search for: eh_ptr

...we agree on what the problem is. Suppose we don't artificially add catch-alls to selectors. Then the above example compiles to: define void @_Z1fv() { ... invoke void @__cxa_throw( something ) noreturn to label %somewhere unwind label %lpad ... lpad: %eh_ptr = tail call i8* @llvm.eh.exception( ) %eh_select8 = tail call i32 (i8*, i8*, ...)* @llvm.eh.selector.i32( i8* %eh_ptr, i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*)) tail call i32 (...)* @_Unwind_Resume( i8* %eh_ptr ) unreachable ... } define i32 @main() { entry:...

(Mail system seems to have eaten this, sorry if it's a repeat) On Dec 8, 2007, at 12:48 AM, Duncan Sands wrote: > Hi Dale, > >> - Why was C++ claiming that every selector has a catch-all handler? > > this is easy: because the semantics of invoke require it. Yes, > really. > If unwinding reaches an invoke then control is required to jump to the > unwind basic

...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...

...i; extern void f(); void g() { try { f(); } catch(A) { i = 1; } } void h() { try { g(); } catch(B) { i = 2; } } Without catch-alls this compiles to something like: define void @_Z1gv() { entry: invoke void @_Z1fv( ) to label %UnifiedReturnBlock unwind label %lpad ... lpad: ; preds = %entry %eh_ptr = tail call i8* @llvm.eh.exception( ) %eh_select = tail call i32 (i8*, i8*, ...)* @llvm.eh.selector.i32( i8* %eh_ptr, i32 (...)* @__gxx_personality_v0, i8* A) %eh_typeid = tail call i32 @llvm.eh.typeid.for.i32( i8* A ) %tmp15 = icmp eq i32 %eh_select, %eh_typeid br i1 %tmp15, label %bb, label %...

Hi Bill, there are a couple of things I didn't understand about your proposal, for example how it interacts with inlining, whether it is feasible to do the "turn invoke-of-Unwind_Resume into a branch" optimization and also whether in "resumedest" you still plan to use _Unwind_Resume to continue unwinding up the stack. Could you please show what the LLVM IR would look like

On Dec 10, 2007, at 11:38 AM, Duncan Sands wrote: >>> ... If you force a "cleanup" by changing the selector call to: >>> %eh_select8.i = tail call i32 (i8*, i8*, ...)* >>> @llvm.eh.selector.i32( i8* %eh_ptr.i, i8* bitcast (i32 (...)* >>> @__gxx_personality_v0 to i8*), i32 0) >>> then it doesn't work either: the unwinder observes that there is >>> only a cleanup, and >>> using some special logic (bogus in this case) deduces that the >>> exception will be...

...n't artificially add catch-alls to > selectors. Then > the above example compiles to: > > define void @_Z1fv() { > ... > invoke void @__cxa_throw( something ) noreturn > to label %somewhere unwind label %lpad > ... > lpad: > %eh_ptr = tail call i8* @llvm.eh.exception( ) > %eh_select8 = tail call i32 (i8*, i8*, ...)* > @llvm.eh.selector.i32( i8* %eh_ptr, i8* bitcast (i32 (...)* > @__gxx_personality_v0 to i8*)) I wasn't advocating this; agree it is wrong. > tail call i32 (...)* @_Unwind_Resume...

...ZTIi to i8*), void (i8*)* null) noreturn 52 to label %invcont unwind label %lpad 53 54 invcont: ; preds = %entry 55 unreachable 56 57 bb: ; preds = %lpad 58 %2 = tail call i8* @__cxa_begin_catch(i8* %eh_ptr) nounwind ; <i8*> [#uses=0] 59 %3 = invoke %"struct.std::basic_ostream<char,std::char_traits<char> >"* @_ZStlsISt11char_traitsIcEERSt13basic_ostreamIcT_ES5_PKc(%"struct.std::basic_ostream<char,std::char_traits<char> >"* @_ZS...

...; So I tried what you suggested, and it just gives me a bus error: define i32 @main(i32, i8**) nounwind { entry: call void @print(i8* bitcast ([6 x i8]* @str_begin to i8 *)) invoke fastcc void @throwSomething() to label %nounwind unwind label %catch; catch: %eh_ptr = call i8* @llvm.eh.exception(); %eh_select34 = call i32 (i8*, i8*, ...)* @llvm.eh.selector.i32 ( i8* %eh_ptr, i8* bitcast (i32 (i32, i32, i64, i8*, %UnwindContext*)* @__gcc_personality_v0 to i8*), i32 1) call void @print(i8* bitc...

