Switch Cranelift over to regalloc2.

cranelift/codegen/Cargo.toml

@@ -23,7 +23,7 @@ serde = { version = "1.0.94", features = ["derive"], optional = true }
 bincode = { version = "1.2.1", optional = true }
 gimli = { version = "0.26.0", default-features = false, features = ["write"], optional = true }
 smallvec = { version = "1.6.1" }
-regalloc = "0.0.34"
+regalloc2 = { version = "0.1.1", features = ["checker"] }
 souper-ir = { version = "2.1.0", optional = true }
 # It is a goal of the cranelift-codegen crate to have minimal external dependencies.
 # Please don't add any unless they are essential to the task of creating binary
@@ -77,14 +77,10 @@ all-arch = [
 # For dependent crates that want to serialize some parts of cranelift
 enable-serde = [
     "serde",
-    "regalloc/enable-serde",
     "cranelift-entity/enable-serde",
+    "regalloc2/enable-serde",
 ]
 
-# Allow snapshotting regalloc test cases. Useful only to report bad register
-# allocation failures, or for regalloc.rs developers.
-regalloc-snapshot = ["bincode", "regalloc/enable-serde"]
-
 # Enable support for the Souper harvester.
 souper-harvest = ["souper-ir", "souper-ir/stringify"]
 

cranelift/codegen/meta/src/shared/settings.rs

@@ -3,39 +3,6 @@ use crate::cdsl::settings::{SettingGroup, SettingGroupBuilder};
 pub(crate) fn define() -> SettingGroup {
     let mut settings = SettingGroupBuilder::new("shared");
 
-    settings.add_enum(
-        "regalloc",
-        "Register allocator to use with the MachInst backend.",
-        r#"
-            This selects the register allocator as an option among those offered by the `regalloc.rs`
-            crate. Please report register allocation bugs to the maintainers of this crate whenever
-            possible.
-
-            Note: this only applies to target that use the MachInst backend. As of 2020-04-17, this
-            means the x86_64 backend doesn't use this yet.
-
-            Possible values:
-
-            - `backtracking` is a greedy, backtracking register allocator as implemented in
-            Spidermonkey's optimizing tier IonMonkey. It may take more time to allocate registers, but
-            it should generate better code in general, resulting in better throughput of generated
-            code.
-            - `backtracking_checked` is the backtracking allocator with additional self checks that may
-            take some time to run, and thus these checks are disabled by default.
-            - `experimental_linear_scan` is an experimental linear scan allocator. It may take less
-            time to allocate registers, but generated code's quality may be inferior. As of
-            2020-04-17, it is still experimental and it should not be used in production settings.
-            - `experimental_linear_scan_checked` is the linear scan allocator with additional self
-            checks that may take some time to run, and thus these checks are disabled by default.
-        "#,
-        vec![
-            "backtracking",
-            "backtracking_checked",
-            "experimental_linear_scan",
-            "experimental_linear_scan_checked",
-        ],
-    );
-
     settings.add_enum(
         "opt_level",
         "Optimization level for generated code.",