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Instrument compiler to add code that does timing measurements #8

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merged 6 commits into from
Oct 18, 2024
Merged

Instrument compiler to add code that does timing measurements #8

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19f0453
measure cycles using new runtime
oflatt Oct 9, 2024
40a78c3
llvm inject timing
oflatt Oct 11, 2024
fe8356c
make timing hack more correct
oflatt Oct 14, 2024
5292b5b
disable inlining of get ticks
oflatt Oct 16, 2024
4f4ff15
comments
oflatt Oct 16, 2024
fe255de
add_timing in interface
oflatt Oct 16, 2024
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5 changes: 4 additions & 1 deletion bril-rs/brillvm/src/cli.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,9 @@ pub struct Cli {
/// Arguments for the main function
#[arg(action)]
pub args: Vec<String>,

#[arg(action)]
pub add_timing: bool,
}

pub fn run(args: &Cli) -> String {
Expand All @@ -49,7 +52,7 @@ pub fn run(args: &Cli) -> String {
let runtime_path = args.runtime.as_ref().map_or("rt.bc", |f| f);
// create a module from the runtime library for functions like printing/parsing
let runtime_module = Module::parse_bitcode_from_path(runtime_path, &context).unwrap();
let llvm_prog = create_module_from_program(&context, &prog, runtime_module);
let llvm_prog = create_module_from_program(&context, &prog, runtime_module, args.add_timing);

//println!("{}", prog);
//llvm_prog.print_to_file("tmp.ll").unwrap();
Expand Down
240 changes: 181 additions & 59 deletions bril-rs/brillvm/src/llvm.rs
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -6,9 +6,7 @@ use inkwell::{
context::Context,
module::Module,
types::{BasicMetadataTypeEnum, BasicType, BasicTypeEnum, FunctionType},
values::{
AsValueRef, BasicValue, BasicValueEnum, FloatValue, FunctionValue, IntValue, PointerValue,
},
values::{BasicValue, BasicValueEnum, FloatValue, FunctionValue, IntValue, PointerValue},
AddressSpace, FloatPredicate, IntPredicate,
};

Expand Down Expand Up @@ -675,20 +673,24 @@ fn build_instruction<'a, 'b>(
heap,
fresh,
|v| {
builder.build_select(
builder.build_int_compare::<IntValue>(
IntPredicate::SGT,
v[0].try_into().unwrap(),
v[1].try_into().unwrap(),
&cmp_name
).unwrap(),
v[0],
v[1],
&name
).unwrap()
builder
.build_select(
builder
.build_int_compare::<IntValue>(
IntPredicate::SGT,
v[0].try_into().unwrap(),
v[1].try_into().unwrap(),
&cmp_name,
)
.unwrap(),
v[0],
v[1],
&name,
)
.unwrap()
},
args,
dest
dest,
);
}

Expand All @@ -708,20 +710,24 @@ fn build_instruction<'a, 'b>(
heap,
fresh,
|v| {
builder.build_select(
builder.build_int_compare::<IntValue>(
IntPredicate::SLT,
v[0].try_into().unwrap(),
v[1].try_into().unwrap(),
&cmp_name
).unwrap(),
v[0],
v[1],
&name
).unwrap()
builder
.build_select(
builder
.build_int_compare::<IntValue>(
IntPredicate::SLT,
v[0].try_into().unwrap(),
v[1].try_into().unwrap(),
&cmp_name,
)
.unwrap(),
v[0],
v[1],
&name,
)
.unwrap()
},
args,
dest
dest,
);
}

Expand All @@ -744,7 +750,7 @@ fn build_instruction<'a, 'b>(
.build_left_shift::<IntValue>(
v[0].try_into().unwrap(),
v[1].try_into().unwrap(),
&ret_name
&ret_name,
)
.unwrap()
.into()
Expand Down Expand Up @@ -774,7 +780,7 @@ fn build_instruction<'a, 'b>(
v[0].try_into().unwrap(),
v[1].try_into().unwrap(),
false, // sign extend
&ret_name
&ret_name,
)
.unwrap()
.into()
Expand Down Expand Up @@ -1057,20 +1063,24 @@ fn build_instruction<'a, 'b>(
heap,
fresh,
|v| {
builder.build_select(
builder.build_float_compare::<FloatValue>(
FloatPredicate::OGT,
v[0].try_into().unwrap(),
v[1].try_into().unwrap(),
&cmp_name
).unwrap(),
v[0],
v[1],
&name
).unwrap()
builder
.build_select(
builder
.build_float_compare::<FloatValue>(
FloatPredicate::OGT,
v[0].try_into().unwrap(),
v[1].try_into().unwrap(),
&cmp_name,
)
.unwrap(),
v[0],
v[1],
&name,
)
.unwrap()
},
args,
dest
dest,
);
}
Instruction::Value {
Expand All @@ -1089,20 +1099,24 @@ fn build_instruction<'a, 'b>(
heap,
fresh,
|v| {
builder.build_select(
builder.build_float_compare::<FloatValue>(
FloatPredicate::OLT,
v[0].try_into().unwrap(),
v[1].try_into().unwrap(),
&cmp_name
).unwrap(),
v[0],
v[1],
&name
).unwrap()
builder
.build_select(
builder
.build_float_compare::<FloatValue>(
FloatPredicate::OLT,
v[0].try_into().unwrap(),
v[1].try_into().unwrap(),
&cmp_name,
)
.unwrap(),
v[0],
v[1],
&name,
)
.unwrap()
},
args,
dest
dest,
);
}

