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https://github.com/RPCS3/llvm-mirror.git
synced 2024-11-26 12:43:36 +01:00
[DebugInstrRef] Convert DBG_INSTR_REFs into variable locations
Handle DBG_INSTR_REF instructions in LiveDebugValues, to determine and propagate variable locations. The logic is fairly straight forwards: Collect a map of debug-instruction-number to the machine value numbers generated in the first walk through the function. When building the variable value transfer function and we see a DBG_INSTR_REF, look up the instruction it refers to, and pick the machine value number it generates, That's it; the rest of LiveDebugValues continues as normal. Awkwardly, there are two kinds of instruction numbering happening here: the offset into the block (which is how machine value numbers are determined), and the numbers that we label instructions with when generating DBG_INSTR_REFs. I've also restructured the TransferTracker redefVar code a little, to separate some DBG_VALUE specific operations into its own method. The changes around redefVar should be largely NFC, while allowing DBG_INSTR_REFs to specify a value number rather than just a location. Differential Revision: https://reviews.llvm.org/D85771
This commit is contained in:
Jeremy Morse
parent
45a7f324f8
commit
7b0445fed2
@ -900,12 +900,11 @@ public:
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public:
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VLocTracker() {}
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void defVar(const MachineInstr &MI, Optional<ValueIDNum> ID) {
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// XXX skipping overlapping fragments for now.
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assert(MI.isDebugValue());
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void defVar(const MachineInstr &MI, const DbgValueProperties &Properties,
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Optional<ValueIDNum> ID) {
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assert(MI.isDebugValue() || MI.isDebugRef());
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DebugVariable Var(MI.getDebugVariable(), MI.getDebugExpression(),
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MI.getDebugLoc()->getInlinedAt());
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DbgValueProperties Properties(MI);
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DbgValue Rec = (ID) ? DbgValue(*ID, Properties, DbgValue::Def)
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: DbgValue(Properties, DbgValue::Undef);
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@ -917,7 +916,7 @@ public:
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}
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void defVar(const MachineInstr &MI, const MachineOperand &MO) {
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// XXX skipping overlapping fragments for now.
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// Only DBG_VALUEs can define constant-valued variables.
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assert(MI.isDebugValue());
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DebugVariable Var(MI.getDebugVariable(), MI.getDebugExpression(),
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MI.getDebugLoc()->getInlinedAt());
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@ -1083,50 +1082,64 @@ public:
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}
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}
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/// Handle a DBG_VALUE within a block. Terminate the variables current
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/// location, and record the value its DBG_VALUE refers to, so that we can
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/// detect location transfers later on.
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/// Change a variable value after encountering a DBG_VALUE inside a block.
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void redefVar(const MachineInstr &MI) {
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DebugVariable Var(MI.getDebugVariable(), MI.getDebugExpression(),
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MI.getDebugLoc()->getInlinedAt());
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DbgValueProperties Properties(MI);
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const MachineOperand &MO = MI.getOperand(0);
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// Erase any previous location,
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auto It = ActiveVLocs.find(Var);
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if (It != ActiveVLocs.end()) {
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ActiveMLocs[It->second.Loc].erase(Var);
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}
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// Insert a new variable location. Ignore non-register locations, we don't
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// transfer those, and can't currently describe spill locs independently of
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// regs.
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// (This is because a spill location is a DBG_VALUE of the stack pointer).
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// Ignore non-register locations, we don't transfer those.
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if (!MO.isReg() || MO.getReg() == 0) {
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if (It != ActiveVLocs.end())
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auto It = ActiveVLocs.find(Var);
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if (It != ActiveVLocs.end()) {
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ActiveMLocs[It->second.Loc].erase(Var);
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ActiveVLocs.erase(It);
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}
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return;
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}
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Register Reg = MO.getReg();
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LocIdx MLoc = MTracker->getRegMLoc(Reg);
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DbgValueProperties Properties(MI);
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LocIdx NewLoc = MTracker->getRegMLoc(Reg);
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redefVar(MI, Properties, NewLoc);
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}
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/// Handle a change in variable location within a block. Terminate the
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/// variables current location, and record the value it now refers to, so
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/// that we can detect location transfers later on.
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void redefVar(const MachineInstr &MI, const DbgValueProperties &Properties,
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Optional<LocIdx> OptNewLoc) {
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DebugVariable Var(MI.getDebugVariable(), MI.getDebugExpression(),
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MI.getDebugLoc()->getInlinedAt());
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// Erase any previous location,
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auto It = ActiveVLocs.find(Var);
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if (It != ActiveVLocs.end())
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ActiveMLocs[It->second.Loc].erase(Var);
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// If there _is_ no new location, all we had to do was erase.
