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Instruction count CI has transformed the way we work on FEX… I love the system and want to make it better. there’s one part of instruction count CI that isn’t so lovable: the problematic “optimal” flag on instructions. There are several issues with this flag, both philosophical and practical. – it is tedious to update the optimal flag when making an implementation optimal. The effect of that is discouraging people from making instructions, optimal, or encouraging people to fail to update the flag, and dilute the value of it. Either way, since we care far more about optimal implementations, then we do about updating the flag, clearly we should prioritize the implementation and not the flag. This issue was not obvious at the outset, when instruction count, CI was introduced, and still quite small. The problem magnified when we started duplicating instructions in bulk for different combinations of CPU features (flagm, AFP, etc.) that intern multiplies the manual work required to update the flags by the corresponding constant factor. if it comes down to a choice between removing this extra coverage and removing the flag, I think we all agree that removing the flag is the lesser evil. – The definition of “optimal” is fundamentally problematic. I have often improved the instruction count of an instruction that was already “optimal”. This is all kinds of silly, and calls into question whether there’s any value whatsoever in the existing classifications of the flag. Furthermore, it is often unknowable, whether an implementation really is optimal. Is it possible to implement BZHI (with flag calculations) in fewer than eight instructions? We don’t know, and it’s silly to pretend that we do. – as a consequence of the problematic definitions , there are so many errors in both directions that I don’t think there’s much value in preserving the existing classification at the expense of +progress. Being able to say “32% of instructions are translated optimally” is neat, but it really doesn’t tell us anything whatsoever when you dig a little deeper. So, as the flag is misleading at best and perhaps harmful at worst, let’s remove it and make the instruction count CI, more useful overall. let’s let the expected count and the assembly speak for themselves, and cut away the chaff. if we want a meaningless number to report to management, we can instead calculate the average blowup factor ;-) Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
245 lines
7.5 KiB
Python
Executable File
245 lines
7.5 KiB
Python
Executable File
#!/usr/bin/python3
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import base64
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from dataclasses import dataclass, field
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from enum import Flag
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import json
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import struct
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import sys
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import subprocess
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import os
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import logging
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logger = logging.getLogger()
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logger.setLevel(logging.ERROR)
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@dataclass
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class TestData:
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name: str
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expectedinstructioncount: int
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code: bytes
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instructions: list
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def __init__(self, Name, ExpectedInstructionCount, Code, Instructions):
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self.name = Name
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self.expectedinstructioncount = ExpectedInstructionCount
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self.code = Code
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self.instructions = Instructions
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@property
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def Name(self):
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return self.name
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@property
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def ExpectedInstructionCount(self):
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return self.expectedinstructioncount
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@property
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def Code(self):
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return self.code
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@property
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def Instructions(self):
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return self.instructions
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TestDataMap = {}
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class HostFeatures(Flag) :
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FEATURE_ANY = 0
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FEATURE_SVE128 = (1 << 0)
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FEATURE_SVE256 = (1 << 1)
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FEATURE_CLZERO = (1 << 2)
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FEATURE_RNG = (1 << 3)
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FEATURE_FCMA = (1 << 4)
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FEATURE_CSSC = (1 << 5)
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FEATURE_AFP = (1 << 6)
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FEATURE_RPRES = (1 << 7)
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FEATURE_FLAGM = (1 << 8)
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FEATURE_FLAGM2 = (1 << 9)
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HostFeaturesLookup = {
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"SVE128" : HostFeatures.FEATURE_SVE128,
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"SVE256" : HostFeatures.FEATURE_SVE256,
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"CLZERO" : HostFeatures.FEATURE_CLZERO,
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"RNG" : HostFeatures.FEATURE_RNG,
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"FCMA" : HostFeatures.FEATURE_FCMA,
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"CSSC" : HostFeatures.FEATURE_CSSC,
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"AFP" : HostFeatures.FEATURE_AFP,
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"RPRES" : HostFeatures.FEATURE_RPRES,
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"FLAGM" : HostFeatures.FEATURE_FLAGM,
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"FLAGM2" : HostFeatures.FEATURE_FLAGM2,
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}
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def GetHostFeatures(data):
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HostFeaturesData = HostFeatures.FEATURE_ANY
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if not (type(data) is list):
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sys.exit("Features value must be list of features")
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for data_key in data:
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data_key = data_key.upper()
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if not (data_key in HostFeaturesLookup):
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sys.exit("Invalid host feature")
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HostFeaturesData |= HostFeaturesLookup[data_key]
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return HostFeaturesData
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def parse_json_data(json_filepath, json_filename, json_data, output_binary_path):
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Bitness = 64
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EnabledHostFeatures = HostFeatures.FEATURE_ANY
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DisabledHostFeatures = HostFeatures.FEATURE_ANY
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OptionEnvironmentVariables = {}
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if "Features" in json_data:
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items = json_data["Features"]
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if ("Bitness" in items):
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Bitness = int(items["Bitness"])
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if ("EnabledHostFeatures" in items):
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EnabledHostFeatures = GetHostFeatures(items["EnabledHostFeatures"])
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if ("DisabledHostFeatures" in items):
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DisabledHostFeatures = GetHostFeatures(items["DisabledHostFeatures"])
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if ("Env" in items):
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data = items["Env"]
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if not (type(data) is dict):
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sys.exit("Environment variables value must be list of key:value pairs")
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for data_key, data_val in data.items():
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OptionEnvironmentVariables[data_key] = data_val
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for key, items in json_data["Instructions"].items():
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ExpectedInstructionCount = 0
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Instructions = []
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if ("ExpectedInstructionCount" in items):
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ExpectedInstructionCount = int(items["ExpectedInstructionCount"])
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if ("Skip" in items):
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if items["Skip"].upper() == "YES":
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continue
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if "x86Insts" in items:
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Instructions = items["x86Insts"]
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else:
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# No list of instructions, only one which is the key.
