From 0648177ed7a1ad5364c478b63ec28a6de15e4ad9 Mon Sep 17 00:00:00 2001
From: Andrew Kelley <andrew@ziglang.org>
Date: Mon, 8 Aug 2022 20:29:22 -0700
Subject: [PATCH] AstGen: avoid multiple dbg_stmt instructions in a row

This is purely an optimization to emit fewer ZIR instructions.
---
 src/AstGen.zig | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/src/AstGen.zig b/src/AstGen.zig
index e53c59817ad5cf5374d74ce8f1a6c71a651f3eb0..5087ea629330f42c4bf471afa3437e4954f96dec 100644
--- a/src/AstGen.zig
+++ b/src/AstGen.zig
@@ -3071,6 +3071,19 @@ fn emitDbgNode(gz: *GenZir, node: Ast.Node.Index) !void {
     const line = astgen.source_line - gz.decl_line;
     const column = astgen.source_column;
 
+    if (gz.instructions.items.len > 0) {
+        const last = gz.instructions.items[gz.instructions.items.len - 1];
+        const zir_tags = astgen.instructions.items(.tag);
+        if (zir_tags[last] == .dbg_stmt) {
+            const zir_datas = astgen.instructions.items(.data);
+            zir_datas[last].dbg_stmt = .{
+                .line = line,
+                .column = column,
+            };
+            return;
+        }
+    }
+
     _ = try gz.add(.{ .tag = .dbg_stmt, .data = .{
         .dbg_stmt = .{
             .line = line,
-- 
2.54.0