[Debug info] Transfer DI to fragment expressions for split integer values.

This patch teaches the SDag type legalizer how to split up debug info for
integer values that are split into a hi and lo part.

Differential Revision: https://reviews.llvm.org/D36805

llvm-svn: 311102

3 files changed, 62 insertions, 19 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp
index 001eed9fb8f..7bef90d01a0 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp
@@ -14,8 +14,12 @@
 //===----------------------------------------------------------------------===//
 
 #include "LegalizeTypes.h"
+#include "SDNodeDbgValue.h"
 #include "llvm/ADT/SetVector.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineModuleInfo.h"
 #include "llvm/IR/CallingConv.h"
+#include "llvm/IR/DIBuilder.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/ErrorHandling.h"
@@ -822,6 +826,34 @@ void DAGTypeLegalizer::GetExpandedInteger(SDValue Op, SDValue &Lo,
   Hi = Entry.second;
 }
 
+/// Transfer debug valies by generating fragment expressions for split-up
+/// values.
+static void transferDbgValues(SelectionDAG &DAG, DIBuilder &DIB, SDValue From,
+                              SDValue To, unsigned OffsetInBits) {
+  SDNode *FromNode = From.getNode();
+  SDNode *ToNode = To.getNode();
+  assert(FromNode != ToNode);
+
+  for (SDDbgValue *Dbg : DAG.GetDbgValues(FromNode)) {
+    if (Dbg->getKind() != SDDbgValue::SDNODE)
+      break;
+
+    DIVariable *Var = Dbg->getVariable();
+    DIExpression *Fragment = DIB.createFragmentExpression(
+        OffsetInBits, To.getValueSizeInBits(),
+        cast_or_null<DIExpression>(Dbg->getExpression()));
+    SDDbgValue *Clone =
+        DAG.getDbgValue(Var, Fragment, ToNode, To.getResNo(), Dbg->isIndirect(),
+                        Dbg->getDebugLoc(), Dbg->getOrder());
+    Dbg->setIsInvalidated();
+    DAG.AddDbgValue(Clone, ToNode, false);
+
+    // Add the expression to the metadata graph so isn't lost in MIR dumps.
+    const Module *M = DAG.getMachineFunction().getMMI().getModule();
+    M->getNamedMetadata("llvm.dbg.mir")->addOperand(Fragment);
+  }
+}
+
 void DAGTypeLegalizer::SetExpandedInteger(SDValue Op, SDValue Lo,
                                           SDValue Hi) {
   assert(Lo.getValueType() ==
@@ -832,6 +864,12 @@ void DAGTypeLegalizer::SetExpandedInteger(SDValue Op, SDValue Lo,
   AnalyzeNewValue(Lo);
   AnalyzeNewValue(Hi);
 
+  // Transfer debug values.
+  const Module *M = DAG.getMachineFunction().getMMI().getModule();
+  DIBuilder DIB(*const_cast<Module *>(M));
+  transferDbgValues(DAG, DIB, Op, Lo, 0);
+  transferDbgValues(DAG, DIB, Op, Hi, Lo.getValueSizeInBits());
+
   // Remember that this is the result of the node.
   std::pair<SDValue, SDValue> &Entry = ExpandedIntegers[Op];
   assert(!Entry.first.getNode() && "Node already expanded");
diff --git a/llvm/lib/CodeGen/SelectionDAG/SDNodeDbgValue.h b/llvm/lib/CodeGen/SelectionDAG/SDNodeDbgValue.h
index a1b1c78fb8c..cd5b4c12f1d 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SDNodeDbgValue.h
+++ b/llvm/lib/CodeGen/SelectionDAG/SDNodeDbgValue.h
@@ -20,7 +20,8 @@
 
 namespace llvm {
 
-class MDNode;
+class DIVariable;
+class DIExpression;
 class SDNode;
 class Value;
 
