diff options
Diffstat (limited to 'lib/Transforms/IPO/StripSymbols.cpp')
-rw-r--r-- | lib/Transforms/IPO/StripSymbols.cpp | 155 |
1 files changed, 93 insertions, 62 deletions
diff --git a/lib/Transforms/IPO/StripSymbols.cpp b/lib/Transforms/IPO/StripSymbols.cpp index 3d601b6a38..fe9667ea8f 100644 --- a/lib/Transforms/IPO/StripSymbols.cpp +++ b/lib/Transforms/IPO/StripSymbols.cpp @@ -332,76 +332,107 @@ bool StripDebugDeclare::runOnModule(Module &M) { return true; } +/// Remove any debug info for global variables/functions in the given module for +/// which said global variable/function no longer exists (i.e. is null). +/// +/// Debugging information is encoded in llvm IR using metadata. This is designed +/// such a way that debug info for symbols preserved even if symbols are +/// optimized away by the optimizer. This special pass removes debug info for +/// such symbols. bool StripDeadDebugInfo::runOnModule(Module &M) { bool Changed = false; - // Debugging information is encoded in llvm IR using metadata. This is designed - // such a way that debug info for symbols preserved even if symbols are - // optimized away by the optimizer. This special pass removes debug info for - // such symbols. - - // llvm.dbg.gv keeps track of debug info for global variables. - if (NamedMDNode *NMD = M.getNamedMetadata("llvm.dbg.gv")) { - SmallVector<MDNode *, 8> MDs; - for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i) - if (NMD->getOperand(i)) { - assert(DIGlobalVariable(NMD->getOperand(i)).isGlobalVariable() && - "A MDNode in llvm.dbg.gv should be a DIGlobalVariable."); - MDs.push_back(NMD->getOperand(i)); - } - else - Changed = true; - NMD->eraseFromParent(); - NMD = NULL; - - for (SmallVectorImpl<MDNode *>::iterator I = MDs.begin(), - E = MDs.end(); I != E; ++I) { - GlobalVariable *GV = DIGlobalVariable(*I).getGlobal(); - if (GV && M.getGlobalVariable(GV->getName(), true)) { - if (!NMD) - NMD = M.getOrInsertNamedMetadata("llvm.dbg.gv"); - NMD->addOperand(*I); - } + LLVMContext &C = M.getContext(); + + // Find all debug info in F. This is actually overkill in terms of what we + // want to do, but we want to try and be as redundent as possible in the face + // of potential debug info changes by using the formal interfaces given to us + // as much as possible. + DebugInfoFinder F; + F.processModule(M); + + // For each compile unit, find the live set of global variables/functions and + // replace the current list of potentially dead global variables/functions + // with the live list. + SmallVector<Value *, 64> LiveGlobalVariables; + SmallVector<Value *, 64> LiveSubprograms; + DenseSet<const MDNode *> VisitedSet; + + for (DebugInfoFinder::iterator CI = F.compile_unit_begin(), + CE = F.compile_unit_end(); CI != CE; ++CI) { + // Create our compile unit. + DICompileUnit DIC(*CI); + assert(DIC.Verify() && "DIC must verify as a DICompileUnit."); + + // Create our live subprogram list. + DIArray SPs = DIC.getSubprograms(); + bool SubprogramChange = false; + for (unsigned i = 0, e = SPs.getNumElements(); i != e; ++i) { + DISubprogram DISP(SPs.getElement(i)); + assert(DISP.Verify() && "DISP must verify as a DISubprogram."); + + // Make sure we visit each subprogram only once. + if (!VisitedSet.insert(DISP).second) + continue; + + // If the function referenced by DISP is not null, the function is live. + if (DISP.getFunction()) + LiveSubprograms.push_back(DISP); else - Changed = true; + SubprogramChange = true; } - } - // llvm.dbg.sp keeps track of debug info for subprograms. - if (NamedMDNode *NMD = M.getNamedMetadata("llvm.dbg.sp")) { - SmallVector<MDNode *, 8> MDs; - for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i) - if (NMD->getOperand(i)) { - assert(DISubprogram(NMD->getOperand(i)).isSubprogram() && - "A MDNode in llvm.dbg.sp should be a DISubprogram."); - MDs.push_back(NMD->getOperand(i)); - } + // Create our live global variable list. + DIArray GVs = DIC.getGlobalVariables(); + bool GlobalVariableChange = false; + for (unsigned i = 0, e = GVs.getNumElements(); i != e; ++i) { + DIGlobalVariable DIG(GVs.getElement(i)); + assert(DIG.Verify() && "DIG must verify as DIGlobalVariable."); + + // Make sure we only visit each global variable only once. + if (!VisitedSet.insert(DIG).second) + continue; + + // If the global variable referenced by DIG is not null, the global + // variable is live. + if (DIG.getGlobal()) + LiveGlobalVariables.push_back(DIG); else - Changed = true; - NMD->eraseFromParent(); - NMD = NULL; - - for (SmallVectorImpl<MDNode *>::iterator I = MDs.begin(), - E = MDs.end(); I != E; ++I) { - bool FnIsLive = false; - if (Function *F = DISubprogram(*I).getFunction()) - if (M.getFunction(F->getName())) - FnIsLive = true; - if (FnIsLive) { - if (!NMD) - NMD = M.getOrInsertNamedMetadata("llvm.dbg.sp"); - NMD->addOperand(*I); - } else { - // Remove llvm.dbg.lv.fnname named mdnode which may have been used - // to hold debug info for dead function's local variables. - StringRef FName = DISubprogram(*I).getLinkageName(); - if (FName.empty()) - FName = DISubprogram(*I).getName(); - if (NamedMDNode *LVNMD = M.getNamedMetadata( - "llvm.dbg.lv." + Function::getRealLinkageName(FName))) - LVNMD->eraseFromParent(); - } + GlobalVariableChange = true; } + + // If we found dead subprograms or global variables, replace the current + // subprogram list/global variable list with our new live subprogram/global + // variable list. + if (SubprogramChange) { + // Make sure that 9 is still the index of the subprograms. This is to make + // sure that an assert is hit if the location of the subprogram array + // changes. This is just to make sure that this is updated if such an + // event occurs. + assert(DIC->getNumOperands() >= 10 && + SPs == DIC->getOperand(9) && + "DICompileUnits is expected to store Subprograms in operand " + "9."); + DIC->replaceOperandWith(9, MDNode::get(C, LiveSubprograms)); + Changed = true; + } + + if (GlobalVariableChange) { + // Make sure that 10 is still the index of global variables. This is to + // make sure that an assert is hit if the location of the subprogram array + // changes. This is just to make sure that this index is updated if such + // an event occurs. + assert(DIC->getNumOperands() >= 11 && + GVs == DIC->getOperand(10) && + "DICompileUnits is expected to store Global Variables in operand " + "10."); + DIC->replaceOperandWith(10, MDNode::get(C, LiveGlobalVariables)); + Changed = true; + } + + // Reset lists for the next iteration. + LiveSubprograms.clear(); + LiveGlobalVariables.clear(); } return Changed; |