On Sep 12, 2012, at 4:40 AM, SENTHIL KUMAR THANGAVELU wrote:
> Hello all, John McCall,
> I have attached a patch for the issue we discussed previously
> "http://clang-developers.42468.n3.nabble.com/Throwing-exceptions-from-temporary-object-s-destructor-td4026498.html";
> specifically targetting only init-temp1.C(from gcc test suite) . Tested the
> patch on X86-linux and ARM-linux ran clang regression, all test cases passed
> except CodeGenCXX/temporaries.cpp.
> The issue was due to same landingpad being used for constructor and
> destructor of the same object and the parent auto var decl is not cleaned
> up(destructor called) when the destructor threw an exception. This patch
> creates a new landing pad containing a call to parent auto var decl's
> destructor. Once this destructor is called all other cleanup items are
> threaded through.
> I met with regression failure for the case CodeGenCXX/temporaries.cpp. I
> have reduced the test case only to contain the failure portion attached in
> email(temporaries.test.cpp). There is some pattern which the test case
> expects and the fix changes the pattern so the test case fails. I have
> attached the .ll file generated with and without the patch. Can someone
> suggest how to modify the test case? also I would like to know the rational
> required to modify the test case. The 2 ".ll" files were generated with the
> patch on 3.1 branch. Please let me know your comments.
>
> Description of attachments:
> 1) patch.p0.txt - patch based on svn revision 163683
> 2) temporaries.test.cpp - reduced test case from CodeGenCXX/temporaries.cpp
> containing only the snippet causing failure. If this snippet is removed from
> original test case, test passes.
> 3) temporaries.base.ll - clang output without my changes for
> temporaries.test.cpp
> 4) temporaries.withchanges.ll - clang output with my changes for
> temporaries.test.cpp
> 5) init-temp1.C - test case from gcc test suite
Index: lib/CodeGen/CGException.cpp
===================================================================
--- lib/CodeGen/CGException.cpp (revision 163683)
+++ lib/CodeGen/CGException.cpp (working copy)
@@ -745,6 +745,50 @@
};
const CleanupHackLevel_t CleanupHackLevel = CHL_MandatoryCleanup;
+// Create a new landing pad for tmp objects destructor's unwind
+// To be used only by auto var decl parent creating tmp objs
+llvm::BasicBlock *CodeGenFunction::EmitAutoVarDeclCleanupLpad() {
This function is unnecessary (and quite buggy, but fortunately being wrong is
adequate). You should just push an EH cleanup during the emission of a
normal cleanup in which there's an auto var emission active.
+ AutoVarEmission CurAutoVarEmission; // tmp obj eh_cleanup will need
Comments on instance variables should be documentation comments
(i.e. should start with ///) and should actually document the variable.
For example, saying *why* EH cleanups need this information is a good
start (as a hint, they don't — it's *normal* cleanups that need it).
Also, please don't randomly copy the AutoVarEmission. You need an
llvm::Value * (the address of the object) and a QualType.
AutoVarEmission EmitAutoVarAlloca(const VarDecl &var);
+ bool ShouldConsiderParentVarDecCleanUp();
This method is just a buggier and less general version of
Variable && needsEHCleanup(Variable->getType()->isDestructedType()).
John.
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