Move logic for calculating DBG_VALUE history map into separate file/class.

Summary: No functionality change.

Test Plan: llvm regression test suite.

Reviewers: dblaikie

Reviewed By: dblaikie

Subscribers: echristo, llvm-commits

Differential Revision: http://reviews.llvm.org/D3573

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207708 91177308-0d34-0410-b5e6-96231b3b80d8

5 files changed, 207 insertions, 124 deletions

diff --git a/lib/CodeGen/AsmPrinter/CMakeLists.txt b/lib/CodeGen/AsmPrinter/CMakeLists.txt
index a9afc84e84..b4ef185b0a 100644
--- a/lib/CodeGen/AsmPrinter/CMakeLists.txt
+++ b/lib/CodeGen/AsmPrinter/CMakeLists.txt
@@ -4,6 +4,7 @@ add_llvm_library(LLVMAsmPrinter
   AsmPrinter.cpp
   AsmPrinterDwarf.cpp
   AsmPrinterInlineAsm.cpp
+  DbgValueHistoryCalculator.cpp
   DIE.cpp
   DIEHash.cpp
   DwarfAccelTable.cpp
diff --git a/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp b/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp
new file mode 100644
index 0000000000..cae3e916cd
--- /dev/null
+++ b/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp
@@ -0,0 +1,152 @@
+//===-- llvm/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp -------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "DbgValueHistoryCalculator.h"
+#include "llvm/CodeGen/MachineBasicBlock.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+
+#define DEBUG_TYPE "dwarfdebug"
+
+namespace llvm {
+
+// Return true if debug value, encoded by DBG_VALUE instruction, is in a
+// defined reg.
+static bool isDbgValueInDefinedReg(const MachineInstr *MI) {
+  assert(MI->isDebugValue() && "Invalid DBG_VALUE machine instruction!");
+  return MI->getNumOperands() == 3 && MI->getOperand(0).isReg() &&
+         MI->getOperand(0).getReg() &&
+         (MI->getOperand(1).isImm() ||
+          (MI->getOperand(1).isReg() && MI->getOperand(1).getReg() == 0U));
+}
+
+void calculateDbgValueHistory(const MachineFunction *MF,
+                              const TargetRegisterInfo *TRI,
+                              DbgValueHistoryMap &Result) {
+  // LiveUserVar - Map physreg numbers to the MDNode they contain.
+  std::vector<const MDNode *> LiveUserVar(TRI->getNumRegs());
+
+  for (MachineFunction::const_iterator I = MF->begin(), E = MF->end(); I != E;
+       ++I) {
+    bool AtBlockEntry = true;
+    for (MachineBasicBlock::const_iterator II = I->begin(), IE = I->end();
+         II != IE; ++II) {
+      const MachineInstr *MI = II;
+
+      if (MI->isDebugValue()) {
+        assert(MI->getNumOperands() > 1 && "Invalid machine instruction!");
+
+        // Keep track of user variables.
+        const MDNode *Var = MI->getDebugVariable();
+
+        // Variable is in a register, we need to check for clobbers.
+        if (isDbgValueInDefinedReg(MI))
+          LiveUserVar[MI->getOperand(0).getReg()] = Var;
+
+        // Check the history of this variable.
+        SmallVectorImpl<const MachineInstr *> &History = Result[Var];
+        if (!History.empty()) {
+          // We have seen this variable before. Try to coalesce DBG_VALUEs.
+          const MachineInstr *Prev = History.back();
+          if (Prev->isDebugValue()) {
+            // Coalesce identical entries at the end of History.
+            if (History.size() >= 2 &&
+                Prev->isIdenticalTo(History[History.size() - 2])) {
+              DEBUG(dbgs() << "Coalescing identical DBG_VALUE entries:\n"
+                           << "\t" << *Prev << "\t"
+                           << *History[History.size() - 2] << "\n");
+              History.pop_back();
+            }
+
+            // Terminate old register assignments that don't reach MI;
+            MachineFunction::const_iterator PrevMBB = Prev->getParent();
+            if (PrevMBB != I && (!AtBlockEntry || std::next(PrevMBB) != I) &&
+                isDbgValueInDefinedReg(Prev)) {
+              // Previous register assignment needs to terminate at the end of
+              // its basic block.
+              MachineBasicBlock::const_iterator LastMI =
+                  PrevMBB->getLastNonDebugInstr();
+              if (LastMI == PrevMBB->end()) {
