From cb21d65c0ef4c105c4daf9a977551d0c56e37bb4 Mon Sep 17 00:00:00 2001
From: clubby789 <jamie@hill-daniel.co.uk>
Date: Thu, 21 Mar 2024 22:38:22 +0000
Subject: [PATCH] Don't emit load metadata in debug mode

---
 compiler/rustc_codegen_llvm/src/builder.rs | 11 +++++++++++
 tests/codegen/intrinsics/typed_swap.rs     | 13 ++++++-------
 tests/codegen/loads.rs                     |  3 ++-
 3 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/compiler/rustc_codegen_llvm/src/builder.rs b/compiler/rustc_codegen_llvm/src/builder.rs
index a5a5ae73d77a1..79e35e927bc73 100644
--- a/compiler/rustc_codegen_llvm/src/builder.rs
+++ b/compiler/rustc_codegen_llvm/src/builder.rs
@@ -20,6 +20,7 @@ use rustc_middle::ty::layout::{
     FnAbiError, FnAbiOfHelpers, FnAbiRequest, LayoutError, LayoutOfHelpers, TyAndLayout,
 };
 use rustc_middle::ty::{self, Instance, Ty, TyCtxt};
+use rustc_session::config::OptLevel;
 use rustc_span::Span;
 use rustc_symbol_mangling::typeid::{
     kcfi_typeid_for_fnabi, kcfi_typeid_for_instance, typeid_for_fnabi, typeid_for_instance,
@@ -551,6 +552,11 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
             layout: TyAndLayout<'tcx>,
             offset: Size,
         ) {
+            if bx.cx.sess().opts.optimize == OptLevel::No {
+                // Don't emit metadata we're not going to use
+                return;
+            }
+
             if !scalar.is_uninit_valid() {
                 bx.noundef_metadata(load);
             }
@@ -667,6 +673,11 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
             return;
         }
 
+        if self.cx.sess().opts.optimize == OptLevel::No {
+            // Don't emit metadata we're not going to use
+            return;
+        }
+
         unsafe {
             let llty = self.cx.val_ty(load);
             let v = [
diff --git a/tests/codegen/intrinsics/typed_swap.rs b/tests/codegen/intrinsics/typed_swap.rs
index b55fb8ee36fd6..e73931d1d547e 100644
--- a/tests/codegen/intrinsics/typed_swap.rs
+++ b/tests/codegen/intrinsics/typed_swap.rs
@@ -24,9 +24,8 @@ pub unsafe fn swap_i32(x: &mut i32, y: &mut i32) {
     // CHECK-NOT: alloca
 
     // CHECK: %[[TEMP:.+]] = load i32, ptr %x, align 4
-    // CHECK-SAME: !noundef
+    // OPT3-SAME: !noundef
     // OPT0: %[[TEMP2:.+]] = load i32, ptr %y, align 4
-    // OPT0-SAME: !noundef
     // OPT0: store i32 %[[TEMP2]], ptr %x, align 4
     // OPT0-NOT: memcpy
     // OPT3-NOT: load
@@ -42,9 +41,9 @@ pub unsafe fn swap_pair(x: &mut (i32, u32), y: &mut (i32, u32)) {
     // CHECK-NOT: alloca
 
     // CHECK: load i32
-    // CHECK-SAME: !noundef
+    // OPT3-SAME: !noundef
     // CHECK: load i32
-    // CHECK-SAME: !noundef
+    // OPT3-SAME: !noundef
     // CHECK: call void @llvm.memcpy.p0.p0.i64(ptr align 4 %x, ptr align 4 %y, i64 8, i1 false)
     // CHECK: store i32
     // CHECK: store i32
@@ -57,10 +56,10 @@ pub unsafe fn swap_str<'a>(x: &mut &'a str, y: &mut &'a str) {
     // CHECK-NOT: alloca
 
     // CHECK: load ptr
-    // CHECK-SAME: !nonnull
-    // CHECK-SAME: !noundef
+    // OPT3-SAME: !nonnull
+    // OPT3-SAME: !noundef
     // CHECK: load i64
-    // CHECK-SAME: !noundef
+    // OPT3-SAME: !noundef
     // CHECK: call void @llvm.memcpy.p0.p0.i64(ptr align 8 %x, ptr align 8 %y, i64 16, i1 false)
     // CHECK: store ptr
     // CHECK: store i64
diff --git a/tests/codegen/loads.rs b/tests/codegen/loads.rs
index b86b3dd3a1967..ba4de77ce6fd4 100644
--- a/tests/codegen/loads.rs
+++ b/tests/codegen/loads.rs
@@ -1,4 +1,5 @@
-//@ compile-flags: -C no-prepopulate-passes -Zmir-opt-level=0
+//@ compile-flags: -C no-prepopulate-passes -Zmir-opt-level=0 -O
+
 #![crate_type = "lib"]
 #![feature(generic_nonzero)]