[PATCH] D105026: [2/2][LiveDebugVariables] Avoid reduntant DBG_VALUEs after virtregrewrite

[Djordje Todorovic via Phabricator via llvm-commits]

djtodoro created this revision.
djtodoro added reviewers: jmorse, Orlando, aprantl, dstenb.
djtodoro added a project: debug-info.
Herald added subscribers: hiraditya, nemanjai.
djtodoro requested review of this revision.
Herald added a project: LLVM.
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This is a follow-up for the D105025 <https://reviews.llvm.org/D105025>. It tries to find duplicates even further.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D105026

Files:
  llvm/lib/CodeGen/LiveDebugVariables.cpp
  llvm/test/CodeGen/PowerPC/non-debug-mi-search-frspxsrsp.ll


Index: llvm/test/CodeGen/PowerPC/non-debug-mi-search-frspxsrsp.ll
===================================================================
--- llvm/test/CodeGen/PowerPC/non-debug-mi-search-frspxsrsp.ll
+++ llvm/test/CodeGen/PowerPC/non-debug-mi-search-frspxsrsp.ll
@@ -29,7 +29,6 @@
 ; CHECK-NEXT:          xvcvdpsp 34, 0
 ; CHECK-NEXT:          xvcvdpsp 35, 1
 ; CHECK-NEXT:          vmrgew 2, 2, 3
-; CHECK-NEXT:          #DEBUG_VALUE: test:Vptr <- $x4
 ; CHECK-NEXT:          .loc    1 3 9 is_stmt 0
 ; CHECK-NEXT:          stvx 2, 0, 4
 ; CHECK-NEXT:          .loc    1 4 1 is_stmt 1
Index: llvm/lib/CodeGen/LiveDebugVariables.cpp
===================================================================
--- llvm/lib/CodeGen/LiveDebugVariables.cpp
+++ llvm/lib/CodeGen/LiveDebugVariables.cpp
@@ -1642,14 +1642,28 @@
                                    const DILocalVariable *Variable,
                                    const MachineOperand &LocOp,
                                    const DIExpression *Expr, DebugLoc &dl) {
+  if (!LocOp.isReg())
+    return false;
+
   MachineBasicBlock::reverse_iterator it =
       std::next(MachineBasicBlock::reverse_iterator(MI));
   while (it != MBB->rend()) {
-    if (!it->isDebugValue())
-      return false;
+    if (!it->isDebugValue()) {
+      if (it->isMetaInstruction()) {
+        it = std::next(it);
+        continue;
+      }
+
+      const auto *TRI = MI.getMF()->getSubtarget().getRegisterInfo();
+      if (it->modifiesRegister(LocOp.getReg(), TRI))
+        return false;
+
+      it = std::next(it);
+      continue;
+    }
 
     MachineOperand &loc = it->getDebugOperand(0);
-    if (Variable == it->getDebugVariable() && loc.isReg() && LocOp.isReg() &&
+    if (Variable == it->getDebugVariable() && loc.isReg() &&
         loc.getReg() == LocOp.getReg() && Expr == it->getDebugExpression() &&
         dl == it->getDebugLoc()) {
       LLVM_DEBUG(llvm::dbgs() << "\navoiding duplicated "; it->dump(););


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