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Extend eh.selector to support both catches and filters.
Drop the eh.filter intrinsic. llvm-svn: 37875
This commit is contained in:
Duncan Sands
parent
c02ea23dea
commit
4441eff1ac
@ -29,7 +29,6 @@
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<ol>
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<li><a href="#llvm_eh_exception"><tt>llvm.eh.exception</tt></a></li>
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<li><a href="#llvm_eh_selector"><tt>llvm.eh.selector</tt></a></li>
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<li><a href="#llvm_eh_filter"><tt>llvm.eh.filter</tt></a></li>
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<li><a href="#llvm_eh_typeid_for"><tt>llvm.eh.typeid.for</tt></a></li>
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</ol></li>
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<li><a href="#asm">Asm Table Formats</a>
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@ -212,13 +211,18 @@ further use in the landing pad and catch code.</p>
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<p><a href="#llvm_eh_selector"><tt>llvm.eh.selector</tt></a> takes a minimum of
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three arguments. The first argument is the reference to the exception
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structure. The second argument is a reference to the personality function to be
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used for this try catch sequence. The remaining arguments are references to the
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type infos for each of the catch statements in the order they should be tested.
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used for this try catch sequence. Each of the remaining arguments is either a
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reference to the type info for a catch statement, or a non-negative integer
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followed by that many type info references, representing a
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<a href="#throw_filters">filter</a>.
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The exception is tested against the arguments sequentially from first to last.
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The <i>catch all</i> (...) is represented with a <tt>null i8*</tt>. The result
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of the <a href="#llvm_eh_selector"><tt>llvm.eh.selector</tt></a> is the index of
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the type info in the corresponding exception table. The LLVM C++ front end
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generates code to save this value in an alloca location for further use in the
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landing pad and catch code.</p>
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of the <a href="#llvm_eh_selector"><tt>llvm.eh.selector</tt></a> is a positive
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number if the exception matched a type info, a negative number if it matched a
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filter, and zero if it didn't match anything. If a type info matched then the
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returned value is the index of the type info in the exception table.
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The LLVM C++ front end generates code to save this value in an alloca location
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for further use in the landing pad and catch code.</p>
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<p>Once the landing pad has the type info selector, the code branches to the
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code for the first catch. The catch then checks the value of the type info
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@ -268,12 +272,12 @@ constructor), there may be several landing pads for a given try.</p>
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<p>C++ allows the specification of which exception types that can be thrown from
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a function. To represent this a top level landing pad may exist to filter out
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invalid types. To express this in LLVM code the landing pad will call <a
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href="#llvm_eh_filter"><tt>llvm.eh.filter</tt></a> instead of <a
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href="#llvm_eh_selector"><tt>llvm.eh.selector</tt></a>. The arguments are the
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same, but what gets created in the exception table is different. <a
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href="#llvm_eh_filter"><tt>llvm.eh.filter</tt></a> will return a negative value
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if it doesn't find a match. If no match is found then a call to
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<tt>__cxa_call_unexpected</tt> should be made, otherwise
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number of different type infos the function may throw, followed by the type
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infos themselves.
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<a href="#llvm_eh_selector"><tt>llvm.eh.selector</tt></a> will return a negative
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value if the exception does not match any of the type infos. If no match is
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found then a call to <tt>__cxa_call_unexpected</tt> should be made, otherwise
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<tt>_Unwind_Resume</tt>. Each of these functions require a reference to the
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exception structure.</p>
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@ -326,32 +330,16 @@ exception selector.</p>
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<p><a href="#llvm_eh_selector"><tt>llvm.eh.selector</tt></a> takes a minimum of
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three arguments. The first argument is the reference to the exception
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structure. The second argument is a reference to the personality function to be
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used for this try catch sequence. The remaining arguments are references to the
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type infos for each of the catch statements in the order they should be tested.
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The <i>catch all</i> (...) is represented with a <tt>null i8*</tt>.</p>
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</div>
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<!-- ======================================================================= -->
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<div class="doc_subsubsection">
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<a name="llvm_eh_filter">llvm.eh.filter</a>
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</div>
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<div class="doc_text">
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<pre>
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i32 %<a href="#llvm_eh_filter">llvm.eh.filter</a>(i8*, i8*, i8*, ...)
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</pre>
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<p>This intrinsic indicates that the exception selector is available at this
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point in the code. The backend will replace this intrinsic with code to fetch
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the second argument of a call. The effect is that the intrinsic result is the
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exception selector.</p>
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<p><a href="#llvm_eh_filter"><tt>llvm.eh.filter</tt></a> takes a minimum of
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three arguments. The first argument is the reference to the exception
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structure. The second argument is a reference to the personality function to be
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used for this function. The remaining arguments are references to the type infos
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for each type that can be thrown by the current function.</p>
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used for this try catch sequence. Each of the remaining arguments is either a
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reference to the type info for a catch statement, or a non-negative integer
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followed by that many type info references, representing a
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<a href="#throw_filters">filter</a>.
