[LLVMdev] How distinguish Catch all llvm-IR from other catch type ?

[zhengjian zhang]

Hi,

catch_all.cpp:

     1  int main()
     2  {
     3      try {
     4          throw 34;
     5      }
     6      catch (...) {}
     7  }


llvm-gcc -O3 -S -emit-llvm  catch_all.cpp   -o catch_all.ll:

     1  ; ModuleID = 'catch_all.cpp'
     2  target datalayout =
"e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32"
     3  target triple = "i386-pc-linux-gnu"
     4          %struct.__fundamental_type_info_pseudo = type {
%struct.__type_info_pseudo }
     5          %struct.__type_info_pseudo = type { i8*, i8* }
     6  @_ZTIi = external constant
%struct.__fundamental_type_info_pseudo               ;
<%struct.__fundamental_type_info_pseudo*> [#uses=1]
     7
     8  define i32 @main() {
     9  entry:
    10          %0 = tail call i8* @__cxa_allocate_exception(i32 4)
nounwind            ; <i8*> [#uses=2]
    11          %1 = bitcast i8* %0 to i32*             ; <i32*> [#uses=1]
    12          store i32 34, i32* %1, align 4
    13          invoke void @__cxa_throw(i8* %0, i8* bitcast
(%struct.__fundamental_type_info_pseudo* @_ZTIi to i8*), void (i8*)*
null) noreturn
    14                          to label %invcont unwind label %lpad
    15
    16  invcont:                ; preds = %entry
    17          unreachable
    18
    19  lpad:           ; preds = %entry
    20          %eh_ptr = tail call i8* @llvm.eh.exception()
 ; <i8*> [#uses=2]
    21          %eh_select = tail call i32 (i8*, i8*, ...)*
@llvm.eh.selector.i32(i8* %eh_ptr, i8* bitcast (i32 (...)*
@__gxx_personality_sj0 to i8*))          ; <i32> [#uses=0]
    22          %2 = tail call i8* @__cxa_begin_catch(i8* %eh_ptr)
nounwind             ; <i8*> [#uses=0]
    23          tail call void @__cxa_end_catch()
    24          ret i32 0
    25  }
    26
    27  declare i8* @__cxa_allocate_exception(i32) nounwind
    28
    29  declare void @__cxa_throw(i8*, i8*, void (i8*)*) noreturn
    30
    31  declare i8* @__cxa_begin_catch(i8*) nounwind
    32
    33  declare i8* @llvm.eh.exception() nounwind
    34
    35  declare i32 @llvm.eh.selector.i32(i8*, i8*, ...) nounwind
    36
    37  declare void @__cxa_end_catch()
    38
    39  declare i32 @__gxx_personality_sj0(...)


from the LLVM-IR, catch all  was  translated  to  LLVM-IR :
%eh_select = tail call i32 (i8*, i8*, ...)* @llvm.eh.selector.i32(i8*
%eh_ptr, i8* bitcast (i32 (...)* @__gxx_personality_sj0 to i8*))
here llvm.eh.selector.i32 has only two args,  but from the doc, it
says llvm.eh.selector takes a minimum of three arguments.

The first argument is the reference to the exception structure.
The second argument is a reference to the personality function to be
used for this try catch sequence.
Each of the remaining arguments is either a reference to the type info
for a catch statement, a filter expression, or the number zero
representing a cleanup.

are llvm.eh.selector.i32 has other semantics ?
may be  llvm-gcc deal  call all as a special case ?


best regards
zhangzw