Run GVN on monomorphic MIR.

Author: cjgillot

compiler/rustc_codegen_ssa/src/mir/mod.rs

@@ -8,8 +8,8 @@ use rustc_middle::ty::layout::{FnAbiOf, HasTyCtxt, TyAndLayout};
 use rustc_middle::ty::{self, Instance, Ty, TypeVisitableExt};
 use rustc_middle::{bug, mir, span_bug};
 use rustc_mir_transform::{
-    add_call_guards, dump_mir, pass_manager, remove_unneeded_drops, remove_zsts, simplify,
-    unreachable_enum_branching, unreachable_prop,
+    add_call_guards, dead_store_elimination, dump_mir, gvn, pass_manager, remove_unneeded_drops,
+    remove_zsts, simplify, simplify_branches, unreachable_enum_branching, unreachable_prop,
 };
 use rustc_target::abi::call::{FnAbi, PassMode};
 use tracing::{debug, instrument};
@@ -173,6 +173,11 @@ pub fn codegen_mir<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
             &unreachable_enum_branching::UnreachableEnumBranching,
             &unreachable_prop::UnreachablePropagation,
             &simplify::SimplifyCfg::AfterUnreachableEnumBranching,
+            &dead_store_elimination::DeadStoreElimination::Initial,
+            &gvn::GVN,
+            &simplify::SimplifyLocals::AfterGVN,
+            &simplify_branches::SimplifyConstCondition::Final,
+            &simplify::SimplifyCfg::Final,
             // Some cleanup necessary at least for LLVM and potentially other codegen backends.
             &add_call_guards::CriticalCallEdges,
             // Dump the end result for testing and debugging purposes.

compiler/rustc_mir_transform/src/lib.rs

@@ -59,7 +59,7 @@ mod coverage;
 mod cross_crate_inline;
 mod ctfe_limit;
 mod dataflow_const_prop;
-mod dead_store_elimination;
+pub mod dead_store_elimination;
 mod deduce_param_attrs;
 mod deduplicate_blocks;
 mod deref_separator;
@@ -71,7 +71,7 @@ mod elaborate_drops;
 mod errors;
 mod ffi_unwind_calls;
 mod function_item_references;
-mod gvn;
+pub mod gvn;
 pub mod inline;
 mod instsimplify;
 mod jump_threading;
@@ -97,13 +97,12 @@ mod required_consts;
 mod reveal_all;
 mod sanity_check;
 mod shim;
-mod ssa;
-// This pass is public to allow external drivers to perform MIR cleanup
 pub mod simplify;
-mod simplify_branches;
+pub mod simplify_branches;
 mod simplify_comparison_integral;
 mod single_use_consts;
 mod sroa;
+mod ssa;
 pub mod unreachable_enum_branching;
 pub mod unreachable_prop;
 mod validate;

tests/codegen/intrinsics/transmute.rs

@@ -85,7 +85,7 @@ pub unsafe fn check_from_empty_array(x: [u32; 0]) -> [u32; 5] {
 
 // CHECK-LABEL: @check_to_uninhabited(
 #[no_mangle]
-#[custom_mir(dialect = "runtime", phase = "optimized")]
+#[custom_mir(dialect = "runtime", phase = "monomorphic")]
 pub unsafe fn check_to_uninhabited(x: u16) {
     // CHECK-NOT: trap
     // CHECK: call void @llvm.trap

tests/codegen/skip-mono-inside-if-false.rs

@@ -13,13 +13,9 @@ pub fn demo_for_i32() {
 
 // CHECK-LABEL: ; skip_mono_inside_if_false::generic_impl
 // CHECK: start:
-// CHECK-NEXT: br label %[[ELSE_BRANCH:bb[0-9]+]]
-// CHECK: [[ELSE_BRANCH]]:
 // CHECK-NEXT: call skip_mono_inside_if_false::small_impl
-// CHECK: bb{{[0-9]+}}:
+// CHECK-NEXT: call void @{{.*small_impl.*}}()
 // CHECK-NEXT: ret void
-// CHECK: bb{{[0-9+]}}:
-// CHECK-NEXT: unreachable
 
 fn generic_impl<T>() {
     trait MagicTrait {