Auto merge of rust-lang#128265 - DianQK:instsimplify-before-inline, r…

…=<try> Perform instsimplify before inline to eliminate some trivial calls I am currently working on rust-lang#128081. In the current pipeline, we can get the following clone statements ([godbolt](https://rust.godbolt.org/z/931316fhP)): ``` bb0: { StorageLive(_2); _2 = ((*_1).0: i32); StorageLive(_3); _3 = ((*_1).1: u64); _0 = Foo { a: move _2, b: move _3 }; StorageDead(_3); StorageDead(_2); return; } ``` Analyzing such statements will be simple and fast. We don't need to consider branches or some interfering statements. However, this requires us to run `InstSimplify`, `ReferencePropagation`, and `SimplifyCFG` at least once. I can introduce a new pass, but I think the best place for it would be within `InstSimplify`. I put `InstSimplify` before `Inline`, which takes some of the burden away from `Inline`. r? `@saethlin`
rust-lang-ci · Jul 27, 2024 · 3689ca8 · 3689ca8
2 parents a526d7c + 5dc8f5f
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diff --git a/compiler/rustc_mir_transform/src/instsimplify.rs b/compiler/rustc_mir_transform/src/instsimplify.rs
@@ -13,9 +13,25 @@ use rustc_span::sym;
 use rustc_span::symbol::Symbol;
 use rustc_target::spec::abi::Abi;
 
-pub struct InstSimplify;
+pub enum InstSimplify {
+    BeforeInline,
+    AfterSimplifyCfg,
+}
+
+impl InstSimplify {
+    pub fn name(&self) -> &'static str {
+        match self {
+            InstSimplify::BeforeInline => "InstSimplify-before-inline",
+            InstSimplify::AfterSimplifyCfg => "InstSimplify-after-simplifycfg",
+        }
+    }
+}
 
 impl<'tcx> MirPass<'tcx> for InstSimplify {
+    fn name(&self) -> &'static str {
+        self.name()
+    }
+
     fn is_enabled(&self, sess: &rustc_session::Session) -> bool {
         sess.mir_opt_level() > 0
     }

diff --git a/compiler/rustc_mir_transform/src/lib.rs b/compiler/rustc_mir_transform/src/lib.rs
@@ -572,6 +572,8 @@ fn run_optimization_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
             // Has to be done before inlining, otherwise actual call will be almost always inlined.
             // Also simple, so can just do first
             &lower_slice_len::LowerSliceLenCalls,
+            // Perform instsimplify before inline to eliminate some trivial calls (like clone).
+            &instsimplify::InstSimplify::BeforeInline,
             // Perform inlining, which may add a lot of code.
             &inline::Inline,
             // Code from other crates may have storage markers, so this needs to happen after inlining.
@@ -591,7 +593,8 @@ fn run_optimization_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
             &match_branches::MatchBranchSimplification,
             // inst combine is after MatchBranchSimplification to clean up Ne(_1, false)
             &multiple_return_terminators::MultipleReturnTerminators,
-            &instsimplify::InstSimplify,
+            // After simplifycfg, it allows us to discover new opportunities for peephole optimizations.
+            &instsimplify::InstSimplify::AfterSimplifyCfg,
             &simplify::SimplifyLocals::BeforeConstProp,
             &dead_store_elimination::DeadStoreElimination::Initial,
             &gvn::GVN,

diff --git a/compiler/rustc_mir_transform/src/shim.rs b/compiler/rustc_mir_transform/src/shim.rs
@@ -154,7 +154,7 @@ fn make_shim<'tcx>(tcx: TyCtxt<'tcx>, instance: ty::InstanceKind<'tcx>) -> Body<
             &deref_separator::Derefer,
             &remove_noop_landing_pads::RemoveNoopLandingPads,
             &simplify::SimplifyCfg::MakeShim,
-            &instsimplify::InstSimplify,
+            &instsimplify::InstSimplify::BeforeInline,
             &abort_unwinding_calls::AbortUnwindingCalls,
             &add_call_guards::CriticalCallEdges,
         ],

diff --git a/tests/mir-opt/const_prop/slice_len.rs b/tests/mir-opt/const_prop/slice_len.rs
@@ -1,5 +1,5 @@
 //@ test-mir-pass: GVN
-//@ compile-flags: -Zmir-enable-passes=+InstSimplify -Zdump-mir-exclude-alloc-bytes
+//@ compile-flags: -Zmir-enable-passes=+InstSimplify-before-inline -Zdump-mir-exclude-alloc-bytes
 // EMIT_MIR_FOR_EACH_PANIC_STRATEGY
 // EMIT_MIR_FOR_EACH_BIT_WIDTH
 