+                // Drop DBG_VALUE for empty range.
+                DEBUG(dbgs() << "Dropping DBG_VALUE for empty range:\n"
+                             << "\t" << *Prev << "\n");
+                History.pop_back();
+              } else if (std::next(PrevMBB) != PrevMBB->getParent()->end())
+                // Terminate after LastMI.
+                History.push_back(LastMI);
+            }
+          }
+        }
+        History.push_back(MI);
+      } else {
+        // Not a DBG_VALUE instruction.
+        if (!MI->isPosition())
+          AtBlockEntry = false;
+
+        // Check if the instruction clobbers any registers with debug vars.
+        for (const MachineOperand &MO : MI->operands()) {
+          if (!MO.isReg() || !MO.isDef() || !MO.getReg())
+            continue;
+          for (MCRegAliasIterator AI(MO.getReg(), TRI, true); AI.isValid();
+               ++AI) {
+            unsigned Reg = *AI;
+            const MDNode *Var = LiveUserVar[Reg];
+            if (!Var)
+              continue;
+            // Reg is now clobbered.
+            LiveUserVar[Reg] = nullptr;
+
+            // Was MD last defined by a DBG_VALUE referring to Reg?
+            auto HistI = Result.find(Var);
+            if (HistI == Result.end())
+              continue;
+            SmallVectorImpl<const MachineInstr *> &History = HistI->second;
+            if (History.empty())
+              continue;
+            const MachineInstr *Prev = History.back();
+            // Sanity-check: Register assignments are terminated at the end of
+            // their block.
+            if (!Prev->isDebugValue() || Prev->getParent() != MI->getParent())
+              continue;
+            // Is the variable still in Reg?
+            if (!isDbgValueInDefinedReg(Prev) ||
+                Prev->getOperand(0).getReg() != Reg)
+              continue;
+            // Var is clobbered. Make sure the next instruction gets a label.
+            History.push_back(MI);
+          }
+        }
+      }
+    }
+  }
+
+  // Make sure the final register assignments are terminated.
+  for (auto &I : Result) {
+    SmallVectorImpl<const MachineInstr *> &History = I.second;
+    if (History.empty())
+      continue;
+
+    const MachineInstr *Prev = History.back();
+    if (Prev->isDebugValue() && isDbgValueInDefinedReg(Prev)) {
+      const MachineBasicBlock *PrevMBB = Prev->getParent();
+      MachineBasicBlock::const_iterator LastMI =
+          PrevMBB->getLastNonDebugInstr();
+      if (LastMI == PrevMBB->end())
+        // Drop DBG_VALUE for empty range.
+        History.pop_back();
+      else if (PrevMBB != &PrevMBB->getParent()->back()) {
+        // Terminate after LastMI.
+        History.push_back(LastMI);
+      }
+    }
+  }
+}
+
+}
diff --git a/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.h b/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.h
new file mode 100644
index 0000000000..d919522f9b
--- /dev/null
+++ b/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.h
@@ -0,0 +1,34 @@
+//===-- llvm/CodeGen/AsmPrinter/DbgValueHistoryCalculator.h ----*- C++ -*--===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef CODEGEN_ASMPRINTER_DBGVALUEHISTORYCALCULATOR_H_
+#define CODEGEN_ASMPRINTER_DBGVALUEHISTORYCALCULATOR_H_
+
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SmallVector.h"
+
+namespace llvm {
+
+class MachineFunction;
+class MachineInstr;
+class MDNode;
+class TargetRegisterInfo;
+
+// For each user variable, keep a list of DBG_VALUE instructions in order.
+// The list can also contain normal instructions that clobber the previous
+// DBG_VALUE.
+typedef DenseMap<const MDNode *, SmallVector<const MachineInstr *, 4>>
+DbgValueHistoryMap;
+
+void calculateDbgValueHistory(const MachineFunction *MF,
+                              const TargetRegisterInfo *TRI,
+                              DbgValueHistoryMap &Result);
+}
+
+#endif
diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index d9ef6c0428..e0bc4bd723 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -1158,16 +1158,6 @@ void DwarfDebug::collectVariableInfoFromMMITable(
   }
 }
 
