[llvm] 54a61c9 - [DebugInfo][InstrRef] Honour too-much-debug-info cutouts
Jeremy Morse via llvm-commits
llvm-commits at lists.llvm.org
Mon Aug 16 07:07:22 PDT 2021
Author: Jeremy Morse
Date: 2021-08-16T15:06:40+01:00
New Revision: 54a61c94f932f894f2695e0c18bb288d2d1407b7
URL: https://github.com/llvm/llvm-project/commit/54a61c94f932f894f2695e0c18bb288d2d1407b7
DIFF: https://github.com/llvm/llvm-project/commit/54a61c94f932f894f2695e0c18bb288d2d1407b7.diff
LOG: [DebugInfo][InstrRef] Honour too-much-debug-info cutouts
VarLoc based LiveDebugValues will abandon variable location propagation if
there are too many blocks and variable assignments in the function. If it
didn't, and we had (say) 1000 blocks and 1000 variables in scope, we'd end
up with 1 million DBG_VALUEs just at the start of blocks.
Instruction-referencing LiveDebugValues should honour this limitation too
(because the same limitation applies to it). Hoist the relevant command
line options into LiveDebugValues.cpp and pass it down into the
implementation classes as an argument to ExtendRanges. I've duplicated all
the run-lines in live-debug-values-cutoffs.mir to have an
instruction-referencing flavour.
Differential Revision: https://reviews.llvm.org/D107823
Added:
Modified:
llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp
llvm/lib/CodeGen/LiveDebugValues/LiveDebugValues.cpp
llvm/lib/CodeGen/LiveDebugValues/LiveDebugValues.h
llvm/lib/CodeGen/LiveDebugValues/VarLocBasedImpl.cpp
llvm/test/DebugInfo/MIR/X86/live-debug-values-cutoffs.mir
Removed:
################################################################################
diff --git a/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp b/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp
index dc99070583406..a653c0a994e93 100644
--- a/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp
+++ b/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp
@@ -1684,7 +1684,8 @@ class InstrRefBasedLDV : public LDVImpl {
/// RPOT block ordering.
void initialSetup(MachineFunction &MF);
- bool ExtendRanges(MachineFunction &MF, TargetPassConfig *TPC) override;
+ bool ExtendRanges(MachineFunction &MF, TargetPassConfig *TPC,
+ unsigned InputBBLimit, unsigned InputDbgValLimit) override;
public:
/// Default construct and initialize the pass.
@@ -3523,8 +3524,9 @@ void InstrRefBasedLDV::initialSetup(MachineFunction &MF) {
/// Calculate the liveness information for the given machine function and
/// extend ranges across basic blocks.
-bool InstrRefBasedLDV::ExtendRanges(MachineFunction &MF,
- TargetPassConfig *TPC) {
+bool InstrRefBasedLDV::ExtendRanges(MachineFunction &MF, TargetPassConfig *TPC,
+ unsigned InputBBLimit,
+ unsigned InputDbgValLimit) {
// No subprogram means this function contains no debuginfo.
if (!MF.getFunction().getSubprogram())
return false;
@@ -3626,6 +3628,7 @@ bool InstrRefBasedLDV::ExtendRanges(MachineFunction &MF,
// To mirror old LiveDebugValues, enumerate variables in RPOT order. Otherwise
// the order is unimportant, it just has to be stable.
+ unsigned VarAssignCount = 0;
for (unsigned int I = 0; I < OrderToBB.size(); ++I) {
auto *MBB = OrderToBB[I];
auto *VTracker = &vlocs[MBB->getNumber()];
@@ -3643,9 +3646,21 @@ bool InstrRefBasedLDV::ExtendRanges(MachineFunction &MF,
ScopeToVars[Scope].insert(Var);
ScopeToBlocks[Scope].insert(VTracker->MBB);
ScopeToDILocation[Scope] = ScopeLoc;
+ ++VarAssignCount;
}
}
+ // If we have an extremely large number of variable assignments and blocks,
+ // bail out at this point. We've burnt some time doing analysis already,
+ // however we should cut our losses.
