Rollup merge of #82736 - spastorino:mir-opt-level-perf-changes, r=oli-obk

Bump optimization from mir_opt_level 2 to 3 and 3 to 4 and make "release" be level 2 by default

r? `@oli-obk`

Author: GuillaumeGomez

compiler/rustc_interface/src/tests.rs

@@ -566,7 +566,7 @@ fn test_debugging_options_tracking_hash() {
     tracked!(link_only, true);
     tracked!(merge_functions, Some(MergeFunctions::Disabled));
     tracked!(mir_emit_retag, true);
-    tracked!(mir_opt_level, 3);
+    tracked!(mir_opt_level, Some(4));
     tracked!(mutable_noalias, true);
     tracked!(new_llvm_pass_manager, true);
     tracked!(no_codegen, true);

compiler/rustc_mir/src/transform/const_goto.rs

@@ -28,7 +28,7 @@ pub struct ConstGoto;
 
 impl<'tcx> MirPass<'tcx> for ConstGoto {
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
-        if tcx.sess.opts.debugging_opts.mir_opt_level < 3 {
+        if tcx.sess.mir_opt_level() < 4 {
             return;
         }
         trace!("Running ConstGoto on {:?}", body.source);

compiler/rustc_mir/src/transform/const_prop.rs

@@ -725,7 +725,7 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
             return None;
         }
 
-        if self.tcx.sess.opts.debugging_opts.mir_opt_level >= 3 {
+        if self.tcx.sess.mir_opt_level() >= 4 {
             self.eval_rvalue_with_identities(rvalue, place)
         } else {
             self.use_ecx(|this| this.ecx.eval_rvalue_into_place(rvalue, place))
@@ -903,7 +903,7 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
 
     /// Returns `true` if and only if this `op` should be const-propagated into.
     fn should_const_prop(&mut self, op: &OpTy<'tcx>) -> bool {
-        let mir_opt_level = self.tcx.sess.opts.debugging_opts.mir_opt_level;
+        let mir_opt_level = self.tcx.sess.mir_opt_level();
 
         if mir_opt_level == 0 {
             return false;
@@ -1071,9 +1071,9 @@ impl<'mir, 'tcx> MutVisitor<'tcx> for ConstPropagator<'mir, 'tcx> {
     fn visit_operand(&mut self, operand: &mut Operand<'tcx>, location: Location) {
         self.super_operand(operand, location);
 
-        // Only const prop copies and moves on `mir_opt_level=2` as doing so
+        // Only const prop copies and moves on `mir_opt_level=3` as doing so
         // currently slightly increases compile time in some cases.
-        if self.tcx.sess.opts.debugging_opts.mir_opt_level >= 2 {
+        if self.tcx.sess.mir_opt_level() >= 3 {
             self.propagate_operand(operand)
         }
     }
@@ -1253,7 +1253,7 @@ impl<'mir, 'tcx> MutVisitor<'tcx> for ConstPropagator<'mir, 'tcx> {
             TerminatorKind::SwitchInt { ref mut discr, .. } => {
                 // FIXME: This is currently redundant with `visit_operand`, but sadly
                 // always visiting operands currently causes a perf regression in LLVM codegen, so
-                // `visit_operand` currently only runs for propagates places for `mir_opt_level=3`.
+                // `visit_operand` currently only runs for propagates places for `mir_opt_level=4`.
                 self.propagate_operand(discr)
             }
             // None of these have Operands to const-propagate.
@@ -1272,7 +1272,7 @@ impl<'mir, 'tcx> MutVisitor<'tcx> for ConstPropagator<'mir, 'tcx> {
             // Every argument in our function calls have already been propagated in `visit_operand`.
             //
             // NOTE: because LLVM codegen gives slight performance regressions with it, so this is
-            // gated on `mir_opt_level=2`.
+            // gated on `mir_opt_level=3`.
             TerminatorKind::Call { .. } => {}
         }
 

compiler/rustc_mir/src/transform/deduplicate_blocks.rs

@@ -16,7 +16,7 @@ pub struct DeduplicateBlocks;
 
 impl<'tcx> MirPass<'tcx> for DeduplicateBlocks {
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
-        if tcx.sess.opts.debugging_opts.mir_opt_level < 3 {
+        if tcx.sess.mir_opt_level() < 4 {
             return;
         }
         debug!("Running DeduplicateBlocks on `{:?}`", body.source);