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if (!OptNewLoc)
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return;
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LocIdx NewLoc = *OptNewLoc;
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// Check whether our local copy of values-by-location in #VarLocs is out of
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// date. Wipe old tracking data for the location if it's been clobbered in
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// the meantime.
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if (MTracker->getNumAtPos(MLoc) != VarLocs[MLoc.asU64()]) {
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for (auto &P : ActiveMLocs[MLoc.asU64()]) {
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if (MTracker->getNumAtPos(NewLoc) != VarLocs[NewLoc.asU64()]) {
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for (auto &P : ActiveMLocs[NewLoc]) {
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ActiveVLocs.erase(P);
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}
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ActiveMLocs[MLoc].clear();
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VarLocs[MLoc.asU64()] = MTracker->getNumAtPos(MLoc);
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ActiveMLocs[NewLoc.asU64()].clear();
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VarLocs[NewLoc.asU64()] = MTracker->getNumAtPos(NewLoc);
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}
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ActiveMLocs[MLoc].insert(Var);
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ActiveMLocs[NewLoc].insert(Var);
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if (It == ActiveVLocs.end()) {
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ActiveVLocs.insert(std::make_pair(Var, LocAndProperties{MLoc, Properties}));
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ActiveVLocs.insert(
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std::make_pair(Var, LocAndProperties{NewLoc, Properties}));
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} else {
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It->second.Loc = MLoc;
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It->second.Loc = NewLoc;
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It->second.Properties = Properties;
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}
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}
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@ -1272,6 +1285,13 @@ private:
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DenseMap<MachineBasicBlock *, unsigned int> BBToOrder;
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DenseMap<unsigned, unsigned> BBNumToRPO;
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/// Pair of MachineInstr, and its 1-based offset into the containing block.
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typedef std::pair<const MachineInstr *, unsigned> InstAndNum;
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/// Map from debug instruction number to the MachineInstr labelled with that
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/// number, and its location within the function. Used to transform
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/// instruction numbers in DBG_INSTR_REFs into machine value numbers.
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std::map<uint64_t, InstAndNum> DebugInstrNumToInstr;
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// Map of overlapping variable fragments.
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OverlapMap OverlapFragments;
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VarToFragments SeenFragments;
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@ -1304,6 +1324,10 @@ private:
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/// \returns true if MI was recognized and processed.
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bool transferDebugValue(const MachineInstr &MI);
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/// Examines whether \p MI is a DBG_INSTR_REF and notifies trackers.
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/// \returns true if MI was recognized and processed.
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bool transferDebugInstrRef(MachineInstr &MI);
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/// Examines whether \p MI is copy instruction, and notifies trackers.
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/// \returns true if MI was recognized and processed.
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bool transferRegisterCopy(MachineInstr &MI);
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@ -1497,6 +1521,7 @@ bool InstrRefBasedLDV::transferDebugValue(const MachineInstr &MI) {
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"Expected inlined-at fields to agree");
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DebugVariable V(Var, Expr, InlinedAt);
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DbgValueProperties Properties(MI);
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// If there are no instructions in this lexical scope, do no location tracking
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// at all, this variable shouldn't get a legitimate location range.
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@ -1519,9 +1544,9 @@ bool InstrRefBasedLDV::transferDebugValue(const MachineInstr &MI) {
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// Feed defVar the new variable location, or if this is a
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// DBG_VALUE $noreg, feed defVar None.
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if (MO.getReg())
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VTracker->defVar(MI, MTracker->readReg(MO.getReg()));
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VTracker->defVar(MI, Properties, MTracker->readReg(MO.getReg()));
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else
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VTracker->defVar(MI, None);
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VTracker->defVar(MI, Properties, None);
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} else if (MI.getOperand(0).isImm() || MI.getOperand(0).isFPImm() ||
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MI.getOperand(0).isCImm()) {
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VTracker->defVar(MI, MI.getOperand(0));
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@ -1535,6 +1560,116 @@ bool InstrRefBasedLDV::transferDebugValue(const MachineInstr &MI) {
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return true;
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}
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bool InstrRefBasedLDV::transferDebugInstrRef(MachineInstr &MI) {
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if (!MI.isDebugRef())
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return false;
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// Only handle this instruction when we are building the variable value
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// transfer function.
