[llvm-commits] [llvm] r127912 - /llvm/trunk/lib/CodeGen/LiveDebugVariables.cpp
Jakob Stoklund Olesen
stoklund at 2pi.dk
Fri Mar 18 14:42:19 PDT 2011
Author: stoklund
Date: Fri Mar 18 16:42:19 2011
New Revision: 127912
URL: http://llvm.org/viewvc/llvm-project?rev=127912&view=rev
Log:
Extend live debug values down the dominator tree by following copies.
The llvm.dbg.value intrinsic refers to SSA values, not virtual registers, so we
should be able to extend the range of a value by tracking that value through
register copies. This greatly improves the debug value tracking for function
arguments that for some reason are copied to a second virtual register at the
end of the entry block.
We only extend the debug value range where its register is killed. All original
llvm.dbg.value locations are still respected.
Copies from physical registers are ignored. That should not be a problem since
the entry block already adds DBG_VALUE instructions for the virtual registers
holding the function arguments.
Modified:
llvm/trunk/lib/CodeGen/LiveDebugVariables.cpp
Modified: llvm/trunk/lib/CodeGen/LiveDebugVariables.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/LiveDebugVariables.cpp?rev=127912&r1=127911&r2=127912&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/LiveDebugVariables.cpp (original)
+++ llvm/trunk/lib/CodeGen/LiveDebugVariables.cpp Fri Mar 18 16:42:19 2011
@@ -30,6 +30,7 @@
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
@@ -76,6 +77,7 @@
/// held by the same virtual register. The equivalence class is the transitive
/// closure of that relation.
namespace {
+class LDVImpl;
class UserValue {
const MDNode *variable; ///< The debug info variable we are part of.
unsigned offset; ///< Byte offset into variable.
@@ -146,17 +148,31 @@
/// getLocationNo - Return the location number that matches Loc.
unsigned getLocationNo(const MachineOperand &LocMO) {
- if (LocMO.isReg() && LocMO.getReg() == 0)
- return ~0u;
- for (unsigned i = 0, e = locations.size(); i != e; ++i)
- if (LocMO.isIdenticalTo(locations[i]))
- return i;
+ if (LocMO.isReg()) {
+ if (LocMO.getReg() == 0)
+ return ~0u;
+ // For register locations we dont care about use/def and other flags.
+ for (unsigned i = 0, e = locations.size(); i != e; ++i)
+ if (locations[i].isReg() &&
+ locations[i].getReg() == LocMO.getReg() &&
+ locations[i].getSubReg() == LocMO.getSubReg())
+ return i;
+ } else
+ for (unsigned i = 0, e = locations.size(); i != e; ++i)
+ if (LocMO.isIdenticalTo(locations[i]))
+ return i;
locations.push_back(LocMO);
// We are storing a MachineOperand outside a MachineInstr.
locations.back().clearParent();
+ // Don't store def operands.
+ if (locations.back().isReg())
+ locations.back().setIsUse();
return locations.size() - 1;
}
+ /// mapVirtRegs - Ensure that all virtual register locations are mapped.
+ void mapVirtRegs(LDVImpl *LDV);
+
/// addDef - Add a definition point to this value.
void addDef(SlotIndex Idx, const MachineOperand &LocMO) {
// Add a singular (Idx,Idx) -> Loc mapping.
@@ -168,19 +184,36 @@
/// extendDef - Extend the current definition as far as possible down the
/// dominator tree. Stop when meeting an existing def or when leaving the live
/// range of VNI.
+ /// End points where VNI is no longer live are added to Kills.
/// @param Idx Starting point for the definition.
/// @param LocNo Location number to propagate.
/// @param LI Restrict liveness to where LI has the value VNI. May be null.
/// @param VNI When LI is not null, this is the value to restrict to.
+ /// @param Kills Append end points of VNI's live range to Kills.
/// @param LIS Live intervals analysis.
/// @param MDT Dominator tree.
void extendDef(SlotIndex Idx, unsigned LocNo,
LiveInterval *LI, const VNInfo *VNI,
+ SmallVectorImpl<SlotIndex> *Kills,
LiveIntervals &LIS, MachineDominatorTree &MDT);
+ /// addDefsFromCopies - The value in LI/LocNo may be copies to other
+ /// registers. Determine if any of the copies are available at the kill
+ /// points, and add defs if possible.
+ /// @param LI Scan for copies of the value in LI->reg.
+ /// @param LocNo Location number of LI->reg.
+ /// @param Kills Points where the range of LocNo could be extended.
+ /// @param NewDefs Append (Idx, LocNo) of inserted defs here.
