search for: _try

...semantic. There is NO need to precisely model HW exception control flow at instruction-level. Your example about memcpy() is just a bug in current implementation. I will fix it so that it’s volatilized in some manner. We are not in Code Review stage yet. let’s focus on design. There is one seh_try_begin() invoke at the beginning of _try and one seh_try_end() invoke at the end of _try. Their EH edge will point to _except handler. So your example below will not happen. Compiler should not generate code like that. Thanks, --Ten From: Eli Friedman <efriedma at quicinc.com> Sent: Thur...

...impression that threw_exception() will not be called if optimizations are enabled? I don’t know if the -EHa Spec is clearly described in MSFT Webs. At least this proposal has described the rules for both C & C++ code. The very first rule clearly said that “no exception can move in or out of _try region., i.e., no potential faulty instruction can be moved across _try boundary”. As such the dereference of statement return *(C*)0 must be kept in _try scope and the access-violation fault will be caught in _except handler where threw_exception() will be called. I don’t see why Register alloc...

...3b934fb5e It passes all MSVC SEH suite (excluding those with “Jumping out of _finally” ( _Local_Unwind)). Thanks, --Ten **** The rules for C code: **** For C-code, one way (MSVC approach) to achieve SEH -EHa semantic is to follow three rules. First, no exception can move in or out of _try region., i.e., no "potential faulty instruction can be moved across _try boundary. Second, the order of exceptions for instructions 'directly' under a _try must be preserved (not applied to those in callees). Finally, global states (local/global/heap variables) that can...

...e target code, not just "jump" to target label I'm not sure what you're trying to say here. In the Microsoft ABI, goto out of a catch block also calls into the unwinder. We have to run any destructors, and return from the funclet (catchret/cleanupret). * The call inside a _try is an invoke with EH edge. So it's perfectly modeled. If you call a nounwind function, the invoke will be transformed to a plain call. And we're likely to infer nounwind in many cases (for example, functions that don't call any other functions). There isn't any way to stop this...

...page as an example, the control flowing from normal execution of inner _finlly, passing through outer _finally, and landing in $t10 cannot be represented by LLVM IR. Or could you elaborate how to achieve it? (Bear with me as I'm new in Clang&LLVM world). Take your example, replace "_try" with C++ "try", replace the "_finally" with "catch(....)" with a "throw;" at the end of the catch block, replace the "_except()" with "catch(...)", and see what clang currently generates. That seems roughly equivalent to what you...

...<label>:45: ; preds = %43 %46 = catchpad within %44 [i8* bitcast (i32 (i8*, i8*)* @"?filt at 0@main@@" to i8*)], catchret from %46 to label %47, ; <label>:47: ; preds = %45 // except handler block .. br label %53, !dbg !155 ; <label>:53: ; preds = %47, %34 // after outer _try block .. br label %56, !dbg !156 ; <label>:t10: .. .. define internal void @"?fin at 0@main@@"(i8, i8* %1) #2 { .. %2 = blockaddress($main, $t10) call void @"?local_unwind@@"(i8* %1, i8* %2) ________________________________ The new IR is illustrated below. Changes are high...

Resending; I accidentally dropped llvm-dev. -Eli From: Eli Friedman Sent: Wednesday, April 1, 2020 1:01 PM To: Ten Tzen <tentzen at microsoft.com> Cc: aaron.smith at microsoft.com Subject: RE: [EXT] [llvm-dev] [RFC] [Windows SEH] Local_Unwind (Jumping out of a _finally) and -EHa (Hardware Exception Handling) This looks like it outlines the implementation pretty well. For goto in finally,

...ome time ago all project files for MSVC 6 were removed; it makes sense to remove the code that is necessary only for MSVC 6 and older compilers. --- a\src\libFLAC\cpu.c 2013-08-13 13:30:24.000000000 +0400 +++ b\src\libFLAC\cpu.c 2013-08-16 21:46:42.177485300 +0400 @@ -285,14 +285,7 @@ # ifdef USE_TRY_CATCH_FLAVOR _try { __asm { -# if _MSC_VER <= 1200 - /* VC6 assembler doesn't know SSE, have to emit bytecode instead */ - _emit 0x0F - _emit 0x57 - _emit 0xC0 -# else xorps xmm0,xmm0 -# endif } } _except(EXCEPTION_EXECUTE_HANDLER) { @@ -3...

...ously when it’s combined with -EHa. Major code is surrounding at SehTryStmt and _Finally in CGexception.cpp that is the place to house Windows SEH specific code anyways. The implementation chose to lever Parser/Semantic phase (SemaStmt.cpp, JumpDiagnostics.cpp, scope.h, etc) to identify the right _Try scope for LU dispatching because that is the place “warn_jump_out_of_seh_finally” is diagnosed and reported. I feel this is the most robust approach. Local_unwind is an important feature, broadly used in Windows Kernel for all architectures. Without LU, Windows SEH is incomplete! Thanks, --Ten...