+ if (MaxNumBlocks > InputBBLimit && VarAssignCount > InputDbgValLimit) {
+ LLVM_DEBUG(dbgs() << "Disabling InstrRefBasedLDV: " << MF.getName()
+ << " has " << MaxNumBlocks << " basic blocks and "
+ << VarAssignCount
+ << " variable assignments, exceeding limits.\n");
+ return false;
+ }
+
// OK. Iterate over scopes: there might be something to be said for
// ordering them by size/locality, but that's for the future. For each scope,
// solve the variable value problem, producing a map of variables to values
diff --git a/llvm/lib/CodeGen/LiveDebugValues/LiveDebugValues.cpp b/llvm/lib/CodeGen/LiveDebugValues/LiveDebugValues.cpp
index 38e803d1abb55..bc1eaff60440f 100644
--- a/llvm/lib/CodeGen/LiveDebugValues/LiveDebugValues.cpp
+++ b/llvm/lib/CodeGen/LiveDebugValues/LiveDebugValues.cpp
@@ -40,6 +40,18 @@ static cl::opt<bool>
"normal DBG_VALUE inputs"),
cl::init(false));
+// Options to prevent pathological compile-time behavior. If InputBBLimit and
+// InputDbgValueLimit are both exceeded, range extension is disabled.
+static cl::opt<unsigned> InputBBLimit(
+ "livedebugvalues-input-bb-limit",
+ cl::desc("Maximum input basic blocks before DBG_VALUE limit applies"),
+ cl::init(10000), cl::Hidden);
+static cl::opt<unsigned> InputDbgValueLimit(
+ "livedebugvalues-input-dbg-value-limit",
+ cl::desc(
+ "Maximum input DBG_VALUE insts supported by debug range extension"),
+ cl::init(50000), cl::Hidden);
+
/// Generic LiveDebugValues pass. Calls through to VarLocBasedLDV or
/// InstrRefBasedLDV to perform location propagation, via the LDVImpl
/// base class.
@@ -103,5 +115,5 @@ bool LiveDebugValues::runOnMachineFunction(MachineFunction &MF) {
TheImpl = llvm::makeVarLocBasedLiveDebugValues();
}
- return TheImpl->ExtendRanges(MF, TPC);
+ return TheImpl->ExtendRanges(MF, TPC, InputBBLimit, InputDbgValueLimit);
}
diff --git a/llvm/lib/CodeGen/LiveDebugValues/LiveDebugValues.h b/llvm/lib/CodeGen/LiveDebugValues/LiveDebugValues.h
index 9c910f180b9fb..e38360b08bafa 100644
--- a/llvm/lib/CodeGen/LiveDebugValues/LiveDebugValues.h
+++ b/llvm/lib/CodeGen/LiveDebugValues/LiveDebugValues.h
@@ -23,7 +23,9 @@ inline namespace SharedLiveDebugValues {
// implementation.
class LDVImpl {
public:
- virtual bool ExtendRanges(MachineFunction &MF, TargetPassConfig *TPC) = 0;
+ virtual bool ExtendRanges(MachineFunction &MF, TargetPassConfig *TPC,
+ unsigned InputBBLimit,
+ unsigned InputDbgValLimit) = 0;
virtual ~LDVImpl() {}
};
diff --git a/llvm/lib/CodeGen/LiveDebugValues/VarLocBasedImpl.cpp b/llvm/lib/CodeGen/LiveDebugValues/VarLocBasedImpl.cpp
index 1e6d65c189535..977d3ede5c776 100644
--- a/llvm/lib/CodeGen/LiveDebugValues/VarLocBasedImpl.cpp
+++ b/llvm/lib/CodeGen/LiveDebugValues/VarLocBasedImpl.cpp
@@ -166,18 +166,6 @@ using namespace llvm;
STATISTIC(NumInserted, "Number of DBG_VALUE instructions inserted");
-// Options to prevent pathological compile-time behavior. If InputBBLimit and
-// InputDbgValueLimit are both exceeded, range extension is disabled.
-static cl::opt<unsigned> InputBBLimit(
- "livedebugvalues-input-bb-limit",
- cl::desc("Maximum input basic blocks before DBG_VALUE limit applies"),
- cl::init(10000), cl::Hidden);
-static cl::opt<unsigned> InputDbgValueLimit(
- "livedebugvalues-input-dbg-value-limit",
- cl::desc(
- "Maximum input DBG_VALUE insts supported by debug range extension"),
- cl::init(50000), cl::Hidden);
-
/// If \p Op is a stack or frame register return true, otherwise return false.
/// This is used to avoid basing the debug entry values on the registers, since
/// we do not support it at the moment.
@@ -1007,7 +995,8 @@ class VarLocBasedLDV : public LDVImpl {
/// had their instruction creation deferred.
void flushPendingLocs(VarLocInMBB &PendingInLocs, VarLocMap &VarLocIDs);
- bool ExtendRanges(MachineFunction &MF, TargetPassConfig *TPC) override;
+ bool ExtendRanges(MachineFunction &MF, TargetPassConfig *TPC,
+ unsigned InputBBLimit, unsigned InputDbgValLimit) override;
public:
/// Default construct and initialize the pass.