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The exception is tested against the arguments sequentially from first to last.
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The <i>catch all</i> (...) is represented with a <tt>null i8*</tt>. The result
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of the <a href="#llvm_eh_selector"><tt>llvm.eh.selector</tt></a> is a positive
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number if the exception matched a type info, a negative number if it matched a
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filter, and zero if it didn't match anything. If a type info matched then the
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returned value is the index of the type info in the exception table.</p>
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</div>
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@ -427,15 +415,6 @@ only calls to non-throwing functions will not need an exception table.</p>
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<ol>
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<li><p>Need to create landing pads for code in between explicit landing pads.
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The landing pads will have a zero action and a NULL landing pad address and are
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used to inform the runtime that the exception should be rethrown.</li></p>
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<li><p>Actions for a given function should be folded to save space.</p></li>
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<li><p>Filters for inlined functions need to be handled more extensively.
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Currently it's hardwired for one filter per function.</li></p>
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<li><p>Testing/Testing/Testing.</li></p>
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</ol>
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@ -231,8 +231,6 @@ def int_dbg_declare : Intrinsic<[llvm_void_ty, llvm_descriptor_ty,
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def int_eh_exception : Intrinsic<[llvm_ptr_ty]>;
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def int_eh_selector : Intrinsic<[llvm_i32_ty, llvm_ptr_ty, llvm_ptr_ty,
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llvm_vararg_ty]>;
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def int_eh_filter : Intrinsic<[llvm_i32_ty, llvm_ptr_ty, llvm_ptr_ty,
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llvm_vararg_ty]>;
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def int_eh_typeid_for : Intrinsic<[llvm_i32_ty, llvm_ptr_ty]>;
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//===---------------- Generic Variable Attribute Intrinsics----------------===//
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@ -708,7 +708,6 @@ void IntrinsicLowering::LowerIntrinsicCall(CallInst *CI) {
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case Intrinsic::dbg_declare:
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case Intrinsic::eh_exception:
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case Intrinsic::eh_selector:
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case Intrinsic::eh_filter:
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break; // Simply strip out debugging and eh intrinsics
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case Intrinsic::var_annotation:
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@ -205,12 +205,11 @@ namespace llvm {
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};
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}
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/// isFilterOrSelector - Return true if this instruction is a call to the
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/// eh.filter or the eh.selector intrinsic.
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static bool isFilterOrSelector(Instruction *I) {
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/// isSelector - Return true if this instruction is a call to the
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/// eh.selector intrinsic.
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static bool isSelector(Instruction *I) {
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if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I))
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return II->getIntrinsicID() == Intrinsic::eh_selector
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|| II->getIntrinsicID() == Intrinsic::eh_filter;
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return II->getIntrinsicID() == Intrinsic::eh_selector;
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return false;
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}
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@ -2293,12 +2292,12 @@ void SelectionDAGLowering::visitTargetIntrinsic(CallInst &I,
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}
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}
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/// ExtractGlobalVariable - If C is a global variable, or a bitcast of one
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/// ExtractGlobalVariable - If V is a global variable, or a bitcast of one
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/// (possibly constant folded), return it. Otherwise return NULL.
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static GlobalVariable *ExtractGlobalVariable (Constant *C) {
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if (GlobalVariable *GV = dyn_cast<GlobalVariable>(C))
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static GlobalVariable *ExtractGlobalVariable (Value *V) {
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if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V))
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return GV;
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else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
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else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
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if (CE->getOpcode() == Instruction::BitCast)
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return dyn_cast<GlobalVariable>(CE->getOperand(0));
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else if (CE->getOpcode() == Instruction::GetElementPtr) {
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@ -2311,8 +2310,16 @@ static GlobalVariable *ExtractGlobalVariable (Constant *C) {
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return NULL;
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}
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/// ExtractTypeInfo - Extracts the type info from a value.
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static GlobalVariable *ExtractTypeInfo (Value *V) {
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GlobalVariable *GV = ExtractGlobalVariable(V);
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assert (GV || isa<ConstantPointerNull>(V) &&
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"TypeInfo must be a global variable or NULL");
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return GV;
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}
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/// addCatchInfo - Extract the personality and type infos from an eh.selector
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/// or eh.filter call, and add them to the specified machine basic block.
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/// call, and add them to the specified machine basic block.
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static void addCatchInfo(CallInst &I, MachineModuleInfo *MMI,
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MachineBasicBlock *MBB) {
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// Inform the MachineModuleInfo of the personality for this landing pad.
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@ -2325,17 +2332,38 @@ static void addCatchInfo(CallInst &I, MachineModuleInfo *MMI,
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// Gather all the type infos for this landing pad and pass them along to
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// MachineModuleInfo.
