GPUCompiler.compile replaces dots with underscores in extern functions

[giordano]

using GPUCompiler

f() = ccall("extern foo.bar", llvmcall, Nothing, ())
struct MyCompilerParams <: AbstractCompilerParams end

GPUCompiler.runtime_module(::CompilerJob{<:Any,MyCompilerParams}) = @__MODULE__
GPUCompiler.isintrinsic(@nospecialize(job::CompilerJob{<:Any,MyCompilerParams}), fn::String) =
    contains(fn, r"foo.bar")

target = NativeCompilerTarget()
source = methodinstance(typeof(f), Tuple{})
config = CompilerConfig(target, MyCompilerParams())
job = CompilerJob(source, config)
llvm_ir = JuliaContext() do ctx
    string(GPUCompiler.compile(:llvm, job; ctx)[1])
end

results in

; ModuleID = 'start'
source_filename = "start"
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-linux-gnu"

define void @_Z1f() local_unnamed_addr #0 !dbg !5 {
top:
  call void @foo_bar(), !dbg !8
  ret void, !dbg !8
}

declare void @foo_bar() local_unnamed_addr

attributes #0 = { "frame-pointer"="all" "probe-stack"="inline-asm" }

!llvm.module.flags = !{!0, !1}
!llvm.dbg.cu = !{!2}
!julia.kernel = !{!4}

!0 = !{i32 2, !"Dwarf Version", i32 4}
!1 = !{i32 2, !"Debug Info Version", i32 3}
!2 = distinct !DICompileUnit(language: DW_LANG_Julia, file: !3, producer: "julia", isOptimized: true, runtimeVersion: 0, emissionKind: LineTablesOnly, nameTableKind: None)
!3 = !DIFile(filename: "/tmp/foo.jl", directory: ".")
!4 = !{void ()* @_Z1f}
!5 = distinct !DISubprogram(name: "f", linkageName: "julia_f_936", scope: null, file: !3, line: 3, type: !6, scopeLine: 3, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2, retainedNodes: !7)
!6 = !DISubroutineType(types: !7)
!7 = !{}
!8 = !DILocation(line: 3, scope: !5)

Note that the call to foo.bar became foo_bar, despite the fact code_llvm retains the dot:

julia> code_llvm(f, ())

;  @ /tmp/foo.jl:3 within `f`
define void @julia_f_999() #0 {
top:
  call void @foo.bar()
  ret void
}

and trying to call the function fails with

julia> f()
JIT session error: Symbols not found: [ foo.bar ]
JIT session error: Symbols not found: [ foo.bar ]

[9451] signal (11.1): Segmentation fault

The dot is still there.