Names of subroutines do not match between caller, callee, and declaration in same compilation unit

[carlobertolli]

No description provided.

[jleidel]

Carlo, do you have a sample code to elicit the bug?

[carlobertolli]

Yep:

 SUBROUTINE MYSUB(B,N)
  CHARACTER*1 B(1)
  CHARACTER*1 BLNK
  SAVE        BLNK
  DATA        BLNK /' '/

  DO 10 I=1,N
     B(I)=BLNK

10 CONTINUE
RETURN
END

  program invokecharblank
  character*1 STRING(10)
  integer*4 N
  external MYSUB

  N = 10
  call MYSUB(STRING,N)

  do 20 I=1,10
     print *, 'string = ', STRING(I), '.'

20 continue

  end

Compile with -S -emit-llvm and then pass it to clang with the rt library linked.
It will fail saying that the called function does not exist.

[jleidel]

In examining the IR, Flang appears to mangle the caller beyond appending the underscore. The IR shows:

subroutine definition:
define void @mysub_([1 x i8]* noalias %b, i32* noalias %n)

call location:
call void @mysub_.1([1 x i8]* %0, i32* %n)

The symbol is declared at the bottom of the IR as follows:
declare void @mysub_.1([1 x i8], i32)

[jleidel]

The bug occurs when the subroutines are defined as "external"