Auto merge of #107404 - cjgillot:const-debuginfo, r=oli-obk

Turn on ConstDebugInfo pass.

Split from https://github.com/rust-lang/rust/pull/103657

Moving those constant into debuginfo allows to shrink the number of locals and the actual size of the MIR body.

1 files changed, 28 insertions, 0 deletions

diff --git a/tests/codegen/debuginfo-constant-locals.rs b/tests/codegen/debuginfo-constant-locals.rs
new file mode 100644
index 00000000000..95a1b8c9d21
--- /dev/null
+++ b/tests/codegen/debuginfo-constant-locals.rs
@@ -0,0 +1,28 @@
+// compile-flags: -g -O
+
+// Check that simple constant values are preserved in debuginfo across both MIR opts and LLVM opts
+
+#![crate_type = "lib"]
+
+#[no_mangle]
+pub fn check_it() {
+    let a = 1;
+    let b = 42;
+
+    foo(a + b);
+}
+
+#[inline(never)]
+fn foo(x: i32) {
+    std::process::exit(x);
+}
+
+// CHECK-LABEL: @check_it
+// CHECK: call void @llvm.dbg.value(metadata i32 1, metadata ![[a_metadata:[0-9]+]], metadata !DIExpression())
+// CHECK: call void @llvm.dbg.value(metadata i32 42, metadata ![[b_metadata:[0-9]+]], metadata !DIExpression())
+
+// CHECK: ![[a_metadata]] = !DILocalVariable(name: "a"
+// CHECK-SAME: line: 9
+
+// CHECK: ![[b_metadata]] = !DILocalVariable(name: "b"
+// CHECK-SAME: line: 10