T0b1/wasmtime
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Avoid reusing a register during constant loading (#5379)

Browse Source 
Avoid reusing a register when loading a constant, allocating a temporary instead.
This commit is contained in:
Trevor Elliott
2022-12-05 18:37:53 -08:00
committed by GitHub
parent 4933762d81
commit 353a681671
3 changed files with 46 additions and 41 deletions
Download Patch File Download Diff File Expand all files Collapse all files

15
cranelift/codegen/src/isa/riscv64/inst/emit.rs
View File

@@ -53,11 +53,16 @@ impl LoadConstant {
}
}
pub(crate) fn load_constant(self, rd: Writable<Reg>) -> SmallInstVec<Inst> {
pub(crate) fn load_constant<F: FnMut(Type) -> Writable<Reg>>(
self,
rd: Writable<Reg>,
alloc_tmp: &mut F,
) -> SmallInstVec<Inst> {
let mut insts = SmallInstVec::new();
// get current pc.
let pc = alloc_tmp(I64);
insts.push(Inst::Auipc {
rd,
rd: pc,
imm: Imm20 { bits: 0 },
});
// load
@@ -65,7 +70,7 @@ impl LoadConstant {
rd,
op: self.load_op(),
flags: MemFlags::new(),
from: AMode::RegOffset(rd.to_reg(), 12, self.load_ty()),
from: AMode::RegOffset(pc.to_reg(), 12, self.load_ty()),
});
let data = self.to_le_bytes();
// jump over.
@@ -78,10 +83,10 @@ impl LoadConstant {
// load and perform an extra add.
pub(crate) fn load_constant_and_add(self, rd: Writable<Reg>, rs: Reg) -> SmallInstVec<Inst> {
let mut insts = self.load_constant(rd);
let mut insts = self.load_constant(rd, &mut |_| rd);
insts.push(Inst::AluRRR {
alu_op: AluOPRRR::Add,
rd: rd,
rd,
rs1: rd.to_reg(),
rs2: rs,
});

4
cranelift/codegen/src/isa/riscv64/inst/mod.rs
View File

@@ -235,7 +235,7 @@ impl Inst {
alloc_tmp: &mut F,
) -> SmallInstVec<Inst> {
let insts = Inst::load_const_imm(rd, value, alloc_tmp);
insts.unwrap_or(LoadConstant::U32(value as u32).load_constant(rd))
insts.unwrap_or(LoadConstant::U32(value as u32).load_constant(rd, alloc_tmp))
}
pub fn load_constant_u64<F: FnMut(Type) -> Writable<Reg>>(
@@ -244,7 +244,7 @@ impl Inst {
alloc_tmp: &mut F,
) -> SmallInstVec<Inst> {
let insts = Inst::load_const_imm(rd, value, alloc_tmp);
insts.unwrap_or(LoadConstant::U64(value).load_constant(rd))
insts.unwrap_or(LoadConstant::U64(value).load_constant(rd, alloc_tmp))
}
pub(crate) fn construct_auipc_and_jalr(