[DebugInfo][InstrRef] Honour too-much-debug-info cutouts

This reapplies 54a61c94f93, its follow up in 547b712500e, which were
reverted 95fe61e63954. Original commit message:

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

1 files changed, 6 insertions, 15 deletions

diff --git a/llvm/lib/CodeGen/LiveDebugValues/VarLocBasedImpl.cpp b/llvm/lib/CodeGen/LiveDebugValues/VarLocBasedImpl.cpp
index 1e6d65c..977d3ed 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 @@ private:
   /// 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