Provide utility to extract and use lexical scoping information from machine instructions.
llvm-svn: 137237
diff --git a/llvm/lib/CodeGen/LexicalScopes.cpp b/llvm/lib/CodeGen/LexicalScopes.cpp
new file mode 100644
index 0000000..2276004
--- /dev/null
+++ b/llvm/lib/CodeGen/LexicalScopes.cpp
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+//===- LexicalScopes.cpp - Collecting lexical scope info ------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements LexicalScopes analysis.
+//
+// This pass collects lexical scope information and maps machine instructions
+// to respective lexical scopes.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "lexicalscopes"
+#include "llvm/CodeGen/LexicalScopes.h"
+#include "llvm/Function.h"
+#include "llvm/Analysis/DebugInfo.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/FormattedStream.h"
+using namespace llvm;
+
+LexicalScopes::~LexicalScopes() {
+ releaseMemory();
+}
+
+/// releaseMemory - release memory.
+void LexicalScopes::releaseMemory() {
+ MF = NULL;
+ CurrentFnLexicalScope = NULL;
+ DeleteContainerSeconds(LexicalScopeMap);
+ DeleteContainerSeconds(AbstractScopeMap);
+ InlinedLexicalScopeMap.clear();
+ AbstractScopesList.clear();
+}
+
+/// initialize - Scan machine function and constuct lexical scope nest.
+void LexicalScopes::initialize(const MachineFunction &Fn) {
+ releaseMemory();
+ MF = &Fn;
+ SmallVector<InsnRange, 4> MIRanges;
+ DenseMap<const MachineInstr *, LexicalScope *> MI2ScopeMap;
+ extractLexicalScopes(MIRanges, MI2ScopeMap);
+ if (CurrentFnLexicalScope) {
+ constructScopeNest(CurrentFnLexicalScope);
+ assignInstructionRanges(MIRanges, MI2ScopeMap);
+ }
+}
+
+/// extractLexicalScopes - Extract instruction ranges for each lexical scopes
+/// for the given machine function.
+void LexicalScopes::
+extractLexicalScopes(SmallVectorImpl<InsnRange> &MIRanges,
+ DenseMap<const MachineInstr *, LexicalScope *> &MI2ScopeMap) {
+
+ // Scan each instruction and create scopes. First build working set of scopes.
+ for (MachineFunction::const_iterator I = MF->begin(), E = MF->end();
+ I != E; ++I) {
+ const MachineInstr *RangeBeginMI = NULL;
+ const MachineInstr *PrevMI = NULL;
+ DebugLoc PrevDL;
+ for (MachineBasicBlock::const_iterator II = I->begin(), IE = I->end();
+ II != IE; ++II) {
+ const MachineInstr *MInsn = II;
+
+ // Check if instruction has valid location information.
+ const DebugLoc MIDL = MInsn->getDebugLoc();
+ if (MIDL.isUnknown()) {
+ PrevMI = MInsn;
+ continue;
+ }
+
+ // If scope has not changed then skip this instruction.
+ if (MIDL == PrevDL) {
+ PrevMI = MInsn;
+ continue;
+ }
+
+ // Ignore DBG_VALUE. It does not contribute to any instruction in output.
+ if (MInsn->isDebugValue())
+ continue;
+
+ if (RangeBeginMI) {
+ // If we have already seen a beginning of an instruction range and
+ // current instruction scope does not match scope of first instruction
+ // in this range then create a new instruction range.
+ InsnRange R(RangeBeginMI, PrevMI);
+ MI2ScopeMap[RangeBeginMI] = getOrCreateLexicalScope(PrevDL);
+ MIRanges.push_back(R);
+ }
+
+ // This is a beginning of a new instruction range.
+ RangeBeginMI = MInsn;
+
+ // Reset previous markers.
+ PrevMI = MInsn;
+ PrevDL = MIDL;
+ }
+
+ // Create last instruction range.
+ if (RangeBeginMI && PrevMI && !PrevDL.isUnknown()) {
+ InsnRange R(RangeBeginMI, PrevMI);
+ MIRanges.push_back(R);
+ MI2ScopeMap[RangeBeginMI] = getOrCreateLexicalScope(PrevDL);
+ }
+ }
+}
+
+/// findLexicalScope - Find lexical scope, either regular or inlined, for the
+/// given DebugLoc. Return NULL if not found.
