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GH-113464: Speed up JIT builds#122839

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Merged
brandtbucher merged 2 commits into from
Aug 14, 2024
Merged

GH-113464: Speed up JIT builds #122839

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60b7e71
Only include one case when compiling a stencil
brandtbucher Jul 27, 2024
a32111d
Add a comment about faster compilation
brandtbucher Aug 14, 2024
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18 changes: 15 additions & 3 deletions Tools/jit/_targets.py
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Original file line numberDiff line numberDiff line change
Expand Up@@ -182,15 +182,27 @@ async def _compile(

async def _build_stencils(self) -> dict[str, _stencils.StencilGroup]:
generated_cases = PYTHON_EXECUTOR_CASES_C_H.read_text()
opnames = sorted(re.findall(r"\n{8}case (\w+): \{\n", generated_cases))
cases_and_opnames = sorted(
re.findall(
r"\n{8}(case (\w+): \{\n.*?\n{8}\})", generated_cases, flags=re.DOTALL
)
)
tasks = []
with tempfile.TemporaryDirectory() as tempdir:
work = pathlib.Path(tempdir).resolve()
async with asyncio.TaskGroup() as group:
coro = self._compile("trampoline", TOOLS_JIT / "trampoline.c", work)
tasks.append(group.create_task(coro, name="trampoline"))
for opname in opnames:
coro = self._compile(opname, TOOLS_JIT_TEMPLATE_C, work)
template = TOOLS_JIT_TEMPLATE_C.read_text()
for case, opname in cases_and_opnames:
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@savannahostrowskisavannahostrowskiAug 9, 2024

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Would it be good to add a comment here about why each of these is compiled independently (e.g., because of the performance benefit)? I'm not sure that would be abundantly clear if I just stumbled upon this code.

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@brandtbucherbrandtbucherAug 14, 2024

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Good idea, I'll add a comment.

# Write out a copy of the template with *only* this case
# inserted. This is about twice as fast as #include'ing all
# of executor_cases.c.h each time we compile (since the C
# compiler wastes a bunch of time parsing the dead code for
# all of the other cases):
c = work / f"{opname}.c"
c.write_text(template.replace("CASE", case))
coro = self._compile(opname, c, work)
tasks.append(group.create_task(coro, name=opname))
return{task.get_name(): task.result() for task in tasks}

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6 changes: 4 additions & 2 deletions Tools/jit/template.c
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Expand Up@@ -84,6 +84,8 @@ do{\
#undef WITHIN_STACK_BOUNDS
#define WITHIN_STACK_BOUNDS() 1

#define TIER_TWO 2

_Py_CODEUNIT *
_JIT_ENTRY(_PyInterpreterFrame *frame, _PyStackRef *stack_pointer, PyThreadState *tstate)
{
Expand All@@ -107,9 +109,9 @@ _JIT_ENTRY(_PyInterpreterFrame *frame, _PyStackRef *stack_pointer, PyThreadState
OPT_STAT_INC(uops_executed);
UOP_STAT_INC(uopcode, execution_count);

// The actual instruction definitions (only one will be used):
switch (uopcode){
#include "executor_cases.c.h"
// The actual instruction definition gets inserted here:
CASE
default:
Py_UNREACHABLE();
}
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