compiler/rustc_mir/src/transform/dest_prop.rs

@@ -127,9 +127,9 @@ pub struct DestinationPropagation;
 
 impl<'tcx> MirPass<'tcx> for DestinationPropagation {
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
-        // Only run at mir-opt-level=2 or higher for now (we don't fix up debuginfo and remove
+        // Only run at mir-opt-level=3 or higher for now (we don't fix up debuginfo and remove
         // storage statements at the moment).
-        if tcx.sess.opts.debugging_opts.mir_opt_level <= 1 {
+        if tcx.sess.mir_opt_level() < 3 {
             return;
         }
 

compiler/rustc_mir/src/transform/early_otherwise_branch.rs

@@ -26,7 +26,7 @@ pub struct EarlyOtherwiseBranch;
 
 impl<'tcx> MirPass<'tcx> for EarlyOtherwiseBranch {
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
-        if tcx.sess.opts.debugging_opts.mir_opt_level < 2 {
+        if tcx.sess.mir_opt_level() < 3 {
             return;
         }
         trace!("running EarlyOtherwiseBranch on {:?}", body.source);

compiler/rustc_mir/src/transform/inline.rs

@@ -52,7 +52,7 @@ crate fn is_enabled(tcx: TyCtxt<'_>) -> bool {
         return enabled;
     }
 
-    tcx.sess.opts.debugging_opts.mir_opt_level >= 2
+    tcx.sess.mir_opt_level() >= 3
 }
 
 impl<'tcx> MirPass<'tcx> for Inline {

compiler/rustc_mir/src/transform/match_branches.rs

@@ -40,7 +40,7 @@ pub struct MatchBranchSimplification;
 
 impl<'tcx> MirPass<'tcx> for MatchBranchSimplification {
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
-        if tcx.sess.opts.debugging_opts.mir_opt_level <= 1 {
+        if tcx.sess.mir_opt_level() < 3 {
             return;
         }
 

compiler/rustc_mir/src/transform/mod.rs

@@ -475,7 +475,7 @@ fn run_post_borrowck_cleanup_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tc
 }
 
 fn run_optimization_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
-    let mir_opt_level = tcx.sess.opts.debugging_opts.mir_opt_level;
+    let mir_opt_level = tcx.sess.mir_opt_level();
 
     // Lowering generator control-flow and variables has to happen before we do anything else
     // to them. We run some optimizations before that, because they may be harder to do on the state

compiler/rustc_mir/src/transform/multiple_return_terminators.rs

@@ -10,7 +10,7 @@ pub struct MultipleReturnTerminators;
 
 impl<'tcx> MirPass<'tcx> for MultipleReturnTerminators {
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
-        if tcx.sess.opts.debugging_opts.mir_opt_level < 3 {
+        if tcx.sess.mir_opt_level() < 4 {
             return;
         }
 

compiler/rustc_mir/src/transform/nrvo.rs

@@ -34,7 +34,7 @@ pub struct RenameReturnPlace;
 
 impl<'tcx> MirPass<'tcx> for RenameReturnPlace {
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut mir::Body<'tcx>) {
-        if tcx.sess.opts.debugging_opts.mir_opt_level == 0 {
+        if tcx.sess.mir_opt_level() == 0 {
             return;
         }
 

compiler/rustc_mir/src/transform/unreachable_prop.rs

@@ -12,8 +12,8 @@ pub struct UnreachablePropagation;
 
 impl MirPass<'_> for UnreachablePropagation {
     fn run_pass<'tcx>(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
-        if tcx.sess.opts.debugging_opts.mir_opt_level < 3 {
-            // Enable only under -Zmir-opt-level=3 as in some cases (check the deeply-nested-opt
+        if tcx.sess.mir_opt_level() < 4 {
+            // Enable only under -Zmir-opt-level=4 as in some cases (check the deeply-nested-opt
             // perf benchmark) LLVM may spend quite a lot of time optimizing the generated code.
             return;
         }

compiler/rustc_session/src/config.rs

@@ -1938,21 +1938,23 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
             Some(SymbolManglingVersion::V0) => {}
         }
 
