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DebugInfo: Remove 'inlinedAt:' field from MDLocalVariable

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Remove 'inlinedAt:' from MDLocalVariable.  Besides saving some memory
(variables with it seem to be single largest `Metadata` contributer to
memory usage right now in -g -flto builds), this stops optimization and
backend passes from having to change local variables.

The 'inlinedAt:' field was used by the backend in two ways:

 1. To tell the backend whether and into what a variable was inlined.
 2. To create a unique id for each inlined variable.

Instead, rely on the 'inlinedAt:' field of the intrinsic's `!dbg`
attachment, and change the DWARF backend to use a typedef called
`InlinedVariable` which is `std::pair<MDLocalVariable*, MDLocation*>`.
This `DebugLoc` is already passed reliably through the backend (as
verified by r234021).

This commit removes the check from r234021, but I added a new check
(that will survive) in r235048, and changed the `DIBuilder` API in
r235041 to require a `!dbg` attachment whose 'scope:` is in the same
`MDSubprogram` as the variable's.

If this breaks your out-of-tree testcases, perhaps the script I used
(mdlocalvariable-drop-inlinedat.sh) will help; I'll attach it to PR22778
in a moment.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235050 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Duncan P. N. Exon Smith
2015-04-15 22:29:27 +00:00
parent 94255c8eb0
commit 88e419d66e
51 changed files with 208 additions and 289 deletions
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25
lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp
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@@ -33,7 +33,7 @@ static unsigned isDescribedByReg(const MachineInstr &MI) {
return MI.getOperand(0).isReg() ? MI.getOperand(0).getReg() : 0;
}
void DbgValueHistoryMap::startInstrRange(const MDNode *Var,
void DbgValueHistoryMap::startInstrRange(InlinedVariable Var,
const MachineInstr &MI) {
// Instruction range should start with a DBG_VALUE instruction for the
// variable.
@@ -48,7 +48,7 @@ void DbgValueHistoryMap::startInstrRange(const MDNode *Var,
Ranges.push_back(std::make_pair(&MI, nullptr));
}
void DbgValueHistoryMap::endInstrRange(const MDNode *Var,
void DbgValueHistoryMap::endInstrRange(InlinedVariable Var,
const MachineInstr &MI) {
auto &Ranges = VarInstrRanges[Var];
// Verify that the current instruction range is not yet closed.
@@ -59,7 +59,7 @@ void DbgValueHistoryMap::endInstrRange(const MDNode *Var,
Ranges.back().second = &MI;
}
unsigned DbgValueHistoryMap::getRegisterForVar(const MDNode *Var) const {
unsigned DbgValueHistoryMap::getRegisterForVar(InlinedVariable Var) const {
const auto &I = VarInstrRanges.find(Var);
if (I == VarInstrRanges.end())
return 0;
@@ -71,12 +71,13 @@ unsigned DbgValueHistoryMap::getRegisterForVar(const MDNode *Var) const {
namespace {
// Maps physreg numbers to the variables they describe.
typedef std::map<unsigned, SmallVector<const MDNode *, 1>> RegDescribedVarsMap;
typedef DbgValueHistoryMap::InlinedVariable InlinedVariable;
typedef std::map<unsigned, SmallVector<InlinedVariable, 1>> RegDescribedVarsMap;
}
// \brief Claim that @Var is not described by @RegNo anymore.
static void dropRegDescribedVar(RegDescribedVarsMap &RegVars,
unsigned RegNo, const MDNode *Var) {
static void dropRegDescribedVar(RegDescribedVarsMap &RegVars, unsigned RegNo,
InlinedVariable Var) {
const auto &I = RegVars.find(RegNo);
assert(RegNo != 0U && I != RegVars.end());
auto &VarSet = I->second;
@@ -89,8 +90,8 @@ static void dropRegDescribedVar(RegDescribedVarsMap &RegVars,
}
// \brief Claim that @Var is now described by @RegNo.
static void addRegDescribedVar(RegDescribedVarsMap &RegVars,
unsigned RegNo, const MDNode *Var) {
static void addRegDescribedVar(RegDescribedVarsMap &RegVars, unsigned RegNo,
InlinedVariable Var) {
assert(RegNo != 0U);
auto &VarSet = RegVars[RegNo];
assert(std::find(VarSet.begin(), VarSet.end(), Var) == VarSet.end());
@@ -203,9 +204,13 @@ void llvm::calculateDbgValueHistory(const MachineFunction *MF,
// Use the base variable (without any DW_OP_piece expressions)
// as index into History. The full variables including the
// piece expressions are attached to the MI.
DIVariable Var = MI.getDebugVariable();
assert(Var->isValidLocationForIntrinsic(MI.getDebugLoc()) &&
MDLocalVariable *RawVar = MI.getDebugVariable();
assert(RawVar->isValidLocationForIntrinsic(MI.getDebugLoc()) &&
"Expected inlined-at fields to agree");
MDLocation *IA = nullptr;
if (MDLocation *Loc = MI.getDebugLoc())
IA = Loc->getInlinedAt();
InlinedVariable Var(RawVar, IA);
if (unsigned PrevReg = Result.getRegisterForVar(Var))
dropRegDescribedVar(RegVars, PrevReg, Var);