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WIP #23669

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WIP #23669

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05b2991
WIP
Araq Jun 1, 2024
7906c05
use CPU flag instead of thread local storage for the error indicator;…
Araq Jun 2, 2024
4a6eea6
progress
Araq Jun 4, 2024
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38 changes: 28 additions & 10 deletions compiler/ccgstmts.nim
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Original file line number Diff line number Diff line change
Expand Up @@ -731,9 731,9 @@ proc raiseExit(p: BProc) =
if p.nestedTryStmts.len == 0:
p.flags.incl beforeRetNeeded
# easy case, simply goto 'ret':
lineCg(p, cpsStmts, "if (NIM_UNLIKELY(*nimErr_)) goto BeforeRet_;$n", [])
lineCg(p, cpsStmts, "NIM_ERR_JUMP(BeforeRet_);$n", [])
else:
lineCg(p, cpsStmts, "if (NIM_UNLIKELY(*nimErr_)) goto LA$1_;$n",
lineCg(p, cpsStmts, "NIM_ERR_JUMP(LA$1_);$n",
[p.nestedTryStmts[^1].label])

proc finallyActions(p: BProc) =
Expand Down Expand Up @@ -1282,8 1282,14 @@ proc genTryGoto(p: BProc; t: PNode; d: var TLoc) =

expr(p, t[0], d)

var endLabel = -1
if 1 < t.len and t[1].kind == nkExceptBranch:
startBlock(p, "if (NIM_UNLIKELY(*nimErr_)) {$n")
inc p.labels
endLabel = p.labels
#startBlock(p, "if (NIM_UNLIKELY(*nimErr_)) {$n")
linefmt(p, cpsStmts, "NIM_ERR_JUMP(LA$1_);$n", [lab])
linefmt(p, cpsStmts, "goto LA$1_;$n", [endLabel])
startBlock(p, "if (NIM_TRUE) {$n") # so that the `else` works out
else:
startBlock(p)
linefmt(p, cpsStmts, "LA$1_:;$n", [lab])
Expand All @@ -1303,7 1309,7 @@ proc genTryGoto(p: BProc; t: PNode; d: var TLoc) =
if i > 1: lineF(p, cpsStmts, "else", [])
startBlock(p)
# we handled the exception, remember this:
linefmt(p, cpsStmts, "*nimErr_ = NIM_FALSE;$n", [])
linefmt(p, cpsStmts, "NIM_ERR_CLEAR();$n", [])
expr(p, t[i][0], d)
else:
var orExpr = newRopeAppender()
Expand All @@ -1322,7 1328,7 @@ proc genTryGoto(p: BProc; t: PNode; d: var TLoc) =
if i > 1: line(p, cpsStmts, "else ")
startBlock(p, "if ($1) {$n", [orExpr])
# we handled the exception, remember this:
linefmt(p, cpsStmts, "*nimErr_ = NIM_FALSE;$n", [])
linefmt(p, cpsStmts, "NIM_ERR_CLEAR();$n", [])
expr(p, t[i][^1], d)

linefmt(p, cpsStmts, "#popCurrentException();$n", [])
Expand All @@ -1332,6 1338,8 @@ proc genTryGoto(p: BProc; t: PNode; d: var TLoc) =
inc(i)
discard pop(p.nestedTryStmts)
endBlock(p)
if endLabel >= 0:
linefmt(p, cpsStmts, "LA$1_:;$n", [endLabel])

if i < t.len and t[i].kind == nkFinally:
startBlock(p)
Expand All @@ -1342,15 1350,25 @@ proc genTryGoto(p: BProc; t: PNode; d: var TLoc) =
else:
# pretend we did handle the error for the safe execution of the 'finally' section:
p.procSec(cpsLocals).add(ropecg(p.module, "NIM_BOOL oldNimErrFin$1_;$n", [lab]))
linefmt(p, cpsStmts, "oldNimErrFin$1_ = *nimErr_; *nimErr_ = NIM_FALSE;$n", [lab])

inc p.labels, 2
let fLabel = p.labels-1
let tLabel = p.labels

linefmt(p, cpsStmts, "NIM_ERR_JUMP(LA$1_);$n", [tLabel])
linefmt(p, cpsStmts, "oldNimErrFin$1_ = NIM_FALSE; goto LA$2_;$n", [lab, fLabel])
linefmt(p, cpsStmts, "LA$2_: oldNimErrFin$1_ = NIM_TRUE; LA$3_: ;$n", [lab, tLabel, fLabel])
linefmt(p, cpsStmts, "NIM_ERR_CLEAR();$n", [])

#linefmt(p, cpsStmts, "oldNimErrFin$1_ = *nimErr_; NIM_ERR_CLEAR();$n", [lab])
genStmts(p, t[i][0])
# this is correct for all these cases:
# 1. finally is run during ordinary control flow
# 2. finally is run after 'except' block handling: these however set the
# error back to nil.
# 3. finally is run for exception handling code without any 'except'
# handler present or only handlers that did not match.
linefmt(p, cpsStmts, "*nimErr_ = oldNimErrFin$1_;$n", [lab])
linefmt(p, cpsStmts, "if (oldNimErrFin$1_) { NIM_ERR_SET(); } else { NIM_ERR_CLEAR(); }$n", [lab])
endBlock(p)
raiseExit(p)
if hasExcept: inc p.withinTryWithExcept
Expand Down Expand Up @@ -1547,14 1565,14 @@ proc genAsmStmt(p: BProc, t: PNode) =
if whichPragma(i) == wAsmSyntax:
asmSyntax = i[1].strVal