-        if debugging_opts.mir_opt_level > 1 {
-            // Functions inlined during MIR transform can, at best, make it impossible to
-            // effectively cover inlined functions, and, at worst, break coverage map generation
-            // during LLVM codegen. For example, function counter IDs are only unique within a
-            // function. Inlining after these counters are injected can produce duplicate counters,
-            // resulting in an invalid coverage map (and ICE); so this option combination is not
-            // allowed.
-            early_warn(
-                error_format,
-                &format!(
-                    "`-Z mir-opt-level={}` (or any level > 1) enables function inlining, which \
+        if let Some(mir_opt_level) = debugging_opts.mir_opt_level {
+            if mir_opt_level > 1 {
+                // Functions inlined during MIR transform can, at best, make it impossible to
+                // effectively cover inlined functions, and, at worst, break coverage map generation
+                // during LLVM codegen. For example, function counter IDs are only unique within a
+                // function. Inlining after these counters are injected can produce duplicate counters,
+                // resulting in an invalid coverage map (and ICE); so this option combination is not
+                // allowed.
+                early_warn(
+                    error_format,
+                    &format!(
+                        "`-Z mir-opt-level={}` (or any level > 1) enables function inlining, which \
                     is incompatible with `-Z instrument-coverage`. Inlining will be disabled.",
-                    debugging_opts.mir_opt_level,
-                ),
-            );
+                        mir_opt_level,
+                    ),
+                );
+            }
         }
     }
 

compiler/rustc_session/src/options.rs

@@ -999,8 +999,8 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
     mir_emit_retag: bool = (false, parse_bool, [TRACKED],
         "emit Retagging MIR statements, interpreted e.g., by miri; implies -Zmir-opt-level=0 \
         (default: no)"),
-    mir_opt_level: usize = (1, parse_uint, [TRACKED],
-        "MIR optimization level (0-3; default: 1)"),
+    mir_opt_level: Option<usize> = (None, parse_opt_uint, [TRACKED],
+        "MIR optimization level (0-4; default: 1 in non optimized builds and 2 in optimized builds)"),
     mutable_noalias: bool = (false, parse_bool, [TRACKED],
         "emit noalias metadata for mutable references (default: no)"),
     new_llvm_pass_manager: bool = (false, parse_bool, [TRACKED],

compiler/rustc_session/src/session.rs

@@ -640,6 +640,12 @@ impl Session {
     pub fn binary_dep_depinfo(&self) -> bool {
         self.opts.debugging_opts.binary_dep_depinfo
     }
+    pub fn mir_opt_level(&self) -> usize {
+        self.opts
+            .debugging_opts
+            .mir_opt_level
+            .unwrap_or_else(|| if self.opts.optimize != config::OptLevel::No { 2 } else { 1 })
+    }
 
     /// Gets the features enabled for the current compilation session.
     /// DO NOT USE THIS METHOD if there is a TyCtxt available, as it circumvents

src/test/codegen/issue-59352.rs

@@ -5,8 +5,8 @@
 // Once the optimizer can do that, mir-opt/issues/issue-59352.rs will need to be updated and this
 // test case should be removed as it will become redundant.
 
-// mir-opt-level=2 enables inlining and enables LLVM to optimize away the unreachable panic call.
-// compile-flags: -O -Z mir-opt-level=2
+// mir-opt-level=3 enables inlining and enables LLVM to optimize away the unreachable panic call.
+// compile-flags: -O -Z mir-opt-level=3
 
 #![crate_type = "rlib"]
 

src/test/codegen/naked-noinline.rs

@@ -1,5 +1,5 @@
 // Checks that naked functions are never inlined.
-// compile-flags: -O -Zmir-opt-level=2
+// compile-flags: -O -Zmir-opt-level=3
 // ignore-wasm32
 #![crate_type = "lib"]
 #![feature(asm)]

src/test/codegen/sanitizer-no-sanitize-inlining.rs

@@ -4,8 +4,8 @@
 // needs-sanitizer-address
 // needs-sanitizer-leak
 // revisions: ASAN LSAN
-//[ASAN] compile-flags: -Zsanitizer=address -C opt-level=3 -Z mir-opt-level=3
-//[LSAN] compile-flags: -Zsanitizer=leak    -C opt-level=3 -Z mir-opt-level=3
+//[ASAN] compile-flags: -Zsanitizer=address -C opt-level=3 -Z mir-opt-level=4
+//[LSAN] compile-flags: -Zsanitizer=leak    -C opt-level=3 -Z mir-opt-level=4
 