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if (!VTracker)
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return false;
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unsigned InstNo = MI.getOperand(0).getImm();
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unsigned OpNo = MI.getOperand(1).getImm();
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const DILocalVariable *Var = MI.getDebugVariable();
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const DIExpression *Expr = MI.getDebugExpression();
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const DILocation *DebugLoc = MI.getDebugLoc();
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const DILocation *InlinedAt = DebugLoc->getInlinedAt();
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assert(Var->isValidLocationForIntrinsic(DebugLoc) &&
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"Expected inlined-at fields to agree");
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DebugVariable V(Var, Expr, InlinedAt);
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auto *Scope = LS.findLexicalScope(MI.getDebugLoc().get());
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if (Scope == nullptr)
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return true; // Handled by doing nothing. This variable is never in scope.
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const MachineFunction &MF = *MI.getParent()->getParent();
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// Various optimizations may have happened to the value during codegen,
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// recorded in the value substitution table. Apply any substitutions to
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// the instruction / operand number in this DBG_INSTR_REF.
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auto Sub = MF.DebugValueSubstitutions.find(std::make_pair(InstNo, OpNo));
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while (Sub != MF.DebugValueSubstitutions.end()) {
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InstNo = Sub->second.first;
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OpNo = Sub->second.second;
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Sub = MF.DebugValueSubstitutions.find(std::make_pair(InstNo, OpNo));
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}
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// Default machine value number is <None> -- if no instruction defines
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// the corresponding value, it must have been optimized out.
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Optional<ValueIDNum> NewID = None;
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// Try to lookup the instruction number, and find the machine value number
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// that it defines.
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auto InstrIt = DebugInstrNumToInstr.find(InstNo);
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if (InstrIt != DebugInstrNumToInstr.end()) {
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const MachineInstr &TargetInstr = *InstrIt->second.first;
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uint64_t BlockNo = TargetInstr.getParent()->getNumber();
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// Pick out the designated operand.
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assert(OpNo < TargetInstr.getNumOperands());
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const MachineOperand &MO = TargetInstr.getOperand(OpNo);
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// Today, this can only be a register.
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assert(MO.isReg() && MO.isDef());
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unsigned LocID = MTracker->getLocID(MO.getReg(), false);
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LocIdx L = MTracker->LocIDToLocIdx[LocID];
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NewID = ValueIDNum(BlockNo, InstrIt->second.second, L);
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}
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// We, we have a value number or None. Tell the variable value tracker about
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// it. The rest of this LiveDebugValues implementation acts exactly the same
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// for DBG_INSTR_REFs as DBG_VALUEs (just, the former can refer to values that
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// aren't immediately available).
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DbgValueProperties Properties(Expr, false);
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VTracker->defVar(MI, Properties, NewID);
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// If we're on the final pass through the function, decompose this INSTR_REF
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// into a plain DBG_VALUE.
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if (!TTracker)
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return true;
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// Pick a location for the machine value number, if such a location exists.
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// (This information could be stored in TransferTracker to make it faster).
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Optional<LocIdx> FoundLoc = None;
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for (auto Location : MTracker->locations()) {
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LocIdx CurL = Location.Idx;
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ValueIDNum ID = MTracker->LocIdxToIDNum[CurL];
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if (NewID && ID == NewID) {
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// If this is the first location with that value, pick it. Otherwise,
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// consider whether it's a "longer term" location.
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if (!FoundLoc) {
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FoundLoc = CurL;
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continue;
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}
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if (MTracker->isSpill(CurL))
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FoundLoc = CurL; // Spills are a longer term location.
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else if (!MTracker->isSpill(*FoundLoc) &&
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!MTracker->isSpill(CurL) &&
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!isCalleeSaved(*FoundLoc) &&
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isCalleeSaved(CurL))
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FoundLoc = CurL; // Callee saved regs are longer term than normal.
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}
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}
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// Tell transfer tracker that the variable value has changed.
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TTracker->redefVar(MI, Properties, FoundLoc);
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// Produce a DBG_VALUE representing what this DBG_INSTR_REF meant.
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// This DBG_VALUE is potentially a $noreg / undefined location, if
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// FoundLoc is None.
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// (XXX -- could morph the DBG_INSTR_REF in the future).
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MachineInstr *DbgMI = MTracker->emitLoc(FoundLoc, V, Properties);
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TTracker->PendingDbgValues.push_back(DbgMI);
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TTracker->flushDbgValues(MI.getIterator(), nullptr);
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return true;
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}
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void InstrRefBasedLDV::transferRegisterDef(MachineInstr &MI) {
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// Meta Instructions do not affect the debug liveness of any register they
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// define.
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@ -1916,6 +2051,8 @@ void InstrRefBasedLDV::process(MachineInstr &MI) {
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// definitions.