diff --git a/tests/mir-opt/dataflow-const-prop/slice_len.main.DataflowConstProp.32bit.panic-abort.diff b/tests/mir-opt/dataflow-const-prop/slice_len.main.DataflowConstProp.32bit.panic-abort.diff
@@ -30,8 +30,8 @@
           StorageLive(_3);
           StorageLive(_4);
           _14 = const main::promoted[0];
-          _4 = _14;
-          _3 = _4;
+          _4 = &(*_14);
+          _3 = &(*_4);
           _2 = move _3 as &[u32] (PointerCoercion(Unsize));
           StorageDead(_3);
           StorageLive(_6);

diff --git a/tests/mir-opt/dataflow-const-prop/slice_len.main.DataflowConstProp.32bit.panic-unwind.diff b/tests/mir-opt/dataflow-const-prop/slice_len.main.DataflowConstProp.32bit.panic-unwind.diff
@@ -30,8 +30,8 @@
           StorageLive(_3);
           StorageLive(_4);
           _14 = const main::promoted[0];
-          _4 = _14;
-          _3 = _4;
+          _4 = &(*_14);
+          _3 = &(*_4);
           _2 = move _3 as &[u32] (PointerCoercion(Unsize));
           StorageDead(_3);
           StorageLive(_6);

diff --git a/tests/mir-opt/dataflow-const-prop/slice_len.main.DataflowConstProp.64bit.panic-abort.diff b/tests/mir-opt/dataflow-const-prop/slice_len.main.DataflowConstProp.64bit.panic-abort.diff
@@ -30,8 +30,8 @@
           StorageLive(_3);
           StorageLive(_4);
           _14 = const main::promoted[0];
-          _4 = _14;
-          _3 = _4;
+          _4 = &(*_14);
+          _3 = &(*_4);
           _2 = move _3 as &[u32] (PointerCoercion(Unsize));
           StorageDead(_3);
           StorageLive(_6);

diff --git a/tests/mir-opt/dataflow-const-prop/slice_len.main.DataflowConstProp.64bit.panic-unwind.diff b/tests/mir-opt/dataflow-const-prop/slice_len.main.DataflowConstProp.64bit.panic-unwind.diff
@@ -30,8 +30,8 @@
           StorageLive(_3);
           StorageLive(_4);
           _14 = const main::promoted[0];
-          _4 = _14;
-          _3 = _4;
+          _4 = &(*_14);
+          _3 = &(*_4);
           _2 = move _3 as &[u32] (PointerCoercion(Unsize));
           StorageDead(_3);
           StorageLive(_6);

diff --git a/tests/mir-opt/inline/dyn_trait.get_query.Inline.panic-abort.diff b/tests/mir-opt/inline/dyn_trait.get_query.Inline.panic-abort.diff
@@ -21,14 +21,14 @@
       bb0: {
           StorageLive(_2);
           StorageLive(_3);
-          _3 = &(*_1);
+          _3 = _1;
           _2 = <Q as Query>::cache::<T>(move _3) -> [return: bb1, unwind unreachable];
       }
 
       bb1: {
           StorageDead(_3);
           StorageLive(_4);
-          _4 = &(*_2);
+          _4 = _2;
 -         _0 = try_execute_query::<<Q as Query>::C>(move _4) -> [return: bb2, unwind unreachable];
 +         StorageLive(_5);
 +         _5 = _4 as &dyn Cache<V = <Q as Query>::V> (PointerCoercion(Unsize));

diff --git a/tests/mir-opt/inline/dyn_trait.get_query.Inline.panic-unwind.diff b/tests/mir-opt/inline/dyn_trait.get_query.Inline.panic-unwind.diff
@@ -21,14 +21,14 @@
       bb0: {
           StorageLive(_2);
           StorageLive(_3);
-          _3 = &(*_1);
+          _3 = _1;
           _2 = <Q as Query>::cache::<T>(move _3) -> [return: bb1, unwind continue];
       }
 