-// Return true if debug value, encoded by DBG_VALUE instruction, is in a
-// defined reg.
-static bool isDbgValueInDefinedReg(const MachineInstr *MI) {
-  assert(MI->isDebugValue() && "Invalid DBG_VALUE machine instruction!");
-  return MI->getNumOperands() == 3 && MI->getOperand(0).isReg() &&
-         MI->getOperand(0).getReg() &&
-         (MI->getOperand(1).isImm() ||
-          (MI->getOperand(1).isReg() && MI->getOperand(1).getReg() == 0U));
-}
-
 // Get .debug_loc entry for the instruction range starting at MI.
 static DebugLocEntry::Value getDebugLocValue(const MachineInstr *MI) {
   const MDNode *Var = MI->getDebugVariable();
@@ -1449,138 +1439,47 @@ void DwarfDebug::beginFunction(const MachineFunction *MF) {
   // Assumes in correct section after the entry point.
   Asm->OutStreamer.EmitLabel(FunctionBeginSym);
 
-  const TargetRegisterInfo *TRI = Asm->TM.getRegisterInfo();
-  // LiveUserVar - Map physreg numbers to the MDNode they contain.
-  std::vector<const MDNode *> LiveUserVar(TRI->getNumRegs());
-
+  // Collect user variables, find the end of the prologue.
   for (MachineFunction::const_iterator I = MF->begin(), E = MF->end(); I != E;
        ++I) {
-    bool AtBlockEntry = true;
     for (MachineBasicBlock::const_iterator II = I->begin(), IE = I->end();
          II != IE; ++II) {
       const MachineInstr *MI = II;
-
       if (MI->isDebugValue()) {
         assert(MI->getNumOperands() > 1 && "Invalid machine instruction!");
-
-        // Keep track of user variables.
+        // Keep track of user variables in order of appearance. Store the set
+        // of variables we've already seen as a set of keys in DbgValues.
         const MDNode *Var = MI->getDebugVariable();
-
-        // Variable is in a register, we need to check for clobbers.
-        if (isDbgValueInDefinedReg(MI))
-          LiveUserVar[MI->getOperand(0).getReg()] = Var;
-
-        // Check the history of this variable.
-        SmallVectorImpl<const MachineInstr *> &History = DbgValues[Var];
-        if (History.empty()) {
+        auto IterPair = DbgValues.insert(
+            std::make_pair(Var, SmallVector<const MachineInstr *, 4>()));
+        if (IterPair.second)
           UserVariables.push_back(Var);
-          // The first mention of a function argument gets the FunctionBeginSym
-          // label, so arguments are visible when breaking at function entry.
-          DIVariable DV(Var);
-          if (DV.isVariable() && DV.getTag() == dwarf::DW_TAG_arg_variable &&
-              getDISubprogram(DV.getContext()).describes(MF->getFunction()))
-            LabelsBeforeInsn[MI] = FunctionBeginSym;
-        } else {
-          // We have seen this variable before. Try to coalesce DBG_VALUEs.
-          const MachineInstr *Prev = History.back();
-          if (Prev->isDebugValue()) {
-            // Coalesce identical entries at the end of History.
-            if (History.size() >= 2 &&
-                Prev->isIdenticalTo(History[History.size() - 2])) {
-              DEBUG(dbgs() << "Coalescing identical DBG_VALUE entries:\n"
-                           << "\t" << *Prev << "\t"
-                           << *History[History.size() - 2] << "\n");
-              History.pop_back();
-            }
-
-            // Terminate old register assignments that don't reach MI;
-            MachineFunction::const_iterator PrevMBB = Prev->getParent();
-            if (PrevMBB != I && (!AtBlockEntry || std::next(PrevMBB) != I) &&
-                isDbgValueInDefinedReg(Prev)) {
-              // Previous register assignment needs to terminate at the end of
-              // its basic block.
-              MachineBasicBlock::const_iterator LastMI =
-                  PrevMBB->getLastNonDebugInstr();
-              if (LastMI == PrevMBB->end()) {
-                // Drop DBG_VALUE for empty range.
-                DEBUG(dbgs() << "Dropping DBG_VALUE for empty range:\n"
-                             << "\t" << *Prev << "\n");
-                History.pop_back();
-              } else if (std::next(PrevMBB) != PrevMBB->getParent()->end())
-                // Terminate after LastMI.
-                History.push_back(LastMI);
-            }
-          }
-        }
-        History.push_back(MI);
       } else {
-        // Not a DBG_VALUE instruction.
-        if (!MI->isPosition())
-          AtBlockEntry = false;
-
         // First known non-DBG_VALUE and non-frame setup location marks
         // the beginning of the function body.
         if (!MI->getFlag(MachineInstr::FrameSetup) &&
             (PrologEndLoc.isUnknown() && !MI->getDebugLoc().isUnknown()))
           PrologEndLoc = MI->getDebugLoc();
-
-        // Check if the instruction clobbers any registers with debug vars.
-        for (const MachineOperand &MO : MI->operands()) {
-          if (!MO.isReg() || !MO.isDef() || !MO.getReg())
-            continue;
-          for (MCRegAliasIterator AI(MO.getReg(), TRI, true); AI.isValid();
-               ++AI) {
-            unsigned Reg = *AI;
-            const MDNode *Var = LiveUserVar[Reg];
-            if (!Var)
-              continue;
-            // Reg is now clobbered.
-            LiveUserVar[Reg] = nullptr;
-
-            // Was MD last defined by a DBG_VALUE referring to Reg?
-            DbgValueHistoryMap::iterator HistI = DbgValues.find(Var);
-            if (HistI == DbgValues.end())
-              continue;
-            SmallVectorImpl<const MachineInstr *> &History = HistI->second;
-            if (History.empty())
-              continue;
-            const MachineInstr *Prev = History.back();
-            // Sanity-check: Register assignments are terminated at the end of
-            // their block.
-            if (!Prev->isDebugValue() || Prev->getParent() != MI->getParent())
-              continue;
-            // Is the variable still in Reg?
-            if (!isDbgValueInDefinedReg(Prev) ||
-                Prev->getOperand(0).getReg() != Reg)
-              continue;
-            // Var is clobbered. Make sure the next instruction gets a label.
-            History.push_back(MI);
-          }
-        }
       }
     }
   }
 