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if (transferDebugValue(MI))
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return;
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if (transferDebugInstrRef(MI))
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return;
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if (transferRegisterCopy(MI))
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return;
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if (transferSpillOrRestoreInst(MI))
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@ -1960,6 +2097,20 @@ void InstrRefBasedLDV::produceMLocTransferFunction(
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// Also accumulate fragment map.
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if (MI.isDebugValue())
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accumulateFragmentMap(MI);
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// Create a map from the instruction number (if present) to the
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// MachineInstr and its position.
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if (MI.peekDebugInstrNum()) {
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uint64_t InstrNo = MI.peekDebugInstrNum();
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auto InstrAndPos = std::make_pair(&MI, CurInst);
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auto InsertResult =
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DebugInstrNumToInstr.insert(std::make_pair(InstrNo, InstrAndPos));
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// There should never be duplicate instruction numbers.
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assert(InsertResult.second);
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(void)InsertResult;
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}
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++CurInst;
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}
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@ -3123,6 +3274,7 @@ bool InstrRefBasedLDV::ExtendRanges(MachineFunction &MF,
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OrderToBB.clear();
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BBToOrder.clear();
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BBNumToRPO.clear();
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DebugInstrNumToInstr.clear();
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return Changed;
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}
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@ -0,0 +1,72 @@
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--- |
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; RUN: llc %s -march=x86-64 -run-pass=livedebugvalues -o - -experimental-debug-variable-locations | FileCheck %s -implicit-check-not=DBG_VALUE
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define i32 @_Z8bb_to_bb() local_unnamed_addr !dbg !12 {
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entry:
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ret i32 0, !dbg !17
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}
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!llvm.dbg.cu = !{!0}
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!llvm.module.flags = !{!7, !8, !9, !10}
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!llvm.ident = !{!11}
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!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3, debugInfoForProfiling: true, nameTableKind: None)
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!1 = !DIFile(filename: "main.cpp", directory: "F:\")
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!2 = !{}
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!3 = !{!4}
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!4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression())
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!5 = distinct !DIGlobalVariable(name: "start", scope: !0, file: !1, line: 4, type: !6, isLocal: false, isDefinition: true)
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!6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
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!7 = !{i32 2, !"Dwarf Version", i32 4}
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!8 = !{i32 2, !"Debug Info Version", i32 3}
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!9 = !{i32 1, !"wchar_size", i32 2}
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!10 = !{i32 7, !"PIC Level", i32 2}
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!11 = !{!"clang version 10.0.0"}
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!12 = distinct !DISubprogram(name: "bb_to_bb", linkageName: "bb_to_bb", scope: !1, file: !1, line: 6, type: !13, scopeLine: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !15)
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!13 = !DISubroutineType(types: !14)
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!14 = !{!6, !6}
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!15 = !{!16}
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!16 = !DILocalVariable(name: "myVar", scope: !12, file: !1, line: 7, type: !6)
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!17 = !DILocation(line: 10, scope: !12)
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...
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---
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name: _Z8bb_to_bb
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debugValueSubstitutions:
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- { srcinst: 4, srcop: 0, dstinst: 3, dstop: 0 }
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body: |
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bb.0.entry:
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$rax = MOV64ri 1, debug-instr-number 1, debug-location !17
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; This debug instruction should identify the value as being in $rax.
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DBG_INSTR_REF 1, 0, !16, !DIExpression(), debug-location !17
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; CHECK: DBG_VALUE $rax, $noreg
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$rbx = COPY killed $rax, debug-location !17
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$rax = MOV64ri 1, debug-location !17
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; Presently, this COPY isn't followed. Dealing with that is future work.
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DBG_INSTR_REF 2, 0, !16, !DIExpression(), debug-location !17
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; No instruction is labelled with the number "2". This should produce an
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; empty variable location.
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; CHECK: DBG_VALUE $noreg, $noreg
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$rbx = MOV64ri 1, debug-instr-number 3, debug-location !17
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JMP_1 %bb.1
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; CHECK-LABEL: bb.1:
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bb.1:
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DBG_INSTR_REF 3, 0, !16, !DIExpression(), debug-location !17
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; This refers to a value def'd in a parent block -- but it should be
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; tracked into this block.
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; CHECK: DBG_VALUE $rbx, $noreg
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JMP_1 %bb.2
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; CHECK-LABEL: bb.2:
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bb.2:
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; Just like any other variable location, live-ins should be created for
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; any successor blocks.
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; CHECK: DBG_VALUE $rbx, $noreg
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RETQ $eax, debug-location !17
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...
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