       bb1: {
           StorageDead(_3);
           StorageLive(_4);
-          _4 = &(*_2);
+          _4 = _2;
 -         _0 = try_execute_query::<<Q as Query>::C>(move _4) -> [return: bb2, unwind continue];
 +         StorageLive(_5);
 +         _5 = _4 as &dyn Cache<V = <Q as Query>::V> (PointerCoercion(Unsize));

diff --git a/tests/mir-opt/inline/dyn_trait.mk_cycle.Inline.panic-abort.diff b/tests/mir-opt/inline/dyn_trait.mk_cycle.Inline.panic-abort.diff
@@ -8,7 +8,7 @@
 
       bb0: {
           StorageLive(_2);
-          _2 = &(*_1);
+          _2 = _1;
           _0 = <dyn Cache<V = V> as Cache>::store_nocache(move _2) -> [return: bb1, unwind unreachable];
       }
 

diff --git a/tests/mir-opt/inline/dyn_trait.mk_cycle.Inline.panic-unwind.diff b/tests/mir-opt/inline/dyn_trait.mk_cycle.Inline.panic-unwind.diff
@@ -8,7 +8,7 @@
 
       bb0: {
           StorageLive(_2);
-          _2 = &(*_1);
+          _2 = _1;
           _0 = <dyn Cache<V = V> as Cache>::store_nocache(move _2) -> [return: bb1, unwind continue];
       }
 

diff --git a/tests/mir-opt/inline/dyn_trait.try_execute_query.Inline.panic-abort.diff b/tests/mir-opt/inline/dyn_trait.try_execute_query.Inline.panic-abort.diff
@@ -13,7 +13,7 @@
       bb0: {
           StorageLive(_2);
           StorageLive(_3);
-          _3 = &(*_1);
+          _3 = _1;
           _2 = move _3 as &dyn Cache<V = <C as Cache>::V> (PointerCoercion(Unsize));
           StorageDead(_3);
 -         _0 = mk_cycle::<<C as Cache>::V>(move _2) -> [return: bb1, unwind unreachable];

diff --git a/tests/mir-opt/inline/dyn_trait.try_execute_query.Inline.panic-unwind.diff b/tests/mir-opt/inline/dyn_trait.try_execute_query.Inline.panic-unwind.diff
@@ -13,7 +13,7 @@
       bb0: {
           StorageLive(_2);
           StorageLive(_3);
-          _3 = &(*_1);
+          _3 = _1;
           _2 = move _3 as &dyn Cache<V = <C as Cache>::V> (PointerCoercion(Unsize));
           StorageDead(_3);
 -         _0 = mk_cycle::<<C as Cache>::V>(move _2) -> [return: bb1, unwind continue];

diff --git a/tests/mir-opt/inline/inline_closure_borrows_arg.foo.Inline.after.mir b/tests/mir-opt/inline/inline_closure_borrows_arg.foo.Inline.after.mir
@@ -26,9 +26,9 @@ fn foo(_1: T, _2: &i32) -> i32 {
         _4 = &_3;
         StorageLive(_5);
         StorageLive(_6);
-        _6 = &(*_2);
+        _6 = _2;
         StorageLive(_7);
-        _7 = &(*_2);
+        _7 = _2;
         _5 = (move _6, move _7);
         StorageLive(_8);
         _8 = move (_5.0: &i32);

diff --git a/tests/mir-opt/inline/inline_retag.bar.Inline.after.mir b/tests/mir-opt/inline/inline_retag.bar.Inline.after.mir
@@ -31,14 +31,14 @@ fn bar() -> bool {
         StorageLive(_4);
         _10 = const bar::promoted[1];
         Retag(_10);
-        _4 = &(*_10);
-        _3 = &(*_4);
+        _4 = _10;
+        _3 = _4;
         StorageLive(_6);
         StorageLive(_7);
         _9 = const bar::promoted[0];
         Retag(_9);
-        _7 = &(*_9);
-        _6 = &(*_7);
+        _7 = _9;
+        _6 = _7;
         Retag(_3);
         Retag(_6);
         StorageLive(_11);

diff --git a/tests/mir-opt/inline/inline_trait_method.test.Inline.after.panic-abort.mir b/tests/mir-opt/inline/inline_trait_method.test.Inline.after.panic-abort.mir
@@ -7,7 +7,7 @@ fn test(_1: &dyn X) -> u32 {
 
     bb0: {
         StorageLive(_2);
-        _2 = &(*_1);
+        _2 = _1;
         _0 = <dyn X as X>::y(move _2) -> [return: bb1, unwind unreachable];
     }
 