+LexicalScope *LexicalScopes::findLexicalScope(DebugLoc DL) {
+ MDNode *Scope = NULL;
+ MDNode *IA = NULL;
+ DL.getScopeAndInlinedAt(Scope, IA, MF->getFunction()->getContext());
+ if (!Scope) return NULL;
+ if (IA)
+ return InlinedLexicalScopeMap.lookup(DebugLoc::getFromDILocation(IA));
+ return LexicalScopeMap.lookup(DL.getScope(Scope->getContext()));
+}
+
+/// getOrCreateLexicalScope - Find lexical scope for the given DebugLoc. If
+/// not available then create new lexical scope.
+LexicalScope *LexicalScopes::getOrCreateLexicalScope(DebugLoc DL) {
+ MDNode *Scope = NULL;
+ MDNode *InlinedAt = NULL;
+ DL.getScopeAndInlinedAt(Scope, InlinedAt, MF->getFunction()->getContext());
+ if (InlinedAt) {
+ // Create an abstract scope for inlined function.
+ getOrCreateAbstractScope(Scope);
+ // Create an inlined scope for inlined function.
+ return getOrCreateInlinedScope(Scope, InlinedAt);
+ }
+
+ return getOrCreateRegularScope(Scope);
+}
+
+/// getOrCreateRegularScope - Find or create a regular lexical scope.
+LexicalScope *LexicalScopes::getOrCreateRegularScope(MDNode *Scope) {
+ LexicalScope *WScope = LexicalScopeMap.lookup(Scope);
+ if (WScope)
+ return WScope;
+
+ LexicalScope *Parent = NULL;
+ if (DIDescriptor(Scope).isLexicalBlock())
+ Parent = getOrCreateLexicalScope(DebugLoc::getFromDILexicalBlock(Scope));
+ WScope = new LexicalScope(Parent, DIDescriptor(Scope), NULL, false);
+ LexicalScopeMap.insert(std::make_pair(Scope, WScope));
+ if (!Parent && DIDescriptor(Scope).isSubprogram()
+ && DISubprogram(Scope).describes(MF->getFunction()))
+ CurrentFnLexicalScope = WScope;
+
+ return WScope;
+}
+
+/// getOrCreateInlinedScope - Find or create an inlined lexical scope.
+LexicalScope *LexicalScopes::getOrCreateInlinedScope(MDNode *Scope,
+ MDNode *InlinedAt) {
+ LexicalScope *InlinedScope = LexicalScopeMap.lookup(InlinedAt);
+ if (InlinedScope)
+ return InlinedScope;
+
+ DebugLoc InlinedLoc = DebugLoc::getFromDILocation(InlinedAt);
+ InlinedScope = new LexicalScope(getOrCreateLexicalScope(InlinedLoc),
+ DIDescriptor(Scope), InlinedAt, false);
+ InlinedLexicalScopeMap[InlinedLoc] = InlinedScope;
+ LexicalScopeMap[InlinedAt] = InlinedScope;
+ return InlinedScope;
+}
+
+/// getOrCreateAbstractScope - Find or create an abstract lexical scope.
+LexicalScope *LexicalScopes::getOrCreateAbstractScope(const MDNode *N) {
+ assert(N && "Invalid Scope encoding!");
+
+ LexicalScope *AScope = AbstractScopeMap.lookup(N);
+ if (AScope)
+ return AScope;
+
+ LexicalScope *Parent = NULL;
+ DIDescriptor Scope(N);
+ if (Scope.isLexicalBlock()) {
+ DILexicalBlock DB(N);
+ DIDescriptor ParentDesc = DB.getContext();
+ Parent = getOrCreateAbstractScope(ParentDesc);
+ }
+ AScope = new LexicalScope(Parent, DIDescriptor(N), NULL, true);
+ AbstractScopeMap[N] = AScope;
+ if (DIDescriptor(N).isSubprogram())
+ AbstractScopesList.push_back(AScope);
+ return AScope;
+}
+
+/// constructScopeNest
+void LexicalScopes::constructScopeNest(LexicalScope *Scope) {
+ assert (Scope && "Unable to calculate scop edominance graph!");
+ SmallVector<LexicalScope *, 4> WorkStack;
+ WorkStack.push_back(Scope);
+ unsigned Counter = 0;
+ while (!WorkStack.empty()) {
+ LexicalScope *WS = WorkStack.back();
+ const SmallVector<LexicalScope *, 4> &Children = WS->getChildren();
+ bool visitedChildren = false;
+ for (SmallVector<LexicalScope *, 4>::const_iterator SI = Children.begin(),
+ SE = Children.end(); SI != SE; ++SI) {
+ LexicalScope *ChildScope = *SI;
+ if (!ChildScope->getDFSOut()) {
+ WorkStack.push_back(ChildScope);
+ visitedChildren = true;
+ ChildScope->setDFSIn(++Counter);
+ break;
+ }
+ }
+ if (!visitedChildren) {
+ WorkStack.pop_back();
+ WS->setDFSOut(++Counter);
+ }
+ }
+}
+
+/// assignInstructionRanges - Find ranges of instructions covered by each lexical
+/// scope.
