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Directly use Cranelift instructions for 128bit int shifts

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This commit is contained in:
bjorn3 2021-02-21 12:09:13 +01:00
parent c5f98b586f
commit 9c980276d8
2 changed files with 10 additions and 104 deletions
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67
src/codegen_i128.rs
View File

@ -97,70 +97,23 @@ pub(crate) fn maybe_codegen<'tcx>(
None
};
// Optimize `val >> 64`, because compiler_builtins uses it to deconstruct an 128bit
// integer into its lsb and msb.
// https://github.com/rust-lang-nursery/compiler-builtins/blob/79a6a1603d5672cbb9187ff41ff4d9b5048ac1cb/src/int/mod.rs#L217
if resolve_value_imm(fx.bcx.func, rhs_val) == Some(64) {
let (lhs_lsb, lhs_msb) = fx.bcx.ins().isplit(lhs_val);
let all_zeros = fx.bcx.ins().iconst(types::I64, 0);
let val = match (bin_op, is_signed) {
(BinOp::Shr, false) => {
let val = fx.bcx.ins().iconcat(lhs_msb, all_zeros);
Some(CValue::by_val(val, fx.layout_of(fx.tcx.types.u128)))
}
(BinOp::Shr, true) => {
let sign = fx.bcx.ins().icmp_imm(IntCC::SignedLessThan, lhs_msb, 0);
let all_ones = fx.bcx.ins().iconst(types::I64, u64::MAX as i64);
let all_sign_bits = fx.bcx.ins().select(sign, all_zeros, all_ones);
let val = fx.bcx.ins().iconcat(lhs_msb, all_sign_bits);
Some(CValue::by_val(val, fx.layout_of(fx.tcx.types.i128)))
}
(BinOp::Shl, _) => {
let val_ty = if is_signed {
fx.tcx.types.i128
} else {
fx.tcx.types.u128
};
let val = fx.bcx.ins().iconcat(all_zeros, lhs_lsb);
Some(CValue::by_val(val, fx.layout_of(val_ty)))
}
_ => None,
};
if let Some(val) = val {
if let Some(is_overflow) = is_overflow {
let out_ty = fx.tcx.mk_tup([lhs.layout().ty, fx.tcx.types.bool].iter());
let val = val.load_scalar(fx);
return Some(CValue::by_val_pair(val, is_overflow, fx.layout_of(out_ty)));
} else {
return Some(val);
}
}
}
let truncated_rhs = clif_intcast(fx, rhs_val, types::I32, false);
let truncated_rhs = CValue::by_val(truncated_rhs, fx.layout_of(fx.tcx.types.u32));
let val = match (bin_op, is_signed) {
(BinOp::Shl, false) => {
fx.easy_call("__ashlti3", &[lhs, truncated_rhs], fx.tcx.types.u128)
let val = match bin_op {
BinOp::Shl => fx.bcx.ins().ishl(lhs_val, truncated_rhs),
BinOp::Shr => {
if is_signed {
fx.bcx.ins().sshr(lhs_val, truncated_rhs)
} else {
fx.bcx.ins().ushr(lhs_val, truncated_rhs)
}
}
(BinOp::Shl, true) => {
fx.easy_call("__ashlti3", &[lhs, truncated_rhs], fx.tcx.types.i128)
}
(BinOp::Shr, false) => {
fx.easy_call("__lshrti3", &[lhs, truncated_rhs], fx.tcx.types.u128)
}
(BinOp::Shr, true) => {
fx.easy_call("__ashrti3", &[lhs, truncated_rhs], fx.tcx.types.i128)
}
(_, _) => unreachable!(),
_ => unreachable!(),
};
if let Some(is_overflow) = is_overflow {
let out_ty = fx.tcx.mk_tup([lhs.layout().ty, fx.tcx.types.bool].iter());
let val = val.load_scalar(fx);
Some(CValue::by_val_pair(val, is_overflow, fx.layout_of(out_ty)))
} else {
Some(val)
Some(CValue::by_val(val, lhs.layout()))
}
}
}

47
src/common.rs
View File

@ -3,8 +3,6 @@ use rustc_target::abi::call::FnAbi;
use rustc_target::abi::{Integer, Primitive};
use rustc_target::spec::{HasTargetSpec, Target};
use cranelift_codegen::ir::{InstructionData, Opcode, ValueDef};
use crate::prelude::*;
pub(crate) fn pointer_ty(tcx: TyCtxt<'_>) -> types::Type {
@ -175,51 +173,6 @@ pub(crate) fn codegen_icmp_imm(
}
}
fn resolve_normal_value_imm(func: &Function, val: Value) -> Option<i64> {
if let ValueDef::Result(inst, 0 /*param*/) = func.dfg.value_def(val) {
if let InstructionData::UnaryImm {
opcode: Opcode::Iconst,
imm,
} = func.dfg[inst]
{
Some(imm.into())
} else {
None
}
} else {
None
}
}
fn resolve_128bit_value_imm(func: &Function, val: Value) -> Option<u128> {
let (lsb, msb) = if let ValueDef::Result(inst, 0 /*param*/) = func.dfg.value_def(val) {
if let InstructionData::Binary {
opcode: Opcode::Iconcat,
args: [lsb, msb],
} = func.dfg[inst]
{
(lsb, msb)
} else {
return None;
}
} else {
return None;
};
let lsb = u128::from(resolve_normal_value_imm(func, lsb)? as u64);
let msb = u128::from(resolve_normal_value_imm(func, msb)? as u64);
Some(msb << 64 | lsb)
}
pub(crate) fn resolve_value_imm(func: &Function, val: Value) -> Option<u128> {
if func.dfg.value_type(val) == types::I128 {
resolve_128bit_value_imm(func, val)
} else {
resolve_normal_value_imm(func, val).map(|imm| u128::from(imm as u64))
}
}
pub(crate) fn type_min_max_value(
bcx: &mut FunctionBuilder<'_>,
ty: Type,