From 1dc106121b62562ead6e7d612fa136dc4b35cd5d Mon Sep 17 00:00:00 2001
From: Kyle Huey <khuey@kylehuey.com>
Date: Mon, 4 Nov 2024 11:38:14 -0800
Subject: Add discriminators to DILocations when multiple functions are inlined
 into a single point.

LLVM does not expect to ever see multiple dbg_declares for the same variable at the same
location with different values. proc-macros make it possible for arbitrary code,
including multiple calls that get inlined, to happen at any given location in the source
code. Add discriminators when that happens so these locations are different to LLVM.

This may interfere with the AddDiscriminators pass in LLVM, which is added by the
unstable flag -Zdebug-info-for-profiling.

Fixes #131944
---
 .../debuginfo-proc-macro/auxiliary/macro_def.rs    | 11 +++++
 .../mir_inlined_twice_var_locs.rs                  | 53 ++++++++++++++++++++++
 2 files changed, 64 insertions(+)
 create mode 100644 tests/codegen/debuginfo-proc-macro/auxiliary/macro_def.rs
 create mode 100644 tests/codegen/debuginfo-proc-macro/mir_inlined_twice_var_locs.rs

(limited to 'tests/codegen')

diff --git a/tests/codegen/debuginfo-proc-macro/auxiliary/macro_def.rs b/tests/codegen/debuginfo-proc-macro/auxiliary/macro_def.rs
new file mode 100644
index 00000000000..159ecfd0974
--- /dev/null
+++ b/tests/codegen/debuginfo-proc-macro/auxiliary/macro_def.rs
@@ -0,0 +1,11 @@
+//@ force-host
+//@ no-prefer-dynamic
+#![crate_type = "proc-macro"]
+
+extern crate proc_macro;
+use proc_macro::*;
+
+#[proc_macro]
+pub fn square_twice(_item: TokenStream) -> TokenStream {
+    "(square(env::vars().count() as i32), square(env::vars().count() as i32))".parse().unwrap()
+}
diff --git a/tests/codegen/debuginfo-proc-macro/mir_inlined_twice_var_locs.rs b/tests/codegen/debuginfo-proc-macro/mir_inlined_twice_var_locs.rs
new file mode 100644
index 00000000000..c3858044c0c
--- /dev/null
+++ b/tests/codegen/debuginfo-proc-macro/mir_inlined_twice_var_locs.rs
@@ -0,0 +1,53 @@
+//@ min-llvm-version: 19
+//@ compile-flags: -Cdebuginfo=2 -Copt-level=0 -Zmir-enable-passes=+Inline
+// MSVC is different because of the individual allocas.
+//@ ignore-msvc
+
+//@ aux-build:macro_def.rs
+
+// Find the variable.
+// CHECK-DAG: ![[#var_dbg:]] = !DILocalVariable(name: "n",{{( arg: 1,)?}} scope: ![[#var_scope:]]
+
+// Find both dbg_declares. These will proceed the variable metadata, of course, so we're looking
+// backwards.
+// CHECK-DAG: dbg_declare(ptr %n.dbg.spill{{[0-9]}}, ![[#var_dbg]], !DIExpression(), ![[#var_loc2:]])
+// CHECK-DAG: dbg_declare(ptr %n.dbg.spill, ![[#var_dbg]], !DIExpression(), ![[#var_loc1:]])
+
+// Find the first location definition, looking forwards again.
+// CHECK: ![[#var_loc1]] = !DILocation
+// CHECK-SAME: scope: ![[#var_scope:]], inlinedAt: ![[#var_inlinedAt1:]]
+
+// Find the first location's inlinedAt
+// NB: If we fail here it's *probably* because we failed to produce two
+// different locations and ended up reusing an earlier one.
+// CHECK: ![[#var_inlinedAt1]] = !DILocation
+// CHECK-SAME: scope: ![[var_inlinedAt1_scope:]]
+
+// Find the second location definition, still looking forwards.
+// NB: If we failed to produce two different locations, the test will
+// definitely fail by this point (if it hasn't already) because we won't
+// be able to find the same line again.
+// CHECK: ![[#var_loc2]] = !DILocation
+// CHECK-SAME: scope: ![[#var_scope]], inlinedAt: ![[#var_inlinedAt2:]]
+
+// Find the second location's inlinedAt.
+// CHECK: ![[#var_inlinedAt2]] = !DILocation
+// CHECK-SAME: scope: ![[#var_inlinedAt2_scope:]]
+
+// Finally, check that a discriminator was emitted for the second scope.
+// FIXMEkhuey ideally we would check that *either* scope has a discriminator
+// but I don't know that it's possible to check that with FileCheck.
+// CHECK: ![[#var_inlinedAt2_scope]] = !DILexicalBlockFile
+// CHECK-SAME: discriminator: [[#]]
+extern crate macro_def;
+
+use std::env;
+
+fn square(n: i32) -> i32 {
+    n * n
+}
+
+fn main() {
+    let (z1, z2) = macro_def::square_twice!();
+    println!("{z1} == {z2}");
+}
-- 
cgit 1.4.1-3-g733a5