diff --git a/tests/mir-opt/inline/inline_trait_method.test.Inline.after.panic-unwind.mir b/tests/mir-opt/inline/inline_trait_method.test.Inline.after.panic-unwind.mir
@@ -7,7 +7,7 @@ fn test(_1: &dyn X) -> u32 {
 
     bb0: {
         StorageLive(_2);
-        _2 = &(*_1);
+        _2 = _1;
         _0 = <dyn X as X>::y(move _2) -> [return: bb1, unwind continue];
     }
 

diff --git a/tests/mir-opt/inline/inline_trait_method_2.test2.Inline.after.panic-abort.mir b/tests/mir-opt/inline/inline_trait_method_2.test2.Inline.after.panic-abort.mir
@@ -12,8 +12,8 @@ fn test2(_1: &dyn X) -> bool {
     bb0: {
         StorageLive(_2);
         StorageLive(_3);
-        _3 = &(*_1);
-        _2 = move _3 as &dyn X (PointerCoercion(Unsize));
+        _3 = _1;
+        _2 = move _3;
         StorageDead(_3);
         _0 = <dyn X as X>::y(move _2) -> [return: bb1, unwind unreachable];
     }

diff --git a/tests/mir-opt/inline/inline_trait_method_2.test2.Inline.after.panic-unwind.mir b/tests/mir-opt/inline/inline_trait_method_2.test2.Inline.after.panic-unwind.mir
@@ -12,8 +12,8 @@ fn test2(_1: &dyn X) -> bool {
     bb0: {
         StorageLive(_2);
         StorageLive(_3);
-        _3 = &(*_1);
-        _2 = move _3 as &dyn X (PointerCoercion(Unsize));
+        _3 = _1;
+        _2 = move _3;
         StorageDead(_3);
         _0 = <dyn X as X>::y(move _2) -> [return: bb1, unwind continue];
     }

diff --git a/tests/mir-opt/inline/issue_58867_inline_as_ref_as_mut.a.Inline.after.mir b/tests/mir-opt/inline/issue_58867_inline_as_ref_as_mut.a.Inline.after.mir
@@ -14,11 +14,11 @@ fn a(_1: &mut [T]) -> &mut [T] {
         StorageLive(_2);
         StorageLive(_3);
         StorageLive(_4);
-        _4 = &mut (*_1);
+        _4 = _1;
         _3 = _4;
-        _2 = &mut (*_3);
+        _2 = _3;
         StorageDead(_4);
-        _0 = &mut (*_2);
+        _0 = _2;
         StorageDead(_3);
         StorageDead(_2);
         return;

diff --git a/tests/mir-opt/inline/issue_58867_inline_as_ref_as_mut.b.Inline.after.mir b/tests/mir-opt/inline/issue_58867_inline_as_ref_as_mut.b.Inline.after.mir
@@ -16,17 +16,17 @@ fn b(_1: &mut Box<T>) -> &mut T {
         StorageLive(_2);
         StorageLive(_3);
         StorageLive(_4);
-        _4 = &mut (*_1);
+        _4 = _1;
         StorageLive(_5);
         StorageLive(_6);
         _5 = (*_4);
         _6 = (((_5.0: std::ptr::Unique<T>).0: std::ptr::NonNull<T>).0: *const T);
         _3 = &mut (*_6);
         StorageDead(_6);
         StorageDead(_5);
-        _2 = &mut (*_3);
+        _2 = _3;
         StorageDead(_4);
-        _0 = &mut (*_2);
+        _0 = _2;
         StorageDead(_3);
         StorageDead(_2);
         return;

diff --git a/tests/mir-opt/inline/issue_58867_inline_as_ref_as_mut.c.Inline.after.mir b/tests/mir-opt/inline/issue_58867_inline_as_ref_as_mut.c.Inline.after.mir
@@ -12,9 +12,9 @@ fn c(_1: &[T]) -> &[T] {
     bb0: {
         StorageLive(_2);
         StorageLive(_3);
-        _3 = &(*_1);
+        _3 = _1;
         _2 = _3;
-        _0 = &(*_2);
+        _0 = _2;
         StorageDead(_3);
         StorageDead(_2);
         return;

