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--exception:goto switch for deterministic exception handling (#12977)

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This implements "deterministic" exception handling for Nim based on goto instead of setjmp. This means raising an exception is much cheaper than in C++'s table based implementations. Supports hard realtime systems. Default for --gc:arc and the C target because it's generally a good idea and arc is all about deterministic behavior.

Note: This implies that fatal runtime traps are not catchable anymore! This needs to be documented.
This commit is contained in:
Andreas Rumpf 2020-01-01 10:01:49 +01:00 • committed by GitHub
commit c3344862b0
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23 changed files with 640 additions and 183 deletions
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27
compiler/commands.nim
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@ -219,6 +219,7 @@ const
errNoneBoehmRefcExpectedButXFound = "'none', 'boehm' or 'refc' expected, but '$1' found"
errNoneSpeedOrSizeExpectedButXFound = "'none', 'speed' or 'size' expected, but '$1' found"
errGuiConsoleOrLibExpectedButXFound = "'gui', 'console' or 'lib' expected, but '$1' found"
errInvalidExceptionSystem = "'goto', 'setjump', 'cpp' or 'quirky' expected, but '$1' found"
proc testCompileOptionArg*(conf: ConfigRef; switch, arg: string, info: TLineInfo): bool =
case switch.normalize
@ -254,6 +255,13 @@ proc testCompileOptionArg*(conf: ConfigRef; switch, arg: string, info: TLineInfo
else: localError(conf, info, errGuiConsoleOrLibExpectedButXFound % arg)
of "dynliboverride":
result = isDynlibOverride(conf, arg)
of "exceptions":
case arg.normalize
of "cpp": result = conf.exc == excCpp
of "setjmp": result = conf.exc == excSetjmp
of "quirky": result = conf.exc == excQuirky
of "goto": result = conf.exc == excGoto
else: localError(conf, info, errInvalidExceptionSystem % arg)
else: invalidCmdLineOption(conf, passCmd1, switch, info)
proc testCompileOption*(conf: ConfigRef; switch: string, info: TLineInfo): bool =
@ -411,8 +419,12 @@ proc processSwitch*(switch, arg: string, pass: TCmdLinePass, info: TLineInfo;
expectArg(conf, switch, arg, pass, info)
if {':', '='} in arg:
splitSwitch(conf, arg, key, val, pass, info)
if cmpIgnoreStyle(key, "nimQuirky") == 0:
conf.exc = excQuirky
defineSymbol(conf.symbols, key, val)
else:
if cmpIgnoreStyle(arg, "nimQuirky") == 0:
conf.exc = excQuirky
defineSymbol(conf.symbols, arg)
of "undef", "u":
expectArg(conf, switch, arg, pass, info)
@ -457,6 +469,9 @@ proc processSwitch*(switch, arg: string, pass: TCmdLinePass, info: TLineInfo;
defineSymbol(conf.symbols, "gcmarkandsweep")
of "destructors", "arc":
conf.selectedGC = gcArc
when true:
if conf.cmd != cmdCompileToCpp:
conf.exc = excGoto
defineSymbol(conf.symbols, "gcdestructors")
defineSymbol(conf.symbols, "gcarc")
incl conf.globalOptions, optSeqDestructors
@ -466,6 +481,9 @@ proc processSwitch*(switch, arg: string, pass: TCmdLinePass, info: TLineInfo;
defineSymbol(conf.symbols, "nimV2")
of "orc":
conf.selectedGC = gcOrc
when true:
if conf.cmd != cmdCompileToCpp:
conf.exc = excGoto
defineSymbol(conf.symbols, "gcdestructors")
defineSymbol(conf.symbols, "gcorc")
incl conf.globalOptions, optSeqDestructors
@ -775,8 +793,15 @@ proc processSwitch*(switch, arg: string, pass: TCmdLinePass, info: TLineInfo;
localError(conf, info, "unknown obsolete feature")
of "nocppexceptions":
expectNoArg(conf, switch, arg, pass, info)
incl(conf.globalOptions, optNoCppExceptions)
conf.exc = low(ExceptionSystem)
defineSymbol(conf.symbols, "noCppExceptions")
of "exceptions":
case arg.normalize
of "cpp": conf.exc = excCpp
of "setjmp": conf.exc = excSetjmp
of "quirky": conf.exc = excQuirky
of "goto": conf.exc = excGoto
else: localError(conf, info, errInvalidExceptionSystem % arg)
of "cppdefine":
expectArg(conf, switch, arg, pass, info)
if conf != nil: