Reapply "[DebugInfo] Handle multiple variable location operands in IR"

Fixed section of code that iterated through a SmallDenseMap and added
instructions in each iteration, causing non-deterministic code; replaced
SmallDenseMap with MapVector to prevent non-determinism.

This reverts commit 01ac6d1587e8613ba4278786e8341f8b492ac941.

1 files changed, 5 insertions, 4 deletions

diff --git a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
index 9697e7d..d1a3ae5 100644
--- a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
+++ b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
@@ -407,7 +407,8 @@ static bool removeRedundantDbgInstrsUsingBackwardScan(BasicBlock *BB) {
 /// - Keep track of non-overlapping fragments.
 static bool removeRedundantDbgInstrsUsingForwardScan(BasicBlock *BB) {
   SmallVector<DbgValueInst *, 8> ToBeRemoved;
-  DenseMap<DebugVariable, std::pair<Value *, DIExpression *> > VariableMap;
+  DenseMap<DebugVariable, std::pair<SmallVector<Value *, 4>, DIExpression *>>
+      VariableMap;
   for (auto &I : *BB) {
     if (DbgValueInst *DVI = dyn_cast<DbgValueInst>(&I)) {
       DebugVariable Key(DVI->getVariable(),
@@ -416,10 +417,10 @@ static bool removeRedundantDbgInstrsUsingForwardScan(BasicBlock *BB) {
       auto VMI = VariableMap.find(Key);
       // Update the map if we found a new value/expression describing the
       // variable, or if the variable wasn't mapped already.
-      if (VMI == VariableMap.end() ||
-          VMI->second.first != DVI->getValue() ||
+      SmallVector<Value *, 4> Values(DVI->getValues());
+      if (VMI == VariableMap.end() || VMI->second.first != Values ||
           VMI->second.second != DVI->getExpression()) {
-        VariableMap[Key] = { DVI->getValue(), DVI->getExpression() };
+        VariableMap[Key] = {Values, DVI->getExpression()};
         continue;
       }
       // Found an identical mapping. Remember the instruction for later removal.