+ void addDefsFromCopies(LiveInterval *LI, unsigned LocNo,
+ const SmallVectorImpl<SlotIndex> &Kills,
+ SmallVectorImpl<std::pair<SlotIndex, unsigned> > &NewDefs,
+ MachineRegisterInfo &MRI,
+ LiveIntervals &LIS);
+
/// computeIntervals - Compute the live intervals of all locations after
/// collecting all their def points.
- void computeIntervals(LiveIntervals &LIS, MachineDominatorTree &MDT);
+ void computeIntervals(MachineRegisterInfo &MRI,
+ LiveIntervals &LIS, MachineDominatorTree &MDT);
/// renameRegister - Update locations to rewrite OldReg as NewReg:SubIdx.
void renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx,
@@ -230,9 +263,6 @@
/// lookupVirtReg - Find the EC leader for VirtReg or null.
UserValue *lookupVirtReg(unsigned VirtReg);
- /// mapVirtReg - Map virtual register to an equivalence class.
- void mapVirtReg(unsigned VirtReg, UserValue *EC);
-
/// handleDebugValue - Add DBG_VALUE instruction to our maps.
/// @param MI DBG_VALUE instruction
/// @param Idx Last valid SLotIndex before instruction.
@@ -261,6 +291,9 @@
userVarMap.clear();
}
+ /// mapVirtReg - Map virtual register to an equivalence class.
+ void mapVirtReg(unsigned VirtReg, UserValue *EC);
+
/// renameRegister - Replace all references to OldReg wiht NewReg:SubIdx.
void renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx);
@@ -322,6 +355,13 @@
}
}
+void UserValue::mapVirtRegs(LDVImpl *LDV) {
+ for (unsigned i = 0, e = locations.size(); i != e; ++i)
+ if (locations[i].isReg() &&
+ TargetRegisterInfo::isVirtualRegister(locations[i].getReg()))
+ LDV->mapVirtReg(locations[i].getReg(), this);
+}
+
UserValue *LDVImpl::getUserValue(const MDNode *Var, unsigned Offset,
DebugLoc DL) {
UserValue *&Leader = userVarMap[Var];
@@ -363,14 +403,6 @@
unsigned Offset = MI->getOperand(1).getImm();
const MDNode *Var = MI->getOperand(2).getMetadata();
UserValue *UV = getUserValue(Var, Offset, MI->getDebugLoc());
-
- // If the location is a virtual register, make sure it is mapped.
- if (MI->getOperand(0).isReg()) {
- unsigned Reg = MI->getOperand(0).getReg();
- if (TargetRegisterInfo::isVirtualRegister(Reg))
- mapVirtReg(Reg, UV);
- }
-
UV->addDef(Idx, MI->getOperand(0));
return true;
}
@@ -405,6 +437,7 @@
void UserValue::extendDef(SlotIndex Idx, unsigned LocNo,
LiveInterval *LI, const VNInfo *VNI,
+ SmallVectorImpl<SlotIndex> *Kills,
LiveIntervals &LIS, MachineDominatorTree &MDT) {
SmallVector<SlotIndex, 16> Todo;
Todo.push_back(Idx);
@@ -419,8 +452,11 @@
bool ToEnd = true;
if (LI && VNI) {
LiveRange *Range = LI->getLiveRangeContaining(Start);
- if (!Range || Range->valno != VNI)
+ if (!Range || Range->valno != VNI) {
+ if (Kills)
+ Kills->push_back(Start);
continue;
+ }
if (Range->end < Stop)
Stop = Range->end, ToEnd = false;
}
@@ -438,6 +474,9 @@
// Limited by the next def.
if (I.valid() && I.start() < Stop)
Stop = I.start(), ToEnd = false;
+ // Limited by VNI's live range.
+ else if (!ToEnd && Kills)
+ Kills->push_back(Stop);
if (Start >= Stop)
continue;
@@ -455,7 +494,75 @@
}
void
-UserValue::computeIntervals(LiveIntervals &LIS, MachineDominatorTree &MDT) {
+UserValue::addDefsFromCopies(LiveInterval *LI, unsigned LocNo,
+ const SmallVectorImpl<SlotIndex> &Kills,
+ SmallVectorImpl<std::pair<SlotIndex, unsigned> > &NewDefs,
+ MachineRegisterInfo &MRI, LiveIntervals &LIS) {
+ if (Kills.empty())
+ return;
+ // Don't track copies from physregs, there are too many uses.
+ if (!TargetRegisterInfo::isVirtualRegister(LI->reg))
+ return;
+
+ // Collect all the (vreg, valno) pairs that are copies of LI.
+ SmallVector<std::pair<LiveInterval*, const VNInfo*>, 8> CopyValues;
+ for (MachineRegisterInfo::use_nodbg_iterator
+ UI = MRI.use_nodbg_begin(LI->reg),
+ UE = MRI.use_nodbg_end(); UI != UE; ++UI) {
+ // Copies of the full value.
