Auto merge of #83637 - bjorn3:sync_cg_clif-2021-03-29, r=bjorn3

Sync rustc_codegen_cranelift

The main highlight of this sync is support for cross-compiling to Windows using MinGW. Native compilation with MinGW would also work I think, but using the MSVC toolchain is not yet supported as PE TLS is not yet implemented. Another nice improvement is that crate metadata is now loaded using mmap instead of by reading files. This improves compilation time a bit.

r? `@ghost`

`@rustbot` label +A-codegen +A-cranelift +T-compiler

1 files changed, 47 insertions, 42 deletions

diff --git a/compiler/rustc_codegen_cranelift/src/optimize/stack2reg.rs b/compiler/rustc_codegen_cranelift/src/optimize/stack2reg.rs
index d111f37f5e4..8bb02a3e558 100644
--- a/compiler/rustc_codegen_cranelift/src/optimize/stack2reg.rs
+++ b/compiler/rustc_codegen_cranelift/src/optimize/stack2reg.rs
@@ -181,7 +181,6 @@ impl<'a> OptimizeContext<'a> {
 
 pub(super) fn optimize_function(
     ctx: &mut Context,
-    #[cfg_attr(not(debug_assertions), allow(unused_variables))]
     clif_comments: &mut crate::pretty_clif::CommentWriter,
 ) {
     combine_stack_addr_with_load_store(&mut ctx.func);
@@ -192,8 +191,7 @@ pub(super) fn optimize_function(
 
     remove_unused_stack_addr_and_stack_load(&mut opt_ctx);
 
-    #[cfg(debug_assertions)]
-    {
+    if clif_comments.enabled() {
         for (&OrdStackSlot(stack_slot), usage) in &opt_ctx.stack_slot_usage_map {
             clif_comments.add_comment(stack_slot, format!("used by: {:?}", usage));
         }
@@ -209,25 +207,27 @@ pub(super) fn optimize_function(
         for load in users.stack_load.clone().into_iter() {
             let potential_stores = users.potential_stores_for_load(&opt_ctx.ctx, load);
 
-            #[cfg(debug_assertions)]
-            for &store in &potential_stores {
-                clif_comments.add_comment(
-                    load,
-                    format!(
-                        "Potential store -> load forwarding {} -> {} ({:?}, {:?})",
-                        opt_ctx.ctx.func.dfg.display_inst(store, None),
-                        opt_ctx.ctx.func.dfg.display_inst(load, None),
-                        spatial_overlap(&opt_ctx.ctx.func, store, load),
-                        temporal_order(&opt_ctx.ctx, store, load),
-                    ),
-                );
+            if clif_comments.enabled() {
+                for &store in &potential_stores {
+                    clif_comments.add_comment(
+                        load,
+                        format!(
+                            "Potential store -> load forwarding {} -> {} ({:?}, {:?})",
+                            opt_ctx.ctx.func.dfg.display_inst(store, None),
+                            opt_ctx.ctx.func.dfg.display_inst(load, None),
+                            spatial_overlap(&opt_ctx.ctx.func, store, load),
+                            temporal_order(&opt_ctx.ctx, store, load),
+                        ),
+                    );
+                }
             }
 
             match *potential_stores {
                 [] => {
-                    #[cfg(debug_assertions)]
-                    clif_comments
-                        .add_comment(load, "[BUG?] Reading uninitialized memory".to_string());
+                    if clif_comments.enabled() {
+                        clif_comments
+                            .add_comment(load, "[BUG?] Reading uninitialized memory".to_string());
+                    }
                 }
                 [store]
                     if spatial_overlap(&opt_ctx.ctx.func, store, load) == SpatialOverlap::Full
@@ -237,9 +237,12 @@ pub(super) fn optimize_function(
                     // Only one store could have been the origin of the value.
                     let stored_value = opt_ctx.ctx.func.dfg.inst_args(store)[0];
 
-                    #[cfg(debug_assertions)]
-                    clif_comments
-                        .add_comment(load, format!("Store to load forward {} -> {}", store, load));
+                    if clif_comments.enabled() {
+                        clif_comments.add_comment(
+                            load,
+                            format!("Store to load forward {} -> {}", store, load),
+                        );
+                    }
 
                     users.change_load_to_alias(&mut opt_ctx.ctx.func, load, stored_value);
                 }
@@ -250,33 +253,35 @@ pub(super) fn optimize_function(
         for store in users.stack_store.clone().into_iter() {
             let potential_loads = users.potential_loads_of_store(&opt_ctx.ctx, store);
 
-            #[cfg(debug_assertions)]
-            for &load in &potential_loads {
-                clif_comments.add_comment(
-                    store,
-                    format!(
-                        "Potential load from store {} <- {} ({:?}, {:?})",
-                        opt_ctx.ctx.func.dfg.display_inst(load, None),
-                        opt_ctx.ctx.func.dfg.display_inst(store, None),
-                        spatial_overlap(&opt_ctx.ctx.func, store, load),
-                        temporal_order(&opt_ctx.ctx, store, load),
-                    ),
-                );
+            if clif_comments.enabled() {
+                for &load in &potential_loads {
+                    clif_comments.add_comment(
+                        store,
+                        format!(
+                            "Potential load from store {} <- {} ({:?}, {:?})",
+                            opt_ctx.ctx.func.dfg.display_inst(load, None),
+                            opt_ctx.ctx.func.dfg.display_inst(store, None),
+                            spatial_overlap(&opt_ctx.ctx.func, store, load),
+                            temporal_order(&opt_ctx.ctx, store, load),
+                        ),
+                    );
+                }
             }
 
             if potential_loads.is_empty() {
                 // Never loaded; can safely remove all stores and the stack slot.
                 // FIXME also remove stores when there is always a next store before a load.
 
-                #[cfg(debug_assertions)]
-                clif_comments.add_comment(
-                    store,
-                    format!(
-                        "Remove dead stack store {} of {}",
-                        opt_ctx.ctx.func.dfg.display_inst(store, None),
-                        stack_slot.0
-                    ),
-                );
+                if clif_comments.enabled() {
+                    clif_comments.add_comment(
+                        store,
+                        format!(
+                            "Remove dead stack store {} of {}",
+                            opt_ctx.ctx.func.dfg.display_inst(store, None),
+                            stack_slot.0
+                        ),
+                    );
+                }
 
                 users.remove_dead_store(&mut opt_ctx.ctx.func, store);
             }