not needed to manually comment and uncomment the debug
code.
---
 build.zig                    |  2 ++
 src-self-hosted/link/Elf.zig | 14 +++++++++-----
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/build.zig b/build.zig
index 9c50025375..869fb3f208 100644
--- a/build.zig
+++ b/build.zig
@@ -83,6 +83,7 @@ pub fn build(b: *Builder) !void {
         }
 
         const log_scopes = b.option([]const []const u8, "log", "Which log scopes to enable") orelse &[0][]const u8{};
+        const zir_dumps = b.option([]const []const u8, "dump-zir", "Which functions to dump ZIR for before codegen") orelse &[0][]const u8{};
 
         const opt_version_string = b.option([]const u8, "version-string", "Override Zig version string. Default is to find out with git.");
         const version = if (opt_version_string) |version| version else v: {
@@ -103,6 +104,7 @@ pub fn build(b: *Builder) !void {
         exe.addBuildOption([]const u8, "version", version);
 
         exe.addBuildOption([]const []const u8, "log_scopes", log_scopes);
+        exe.addBuildOption([]const []const u8, "zir_dumps", zir_dumps);
         exe.addBuildOption(bool, "enable_tracy", tracy != null);
         if (tracy) |tracy_path| {
             const client_cpp = fs.path.join(
diff --git a/src-self-hosted/link/Elf.zig b/src-self-hosted/link/Elf.zig
index b67de55dd5..f2a3218118 100644
--- a/src-self-hosted/link/Elf.zig
+++ b/src-self-hosted/link/Elf.zig
@@ -17,6 +17,7 @@ const Type = @import("../type.zig").Type;
 const link = @import("../link.zig");
 const File = link.File;
 const Elf = @This();
+const build_options = @import("build_options");
 
 const default_entry_addr = 0x8000000;
 
@@ -1640,11 +1641,14 @@ pub fn updateDecl(self: *Elf, module: *Module, decl: *Module.Decl) !void {
         else => false,
     };
     if (is_fn) {
-        {
-            //if (mem.eql(u8, mem.spanZ(decl.name), "add")) {
-            //}
-            std.debug.print("\n{}\n", .{decl.name});
-            typed_value.val.cast(Value.Payload.Function).?.func.dump(module.*);
+        const zir_dumps = if (std.builtin.is_test) &[0][]const u8{} else build_options.zir_dumps;
+        if (zir_dumps.len != 0) {
+            for (zir_dumps) |fn_name| {
+                if (mem.eql(u8, mem.spanZ(decl.name), fn_name)) {
+                    std.debug.print("\n{}\n", .{decl.name});
+                    typed_value.val.cast(Value.Payload.Function).?.func.dump(module.*);
+                }
+            }
         }
 
         // For functions we need to add a prologue to the debug line program.