 #![crate_type="lib"]
 #![feature(no_sanitize)]

src/test/codegen/try_identity.rs

@@ -1,4 +1,4 @@
-// compile-flags: -C no-prepopulate-passes -O -Z mir-opt-level=2 -Zunsound-mir-opts
+// compile-flags: -C no-prepopulate-passes -O -Z mir-opt-level=3 -Zunsound-mir-opts
 
 // Ensure that `x?` has no overhead on `Result<T, E>` due to identity `match`es in lowering.
 // This requires inlining to trigger the MIR optimizations in `SimplifyArmIdentity`.

src/test/mir-opt/const_prop/boolean_identities.rs

@@ -1,4 +1,4 @@
-// compile-flags: -O -Zmir-opt-level=3
+// compile-flags: -O -Zmir-opt-level=4
 
 // EMIT_MIR boolean_identities.test.ConstProp.diff
 pub fn test(x: bool, y: bool) -> bool {

src/test/mir-opt/const_prop/issue-66971.rs

@@ -1,4 +1,4 @@
-// compile-flags: -Z mir-opt-level=2
+// compile-flags: -Z mir-opt-level=3
 
 // Due to a bug in propagating scalar pairs the assertion below used to fail. In the expected
 // outputs below, after ConstProp this is how _2 would look like with the bug:

src/test/mir-opt/const_prop/issue-67019.rs

@@ -1,4 +1,4 @@
-// compile-flags: -Z mir-opt-level=2
+// compile-flags: -Z mir-opt-level=3
 
 // This used to ICE in const-prop
 

src/test/mir-opt/const_prop/mult_by_zero.rs

@@ -1,4 +1,4 @@
-// compile-flags: -O -Zmir-opt-level=3
+// compile-flags: -O -Zmir-opt-level=4
 
 // EMIT_MIR mult_by_zero.test.ConstProp.diff
 fn test(x : i32) -> i32 {

src/test/mir-opt/early_otherwise_branch.rs

@@ -1,4 +1,4 @@
-// compile-flags: -Z mir-opt-level=3
+// compile-flags: -Z mir-opt-level=4
 // EMIT_MIR early_otherwise_branch.opt1.EarlyOtherwiseBranch.diff
 fn opt1(x: Option<u32>, y: Option<u32>) -> u32 {
     match (x, y) {

src/test/mir-opt/early_otherwise_branch_3_element_tuple.rs

@@ -1,4 +1,4 @@
-// compile-flags: -Z mir-opt-level=3
+// compile-flags: -Z mir-opt-level=4
 
 // EMIT_MIR early_otherwise_branch_3_element_tuple.opt1.EarlyOtherwiseBranch.diff
 fn opt1(x: Option<u32>, y: Option<u32>, z: Option<u32>) -> u32 {

src/test/mir-opt/early_otherwise_branch_68867.rs

@@ -1,5 +1,5 @@
 // ignore-tidy-linelength
-// compile-flags: -Z mir-opt-level=3 -Zunsound-mir-opts
+// compile-flags: -Z mir-opt-level=4 -Zunsound-mir-opts
 
 // example from #68867
 type CSSFloat = f32;

src/test/mir-opt/early_otherwise_branch_noopt.rs

@@ -1,4 +1,4 @@
-// compile-flags: -Z mir-opt-level=3
+// compile-flags: -Z mir-opt-level=4
 
 // must not optimize as it does not follow the pattern of
 // left and right hand side being the same variant

src/test/mir-opt/inline/inline-into-box-place.rs

@@ -1,6 +1,6 @@
 // ignore-endian-big
 // ignore-wasm32-bare compiled with panic=abort by default
-// compile-flags: -Z mir-opt-level=3
+// compile-flags: -Z mir-opt-level=4
 // EMIT_MIR_FOR_EACH_BIT_WIDTH
 #![feature(box_syntax)]
 // EMIT_MIR inline_into_box_place.main.Inline.diff

src/test/mir-opt/inline/inline-trait-method_2.rs

@@ -1,4 +1,4 @@
-// compile-flags: -Z span_free_formats -Z mir-opt-level=3
+// compile-flags: -Z span_free_formats -Z mir-opt-level=4
 
 // EMIT_MIR inline_trait_method_2.test2.Inline.after.mir
 fn test2(x: &dyn X) -> bool {

src/test/mir-opt/issues/issue-59352.rs

@@ -7,7 +7,7 @@
 // removed.
 