Hi, that's right ! catch(all) has extra null arg, 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] I have doubt that : the llvm-IR like above are all translated from catch(all) statement . zhangzw

...to label %bb2 unwind label %b.dtor bb2: invoke void @_ZN1BD1Ev(%struct.B* %b) to label %bb3 unwind label %a.dtor bb3: invoke void @_ZN1AD1Ev(%struct.A* %a) to label %return unwind label %catch.handlers return: ret void ;; Catch Handlers catch.handlers: landingpad %eh_ptr = call i8* @llvm.eh.exception() dispatch resume to label %... catches [ %struct.__fundamental_type_info_pseudo* @_ZTIi, label %ch.int %struct.__pointer_type_info_pseudo* @_ZTIPKc, label %ch.str ] catchall [i8* null, label % ch.ca] ch.int: %t0 = call i8* @__cxa_begin_cat...

...; } catch (...) { printf("catch-all\n"); } } The llvm IR for foo looks similar to this (simplified for readability): define void @_Z3foov() { entry: invoke void @_Z3barv() to label %return unwind label %lpad return: ret void lpad: %eh_ptr = tail call i8* @llvm.eh.exception() %eh_select27 = tail call i32 (i8*, i8*, ...)* @llvm.eh.selector(i8* %eh_ptr, i8* @__gxx_personality_v0, i8* @_ZTIi, i8* @_ZTIPKc, i8* null) %eh_t...

> that's right ! catch(all) has extra null arg, > > 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] > > I have doubt that : > the llvm-IR like above are all translated from catch(all) statement . I'm not sure what you are saying... Ciao, Duncan.

2009/5/12 Duncan Sands <baldrick at free.fr>: >>  that's  right !  catch(all) has extra null arg, >> >> 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] >> >> I have doubt  that  : >> the llvm-IR like above are  all translated from catch(all) statement . > > I'm not sure what you are saying... > > Ciao, > &g...

...rent from C++. To invoke the personality function and have it catch an exception, the IR that you generate should look like the following: try: ;; Throw some exception invoke { } @"throwSomething"() to label %endTry unwind label %catch catch: ;; Catch and decode the exception %eh_ptr = call i8* @llvm.eh.exception() %eh_action = call i32 (i8*, i8*, ...)* @llvm.eh.selector.i32( i8* %eh_ptr, i8* bitcast (i32 (i32, i32, i64, i8*, i8*)* @__tart_eh_personality to i8*), %tart.reflect.Type* @tart.core.InvalidArgumentException.type, %tart.reflect.Type* @tart.core.Thro...

...} > } > > The llvm IR for foo looks similar to this (simplified for readability): > > define void @_Z3foov() { > entry: > invoke void @_Z3barv() > to label %return unwind label %lpad > > return: > ret void > > lpad: > %eh_ptr = tail call i8* @llvm.eh.exception() > %eh_select27 = tail call i32 (i8*, i8*, ...)* > @llvm.eh.selector(i8* %eh_ptr, > i8* @__gxx_personality_v0, > i8* @_ZTIi, > i8* @_ZTIPKc, >...

Hi Talin, > So I tried what you suggested, and it just gives me a bus error: > %eh_select34 = call i32 (i8*, i8*, ...)* > @llvm.eh.selector.i32 ( > i8* %eh_ptr, > i8* bitcast (i32 (i32, i32, i64, i8*, %UnwindContext*)* > @__gcc_personality_v0 to i8*), > i32 1) try changing i32 1 to i32 0. Also, feel free to send me something I can compile, and I will try it here. Ciao, Duncan.

Talin wrote: > Nicolas Geoffray wrote: >> Hi Talin, >> >> You're not using the llvm intrinsics for exception handling, so your >> code won't work. Using _Unwind_RaiseException should be OK, but your >> main function must at least use llvm.eh.exception, >> llvm.eh.selector.i32/64 and probably __cxa_begin_catch and __cxa_end_catch. >> >

...     |                |               | >            `----------------+---------------' >                             | >                             v >          .----------------------------------------. >          | %sel = phi [%select.1, ..., %select.n] | >          |     %eh_ptr = llvm.eh.exception()      | >          |           [cleanup code]               | >          |           switch on %sel               | >          `----------------------------------------' >                             | >                             v >                  .--...

...ly lists the possible catch areas, filters, personality and belongs to a basic block, that needs an attribute "landingpad" to help optimisations understand that that block is special for EH (this might not be strictly necessary). The general syntax of the dispatch is: lpad: landingpad %eh_ptr = tail call i8* @llvm.eh.exception() dispatch region label %lpad resume to label %unwind catches [ %struct.__fundamental_type_info_pseudo* @_ZTIi, label %ch.int.main ] personality [i32 (...)* @__gxx_personality_v0] This dispatch instruction is the last instruction in its block. It e...