Cranelift: update to latest regalloc2: (#4324)

- Handle call instructions' clobbers with the clobbers API, using RA2's
  clobbers bitmask (bytecodealliance/regalloc2#58) rather than clobbers
  list;

- Pull in changes from bytecodealliance/regalloc2#59 for much more sane
  edge-case behavior w.r.t. liverange splitting.

cranelift/codegen/src/isa/s390x/inst/emit_tests.rs

@@ -6804,8 +6804,9 @@ fn test_s390x_binemit() {
             link: writable_gpr(14),
             info: Box::new(CallInfo {
                 dest: ExternalName::testcase("test0"),
-                uses: Vec::new(),
-                defs: Vec::new(),
+                uses: smallvec![],
+                defs: smallvec![],
+                clobbers: PRegSet::empty(),
                 opcode: Opcode::Call,
             }),
         },
@@ -6818,8 +6819,9 @@ fn test_s390x_binemit() {
             link: writable_gpr(14),
             info: Box::new(CallIndInfo {
                 rn: gpr(1),
-                uses: Vec::new(),
-                defs: Vec::new(),
+                uses: smallvec![],
+                defs: smallvec![],
+                clobbers: PRegSet::empty(),
                 opcode: Opcode::CallIndirect,
             }),
         },

cranelift/codegen/src/isa/s390x/inst/mod.rs

@@ -7,7 +7,7 @@ use crate::{settings, CodegenError, CodegenResult};
 use alloc::boxed::Box;
 use alloc::vec::Vec;
 use core::convert::TryFrom;
-use regalloc2::VReg;
+use regalloc2::{PRegSet, VReg};
 use smallvec::{smallvec, SmallVec};
 use std::string::{String, ToString};
 pub mod regs;
@@ -36,8 +36,9 @@ pub use crate::isa::s390x::lower::isle::generated_code::{
 #[derive(Clone, Debug)]
 pub struct CallInfo {
     pub dest: ExternalName,
-    pub uses: Vec<Reg>,
-    pub defs: Vec<Writable<Reg>>,
+    pub uses: SmallVec<[Reg; 8]>,
+    pub defs: SmallVec<[Writable<Reg>; 8]>,
+    pub clobbers: PRegSet,
     pub opcode: Opcode,
 }
 
@@ -46,8 +47,9 @@ pub struct CallInfo {
 #[derive(Clone, Debug)]
 pub struct CallIndInfo {
     pub rn: Reg,
-    pub uses: Vec<Reg>,
-    pub defs: Vec<Writable<Reg>>,
+    pub uses: SmallVec<[Reg; 8]>,
+    pub defs: SmallVec<[Writable<Reg>; 8]>,
+    pub clobbers: PRegSet,
     pub opcode: Opcode,
 }
 
@@ -660,12 +662,14 @@ fn s390x_get_operands<F: Fn(VReg) -> VReg>(inst: &Inst, collector: &mut OperandC
             collector.reg_def(link);
             collector.reg_uses(&*info.uses);
             collector.reg_defs(&*info.defs);
+            collector.reg_clobbers(info.clobbers);
         }
         &Inst::CallInd { link, ref info } => {
             collector.reg_def(link);
             collector.reg_use(info.rn);
             collector.reg_uses(&*info.uses);
             collector.reg_defs(&*info.defs);
+            collector.reg_clobbers(info.clobbers);
         }
         &Inst::Ret { link, ref rets } => {
             collector.reg_use(link);

cranelift/codegen/src/isa/s390x/inst/regs.rs

@@ -13,11 +13,15 @@ use crate::settings;
 
 /// Get a reference to a GPR (integer register).
 pub fn gpr(num: u8) -> Reg {
-    assert!(num < 16);
-    let preg = PReg::new(num as usize, RegClass::Int);
+    let preg = gpr_preg(num);
     Reg::from(VReg::new(preg.index(), RegClass::Int))
 }
 
+pub(crate) const fn gpr_preg(num: u8) -> PReg {
+    assert!(num < 16);
+    PReg::new(num as usize, RegClass::Int)
+}
+
 /// Get a writable reference to a GPR.
 pub fn writable_gpr(num: u8) -> Writable<Reg> {
     Writable::from_reg(gpr(num))
@@ -25,12 +29,17 @@ pub fn writable_gpr(num: u8) -> Writable<Reg> {
 
 /// Get a reference to a FPR (floating-point register).
 pub fn fpr(num: u8) -> Reg {
-    assert!(num < 16);
-    let preg = PReg::new(num as usize, RegClass::Float);
+    let preg = fpr_preg(num);
     Reg::from(VReg::new(preg.index(), RegClass::Float))
 }
 
-/// Get a writable reference to a V-register.
+pub(crate) const fn fpr_preg(num: u8) -> PReg {
+    assert!(num < 16);
+    PReg::new(num as usize, RegClass::Float)
+}
+
+/// Get a writable reference to a FPR.
+#[allow(dead_code)] // used by tests.
 pub fn writable_fpr(num: u8) -> Writable<Reg> {
     Writable::from_reg(fpr(num))
 }