Don't emit load metadata in debug mode

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 = [

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

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)]
 

tests/codegen/overaligned-constant.rs

@@ -16,7 +16,7 @@ fn main() {
     // CHECK-LABEL: @_ZN20overaligned_constant4main
     // CHECK: [[full:%_.*]] = alloca %SmallStruct, align 8
     // CHECK: call void @llvm.memcpy.p0.p0.i64(ptr align 8 [[full]], ptr align 8 @0, i64 32, i1 false)
-    // CHECK: %b.0 = load i32, ptr @0, align 4,
+    // CHECK: %b.0 = load i32, ptr @0, align 4
     // CHECK: %b.1 = load i32, ptr getelementptr inbounds ({{.*}}), align 4
     let mut s = S(1);