[PATCH] D55333: VirtRegMap: Preserve LiveDebugVariables

[Matt Arsenault via Phabricator via llvm-commits]

arsenm updated this revision to Diff 342487.
arsenm added a comment.
Herald added a subscriber: kerbowa.

Add comment and test for double emission


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D55333/new/

https://reviews.llvm.org/D55333

Files:
  llvm/lib/CodeGen/VirtRegMap.cpp
  llvm/test/CodeGen/AMDGPU/debug-value.ll


Index: llvm/test/CodeGen/AMDGPU/debug-value.ll
===================================================================
--- llvm/test/CodeGen/AMDGPU/debug-value.ll
+++ llvm/test/CodeGen/AMDGPU/debug-value.ll
@@ -71,7 +71,10 @@
   %tmp56 = fmul float %tmp55, %tmp50
   %tmp57 = fmul float %tmp54, %tmp56
   %tmp58 = fdiv float %tmp57, 0.000000e+00
+  ; Make sure this isn't double emitted
+  ; CHECK-NOT: ;DEBUG_VALUE:
   ; CHECK: ;DEBUG_VALUE: foo:var <- [DW_OP_constu 1, DW_OP_swap, DW_OP_xderef]
+  ; CHECK-NOT: ;DEBUG_VALUE:
   call void @llvm.dbg.value(metadata <4 x float> %tmp29, metadata !3, metadata !DIExpression(DW_OP_constu, 1, DW_OP_swap, DW_OP_xderef)) #2, !dbg !5
   %tmp59 = bitcast i64 %tmp35 to <2 x float>
   %tmp60 = insertelement <2 x float> undef, float %tmp58, i32 0
Index: llvm/lib/CodeGen/VirtRegMap.cpp
===================================================================
--- llvm/lib/CodeGen/VirtRegMap.cpp
+++ llvm/lib/CodeGen/VirtRegMap.cpp
@@ -181,6 +181,7 @@
   SlotIndexes *Indexes;
   LiveIntervals *LIS;
   VirtRegMap *VRM;
+  LiveDebugVariables *DebugVars;
   DenseSet<Register> RewriteRegs;
   bool ClearVirtRegs;
 
@@ -238,6 +239,10 @@
   AU.addRequired<LiveStacks>();
   AU.addPreserved<LiveStacks>();
   AU.addRequired<VirtRegMap>();
+
+  if (!ClearVirtRegs)
+    AU.addPreserved<LiveDebugVariables>();
+
   MachineFunctionPass::getAnalysisUsage(AU);
 }
 
@@ -249,6 +254,7 @@
   Indexes = &getAnalysis<SlotIndexes>();
   LIS = &getAnalysis<LiveIntervals>();
   VRM = &getAnalysis<VirtRegMap>();
+  DebugVars = getAnalysisIfAvailable<LiveDebugVariables>();
   LLVM_DEBUG(dbgs() << "********** REWRITE VIRTUAL REGISTERS **********\n"
                     << "********** Function: " << MF->getName() << '\n');
   LLVM_DEBUG(VRM->dump());
@@ -262,10 +268,13 @@
   // Rewrite virtual registers.
   rewrite();
 
-  // Write out new DBG_VALUE instructions.
-  getAnalysis<LiveDebugVariables>().emitDebugValues(VRM);
+  if (DebugVars && ClearVirtRegs) {
+    // Write out new DBG_VALUE instructions.
+
+    // We only do this if ClearVirtRegs is specified since this should be the
+    // final run of the pass and we don't want to emit them multiple times.
+    DebugVars->emitDebugValues(VRM);
 
-  if (ClearVirtRegs) {
     // All machine operands and other references to virtual registers have been
     // replaced. Remove the virtual registers and release all the transient data.
     VRM->clearAllVirt();


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