@@ -2048,7 +2037,9 @@ void VarLocBasedLDV::recordEntryValue(const MachineInstr &MI,
/// Calculate the liveness information for the given machine function and
/// extend ranges across basic blocks.
-bool VarLocBasedLDV::ExtendRanges(MachineFunction &MF, TargetPassConfig *TPC) {
+bool VarLocBasedLDV::ExtendRanges(MachineFunction &MF, TargetPassConfig *TPC,
+ unsigned InputBBLimit,
+ unsigned InputDbgValLimit) {
LLVM_DEBUG(dbgs() << "\nDebug Range Extension\n");
if (!MF.getFunction().getSubprogram())
@@ -2141,7 +2132,7 @@ bool VarLocBasedLDV::ExtendRanges(MachineFunction &MF, TargetPassConfig *TPC) {
for (auto &MI : MBB)
if (MI.isDebugValue())
++NumInputDbgValues;
- if (NumInputDbgValues > InputDbgValueLimit) {
+ if (NumInputDbgValues > InputDbgValLimit) {
LLVM_DEBUG(dbgs() << "Disabling VarLocBasedLDV: " << MF.getName()
<< " has " << RPONumber << " basic blocks and "
<< NumInputDbgValues
diff --git a/llvm/test/DebugInfo/MIR/X86/live-debug-values-cutoffs.mir b/llvm/test/DebugInfo/MIR/X86/live-debug-values-cutoffs.mir
index 4922c36086f16..17b6b9b3149c3 100644
--- a/llvm/test/DebugInfo/MIR/X86/live-debug-values-cutoffs.mir
+++ b/llvm/test/DebugInfo/MIR/X86/live-debug-values-cutoffs.mir
@@ -5,21 +5,41 @@
# RUN: -livedebugvalues-input-bb-limit=1 \
# RUN: -livedebugvalues-input-dbg-value-limit=1 \
# RUN: | FileCheck %s -check-prefix=LDV-DISABLED
+# RUN: llc %s -o - -run-pass=livedebugvalues -mtriple=x86_64-unknown-unknown \
+# RUN: -experimental-debug-variable-locations \
+# RUN: -livedebugvalues-input-bb-limit=1 \
+# RUN: -livedebugvalues-input-dbg-value-limit=1 \
+# RUN: | FileCheck %s -check-prefix=LDV-DISABLED
# RUN: llc %s -o - -run-pass=livedebugvalues -mtriple=x86_64-unknown-unknown \
# RUN: -livedebugvalues-input-bb-limit=1 \
# RUN: -livedebugvalues-input-dbg-value-limit=10 \
# RUN: | FileCheck %s -check-prefix=LDV-ENABLED
+# RUN: llc %s -o - -run-pass=livedebugvalues -mtriple=x86_64-unknown-unknown \
+# RUN: -experimental-debug-variable-locations \
+# RUN: -livedebugvalues-input-bb-limit=1 \
+# RUN: -livedebugvalues-input-dbg-value-limit=10 \
+# RUN: | FileCheck %s -check-prefix=LDV-ENABLED
# RUN: llc %s -o - -run-pass=livedebugvalues -mtriple=x86_64-unknown-unknown \
# RUN: -livedebugvalues-input-bb-limit=10 \
# RUN: -livedebugvalues-input-dbg-value-limit=1 \
# RUN: | FileCheck %s -check-prefix=LDV-ENABLED
+# RUN: llc %s -o - -run-pass=livedebugvalues -mtriple=x86_64-unknown-unknown \
+# RUN: -experimental-debug-variable-locations \
+# RUN: -livedebugvalues-input-bb-limit=10 \
+# RUN: -livedebugvalues-input-dbg-value-limit=1 \
+# RUN: | FileCheck %s -check-prefix=LDV-ENABLED
# RUN: llc %s -o - -run-pass=livedebugvalues -mtriple=x86_64-unknown-unknown \
# RUN: -livedebugvalues-input-bb-limit=10 \
# RUN: -livedebugvalues-input-dbg-value-limit=10 \
# RUN: | FileCheck %s -check-prefix=LDV-ENABLED
+# RUN: llc %s -o - -run-pass=livedebugvalues -mtriple=x86_64-unknown-unknown \
+# RUN: -experimental-debug-variable-locations \
+# RUN: -livedebugvalues-input-bb-limit=10 \
+# RUN: -livedebugvalues-input-dbg-value-limit=10 \
+# RUN: | FileCheck %s -check-prefix=LDV-ENABLED
# LDV-DISABLED-LABEL: bb.1.exit
# LDV-DISABLED-NEXT: $edi = MOV32rm
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