Only call build_value_labels_ranges when necessary

src/base.rs

@@ -73,7 +73,14 @@ pub(crate) fn trans_fn<'tcx, B: Backend + 'static>(
     let local_map = fx.local_map;
     let cold_blocks = fx.cold_blocks;
 
-    crate::pretty_clif::write_clif_file(cx.tcx, "unopt", instance, &context.func, &clif_comments, None);
+    crate::pretty_clif::write_clif_file(
+        cx.tcx,
+        "unopt",
+        None,
+        instance,
+        &context,
+        &clif_comments,
+    );
 
     // Verify function
     verify_func(tcx, &clif_comments, &context.func);
@@ -101,20 +108,14 @@ pub(crate) fn trans_fn<'tcx, B: Backend + 'static>(
     );
 
     // Write optimized function to file for debugging
-    {
-        let value_ranges = context
-            .build_value_labels_ranges(cx.module.isa())
-            .expect("value location ranges");
-
-        crate::pretty_clif::write_clif_file(
-            cx.tcx,
-            "opt",
-            instance,
-            &context.func,
-            &clif_comments,
-            Some(&value_ranges),
-        );
-    }
+    crate::pretty_clif::write_clif_file(
+        cx.tcx,
+        "opt",
+        Some(cx.module.isa()),
+        instance,
+        &context,
+        &clif_comments,
+    );
 
     // Define debuginfo for function
     let isa = cx.module.isa();

src/optimize/mod.rs

@@ -18,6 +18,6 @@ pub(crate) fn optimize_function<'tcx>(
         return; // FIXME classify optimizations over opt levels
     }
     self::stack2reg::optimize_function(ctx, clif_comments);
-    crate::pretty_clif::write_clif_file(tcx, "stack2reg", instance, &ctx.func, &*clif_comments, None);
+    crate::pretty_clif::write_clif_file(tcx, "stack2reg", None, instance, &ctx, &*clif_comments);
     crate::base::verify_func(tcx, &*clif_comments, &ctx.func);
 }

src/pretty_clif.rs

@@ -203,16 +203,22 @@ impl<B: Backend + 'static> FunctionCx<'_, '_, B> {
 pub(crate) fn write_clif_file<'tcx>(
     tcx: TyCtxt<'tcx>,
     postfix: &str,
+    isa: Option<&dyn cranelift_codegen::isa::TargetIsa>,
     instance: Instance<'tcx>,
-    func: &cranelift_codegen::ir::Function,
+    context: &cranelift_codegen::Context,
     mut clif_comments: &CommentWriter,
-    value_ranges: Option<&cranelift_codegen::ValueLabelsRanges>,
 ) {
+    use std::io::Write;
+
     if !cfg!(debug_assertions) && !tcx.sess.opts.output_types.contains_key(&OutputType::LlvmAssembly) {
         return;
     }
 
-    use std::io::Write;
+    let value_ranges = isa.map(|isa| {
+        context
+            .build_value_labels_ranges(isa)
+            .expect("value location ranges")
+    });
 
     let symbol_name = tcx.symbol_name(instance).name.as_str();
     let clif_file_name = format!(
@@ -227,12 +233,12 @@ pub(crate) fn write_clif_file<'tcx>(
     cranelift_codegen::write::decorate_function(
         &mut clif_comments,
         &mut clif,
-        &func,
+        &context.func,
         &DisplayFunctionAnnotations {
             isa: Some(&*crate::build_isa(
                 tcx.sess, true, /* PIC doesn't matter here */
             )),
-            value_ranges,
+            value_ranges: value_ranges.as_ref(),
         },
     )
     .unwrap();