+void LexicalScopes::
+assignInstructionRanges(SmallVectorImpl<InsnRange> &MIRanges,
+ DenseMap<const MachineInstr *, LexicalScope *> &MI2ScopeMap) {
+
+ LexicalScope *PrevLexicalScope = NULL;
+ for (SmallVectorImpl<InsnRange>::const_iterator RI = MIRanges.begin(),
+ RE = MIRanges.end(); RI != RE; ++RI) {
+ const InsnRange &R = *RI;
+ LexicalScope *S = MI2ScopeMap.lookup(R.first);
+ assert (S && "Lost LexicalScope for a machine instruction!");
+ if (PrevLexicalScope && !PrevLexicalScope->dominates(S))
+ PrevLexicalScope->closeInsnRange(S);
+ S->openInsnRange(R.first);
+ S->extendInsnRange(R.second);
+ PrevLexicalScope = S;
+ }
+
+ if (PrevLexicalScope)
+ PrevLexicalScope->closeInsnRange();
+}
+
+/// getMachineBasicBlocks - Populate given set using machine basic blocks which
+/// have machine instructions that belong to lexical scope identified by
+/// DebugLoc.
+void LexicalScopes::
+getMachineBasicBlocks(DebugLoc DL, SmallPtrSet<const MachineBasicBlock*, 4> &MBBs) {
+ MBBs.clear();
+ LexicalScope *Scope = getOrCreateLexicalScope(DL);
+ if (!Scope)
+ return;
+
+ SmallVector<InsnRange, 4> &InsnRanges = Scope->getRanges();
+ for (SmallVector<InsnRange, 4>::iterator I = InsnRanges.begin(),
+ E = InsnRanges.end(); I != E; ++I) {
+ InsnRange &R = *I;
+ MBBs.insert(R.first->getParent());
+ }
+}
+
+/// dominates - Return true if DebugLoc's lexical scope dominates at least one
+/// machine instruction's lexical scope in a given machine basic block.
+bool LexicalScopes::dominates(DebugLoc DL, MachineBasicBlock *MBB) {
+ LexicalScope *Scope = getOrCreateLexicalScope(DL);
+ if (!Scope)
+ return false;
+ bool Result = false;
+ for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end();
+ I != E; ++I) {
+ DebugLoc IDL = I->getDebugLoc();
+ if (IDL.isUnknown())
+ continue;
+ if (LexicalScope *IScope = getOrCreateLexicalScope(IDL))
+ if (Scope->dominates(IScope))
+ return true;
+ }
+ return Result;
+}
+
+/// dump - Print data structures.
+void LexicalScope::dump() const {
+#ifndef NDEBUG
+ raw_ostream &err = dbgs();
+ err.indent(IndentLevel);
+ err << "DFSIn: " << DFSIn << " DFSOut: " << DFSOut << "\n";
+ const MDNode *N = Desc;
+ N->dump();
+ if (AbstractScope)
+ err << "Abstract Scope\n";
+
+ IndentLevel += 2;
+ if (!Children.empty())
+ err << "Children ...\n";
+ for (unsigned i = 0, e = Children.size(); i != e; ++i)
+ if (Children[i] != this)
+ Children[i]->dump();
+
+ IndentLevel -= 2;
+#endif
+}
+