+  // Calculate history for local variables.
+  calculateDbgValueHistory(MF, Asm->TM.getRegisterInfo(), DbgValues);
+
+  // Request labels for the full history.
   for (auto &I : DbgValues) {
-    SmallVectorImpl<const MachineInstr *> &History = I.second;
+    const SmallVectorImpl<const MachineInstr *> &History = I.second;
     if (History.empty())
       continue;
 
-    // Make sure the final register assignments are terminated.
-    const MachineInstr *Prev = History.back();
-    if (Prev->isDebugValue() && isDbgValueInDefinedReg(Prev)) {
-      const MachineBasicBlock *PrevMBB = Prev->getParent();
-      MachineBasicBlock::const_iterator LastMI =
-          PrevMBB->getLastNonDebugInstr();
-      if (LastMI == PrevMBB->end())
-        // Drop DBG_VALUE for empty range.
-        History.pop_back();
-      else if (PrevMBB != &PrevMBB->getParent()->back()) {
-        // Terminate after LastMI.
-        History.push_back(LastMI);
-      }
-    }
-    // Request labels for the full history.
+    // The first mention of a function argument gets the FunctionBeginSym
+    // label, so arguments are visible when breaking at function entry.
+    DIVariable DV(I.first);
+    if (DV.isVariable() && DV.getTag() == dwarf::DW_TAG_arg_variable &&
+        getDISubprogram(DV.getContext()).describes(MF->getFunction()))
+      LabelsBeforeInsn[History.front()] = FunctionBeginSym;
+
     for (const MachineInstr *MI : History) {
       if (MI->isDebugValue())
         requestLabelBeforeInsn(MI);
diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.h b/lib/CodeGen/AsmPrinter/DwarfDebug.h
index 16a314bdb3..e0d7ef4d89 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -17,6 +17,7 @@
 #include "DwarfFile.h"
 #include "AsmPrinterHandler.h"
 #include "DIE.h"
+#include "DbgValueHistoryCalculator.h"
 #include "DebugLocEntry.h"
 #include "DebugLocList.h"
 #include "DwarfAccelTable.h"
@@ -222,11 +223,7 @@ class DwarfDebug : public AsmPrinterHandler {
   // appearance.
   SmallVector<const MDNode *, 8> UserVariables;
 
-  // For each user variable, keep a list of DBG_VALUE instructions in order.
-  // The list can also contain normal instructions that clobber the previous
-  // DBG_VALUE.
-  typedef DenseMap<const MDNode *, SmallVector<const MachineInstr *, 4> >
-  DbgValueHistoryMap;
+  // History of DBG_VALUE and clobber instructions for each user variable.
   DbgValueHistoryMap DbgValues;
 
   // Previous instruction's location information. This is used to determine