+ if (UI.getOperand().getSubReg() || !UI->isCopy())
+ continue;
+ MachineInstr *MI = &*UI;
+ unsigned DstReg = MI->getOperand(0).getReg();
+
+ // Is LocNo extended to reach this copy? If not, another def may be blocking
+ // it, or we are looking at a wrong value of LI.
+ SlotIndex Idx = LIS.getInstructionIndex(MI);
+ LocMap::iterator I = locInts.find(Idx.getUseIndex());
+ if (!I.valid() || I.value() != LocNo)
+ continue;
+
+ if (!LIS.hasInterval(DstReg))
+ continue;
+ LiveInterval *DstLI = &LIS.getInterval(DstReg);
+ const VNInfo *DstVNI = DstLI->getVNInfoAt(Idx.getDefIndex());
+ assert(DstVNI && DstVNI->def == Idx.getDefIndex() && "Bad copy value");
+ CopyValues.push_back(std::make_pair(DstLI, DstVNI));
+ }
+
+ if (CopyValues.empty())
+ return;
+
+ DEBUG(dbgs() << "Got " << CopyValues.size() << " copies of " << *LI << '\n');
+
+ // Try to add defs of the copied values for each kill point.
+ for (unsigned i = 0, e = Kills.size(); i != e; ++i) {
+ SlotIndex Idx = Kills[i];
+ for (unsigned j = 0, e = CopyValues.size(); j != e; ++j) {
+ LiveInterval *DstLI = CopyValues[j].first;
+ const VNInfo *DstVNI = CopyValues[j].second;
+ if (DstLI->getVNInfoAt(Idx) != DstVNI)
+ continue;
+ // Check that there isn't already a def at Idx
+ LocMap::iterator I = locInts.find(Idx);
+ if (I.valid() && I.start() <= Idx)
+ continue;
+ DEBUG(dbgs() << "Kill at " << Idx << " covered by valno #"
+ << DstVNI->id << " in " << *DstLI << '\n');
+ MachineInstr *CopyMI = LIS.getInstructionFromIndex(DstVNI->def);
+ assert(CopyMI && CopyMI->isCopy() && "Bad copy value");
+ unsigned LocNo = getLocationNo(CopyMI->getOperand(0));
+ I.insert(Idx, Idx.getNextSlot(), LocNo);
+ NewDefs.push_back(std::make_pair(Idx, LocNo));
+ break;
+ }
+ }
+}
+
+void
+UserValue::computeIntervals(MachineRegisterInfo &MRI,
+ LiveIntervals &LIS,
+ MachineDominatorTree &MDT) {
SmallVector<std::pair<SlotIndex, unsigned>, 16> Defs;
// Collect all defs to be extended (Skipping undefs).
@@ -463,7 +570,8 @@
if (I.value() != ~0u)
Defs.push_back(std::make_pair(I.start(), I.value()));
- for (unsigned i = 0, e = Defs.size(); i != e; ++i) {
+ // Extend all defs, and possibly add new ones along the way.
+ for (unsigned i = 0; i != Defs.size(); ++i) {
SlotIndex Idx = Defs[i].first;
unsigned LocNo = Defs[i].second;
const MachineOperand &Loc = locations[LocNo];
@@ -472,9 +580,11 @@
if (Loc.isReg() && LIS.hasInterval(Loc.getReg())) {
LiveInterval *LI = &LIS.getInterval(Loc.getReg());
const VNInfo *VNI = LI->getVNInfoAt(Idx);
- extendDef(Idx, LocNo, LI, VNI, LIS, MDT);
+ SmallVector<SlotIndex, 16> Kills;
+ extendDef(Idx, LocNo, LI, VNI, &Kills, LIS, MDT);
+ addDefsFromCopies(LI, LocNo, Kills, Defs, MRI, LIS);
} else
- extendDef(Idx, LocNo, 0, 0, LIS, MDT);
+ extendDef(Idx, LocNo, 0, 0, 0, LIS, MDT);
}
// Finally, erase all the undefs.
@@ -486,8 +596,10 @@
}
void LDVImpl::computeIntervals() {
- for (unsigned i = 0, e = userValues.size(); i != e; ++i)
- userValues[i]->computeIntervals(*LIS, *MDT);
+ for (unsigned i = 0, e = userValues.size(); i != e; ++i) {
+ userValues[i]->computeIntervals(MF->getRegInfo(), *LIS, *MDT);
+ userValues[i]->mapVirtRegs(this);
+ }
}
bool LDVImpl::runOnMachineFunction(MachineFunction &mf) {
More information about the llvm-commits
mailing list