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

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

I get an extra null arg, I don't know why you don't:
    %eh_select = tail call i32 (i8*, i8*, ...)*
@llvm.eh.selector.i32(i8* %eh_ptr, i8* bitcast (i32 (...)*
@__gxx_personality_v0 to i8*), i8* null) ; <i32> [#uses=0]

Compare it with the IR generated for catch(int) or catch(someOtherType).

Here is how catch(int) looks like for me, notice the additional @_ZTIi
parameter, and the icmp for the typeid:

bb: ; preds = %lpad
    %2 = tail call i8* @__cxa_begin_catch(i8* %eh_ptr) nounwind ;
<i8*> [#uses=0]
    tail call void @__cxa_end_catch()
    ret i32 0

lpad: %eh_ptr = tail call i8* @llvm.eh.exception() ; <i8*> [#uses=3]
    %eh_select = tail call i32 (i8*, i8*, ...)*
@llvm.eh.selector.i32(i8* %eh_ptr, i8* bitcast (i32 (...)*
@__gxx_personality_v0 to i8*), i8* bitcast
(%struct.__fundamental_type_info_pseudo* @_ZTIi to i8*), i8* null)
    ; <i32> [#uses=1]
    %eh_typeid = tail call i32 @llvm.eh.typeid.for.i32(i8* bitcast
(%struct.__fundamental_type_info_pseudo* @_ZTIi to i8*)) ; <i32>
[#uses=1]
    %3 = icmp eq i32 %eh_select, %eh_typeid ; <i1> [#uses=1]
    br i1 %3, label %bb, label %Unwind

Unwind: ; preds = %lpad
    tail call void @_Unwind_Resume(i8* %eh_ptr)
    unreachable

Best regards,
--Edwin