Crash in codegen during C type deduction with inline ASM

[mratsim]

The following snippet makes the compiler crash.

It is due to the use of low instead of lo in the asm, Nim tries to check the return type and crashes in ccgtypes.

# GCC/Clang only
proc getticks(): int64 {.inline.} =
  var lo, hi: int64

  # Notice "low" instead of lo in the inline assembly
  {.emit: """asm volatile(
    "lfence\n"
    "rdtsc\n"
    : "=a"(`low`), "=d"(`hi`)
    :
    : "memory"
  );""".}
  return (hi shl 32) or lo


echo getticks()

Error:

fatal.nim(39)            sysFatal
Error: unhandled exception: ccgtypes.nim(196, 17) `false` mapType [AssertionError]

Full stacktrace with debug on the proc names insterted just before genProcParams:

Nim/compiler/ccgtypes.nim

Lines 956 to 957 in 42e83ac

	fillLoc(prc.loc, locProc, prc.ast[namePos], mangleName(m, prc), OnUnknown)
	genProcParams(m, prc.typ, rettype, params, check)

>>> Debug START<<<
nimZeroMem
>>> Debug END<<<
>>> Debug START<<<
nimZeroMem
>>> Debug END<<<
>>> Debug START<<<
nimSetMem_zxfKBYntu9cBapkhrCOk1fgmemory
>>> Debug END<<<
>>> Debug START<<<
nimSetMem_zxfKBYntu9cBapkhrCOk1fgmemory
>>> Debug END<<<
>>> Debug START<<<
getticks_DaT0GSRtc9apiDAhLpobrrwcrash_comp
>>> Debug END<<<
>>> Debug START<<<
getticks_DaT0GSRtc9apiDAhLpobrrwcrash_comp
>>> Debug END<<<
>>> Debug START<<<
low_Rm7OrJxNFFg9aSwESSN9bnXQ
>>> Debug END<<<
/home/beta/Programming/Nim/Nim/compiler/nim.nim(106) nim
/home/beta/Programming/Nim/Nim/compiler/nim.nim(83) handleCmdLine
/home/beta/Programming/Nim/Nim/compiler/cmdlinehelper.nim(92) loadConfigsAndRunMainCommand
/home/beta/Programming/Nim/Nim/compiler/main.nim(198) mainCommand
/home/beta/Programming/Nim/Nim/compiler/main.nim(94) commandCompileToC
/home/beta/Programming/Nim/Nim/compiler/modules.nim(147) compileProject
/home/beta/Programming/Nim/Nim/compiler/modules.nim(88) compileModule
/home/beta/Programming/Nim/Nim/compiler/passes.nim(208) processModule
/home/beta/Programming/Nim/Nim/compiler/passes.nim(86) processTopLevelStmt
/home/beta/Programming/Nim/Nim/compiler/cgen.nim(1883) myProcess
/home/beta/Programming/Nim/Nim/compiler/ccgstmts.nim(1284) genStmts
/home/beta/Programming/Nim/Nim/compiler/ccgexprs.nim(2583) expr
/home/beta/Programming/Nim/Nim/compiler/ccgexprs.nim(2242) genMagicExpr
/home/beta/Programming/Nim/Nim/compiler/ccgexprs.nim(1056) genEcho
/home/beta/Programming/Nim/Nim/compiler/cgen.nim(599) initLocExpr
/home/beta/Programming/Nim/Nim/compiler/ccgexprs.nim(2603) expr
/home/beta/Programming/Nim/Nim/compiler/ccgexprs.nim(2374) genArrayConstr
/home/beta/Programming/Nim/Nim/compiler/ccgexprs.nim(2589) expr
/home/beta/Programming/Nim/Nim/compiler/ccgexprs.nim(1598) genMagicExpr
/home/beta/Programming/Nim/Nim/compiler/cgen.nim(599) initLocExpr
/home/beta/Programming/Nim/Nim/compiler/ccgexprs.nim(2591) expr
/home/beta/Programming/Nim/Nim/compiler/ccgcalls.nim(557) genCall
/home/beta/Programming/Nim/Nim/compiler/ccgcalls.nim(195) genPrefixCall
/home/beta/Programming/Nim/Nim/compiler/cgen.nim(599) initLocExpr
/home/beta/Programming/Nim/Nim/compiler/ccgexprs.nim(2524) expr
/home/beta/Programming/Nim/Nim/compiler/cgen.nim(1182) genProc
/home/beta/Programming/Nim/Nim/compiler/cgen.nim(1116) genProcNoForward
/home/beta/Programming/Nim/Nim/compiler/cgen.nim(1022) genProcAux
/home/beta/Programming/Nim/Nim/compiler/ccgstmts.nim(1284) genStmts
/home/beta/Programming/Nim/Nim/compiler/ccgexprs.nim(2621) expr
/home/beta/Programming/Nim/Nim/compiler/ccgexprs.nim(2398) genStmtList
/home/beta/Programming/Nim/Nim/compiler/ccgstmts.nim(1284) genStmts
/home/beta/Programming/Nim/Nim/compiler/ccgexprs.nim(2679) expr
/home/beta/Programming/Nim/Nim/compiler/ccgstmts.nim(1189) genPragma
/home/beta/Programming/Nim/Nim/compiler/ccgstmts.nim(1152) genEmit
/home/beta/Programming/Nim/Nim/compiler/ccgstmts.nim(1091) genAsmOrEmitStmt
/home/beta/Programming/Nim/Nim/compiler/cgen.nim(599) initLocExpr
/home/beta/Programming/Nim/Nim/compiler/ccgexprs.nim(2524) expr
/home/beta/Programming/Nim/Nim/compiler/cgen.nim(1182) genProc
/home/beta/Programming/Nim/Nim/compiler/cgen.nim(1141) genProcNoForward
/home/beta/Programming/Nim/Nim/compiler/cgen.nim(1079) genProcPrototype
/home/beta/Programming/Nim/Nim/compiler/ccgtypes.nim(960) genProcHeader
/home/beta/Programming/Nim/Nim/compiler/ccgtypes.nim(448) genProcParams
/home/beta/Programming/Nim/Nim/compiler/ccgtypes.nim(224) isInvalidReturnType
/home/beta/Programming/Nim/Nim/compiler/ccgtypes.nim(166) mapType
/home/beta/Programming/Nim/Nim/compiler/ccgtypes.nim(196) mapType
/home/beta/Programming/Nim/Nim/lib/system/assertions.nim(27) failedAssertImpl
/home/beta/Programming/Nim/Nim/lib/system/assertions.nim(20) raiseAssert
/home/beta/Programming/Nim/Nim/lib/system/fatal.nim(39) sysFatal
Error: unhandled exception: /home/beta/Programming/Nim/Nim/compiler/ccgtypes.nim(196, 17) `false` mapType [AssertionError]
FAILURE

[narimiran]

Current error message with Nim devel 1.1.1:

Error: unhandled exception: index out of bounds, the container is empty [IndexError]