[DebugInfo] Handle multiple variable location operands in IR

This patch updates the various IR passes to correctly handle dbg.values with a
DIArgList location. This patch does not actually allow DIArgLists to be produced
by salvageDebugInfo, and it does not affect any pass after codegen-prepare.
Other than that, it should cover every IR pass.

Most of the changes simply extend code that operated on a single debug value to
operate on the list of debug values in the style of any_of, all_of, for_each,
etc. Instances of setOperand(0, ...) have been replaced with with
replaceVariableLocationOp, which takes the value that is being replaced as an
additional argument. In places where this value isn't readily available, we have
to track the old value through to the point where it gets replaced.

Differential Revision: https://reviews.llvm.org/D88232

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.