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Optimize load/store with an iadd_imm operand.

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Fold the immediate into the load/store offset when possible.
This commit is contained in:
Dan Gohman
2018-09-28 22:56:39 -07:00
parent 709eed21c1
commit 54ab1ea533
3 changed files with 159 additions and 89 deletions
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10
lib/codegen/src/ir/immediates.rs
View File

@@ -224,6 +224,16 @@ impl Offset32 {
None
}
}
/// Add in the signed number `x` if possible.
pub fn try_add_i64(self, x: i64) -> Option<Self> {
let casted = x as i32;
if casted as i64 == x {
self.0.checked_add(casted).map(Self::new)
} else {
None
}
}
}
impl Into<i32> for Offset32 {

220
lib/codegen/src/postopt.rs
View File

@@ -179,6 +179,7 @@ struct MemOpInfo {
}
fn optimize_complex_addresses(pos: &mut EncCursor, inst: Inst, isa: &TargetIsa) {
// Look for simple loads and stores we can optimize.
let info = match pos.func.dfg[inst] {
InstructionData::Load {
opcode,
@@ -209,103 +210,144 @@ fn optimize_complex_addresses(pos: &mut EncCursor, inst: Inst, isa: &TargetIsa)
_ => return,
};
let add_args = if let ValueDef::Result(result_inst, _) = pos.func.dfg.value_def(info.arg) {
// Examine the instruction that defines the address operand.
if let ValueDef::Result(result_inst, _) = pos.func.dfg.value_def(info.arg) {
match pos.func.dfg[result_inst] {
InstructionData::Binary {
opcode: Opcode::Iadd,
args,
} => args,
_ => return,
} => match info.opcode {
// Operand is an iadd. Fold it into a memory address with a complex address mode.
Opcode::Load => {
pos.func.dfg.replace(inst).load_complex(
info.itype,
info.flags,
&args,
info.offset,
);
}
Opcode::Uload8 => {
pos.func.dfg.replace(inst).uload8_complex(
info.itype,
info.flags,
&args,
info.offset,
);
}
Opcode::Sload8 => {
pos.func.dfg.replace(inst).sload8_complex(
info.itype,
info.flags,
&args,
info.offset,
);
}
Opcode::Uload16 => {
pos.func.dfg.replace(inst).uload16_complex(
info.itype,
info.flags,
&args,
info.offset,
);
}
Opcode::Sload16 => {
pos.func.dfg.replace(inst).sload16_complex(
info.itype,
info.flags,
&args,
info.offset,
);
}
Opcode::Uload32 => {
pos.func
.dfg
.replace(inst)
.uload32_complex(info.flags, &args, info.offset);
}
Opcode::Sload32 => {
pos.func
.dfg
.replace(inst)
.sload32_complex(info.flags, &args, info.offset);
}
Opcode::Store => {
pos.func.dfg.replace(inst).store_complex(
info.flags,
info.st_arg.unwrap(),
&args,
info.offset,
);
}
Opcode::Istore8 => {
pos.func.dfg.replace(inst).istore8_complex(
info.flags,
info.st_arg.unwrap(),
&args,
info.offset,
);
}
Opcode::Istore16 => {
pos.func.dfg.replace(inst).istore16_complex(
info.flags,
info.st_arg.unwrap(),
&args,
info.offset,
);
}
Opcode::Istore32 => {
pos.func.dfg.replace(inst).istore32_complex(
info.flags,
info.st_arg.unwrap(),
&args,
info.offset,
);
}
_ => panic!("Unsupported load or store opcode"),
},
InstructionData::BinaryImm {
opcode: Opcode::IaddImm,
arg,
imm,
} => match pos.func.dfg[inst] {
// Operand is an iadd_imm. Fold the immediate into the offset if possible.
InstructionData::Load {
arg: ref mut load_arg,
ref mut offset,
..
} => {
if let Some(imm) = offset.try_add_i64(imm.into()) {
*load_arg = arg;
*offset = imm;
} else {
// Overflow.
return;
}
}
InstructionData::Store {
args: ref mut store_args,
ref mut offset,
..
} => {
if let Some(imm) = offset.try_add_i64(imm.into()) {
store_args[0] = arg;
*offset = imm;
} else {
// Overflow.
return;
}
}
_ => panic!(),
},
_ => {
// Address value is defined by some other kind of instruction.
return;
}
}
} else {
// Address value is not the result of an instruction.
return;
};
match info.opcode {
Opcode::Load => {
pos.func
.dfg
.replace(inst)
.load_complex(info.itype, info.flags, &add_args, info.offset);
}
Opcode::Uload8 => {
pos.func.dfg.replace(inst).uload8_complex(
info.itype,
info.flags,
&add_args,
info.offset,
);
}
Opcode::Sload8 => {
pos.func.dfg.replace(inst).sload8_complex(
info.itype,
info.flags,
&add_args,
info.offset,
);
}
Opcode::Uload16 => {
pos.func.dfg.replace(inst).uload16_complex(
info.itype,
info.flags,
&add_args,
info.offset,
);
}
Opcode::Sload16 => {
pos.func.dfg.replace(inst).sload16_complex(
info.itype,
info.flags,
&add_args,
info.offset,
);
}
Opcode::Uload32 => {
pos.func
.dfg
.replace(inst)
.uload32_complex(info.flags, &add_args, info.offset);
}
Opcode::Sload32 => {
pos.func
.dfg
.replace(inst)
.sload32_complex(info.flags, &add_args, info.offset);
}
Opcode::Store => {
pos.func.dfg.replace(inst).store_complex(
info.flags,
info.st_arg.unwrap(),
&add_args,
info.offset,
);
}
Opcode::Istore8 => {
pos.func.dfg.replace(inst).istore8_complex(
info.flags,
info.st_arg.unwrap(),
&add_args,
info.offset,
);
}
Opcode::Istore16 => {
pos.func.dfg.replace(inst).istore16_complex(
info.flags,
info.st_arg.unwrap(),
&add_args,
info.offset,
);
}
Opcode::Istore32 => {
pos.func.dfg.replace(inst).istore32_complex(
info.flags,
info.st_arg.unwrap(),
&add_args,
info.offset,
);
}
_ => return,
}
let ok = pos.func.update_encoding(inst, isa).is_ok();
debug_assert!(ok);
}