From 31a7f22b800c091962726de2dd29f10a8eb25b78 Mon Sep 17 00:00:00 2001 From: mlugg Date: Mon, 25 Mar 2024 03:51:58 +0000 Subject: [PATCH] llvm: update current debug location scope when entering debug scope This issue was causing debug information to sometimes not function correctly for some local variables, with debuggers simply reporting that the variable does not exist. What was happening was that after an AIR body - and thus debug lexical scope - begins, but before any `dbg_stmt` within it, the `scope` on `self.wip.debug_location` refers to the parent scope, but the `scope` field on the `DILocalVariable` metadata passed to `@llvm.dbg.declare` points, correctly, to the nested scope. I haven't looked into precisely what happens here, but in short, it would appear that LLVM Doesn't Like It (tm). The fix is simple: when we change `self.scope` at the start or end of an AIR body, also modify the scope on `self.wip.debug_location`. This is correct as we always want the debug info for an instruction to be associated with the block it is within, even if the line/column are slightly outdated for any reason. --- src/codegen/llvm.zig | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/src/codegen/llvm.zig b/src/codegen/llvm.zig index 69b810ff60..03bd15805c 100644 --- a/src/codegen/llvm.zig +++ b/src/codegen/llvm.zig @@ -5202,6 +5202,16 @@ pub const FuncGen = struct { self.prev_dbg_line, self.prev_dbg_column, ); + + switch (self.wip.debug_location) { + .location => |*l| l.scope = self.scope, + .no_location => {}, + } + defer switch (self.wip.debug_location) { + .location => |*l| l.scope = old_scope, + .no_location => {}, + }; + try self.genBody(body); }