In mem2reg, for all alloca/stores that get promoted where the alloca has an associated llvm.dbg.declare instrinsic, insert an llvm.dbg.var intrinsic before each store

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94260 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 69 insertions, 3 deletions

diff --git a/lib/Transforms/Utils/PromoteMemoryToRegister.cpp b/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
index 9fdcfe5ec3..d9261ac5a1 100644
--- a/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
+++ b/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
@@ -23,6 +23,7 @@
 #include "llvm/Function.h"
 #include "llvm/Instructions.h"
 #include "llvm/IntrinsicInst.h"
+#include "llvm/Analysis/DebugInfo.h"
 #include "llvm/Analysis/Dominators.h"
 #include "llvm/Analysis/AliasSetTracker.h"
 #include "llvm/ADT/DenseMap.h"
@@ -163,6 +164,7 @@ namespace {
     std::vector<AllocaInst*> Allocas;
     DominatorTree &DT;
     DominanceFrontier &DF;
+    DIFactory *DIF;
 
     /// AST - An AliasSetTracker object to update.  If null, don't update it.
     ///
@@ -199,7 +201,7 @@ namespace {
   public:
     PromoteMem2Reg(const std::vector<AllocaInst*> &A, DominatorTree &dt,
                    DominanceFrontier &df, AliasSetTracker *ast)
-      : Allocas(A), DT(dt), DF(df), AST(ast) {}
+      : Allocas(A), DT(dt), DF(df), DIF(0), AST(ast) {}
 
     void run();
 
@@ -241,8 +243,9 @@ namespace {
                                   LargeBlockInfo &LBI);
     void PromoteSingleBlockAlloca(AllocaInst *AI, AllocaInfo &Info,
                                   LargeBlockInfo &LBI);
-
-    
+    void ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI, StoreInst* SI,
+                                         uint64_t Offset);
+                                  
     void RenamePass(BasicBlock *BB, BasicBlock *Pred,
                     RenamePassData::ValVector &IncVals,
                     std::vector<RenamePassData> &Worklist);
@@ -306,6 +309,19 @@ namespace {
 }  // end of anonymous namespace
 
 
+/// Finds the llvm.dbg.declare intrinsic corresponding to an alloca if any.
+static DbgDeclareInst *findDbgDeclare(AllocaInst *AI) {
+  Function *F = AI->getParent()->getParent();
+  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 (DbgDeclareInst *DDI = dyn_cast<DbgDeclareInst>(BI))
+        if (DDI->getAddress() == AI)
+          return DDI;
+
+  return 0;
+}
+
 void PromoteMem2Reg::run() {
   Function &F = *DF.getRoot()->getParent();
 
@@ -344,6 +360,8 @@ void PromoteMem2Reg::run() {
 
       // Finally, after the scan, check to see if the store is all that is left.
       if (Info.UsingBlocks.empty()) {
+        // Record debuginfo for the store before removing it.
+        ConvertDebugDeclareToDebugValue(findDbgDeclare(AI), Info.OnlyStore, 0);
         // Remove the (now dead) store and alloca.
         Info.OnlyStore->eraseFromParent();
         LBI.deleteValue(Info.OnlyStore);
@@ -370,8 +388,11 @@ void PromoteMem2Reg::run() {
       if (Info.UsingBlocks.empty()) {
         
         // Remove the (now dead) stores and alloca.
+        DbgDeclareInst *DDI = findDbgDeclare(AI);
         while (!AI->use_empty()) {
           StoreInst *SI = cast<StoreInst>(AI->use_back());
+          // Record debuginfo for the store before removing it.
+          ConvertDebugDeclareToDebugValue(DDI, SI, 0);
           SI->eraseFromParent();
           LBI.deleteValue(SI);
         }
@@ -833,6 +854,18 @@ void PromoteMem2Reg::PromoteSingleBlockAlloca(AllocaInst *AI, AllocaInfo &Info,
   }
 }
 
+// Inserts a llvm.dbg.value instrinsic before the stores to an alloca'd value
+// that has an associated llvm.dbg.decl intrinsic.
+void PromoteMem2Reg::ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
+                                                     StoreInst* SI,
+                                                     uint64_t Offset) {
+  if (!DDI) return;
+
+  if (!DIF)
+    DIF = new DIFactory(*SI->getParent()->getParent()->getParent());
+  DIF->InsertDbgValueIntrinsic(SI->getOperand(0), Offset,
+                               DIVariable(DDI->getVariable()), SI);
+}
 
 // QueuePhiNode - queues a phi-node to be added to a basic-block for a specific
 // Alloca returns true if there wasn't already a phi-node for that variable
@@ -946,6 +979,8 @@ NextIteration:
       
       // what value were we writing?
       IncomingVals[ai->second] = SI->getOperand(0);
+      // Record debuginfo for the store before removing it.
+      ConvertDebugDeclareToDebugValue(findDbgDeclare(Dest), SI, 0);
       BB->getInstList().erase(SI);
     }
   }
diff --git a/test/Transforms/Mem2Reg/ConvertDebugInfo.ll b/test/Transforms/Mem2Reg/ConvertDebugInfo.ll
new file mode 100644
index 0000000000..8e309c0901
--- /dev/null
+++ b/test/Transforms/Mem2Reg/ConvertDebugInfo.ll
@@ -0,0 +1,31 @@
+; RUN: opt < %s -mem2reg -S | FileCheck %s
+
+target datalayout = "E-p:64:64:64-a0:0:8-f32:32:32-f64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-v64:64:64-v128:128:128"
+
+define double @testfunc(i32 %i, double %j) {
+	%I = alloca i32		; <i32*> [#uses=4]
+  call void @llvm.dbg.declare(metadata !{i32* %I}, metadata !0)
+	%J = alloca double		; <double*> [#uses=2]
+  call void @llvm.dbg.declare(metadata !{double* %J}, metadata !1)
+; CHECK: call void @llvm.dbg.value(metadata !{i32 %i}, i64 0, metadata !0)
+	store i32 %i, i32* %I
+; CHECK: call void @llvm.dbg.value(metadata !{double %j}, i64 0, metadata !1)
+	store double %j, double* %J
+	%t1 = load i32* %I		; <i32> [#uses=1]
+	%t2 = add i32 %t1, 1		; <i32> [#uses=1]
+	store i32 %t2, i32* %I
+	%t3 = load i32* %I		; <i32> [#uses=1]
+	%t4 = sitofp i32 %t3 to double		; <double> [#uses=1]
+	%t5 = load double* %J		; <double> [#uses=1]
+	%t6 = fmul double %t4, %t5		; <double> [#uses=1]
+	ret double %t6
+}
+
+declare void @llvm.dbg.declare(metadata, metadata) nounwind readnone
+
+!bar = !{!0}
+!foo = !{!2}
+
+!0 = metadata !{i32 459008, metadata !1, metadata !"foo", metadata !2, i32 5, metadata !"foo"} ; [ DW_TAG_auto_variable ]
+!1 = metadata !{i32 459008, metadata !1, metadata !"foo", metadata !0, i32 5, metadata !1} ; [ DW_TAG_auto_variable ]
+!2 = metadata !{i32 458804, i32 0, metadata !2, metadata !"foo", metadata !"bar", metadata !"bar", metadata !2, i32 3, metadata !0, i1 false, i1 true} ; [ DW_TAG_variable ]