Expand Down Expand Up @@ -1252,12 +1266,12 @@ fn build_instruction<'a, 'b>(
);
}
Instruction::Value {
args,
dest,
args: __args,
dest: _dest,
funcs: _,
labels,
labels: _,
op: ValueOps::Phi,
op_type,
op_type: _op_type,
} => {
panic!("Phi nodes should be handled by build_phi");
}
Expand Down Expand Up @@ -1404,6 +1418,7 @@ pub fn create_module_from_program<'a>(
context: &'a Context,
Program { functions, .. }: &Program,
runtime_module: Module<'a>,
add_timing: bool,
) -> Module<'a> {
let builder = context.create_builder();

Expand Down Expand Up @@ -1474,19 +1489,122 @@ pub fn create_module_from_program<'a>(
.collect(); // Important to collect, can't be done lazily because we need all functions to be loaded in before a call instruction of a function is processed.

// Now actually build each function
let mut added_timing = false;
let mut ticks_start_ref = None;
funcs
.into_iter()
.for_each(|(llvm_func, instrs, mut block, heap)| {
let mut last_instr = None;

// If their are actually instructions, proceed
// If there are actually instructions, proceed
if !instrs.is_empty() {
builder.position_at_end(block);

// When we are in main, start measuring time
if add_timing && llvm_func.get_name().to_str().unwrap() == "_main" {
let ticks_start_name = fresh.fresh_var();
// get_ticks_start is used on x86 and get_ticks is used on arm
#[cfg(target_arch = "x86_64")]
let get_ticks_start = "_bril_get_ticks_start";
#[cfg(target_arch = "aarch64")]
let get_ticks_start = "_bril_get_ticks";
let ticks_start = builder
.build_call(
runtime_module.get_function(get_ticks_start).unwrap(),
&[],
&ticks_start_name,
)
.unwrap()
.try_as_basic_value()
.unwrap_left();
ticks_start_ref = Some(ticks_start);
// TODO I would like to inline get_ticks_start for less overhead
// however, this results in segfaults for some reason
/*let func = runtime_module.get_function(get_ticks_start).unwrap();
func.remove_enum_attribute(AttributeLoc::Function, 28);
func.add_attribute(AttributeLoc::Function, context.create_enum_attribute(3, 1));*/
// also assert the last instruction is a print
assert!(matches!(
instrs.last().unwrap().clone(),
Code::Instruction(Instruction::Effect {
op: EffectOps::Print,
..
})
));
}

// Maps labels to llvm blocks for jumps
let mut block_map = HashMap::new();
let mut index = 0;
while index < instrs.len() {
// for main, we expect the last instruction to be a print
if add_timing && llvm_func.get_name().to_str().unwrap() == "_main"
&& matches!(
instrs[index],
Code::Instruction(Instruction::Effect {
op: EffectOps::Print,
..
})
)
{
// either this is the last instruction or the next one is a return
assert!(
index == instrs.len() - 1
|| matches!(
instrs[index + 1],
Code::Instruction(Instruction::Effect {
op: EffectOps::Return,
..
})
)
);

// measure cycles and print
let ticks_end_name = fresh.fresh_var();
#[cfg(target_arch = "x86_64")]
let get_ticks_end = "_bril_get_ticks_end";
#[cfg(target_arch = "aarch64")]
let get_ticks_end = "_bril_get_ticks";
// TODO I would like to inline get_ticks_start for less overhead
// however, this results in segfaults for some reason
/*let func = runtime_module.get_function(get_ticks_end).unwrap();
// always inline get_ticks_end
func.remove_enum_attribute(AttributeLoc::Function, 28);
func.add_attribute(
AttributeLoc::Function,
context.create_enum_attribute(3, 1),
);*/

let ticks_end = builder
.build_call(
runtime_module.get_function(get_ticks_end).unwrap(),
&[],
&ticks_end_name,
)
.unwrap()
.try_as_basic_value()
.unwrap_left();

// print out the different between the ticks
let ticks_diff = fresh.fresh_var();
let diff_val = builder
.build_int_sub::<IntValue>(
ticks_end.try_into().unwrap(),
ticks_start_ref.unwrap().try_into().unwrap(),
&ticks_diff,
)
.unwrap();

// use bril_print_unsiged_int to print out the difference
let print_ticks = runtime_module
.get_function("_bril_eprintln_unsigned_int")
.unwrap();
builder
.build_call(print_ticks, &[diff_val.into()], "print_ticks")
.unwrap();
added_timing = true;
}

if is_terminating_instr(&last_instr)
&& matches!(instrs[index], Code::Instruction { .. })
{
Expand Down Expand Up @@ -1581,6 +1699,10 @@ pub fn create_module_from_program<'a>(
}
});

if add_timing {
assert!(added_timing);
}

// Add new main function to act as a entry point to the function.
// Sets up arguments for a _main call
// and always returns zero
Expand Down Expand Up @@ -1682,7 +1804,7 @@ pub fn create_module_from_program<'a>(
runtime_module
}

pub(crate) fn is_phi(i: &Code) -> bool {
pub(crate) const fn is_phi(i: &Code) -> bool {
matches!(
i,
Code::Instruction(Instruction::Value {
Expand Down
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