similar to: [LLVMdev] x86 unwind support

Kenneth Uildriks wrote: > 3. Perhaps a pass that lowers unwinds to an EH intrinsic? Would that > map well without adding more overhead than the current setjmp/longjmp > lowering pass? In the past there have been suggestions that a good approach would be to target the libunwind (http://www.nongnu.org/libunwind/) library interface in a lowering pass. This could provide both low

On Thu, Jul 31, 2008 at 2:19 AM, Duncan Sands <baldrick at free.fr> wrote: > Hi, > > > Can anyone tell me if invoke/unwind is stable in 2.3? I'm seeing some > > really weird stuff -- unwinds are ending up in seemingly arbitrary > places... > > definitely not inside the caller's unwind block My target is x86. > > codegen doesn't know how to

> probably there should be a switch to choose whether codegen should turn > unwind/invoke into dwarf or setjmp/longjmp style code. There is, but it happens before codegen and is slow. -enable-correct-eh-support will translate invoke/unwind into setjmp/longjmp pairs for the correct behavior. See: http://llvm.org/docs/Passes.html#lowerinvoke Nick > > Ciao, > > Duncan. >

Mark Shannon wrote: > Andrew Haley wrote: >> Mark Shannon wrote: >>> Andrew Haley wrote: >>>> Mark Shannon wrote: >>>>> Nick Johnson wrote: >>>>>>> probably there should be a switch to choose whether codegen should turn >>>>>>> unwind/invoke into dwarf or setjmp/longjmp style code. >>>>> It seems

Mark Shannon wrote: > Nick Johnson wrote: >>> probably there should be a switch to choose whether codegen should turn >>> unwind/invoke into dwarf or setjmp/longjmp style code. > > It seems to me that there is an implicit, and undocumented, assumption > that unwinding needs to handle stack-allocated objects. > > In languages without stack-allocated objects

Nick Johnson wrote: >> probably there should be a switch to choose whether codegen should turn >> unwind/invoke into dwarf or setjmp/longjmp style code. It seems to me that there is an implicit, and undocumented, assumption that unwinding needs to handle stack-allocated objects. In languages without stack-allocated objects (ie. most languages that support exceptions) there is no

Jon Harrop wrote: > > Is it? I was just reading the documentation about LLVM's exception > handling > and it sounded ideal for my needs. How much of it does not work as the > docs > imply? > Jon, I ran into this issue in September and re-ignited this discussion in another thread, here: http://www.nabble.com/Unwinds-Gone-Wild-td18747589.html

According to this page: http://lwn.net/Articles/252125/ data coming from L1 is only about three times as expensive as data coming from a register. So putting a register check after *every* call is probably not going to be profitable, compared to a thread-local global variable check after every invoke... if they happen often on a thread, that variable will probably be in cache, and if they

1. Which ones? I know that Windows uses it for the "this" pointer. Anyway, unless the callee is required to preserve it in a given calling convention, that doesn't preclude us using it for a *return* value. It would be checked after calls return, and wouldn't affect the use of the register for passing values in before the call is made. The callee would set it right before

I'm trying to get unwind to work. I was unable to get an unwind example to work directly, so I decided to compile a c program that uses setjmp and longjmp and work backwards. I keep running into a "Abort trap" problem, whatever "Abort trap" is. Anyway, here's an example of a C program that compiles and works properly under normal gcc, but that fails with an

Florian Weimer wrote: > * Wesley W. Terpstra: > >> The documentation of unwind/invoke is quite clear and does exactly >> what I need: unwinding the stack. I don't need it to carry an object >> back. I don't need it to figure out what the type of the object is or >> what catch() blocks it matches. I just need it to unwind the stack. > > You can use your

Andrew Haley wrote: > Mark Shannon wrote: >> Nick Johnson wrote: >>>> probably there should be a switch to choose whether codegen should turn >>>> unwind/invoke into dwarf or setjmp/longjmp style code. >> It seems to me that there is an implicit, and undocumented, assumption >> that unwinding needs to handle stack-allocated objects. >> >>

From what I understand, the unwind instruction is implemented only for the interpreter: there is a -lowerunwind pass for compiling to other systems which will either lower unwind and invoke to setjmp/ longjmp (slow) or turn invokes into calls and unwinds into abort()s. On 26 Dec 2008, at 15:19, Matt Giuca wrote: > > > Jon Harrop wrote: >> >> Is it? I was just reading

Hello LLVM-dev, I think I've found an issue with the MachineSink optimization on a program that uses setjmp. It looks like MachineSink will happily move a machine instruction into a following machine basic block (not necessarily a successor), even when that later block can be reached through a setjmp. Here is some example debug output from llc that I'm seeing: Sinking along critical

On Wed, 20 Apr 2005, Greg Pettyjohn wrote: > I'm trying to get unwind to work. > > I was unable to get an unwind example to work directly, > so I decided to compile a c program that uses setjmp > and longjmp and work backwards. > > I keep running into a "Abort trap" problem, whatever "Abort trap" is. > > Anyway, here's an example of a C

First I try it with bytecodes: ~/compiler/temp$ llvmgcc sjmp01.c -o sjmp01 ~/compiler/temp$ ./sjmp01 Hello World! Abort trap Same results for lli sjmp01.bc Now I try converting to native code: ~/compiler/temp$ llc sjmp01.bc -enable-correct-eh-support -o sjmp01.s ~/compiler/temp$ gcc sjmp01.s -o sjmp01.native ~/compiler/temp$ ./sjmp01.native Hello World! Bus error ~/compiler/temp$ On Apr 20,

Alastair Lynn wrote: > > From what I understand, the unwind instruction is implemented only > for the interpreter: there is a -lowerunwind pass for compiling to > other systems which will either lower unwind and invoke to setjmp/ > longjmp (slow) or turn invokes into calls and unwinds into abort()s. > Ah cheers, Alastair. That could be very useful (at least for me

Hi, Can I interject something at this point. Can I suggest that invoke/unwind be renamed DWARF_invoke/DWARF_unwind to warn the unwary that if they want lightweight exception handling in their Python/ML/whatever implementation they should use some other method. PS. Kenneth, why don't you just use setjmp/longjmp directly. Or, if you want, I can email you my lightweight versions if you want,

Hi zhangzw, > In llvm src the file llvm/lib/Transforms/IPO/LowerSetJmp.cpp, it > seems for sjlj-eh ? it's not for sjlj-eh. The problem with setjmp/longjmp is that they can jump from one part of a function to any other part, which means that the control-flow graph is pointless; this makes everything more complicated. So how to deal with this? LLVM does have constructs that allow

Hi In llvm src the file llvm/lib/Transforms/IPO/LowerSetJmp.cpp, it seems for sjlj-eh ? but this pass has no effect about c++ sjlj-eh. this pass is for future extend? zhangzw