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Instructions.append(key)
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TestName = base64.b64encode("{}.{}.{}".format(str(hash(json_filepath)), json_filename, key).encode("ascii")).decode("ascii")
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tmp_asm = "/tmp/{}.asm".format(TestName)
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tmp_asm_out = "/tmp/{}.asm.o".format(TestName)
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logging.info("'{}' -> '{}' -> '{}'".format(key, tmp_asm, tmp_asm_out))
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if TestName in TestDataMap:
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sys.exit("Duplicate test name {} in tests".format(TestName))
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with open(tmp_asm, "w") as tmp_asm_file:
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tmp_asm_file.write("BITS {};\n".format(Bitness))
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for Inst in Instructions:
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tmp_asm_file.write("{}\n".format(Inst))
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Process = subprocess.Popen(["nasm", tmp_asm, "-o", tmp_asm_out])
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Process.wait()
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ResultCode = Process.returncode
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if ResultCode != 0:
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os.remove(tmp_asm)
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logging.error("Nasm failed to execute")
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logging.error("Couldn't compile: '{}'".format(key))
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return ResultCode
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if not os.path.exists(tmp_asm_out):
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logging.error("Nasm didn't emit code?")
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os.remove(tmp_asm)
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return 1
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logging.info("Generated asm file")
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with open(tmp_asm_out, "rb") as tmp_asm_out_file:
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binary_hex = tmp_asm_out_file.read()
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TestDataMap[TestName] = TestData(key, ExpectedInstructionCount, binary_hex, Instructions)
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os.remove(tmp_asm)
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os.remove(tmp_asm_out)
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# Output the test data as follows
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# struct TestInfo;
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# struct DataHeader {
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# uint64_t Bitness;
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# uint64_t NumTests;
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# uint64_t EnabledHostFeatures;
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# uint64_t DisabledHostFeatures;
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# uint64_t EnvironmentVariableCount;
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# char env[];
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# TestInfo Tests[NumTests];
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# };
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# struct TestInfo {
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# char InstName[128];
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# int64_t ExpectedInstructionCount;
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# uint64_t CodeSize;
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# uint64_t x86InstCount;
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# uint32_t Cookie;
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# uint8_t Code[CodeSize];
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# };
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MemData = bytes()
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# Add the header
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MemData += struct.pack('Q', Bitness)
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MemData += struct.pack('Q', len(TestDataMap))
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MemData += struct.pack('Q', EnabledHostFeatures.value)
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MemData += struct.pack('Q', DisabledHostFeatures.value)
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MemData += struct.pack('Q', len(OptionEnvironmentVariables.items()))
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# Write environment variables
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for key, val in OptionEnvironmentVariables.items():
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MemData += key.encode()
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MemData += struct.pack('B', 0)
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MemData += val.encode()
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MemData += struct.pack('B', 0)
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# Add each test
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for key, item in TestDataMap.items():
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MemData += struct.pack('128s', item.Name.encode("ascii"))
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MemData += struct.pack('q', item.ExpectedInstructionCount)
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MemData += struct.pack('Q', len(item.Code))
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MemData += struct.pack('Q', len(item.Instructions))
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MemData += struct.pack('I', 0x41424344)
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MemData += item.Code
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logging.info("Code goign to {}".format(output_binary_path))
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with open(output_binary_path, "wb") as output_binary_file:
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output_binary_file.write(MemData)
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return 0
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def main():
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if sys.version_info[0] < 3:
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logging.critical ("Python 3 or a more recent version is required.")
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if (len(sys.argv) < 3):
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logging.critical ("usage: %s <PerformanceTests.json> <output_folder>" % (sys.argv[0]))
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json_path = sys.argv[1]
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output_binary_path = sys.argv[2]
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try:
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with open(json_path) as json_file:
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json_text = json_file.read()
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except IOError:
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logging.error("IOError!")
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return 1
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try:
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json_data = json.loads(json_text)
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if not isinstance(json_data, dict):
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raise TypeError('JSON data must be a dict')
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return parse_json_data(json_path, os.path.basename(json_path), json_data, output_binary_path)
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except ValueError as ve:
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logging.error(f'JSON error: {ve}')
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return 1
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return 0
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if __name__ == "__main__":
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# execute only if run as a script
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sys.exit(main())
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