From ef5a654216fad9bb4a7f8272d126064731ce943c Mon Sep 17 00:00:00 2001 From: Duncan Sands Date: Mon, 27 Aug 2007 15:47:50 +0000 Subject: There is an impedance matching problem between LLVM and gcc exception handling: if an exception unwinds through an invoke, then execution must branch to the invoke's unwind target. We previously tried to enforce this by appending a cleanup action to every selector, however this does not always work correctly due to an optimization in the C++ unwinding runtime: if only cleanups would be run while unwinding an exception, then the program just terminates without actually executing the cleanups, as invoke semantics would require. I was hoping this wouldn't be a problem, but in fact it turns out to be the cause of all the remaining failures in the LLVM testsuite (these also fail with -enable-correct-eh-support, so turning on -enable-eh didn't make things worse!). Instead we need to append a full-blown catch-all to the end of each selector. The correct way of doing this depends on the personality function, i.e. it is language dependent, so can only be done by gcc. Thus this patch which generalizes the eh.selector intrinsic so that it can handle all possible kinds of action table entries (before it didn't accomodate cleanups): now 0 indicates a cleanup, and filters have to be specified using the number of type infos plus one rather than the number of type infos. Related gcc patches will cause Ada to pass a cleanup (0) to force the selector to always fire, while C++ will use a C++ catch-all (null). llvm-svn: 41484 --- llvm/lib/CodeGen/MachineModuleInfo.cpp | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'llvm/lib/CodeGen/MachineModuleInfo.cpp') diff --git a/llvm/lib/CodeGen/MachineModuleInfo.cpp b/llvm/lib/CodeGen/MachineModuleInfo.cpp index 77fb643b650..62224fdca84 100644 --- a/llvm/lib/CodeGen/MachineModuleInfo.cpp +++ b/llvm/lib/CodeGen/MachineModuleInfo.cpp @@ -1726,6 +1726,13 @@ void MachineModuleInfo::addFilterTypeInfo(MachineBasicBlock *LandingPad, LP.TypeIds.push_back(getFilterIDFor(IdsInFilter)); } +/// addCleanup - Add a cleanup action for a landing pad. +/// +void MachineModuleInfo::addCleanup(MachineBasicBlock *LandingPad) { + LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad); + LP.TypeIds.push_back(0); +} + /// TidyLandingPads - Remap landing pad labels and remove any deleted landing /// pads. void MachineModuleInfo::TidyLandingPads() { -- cgit v1.2.3