操作系统和体系结构之间的FILE结构是否一致？

Question

对于下面的C代码片段，LLVM将在下面生成IR。

#include <stdio.h>
#include <stdlib.h>

int main(){
  printf("Hello world\n");
  fflush(NULL);
  return 0;
}

; ModuleID = 'a.c'
source_filename = "a.c"
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.15.0"

%struct.__sFILE = type { i8*, i32, i32, i16, i16, %struct.__sbuf, i32, i8*, i32 (i8*)*, i32 (i8*, i8*, i32)*, i64 (i8*, i64, i32)*, i32 (i8*, i8*, i32)*, %struct.__sbuf, %struct.__sFILEX*, i32, [3 x i8], [1 x i8], %struct.__sbuf, i32, i64 }
%struct.__sFILEX = type opaque
%struct.__sbuf = type { i8*, i32 }

@str = private unnamed_addr constant [12 x i8] c"Hello world\00", align 1

; Function Attrs: nounwind ssp uwtable
define i32 @main() local_unnamed_addr #0 {
  %1 = tail call i32 @puts(i8* getelementptr inbounds ([12 x i8], [12 x i8]* @str, i64 0, i64 0))
  %2 = tail call i32 @fflush(%struct.__sFILE* null)
  ret i32 0
}

; Function Attrs: nounwind
declare i32 @fflush(%struct.__sFILE* nocapture) local_unnamed_addr #1

; Function Attrs: nounwind
declare i32 @puts(i8* nocapture readonly) local_unnamed_addr #2

attributes #0 = { nounwind ssp uwtable "correctly-rounded-divide-sqrt-fp-math"="false" "darwin-stkchk-strong-link" "disable-tail-calls"="false" "frame-pointer"="all" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "probe-stack"="___chkstk_darwin" "stack-protector-buffer-size"="8" "target-cpu"="penryn" "target-features"="+cx16,+cx8,+fxsr,+mmx,+sahf,+sse,+sse2,+sse3,+sse4.1,+ssse3,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
attributes #1 = { nounwind "correctly-rounded-divide-sqrt-fp-math"="false" "darwin-stkchk-strong-link" "disable-tail-calls"="false" "frame-pointer"="all" "less-precise-fpmad"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "probe-stack"="___chkstk_darwin" "stack-protector-buffer-size"="8" "target-cpu"="penryn" "target-features"="+cx16,+cx8,+fxsr,+mmx,+sahf,+sse,+sse2,+sse3,+sse4.1,+ssse3,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
attributes #2 = { nounwind }

!llvm.module.flags = !{!0, !1, !2}
!llvm.ident = !{!3}

!0 = !{i32 2, !"SDK Version", [3 x i32] [i32 10, i32 15, i32 4]}
!1 = !{i32 1, !"wchar_size", i32 4}
!2 = !{i32 7, !"PIC Level", i32 2}
!3 = !{!"Apple clang version 11.0.3 (clang-1103.0.32.59)"}

我是否可以认为相应的FILE结构的结构声明在不同的操作系统之间是一致的？是否有一种编程方式来获取该结构的LLVM表示形式？

Answer 1

FILE *后面的类型的结构对于用户来说是不透明的，并且在操作系统之间是可变的。

Answer 2

这是macOS的实现：