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

Address code review comments, simplifying some bits of branch_opt.

Browse Source
This commit is contained in:
Tyler McMullen
2019-04-10 13:41:49 -07:00
committed by Benjamin Bouvier
parent 402d0d9c83
commit 5596b5fadc
2 changed files with 79 additions and 80 deletions
Download Patch File Download Diff File Expand all files Collapse all files

153
cranelift/codegen/src/simple_preopt.rs
View File

@@ -545,14 +545,8 @@ fn simplify(pos: &mut FuncCursor, inst: Inst) {
struct BranchOptInfo {
br_inst: Inst,
cmp_arg: Value,
destination: Ebb,
args: ValueList,
kind: BranchOptKind,
}
enum BranchOptKind {
EqualZero,
NotEqualZero,
new_opcode: Opcode,
}
/// Fold comparisons into branch operations when possible.
@@ -561,80 +555,86 @@ enum BranchOptKind {
/// result in a `brz` or `brnz` branch. It folds those two operations into a
/// single `brz` or `brnz`.
fn branch_opt(pos: &mut FuncCursor, inst: Inst) {
let info = match pos.func.dfg[inst] {
InstructionData::Branch {
opcode,
destination,
ref args,
} => {
let first_arg = {
let args = pos.func.dfg.inst_args(inst);
args[0]
};
let mut info = if let InstructionData::Branch {
opcode, ref args, ..
} = pos.func.dfg[inst]
{
let first_arg = {
let args = pos.func.dfg.inst_args(inst);
args[0]
};
let iconst_inst =
if let ValueDef::Result(iconst_inst, _) = pos.func.dfg.value_def(first_arg) {
iconst_inst
} else {
return;
};
if let InstructionData::IntCompareImm {
opcode: Opcode::IcmpImm,
arg: cmp_arg,
cond: cmp_cond,
imm: cmp_imm,
} = pos.func.dfg[iconst_inst]
{
let cmp_imm: i64 = cmp_imm.into();
if cmp_imm != 0 {
return;
}
// icmp_imm returns non-zero when the comparison is true. So, if
// we're branching on zero, we need to invert the condition.
let cond = match opcode {
Opcode::Brz => cmp_cond.inverse(),
Opcode::Brnz => cmp_cond,
_ => return,
};
let kind = match cond {
IntCC::Equal => BranchOptKind::EqualZero,
IntCC::NotEqual => BranchOptKind::NotEqualZero,
_ => return,
};
BranchOptInfo {
br_inst: inst,
cmp_arg: cmp_arg,
destination: destination,
args: args.clone(),
kind: kind,
}
let iconst_inst =
if let ValueDef::Result(iconst_inst, _) = pos.func.dfg.value_def(first_arg) {
iconst_inst
} else {
return;
};
if let InstructionData::IntCompareImm {
opcode: Opcode::IcmpImm,
arg: cmp_arg,
cond: cmp_cond,
imm: cmp_imm,
} = pos.func.dfg[iconst_inst]
{
let cmp_imm: i64 = cmp_imm.into();
if cmp_imm != 0 {
return;
}
// icmp_imm returns non-zero when the comparison is true. So, if
// we're branching on zero, we need to invert the condition.
let cond = match opcode {
Opcode::Brz => cmp_cond.inverse(),
Opcode::Brnz => cmp_cond,
_ => return,
};
let new_opcode = match cond {
IntCC::Equal => Opcode::Brz,
IntCC::NotEqual => Opcode::Brnz,
_ => return,
};
BranchOptInfo {
br_inst: inst,
cmp_arg: cmp_arg,
args: args.clone(),
new_opcode: new_opcode,
}
} else {
return;
}
_ => return,
} else {
return;
};
match info.kind {
BranchOptKind::EqualZero => {
let args = info.args.as_slice(&pos.func.dfg.value_lists)[1..].to_vec();
pos.func
.dfg
.replace(info.br_inst)
.brz(info.cmp_arg, info.destination, &args);
}
BranchOptKind::NotEqualZero => {
let args = info.args.as_slice(&pos.func.dfg.value_lists)[1..].to_vec();
pos.func
.dfg
.replace(info.br_inst)
.brnz(info.cmp_arg, info.destination, &args);
}
info.args.as_mut_slice(&mut pos.func.dfg.value_lists)[0] = info.cmp_arg;
if let InstructionData::Branch { ref mut opcode, .. } = pos.func.dfg[info.br_inst] {
*opcode = info.new_opcode;
} else {
panic!();
}
/*
match info.kind {
BranchOptKind::EqualZero => {
let args = info.args.as_slice(&pos.func.dfg.value_lists)[1..].to_vec();
pos.func
.dfg
.replace(info.br_inst)
.brz(info.cmp_arg, info.destination, &args);
}
BranchOptKind::NotEqualZero => {
let args = info.args.as_slice(&pos.func.dfg.value_lists)[1..].to_vec();
pos.func
.dfg
.replace(info.br_inst)
.brnz(info.cmp_arg, info.destination, &args);
}
}
*/
}
struct BranchOrderInfo {
@@ -696,7 +696,6 @@ fn branch_order(pos: &mut FuncCursor, cfg: &mut ControlFlowGraph, ebb: Ebb, inst
opcode,
args: ref prev_args,
destination: cond_dest,
..
} => {
let cond_arg = {
let args = pos.func.dfg.inst_args(prev_inst);
@@ -762,7 +761,7 @@ fn branch_order(pos: &mut FuncCursor, cfg: &mut ControlFlowGraph, ebb: Ebb, inst
pos.func
.dfg
.replace(info.term_inst)
.fallthrough(info.cond_dest, &cond_args[1..]);
.jump(info.cond_dest, &cond_args[1..]);
pos.func
.dfg
.replace(info.cond_inst)
@@ -772,7 +771,7 @@ fn branch_order(pos: &mut FuncCursor, cfg: &mut ControlFlowGraph, ebb: Ebb, inst
pos.func
.dfg
.replace(info.term_inst)
.fallthrough(info.cond_dest, &cond_args[1..]);
.jump(info.cond_dest, &cond_args[1..]);
pos.func
.dfg
.replace(info.cond_inst)
@@ -782,7 +781,7 @@ fn branch_order(pos: &mut FuncCursor, cfg: &mut ControlFlowGraph, ebb: Ebb, inst
pos.func
.dfg
.replace(info.term_inst)
.fallthrough(info.cond_dest, &cond_args[2..]);
.jump(info.cond_dest, &cond_args[2..]);
pos.func.dfg.replace(info.cond_inst).br_icmp(
cond.inverse(),
x_arg,