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Implement pinned register usage through set_pinned_reg/get_pinned_reg;

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This commit is contained in:
Benjamin Bouvier
2020-04-21 12:12:03 +02:00
parent d1b5df31fd
commit 241c164e25
7 changed files with 97 additions and 20 deletions
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41
cranelift/codegen/src/isa/aarch64/inst/regs.rs
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@@ -2,6 +2,7 @@
use crate::isa::aarch64::inst::InstSize;
use crate::machinst::*;
use crate::settings;
use regalloc::{RealRegUniverse, Reg, RegClass, RegClassInfo, Writable, NUM_REG_CLASSES};
@@ -10,6 +11,11 @@ use std::string::{String, ToString};
//=============================================================================
// Registers, the Universe thereof, and printing
/// The pinned register on this architecture.
/// It must be the same as Spidermonkey's HeapReg, as found in this file.
/// https://searchfox.org/mozilla-central/source/js/src/jit/arm64/Assembler-arm64.h#103
pub const PINNED_REG: u8 = 21;
#[rustfmt::skip]
const XREG_INDICES: [u8; 31] = [
// X0 - X7
@@ -22,8 +28,12 @@ const XREG_INDICES: [u8; 31] = [
47, 48,
// X18
60,
// X19 - X28
49, 50, 51, 52, 53, 54, 55, 56, 57, 58,
// X19, X20
49, 50,
// X21, put aside because it's the pinned register.
58,
// X22 - X28
51, 52, 53, 54, 55, 56, 57,
// X29
61,
// X30
@@ -131,14 +141,13 @@ pub fn writable_spilltmp_reg() -> Writable<Reg> {
}
/// Create the register universe for AArch64.
pub fn create_reg_universe() -> RealRegUniverse {
pub fn create_reg_universe(flags: &settings::Flags) -> RealRegUniverse {
let mut regs = vec![];
let mut allocable_by_class = [None; NUM_REG_CLASSES];
// Numbering Scheme: we put V-regs first, then X-regs. The X-regs
// exclude several registers: x18 (globally reserved for platform-specific
// purposes), x29 (frame pointer), x30 (link register), x31 (stack pointer
// or zero register, depending on context).
// Numbering Scheme: we put V-regs first, then X-regs. The X-regs exclude several registers:
// x18 (globally reserved for platform-specific purposes), x29 (frame pointer), x30 (link
// register), x31 (stack pointer or zero register, depending on context).
let v_reg_base = 0u8; // in contiguous real-register index space
let v_reg_count = 32;
@@ -159,9 +168,12 @@ pub fn create_reg_universe() -> RealRegUniverse {
let x_reg_base = 32u8; // in contiguous real-register index space
let mut x_reg_count = 0;
let uses_pinned_reg = flags.enable_pinned_reg();
for i in 0u8..32u8 {
// See above for excluded registers.
if i == 15 || i == 18 || i == 29 || i == 30 || i == 31 {
if i == 15 || i == 18 || i == 29 || i == 30 || i == 31 || i == PINNED_REG {
continue;
}
let reg = Reg::new_real(
@@ -188,13 +200,24 @@ pub fn create_reg_universe() -> RealRegUniverse {
});
// Other regs, not available to the allocator.
let allocable = regs.len();
let allocable = if uses_pinned_reg {
// The pinned register is not allocatable in this case, so record the length before adding
// it.
let len = regs.len();
regs.push((xreg(PINNED_REG).to_real_reg(), "x21/pinned_reg".to_string()));
len
} else {
regs.push((xreg(PINNED_REG).to_real_reg(), "x21".to_string()));
regs.len()
};
regs.push((xreg(15).to_real_reg(), "x15".to_string()));
regs.push((xreg(18).to_real_reg(), "x18".to_string()));
regs.push((fp_reg().to_real_reg(), "fp".to_string()));
regs.push((link_reg().to_real_reg(), "lr".to_string()));
regs.push((zero_reg().to_real_reg(), "xzr".to_string()));
regs.push((stack_reg().to_real_reg(), "sp".to_string()));
// FIXME JRS 2020Feb06: unfortunately this pushes the number of real regs
// to 65, which is potentially inconvenient from a compiler performance
// standpoint. We could possibly drop back to 64 by "losing" a vector