if asmSyntax != "" and
if asmSyntax != "" and
not (
asmSyntax == "gcc" and hasGnuAsm in CC[p.config.cCompiler].props or
asmSyntax == "vcc" and hasGnuAsm notin CC[p.config.cCompiler].props):
localError(
p.config, t.info,
p.config, t.info,
"Your compiler does not support the specified inline assembler")

genAsmOrEmitStmt(p, t, isAsmStmt=true, s)
# see bug #2362, "top level asm statements" seem to be a mis-feature
# but even if we don't do this, the example in #2362 cannot possibly
Expand Down
10 changes: 8 additions & 2 deletions compiler/cgen.nim
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Original file line number Diff line number Diff line change
Expand Up @@ -1172,8 1172,9 @@ proc genProcBody(p: BProc; procBody: PNode) =
genStmts(p, procBody) # modifies p.locals, p.init, etc.
if {nimErrorFlagAccessed, nimErrorFlagDeclared, nimErrorFlagDisabled} * p.flags == {nimErrorFlagAccessed}:
p.flags.incl nimErrorFlagDeclared
p.blocks[0].sections[cpsLocals].add(ropecg(p.module, "NIM_BOOL* nimErr_;$n", []))
p.blocks[0].sections[cpsInit].add(ropecg(p.module, "nimErr_ = #nimErrorFlag();$n", []))
p.blocks[0].sections[cpsLocals].add(ropecg(p.module, "NIM_ERR_FLAG();$n", []))
if not isDefined(p.config, "nimUseCpuFlag"):
p.blocks[0].sections[cpsInit].add(ropecg(p.module, "nimErr_ = #nimErrorFlag();$n", []))

proc isNoReturn(m: BModule; s: PSym): bool {.inline.} =
sfNoReturn in s.flags and m.config.exc != excGoto
Expand Down Expand Up @@ -1280,6 1281,8 @@ proc genProcAux*(m: BModule, prc: PSym) =
if beforeRetNeeded in p.flags: generatedProc.add("{")
generatedProc.add(p.s(cpsInit))
generatedProc.add(p.s(cpsStmts))
if m.config.isDefined("nimUseCpuFlag"):
generatedProc.add("\tNIM_ERR_CLEAR();\n")
if beforeRetNeeded in p.flags: generatedProc.add("\t}BeforeRet_: ;\n")
if optStackTrace in prc.options: generatedProc.add(deinitFrame(p))
generatedProc.add(returnStmt)
Expand Down Expand Up @@ -1459,6 1462,9 @@ proc addNimDefines(result: var Rope; conf: ConfigRef) {.inline.} =
if conf.isDefined("nimEmulateOverflowChecks"):
result.add("#define NIM_EmulateOverflowChecks\L")

if conf.isDefined("nimUseCpuFlag"):
result.add("#define NIM_UseCpuFlag\L")

proc headerTop(): Rope =
result = "/* Generated by Nim Compiler v$1 */$N" % [rope(VersionAsString)]

Expand Down
29 changes: 29 additions & 0 deletions lib/nimbase.h
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Expand Up @@ -863,4 863,33 @@ NIM_STATIC_ASSERT(sizeof(NI) == sizeof(void*) && NIM_INTBITS == sizeof(NI)*8, "P
#define NIM_NOALIAS __restrict
/* __restrict is said to work for all the C( ) compilers out there that we support */

#if defined(NIM_UseCpuFlag)
# if defined(__x86_64__) || defined(__i386__)
# define NIM_ERR_FLAG() /* nothing to declare: uses HW flag */
# define NIM_ERR_JUMP(lab) __asm__ goto("jc %l0" \
: \
: \
: \
: lab)
# define NIM_ERR_SET() __asm__ volatile("stc" \
: \
: \
: "cc" \
)

# define NIM_ERR_CLEAR() __asm__ volatile("clc" \
: \
: \
: "cc" \
)
# else
# error "CPU flags not implemented for your platform"
# endif
#else
# define NIM_ERR_FLAG() NIM_BOOL* nimErr_
# define NIM_ERR_JUMP(lab) if (NIM_UNLIKELY(*nimErr_)) goto lab
# define NIM_ERR_CLEAR() *nimErr_ = NIM_FALSE
# define NIM_ERR_SET() *nimErr_ = NIM_TRUE
#endif /* __GNUC__ */

#endif /* NIMBASE_H */
13 changes: 11 additions & 2 deletions lib/system/excpt.nim
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Expand Up @@ -448,6 448,9 @@ when gotoBasedExceptions:
## This proc must be called before `currException` is destroyed.
## It also must be called at the end of every thread to ensure no
## error is swallowed.
when defined(nimUseCpuFlag):
var nimInErrorMode = false
{.emit: "NIM_ERR_JUMP(Lerr_); goto Lend_; Lerr_: `nimInErrorMode` = NIM_TRUE; Lend_: ;".}
if nimInErrorMode and currException != nil:
reportUnhandledError(currException)
currException = nil
Expand All @@ -472,7 475,10 @@ proc raiseExceptionAux(e: sink(ref Exception)) {.nodestroy.} =
elif quirkyExceptions or gotoBasedExceptions:
pushCurrentException(e)
when gotoBasedExceptions:
inc nimInErrorMode
when defined(nimUseCpuFlag):
{.emit: "NIM_ERR_SET();".}
else:
nimInErrorMode = true
else:
if excHandler != nil:
pushCurrentException(e)
Expand Down Expand Up @@ -512,7 518,10 @@ proc reraiseException() {.compilerRtl.} =
sysFatal(ReraiseDefect, "no exception to reraise")
else:
when gotoBasedExceptions:
inc nimInErrorMode
when defined(nimUseCpuFlag):
{.emit: "NIM_ERR_SET();".}
else:
nimInErrorMode = true
else:
raiseExceptionAux(currException)

Expand Down
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