diff --git a/tests/mir-opt/inline/issue_58867_inline_as_ref_as_mut.d.Inline.after.mir b/tests/mir-opt/inline/issue_58867_inline_as_ref_as_mut.d.Inline.after.mir
@@ -14,15 +14,15 @@ fn d(_1: &Box<T>) -> &T {
     bb0: {
         StorageLive(_2);
         StorageLive(_3);
-        _3 = &(*_1);
+        _3 = _1;
         StorageLive(_4);
         StorageLive(_5);
         _4 = (*_3);
         _5 = (((_4.0: std::ptr::Unique<T>).0: std::ptr::NonNull<T>).0: *const T);
         _2 = &(*_5);
         StorageDead(_5);
         StorageDead(_4);
-        _0 = &(*_2);
+        _0 = _2;
         StorageDead(_3);
         StorageDead(_2);
         return;

diff --git a/...y/bool_compare.eq_false.InstSimplify.diff → ....eq_false.InstSimplify-before-inline.diff b/...y/bool_compare.eq_false.InstSimplify.diff → ....eq_false.InstSimplify-before-inline.diff
@@ -1,5 +1,5 @@
-- // MIR for `eq_false` before InstSimplify
-+ // MIR for `eq_false` after InstSimplify
+- // MIR for `eq_false` before InstSimplify-before-inline
++ // MIR for `eq_false` after InstSimplify-before-inline
 
   fn eq_false(_1: bool) -> u32 {
       debug x => _1;

diff --git a/...fy/bool_compare.eq_true.InstSimplify.diff → ...e.eq_true.InstSimplify-before-inline.diff b/...fy/bool_compare.eq_true.InstSimplify.diff → ...e.eq_true.InstSimplify-before-inline.diff
@@ -1,5 +1,5 @@
-- // MIR for `eq_true` before InstSimplify
-+ // MIR for `eq_true` after InstSimplify
+- // MIR for `eq_true` before InstSimplify-before-inline
++ // MIR for `eq_true` after InstSimplify-before-inline
 
   fn eq_true(_1: bool) -> u32 {
       debug x => _1;

diff --git a/...y/bool_compare.false_eq.InstSimplify.diff → ....false_eq.InstSimplify-before-inline.diff b/...y/bool_compare.false_eq.InstSimplify.diff → ....false_eq.InstSimplify-before-inline.diff
@@ -1,5 +1,5 @@
-- // MIR for `false_eq` before InstSimplify
-+ // MIR for `false_eq` after InstSimplify
+- // MIR for `false_eq` before InstSimplify-before-inline
++ // MIR for `false_eq` after InstSimplify-before-inline
 
   fn false_eq(_1: bool) -> u32 {
       debug x => _1;

diff --git a/...y/bool_compare.false_ne.InstSimplify.diff → ....false_ne.InstSimplify-before-inline.diff b/...y/bool_compare.false_ne.InstSimplify.diff → ....false_ne.InstSimplify-before-inline.diff
@@ -1,5 +1,5 @@
-- // MIR for `false_ne` before InstSimplify
-+ // MIR for `false_ne` after InstSimplify
+- // MIR for `false_ne` before InstSimplify-before-inline
++ // MIR for `false_ne` after InstSimplify-before-inline
 
   fn false_ne(_1: bool) -> u32 {
       debug x => _1;

diff --git a/...y/bool_compare.ne_false.InstSimplify.diff → ....ne_false.InstSimplify-before-inline.diff b/...y/bool_compare.ne_false.InstSimplify.diff → ....ne_false.InstSimplify-before-inline.diff
@@ -1,5 +1,5 @@
-- // MIR for `ne_false` before InstSimplify
-+ // MIR for `ne_false` after InstSimplify
+- // MIR for `ne_false` before InstSimplify-before-inline
++ // MIR for `ne_false` after InstSimplify-before-inline
 
   fn ne_false(_1: bool) -> u32 {
       debug x => _1;

diff --git a/...fy/bool_compare.ne_true.InstSimplify.diff → ...e.ne_true.InstSimplify-before-inline.diff b/...fy/bool_compare.ne_true.InstSimplify.diff → ...e.ne_true.InstSimplify-before-inline.diff
@@ -1,5 +1,5 @@
-- // MIR for `ne_true` before InstSimplify
-+ // MIR for `ne_true` after InstSimplify
+- // MIR for `ne_true` before InstSimplify-before-inline
++ // MIR for `ne_true` after InstSimplify-before-inline
 
   fn ne_true(_1: bool) -> u32 {
       debug x => _1;