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std::vector<GlobalVariable *> TyInfo;
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for (unsigned i = 3, N = I.getNumOperands(); i < N; ++i) {
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Constant *C = cast<Constant>(I.getOperand(i));
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GlobalVariable *GV = ExtractGlobalVariable(C);
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assert (GV || isa<ConstantPointerNull>(C) &&
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"TypeInfo must be a global variable or NULL");
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TyInfo.push_back(GV);
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unsigned N = I.getNumOperands();
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for (unsigned i = N - 1; i > 2; --i) {
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if (ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand(i))) {
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unsigned FilterLength = CI->getZExtValue();
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unsigned FirstCatch = i + FilterLength + 1;
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assert (FirstCatch <= N && "Invalid filter length");
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if (FirstCatch < N) {
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TyInfo.reserve(N - FirstCatch);
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for (unsigned j = FirstCatch; j < N; ++j)
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TyInfo.push_back(ExtractTypeInfo(I.getOperand(j)));
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MMI->addCatchTypeInfo(MBB, TyInfo);
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TyInfo.clear();
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}
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TyInfo.reserve(FilterLength);
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for (unsigned j = i + 1; j < FirstCatch; ++j)
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TyInfo.push_back(ExtractTypeInfo(I.getOperand(j)));
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MMI->addFilterTypeInfo(MBB, TyInfo);
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TyInfo.clear();
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N = i;
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}
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}
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if (I.getCalledFunction()->getIntrinsicID() == Intrinsic::eh_filter)
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MMI->addFilterTypeInfo(MBB, TyInfo);
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else
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if (N > 3) {
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TyInfo.reserve(N - 3);
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for (unsigned j = 3; j < N; ++j)
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TyInfo.push_back(ExtractTypeInfo(I.getOperand(j)));
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MMI->addCatchTypeInfo(MBB, TyInfo);
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}
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}
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/// propagateEHRegister - The specified EH register is required in a successor
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@ -2483,8 +2511,7 @@ SelectionDAGLowering::visitIntrinsicCall(CallInst &I, unsigned Intrinsic) {
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return 0;
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}
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case Intrinsic::eh_selector:
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case Intrinsic::eh_filter:{
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case Intrinsic::eh_selector:{
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MachineModuleInfo *MMI = DAG.getMachineModuleInfo();
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if (ExceptionHandling && MMI) {
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@ -2518,10 +2545,7 @@ SelectionDAGLowering::visitIntrinsicCall(CallInst &I, unsigned Intrinsic) {
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if (MMI) {
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// Find the type id for the given typeinfo.
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Constant *C = cast<Constant>(I.getOperand(1));
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GlobalVariable *GV = ExtractGlobalVariable(C);
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assert (GV || isa<ConstantPointerNull>(C) &&
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"TypeInfo must be a global variable or NULL");
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GlobalVariable *GV = ExtractTypeInfo(I.getOperand(1));
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unsigned TypeID = MMI->getTypeIDFor(GV);
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setValue(&I, DAG.getConstant(TypeID, MVT::i32));
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@ -4297,7 +4321,7 @@ static void copyCatchInfo(BasicBlock *SrcBB, BasicBlock *DestBB,
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assert(!FLI.MBBMap[SrcBB]->isLandingPad() &&
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"Copying catch info out of a landing pad!");
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for (BasicBlock::iterator I = SrcBB->begin(), E = --SrcBB->end(); I != E; ++I)
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if (isFilterOrSelector(I)) {
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if (isSelector(I)) {
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// Apply the catch info to DestBB.
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addCatchInfo(cast<CallInst>(*I), MMI, FLI.MBBMap[DestBB]);
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#ifndef NDEBUG
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@ -4341,19 +4365,19 @@ void SelectionDAGISel::BuildSelectionDAG(SelectionDAG &DAG, BasicBlock *LLVMBB,
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// function and list of typeids logically belong to the invoke (or, if you
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// like, the basic block containing the invoke), and need to be associated
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// with it in the dwarf exception handling tables. Currently however the
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// information is provided by intrinsics (eh.filter and eh.selector) that
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// can be moved to unexpected places by the optimizers: if the unwind edge
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// is critical, then breaking it can result in the intrinsics being in the
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// successor of the landing pad, not the landing pad itself. This results
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// in exceptions not being caught because no typeids are associated with
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// the invoke. This may not be the only way things can go wrong, but it
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// is the only way we try to work around for the moment.
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// information is provided by an intrinsic (eh.selector) that can be moved
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// to unexpected places by the optimizers: if the unwind edge is critical,
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// then breaking it can result in the intrinsics being in the successor of
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// the landing pad, not the landing pad itself. This results in exceptions
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// not being caught because no typeids are associated with the invoke.
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// This may not be the only way things can go wrong, but it is the only way
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// we try to work around for the moment.
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BranchInst *Br = dyn_cast<BranchInst>(LLVMBB->getTerminator());
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if (Br && Br->isUnconditional()) { // Critical edge?
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BasicBlock::iterator I, E;
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for (I = LLVMBB->begin(), E = --LLVMBB->end(); I != E; ++I)
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if (isFilterOrSelector(I))
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if (isSelector(I))
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break;
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if (I == E)
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