 // EMIT_MIR issue_59352.num_to_digit.PreCodegen.after.mir
-// compile-flags: -Z mir-opt-level=2 -Z span_free_formats
+// compile-flags: -Z mir-opt-level=3 -Z span_free_formats
 
 pub fn num_to_digit(num: char) -> u32 {
     // CHECK-NOT: panic

src/test/mir-opt/multiple_return_terminators.rs

@@ -1,4 +1,4 @@
-// compile-flags: -Z mir-opt-level=3
+// compile-flags: -Z mir-opt-level=4
 // EMIT_MIR multiple_return_terminators.test.MultipleReturnTerminators.diff
 
 fn test(x: bool) {

src/test/mir-opt/simplify-arm-identity.rs

@@ -1,7 +1,7 @@
 // Checks that `SimplifyArmIdentity` is not applied if enums have incompatible layouts.
 // Regression test for issue #66856.
 //
-// compile-flags: -Zmir-opt-level=2
+// compile-flags: -Zmir-opt-level=3
 // EMIT_MIR_FOR_EACH_BIT_WIDTH
 
 enum Src {

src/test/mir-opt/simplify-arm.rs

@@ -1,4 +1,4 @@
-// compile-flags: -Z mir-opt-level=2 -Zunsound-mir-opts
+// compile-flags: -Z mir-opt-level=3 -Zunsound-mir-opts
 // EMIT_MIR simplify_arm.id.SimplifyArmIdentity.diff
 // EMIT_MIR simplify_arm.id.SimplifyBranchSame.diff
 // EMIT_MIR simplify_arm.id_result.SimplifyArmIdentity.diff

src/test/ui/const-generics/issues/issue-75299.rs

@@ -1,4 +1,4 @@
-// compile-flags: -Zmir-opt-level=3
+// compile-flags: -Zmir-opt-level=4
 // run-pass
 
 #![feature(const_generics)]

src/test/ui/const_prop/inline_spans.rs

@@ -1,5 +1,5 @@
 // build-fail
-// compile-flags: -Zmir-opt-level=2
+// compile-flags: -Zmir-opt-level=3
 
 #![deny(warnings)]
 

src/test/ui/const_prop/inline_spans_lint_attribute.rs

@@ -1,6 +1,6 @@
 // Must be build-pass, because check-pass will not run const prop and thus not emit the lint anyway.
 // build-pass
-// compile-flags: -Zmir-opt-level=2
+// compile-flags: -Zmir-opt-level=3
 
 #![deny(warnings)]
 

src/test/ui/consts/issue-66345.rs

@@ -1,8 +1,8 @@
 // run-pass
-// compile-flags: -Z mir-opt-level=3
+// compile-flags: -Z mir-opt-level=4
 
 // Checks that the compiler does not ICE when passing references to field of by-value struct
-// with -Z mir-opt-level=3
+// with -Z mir-opt-level=4
 
 fn do_nothing(_: &()) {}
 

src/test/ui/consts/issue-67529.rs

@@ -1,4 +1,4 @@
-// compile-flags: -Z mir-opt-level=2
+// compile-flags: -Z mir-opt-level=3
 // run-pass
 
 struct Baz<T: ?Sized> {

src/test/ui/consts/issue-67640.rs

@@ -1,4 +1,4 @@
-// compile-flags: -Z mir-opt-level=3
+// compile-flags: -Z mir-opt-level=4
 // run-pass
 
 struct X {

src/test/ui/consts/issue-67641.rs

@@ -1,4 +1,4 @@
-// compile-flags: -Z mir-opt-level=2
+// compile-flags: -Z mir-opt-level=3
 // run-pass
 
 use std::cell::Cell;

src/test/ui/consts/issue-67862.rs

@@ -1,4 +1,4 @@
-// compile-flags: -Z mir-opt-level=2
+// compile-flags: -Z mir-opt-level=3
 // run-pass
 
 fn e220() -> (i64, i64) {