Clean up debug info after reassociation.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@136480 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Scalar/Reassociate.cpp

@@ -75,6 +75,7 @@ namespace {
   class Reassociate : public FunctionPass {
     DenseMap<BasicBlock*, unsigned> RankMap;
     DenseMap<AssertingVH<>, unsigned> ValueRankMap;
+    DenseMap<Value *, DbgValueInst *> DbgValues;
     SmallVector<WeakVH, 8> RedoInsts;
     SmallVector<WeakVH, 8> DeadInsts;
     bool MadeChange;
@@ -104,6 +105,9 @@ namespace {
     void ReassociateInst(BasicBlock::iterator &BBI);
 
     void RemoveDeadBinaryOp(Value *V);
+
+    /// collectDbgValues - Collect all llvm.dbg.value intrinsics.
+    void collectDbgValues(Function &F);
   };
 }
 
@@ -344,6 +348,11 @@ void Reassociate::LinearizeExprTree(BinaryOperator *I,
 void Reassociate::RewriteExprTree(BinaryOperator *I,
                                   SmallVectorImpl<ValueEntry> &Ops,
                                   unsigned i) {
+  // If this operation was representing debug info of a value then it
+  // is no longer true, so remove the dbg.value instrinsic.
+  if (DbgValueInst *DVI = DbgValues.lookup(I))
+    DeadInsts.push_back(DVI);
+
   if (i+2 == Ops.size()) {
     if (I->getOperand(0) != Ops[i].Op ||
         I->getOperand(1) != Ops[i+1].Op) {
@@ -1094,6 +1103,7 @@ Value *Reassociate::ReassociateExpression(BinaryOperator *I) {
 
 
 bool Reassociate::runOnFunction(Function &F) {
+  collectDbgValues(F);
   // Recalculate the rank map for F
   BuildRankMap(F);
 
@@ -1113,11 +1123,21 @@ bool Reassociate::runOnFunction(Function &F) {
   // Now that we're done, delete any instructions which are no longer used.
   while (!DeadInsts.empty())
     if (Value *V = DeadInsts.pop_back_val())
-      RecursivelyDeleteTriviallyDeadInstructions(V);
+      if (!RecursivelyDeleteTriviallyDeadInstructions(V))
+        if (DbgValueInst *DVI = dyn_cast<DbgValueInst>(V))
+          DVI->eraseFromParent();
 
   // We are done with the rank map.
   RankMap.clear();
   ValueRankMap.clear();
   return MadeChange;
 }
 
+/// collectDbgValues - Collect all llvm.dbg.value intrinsics.
+void Reassociate::collectDbgValues(Function &F) {
+  for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI)
+    for (BasicBlock::iterator BI = FI->begin(), BE = FI->end(); 
+         BI != BE; ++BI)
+      if (DbgValueInst *DVI = dyn_cast<DbgValueInst>(BI))
+        DbgValues[DVI->getValue()] = DVI;
+}

test/Transforms/Reassociate/dbg-value.ll

@@ -0,0 +1,38 @@
+; RUN: opt -reassociate -S < %s | FileCheck %s
+; PR 10176
+define i64 @foo(i64 %a, i64 %b, i64 %c) nounwind uwtable readnone ssp {
+entry:
+  tail call void @llvm.dbg.value(metadata !{i64 %a}, i64 0, metadata !6), !dbg !11
+  tail call void @llvm.dbg.value(metadata !{i64 %b}, i64 0, metadata !7), !dbg !12
+  tail call void @llvm.dbg.value(metadata !{i64 %c}, i64 0, metadata !8), !dbg !13
+  %add = add nsw i64 %c, %b, !dbg !14
+;CHECK-NOT:   call void @llvm.dbg.value(metadata !{i64 %add}
+  tail call void @llvm.dbg.value(metadata !{i64 %add}, i64 0, metadata !9), !dbg !14
+  %add4 = add nsw i64 %add, %a, !dbg !15
+  ret i64 %add4, !dbg !15
+}
+
+declare void @llvm.dbg.declare(metadata, metadata) nounwind readnone
+
+declare void @llvm.dbg.value(metadata, i64, metadata) nounwind readnone
+
+!llvm.dbg.cu = !{!0}
+!llvm.dbg.sp = !{!1}
+!llvm.dbg.lv.foo = !{!6, !7, !8, !9}
+
+!0 = metadata !{i32 655377, i32 0, i32 12, metadata !"dan.c", metadata !"/private/tmp", metadata !"clang version 3.0 (trunk 136263)", i1 true, i1 true, metadata !"", i32 0} ; [ DW_TAG_compile_unit ]
+!1 = metadata !{i32 655406, i32 0, metadata !2, metadata !"foo", metadata !"foo", metadata !"", metadata !2, i32 1, metadata !3, i1 false, i1 true, i32 0, i32 0, i32 0, i32 256, i1 true, i64 (i64, i64, i64)* @foo, null, null} ; [ DW_TAG_subprogram ]
+!2 = metadata !{i32 655401, metadata !"dan.c", metadata !"/private/tmp", metadata !0} ; [ DW_TAG_file_type ]
+!3 = metadata !{i32 655381, metadata !2, metadata !"", metadata !2, i32 0, i64 0, i64 0, i32 0, i32 0, i32 0, metadata !4, i32 0, i32 0} ; [ DW_TAG_subroutine_type ]
+!4 = metadata !{metadata !5}
+!5 = metadata !{i32 655396, metadata !0, metadata !"long int", null, i32 0, i64 64, i64 64, i64 0, i32 0, i32 5} ; [ DW_TAG_base_type ]
+!6 = metadata !{i32 655617, metadata !1, metadata !"a", metadata !2, i32 16777217, metadata !5, i32 0, i32 0} ; [ DW_TAG_arg_variable ]
+!7 = metadata !{i32 655617, metadata !1, metadata !"b", metadata !2, i32 33554433, metadata !5, i32 0, i32 0} ; [ DW_TAG_arg_variable ]
+!8 = metadata !{i32 655617, metadata !1, metadata !"c", metadata !2, i32 50331649, metadata !5, i32 0, i32 0} ; [ DW_TAG_arg_variable ]
+!9 = metadata !{i32 655616, metadata !10, metadata !"d", metadata !2, i32 2, metadata !5, i32 0, i32 0} ; [ DW_TAG_auto_variable ]
+!10 = metadata !{i32 655371, metadata !1, i32 1, i32 34, metadata !2, i32 0} ; [ DW_TAG_lexical_block ]
+!11 = metadata !{i32 1, i32 15, metadata !1, null}
+!12 = metadata !{i32 1, i32 23, metadata !1, null}
+!13 = metadata !{i32 1, i32 31, metadata !1, null}
+!14 = metadata !{i32 2, i32 17, metadata !10, null}
+!15 = metadata !{i32 3, i32 3, metadata !10, null}