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Multi-register value support: framework for Values wider than machine regs.

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This will allow for support for `I128` values everywhere, and `I64`
values on 32-bit targets (e.g., ARM32 and x86-32). It does not alter the
machine backends to build such support; it just adds the framework for
the MachInst backends to *reason* about a `Value` residing in more than
one register.
This commit is contained in:
Chris Fallin
2020-12-12 20:48:56 -08:00
parent 6317290a1d
commit 6eea015d6c
18 changed files with 1024 additions and 561 deletions
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24
cranelift/codegen/src/machinst/mod.rs
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@@ -135,6 +135,8 @@ pub mod helpers;
pub use helpers::*;
pub mod inst_common;
pub use inst_common::*;
pub mod valueregs;
pub use valueregs::*;
/// A machine instruction.
pub trait MachInst: Clone + Debug {
@@ -165,9 +167,9 @@ pub trait MachInst: Clone + Debug {
fn gen_move(to_reg: Writable<Reg>, from_reg: Reg, ty: Type) -> Self;
/// Generate a constant into a reg.
fn gen_constant<F: FnMut(RegClass, Type) -> Writable<Reg>>(
to_reg: Writable<Reg>,
value: u64,
fn gen_constant<F: FnMut(Type) -> Writable<Reg>>(
to_regs: ValueRegs<Writable<Reg>>,
value: u128,
ty: Type,
alloc_tmp: F,
) -> SmallVec<[Self; 4]>;
@@ -180,9 +182,19 @@ pub trait MachInst: Clone + Debug {
/// (e.g., add directly from or directly to memory), like x86.
fn maybe_direct_reload(&self, reg: VirtualReg, slot: SpillSlot) -> Option<Self>;
/// Determine a register class to store the given Cranelift type.
/// May return an error if the type isn't supported by this backend.
fn rc_for_type(ty: Type) -> CodegenResult<RegClass>;
/// Determine register class(es) to store the given Cranelift type, and the
/// Cranelift type actually stored in the underlying register(s). May return
/// an error if the type isn't supported by this backend.
///
/// If the type requires multiple registers, then the list of registers is
/// returned in little-endian order.
///
/// Note that the type actually stored in the register(s) may differ in the
/// case that a value is split across registers: for example, on a 32-bit
/// target, an I64 may be stored in two registers, each of which holds an
/// I32. The actually-stored types are used only to inform the backend when
/// generating spills and reloads for individual registers.
fn rc_for_type(ty: Type) -> CodegenResult<(&'static [RegClass], &'static [Type])>;
/// Generate a jump to another target. Used during lowering of
/// control flow.