@@ -43,8 +44,8 @@ private:
     const Value *Const;     // valid for constants
     unsigned FrameIx;       // valid for stack objects
   } u;
-  MDNode *Var;
-  MDNode *Expr;
+  DIVariable *Var;
+  DIExpression *Expr;
   DebugLoc DL;
   unsigned Order;
   enum DbgValueKind kind;
@@ -53,8 +54,8 @@ private:
 
 public:
   // Constructor for non-constants.
-  SDDbgValue(MDNode *Var, MDNode *Expr, SDNode *N, unsigned R, bool indir,
-             DebugLoc dl, unsigned O)
+  SDDbgValue(DIVariable *Var, DIExpression *Expr, SDNode *N, unsigned R,
+             bool indir, DebugLoc dl, unsigned O)
       : Var(Var), Expr(Expr), DL(std::move(dl)), Order(O), IsIndirect(indir) {
     kind = SDNODE;
     u.s.Node = N;
@@ -62,14 +63,16 @@ public:
   }
 
   // Constructor for constants.
-  SDDbgValue(MDNode *Var, MDNode *Expr, const Value *C, DebugLoc dl, unsigned O)
+  SDDbgValue(DIVariable *Var, DIExpression *Expr, const Value *C, DebugLoc dl,
+             unsigned O)
       : Var(Var), Expr(Expr), DL(std::move(dl)), Order(O), IsIndirect(false) {
     kind = CONST;
     u.Const = C;
   }
 
   // Constructor for frame indices.
-  SDDbgValue(MDNode *Var, MDNode *Expr, unsigned FI, DebugLoc dl, unsigned O)
+  SDDbgValue(DIVariable *Var, DIExpression *Expr, unsigned FI, DebugLoc dl,
+             unsigned O)
       : Var(Var), Expr(Expr), DL(std::move(dl)), Order(O), IsIndirect(false) {
     kind = FRAMEIX;
     u.FrameIx = FI;
@@ -78,11 +81,11 @@ public:
   // Returns the kind.
   DbgValueKind getKind() const { return kind; }
 
-  // Returns the MDNode pointer for the variable.
-  MDNode *getVariable() const { return Var; }
+  // Returns the DIVariable pointer for the variable.
+  DIVariable *getVariable() const { return Var; }
 
-  // Returns the MDNode pointer for the expression.
-  MDNode *getExpression() const { return Expr; }
+  // Returns the DIExpression pointer for the expression.
+  DIExpression *getExpression() const { return Expr; }
 
   // Returns the SDNode* for a register ref
   SDNode *getSDNode() const { assert (kind==SDNODE); return u.s.Node; }
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 0ef8adaabbb..457c9b1fa1e 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -6879,8 +6879,8 @@ SDNode *SelectionDAG::getNodeIfExists(unsigned Opcode, SDVTList VTList,
 /// getDbgValue - Creates a SDDbgValue node.
 ///
 /// SDNode
-SDDbgValue *SelectionDAG::getDbgValue(MDNode *Var, MDNode *Expr, SDNode *N,
-                                      unsigned R, bool IsIndirect,
+SDDbgValue *SelectionDAG::getDbgValue(DIVariable *Var, DIExpression *Expr,
+                                      SDNode *N, unsigned R, bool IsIndirect,
                                       const DebugLoc &DL, unsigned O) {
   assert(cast<DILocalVariable>(Var)->isValidLocationForIntrinsic(DL) &&
          "Expected inlined-at fields to agree");
@@ -6889,7 +6889,8 @@ SDDbgValue *SelectionDAG::getDbgValue(MDNode *Var, MDNode *Expr, SDNode *N,
 }
 
 /// Constant
-SDDbgValue *SelectionDAG::getConstantDbgValue(MDNode *Var, MDNode *Expr,
+SDDbgValue *SelectionDAG::getConstantDbgValue(DIVariable *Var,
+                                              DIExpression *Expr,
                                               const Value *C,
                                               const DebugLoc &DL, unsigned O) {
   assert(cast<DILocalVariable>(Var)->isValidLocationForIntrinsic(DL) &&
@@ -6898,8 +6899,9 @@ SDDbgValue *SelectionDAG::getConstantDbgValue(MDNode *Var, MDNode *Expr,
 }
 
 /// FrameIndex
-SDDbgValue *SelectionDAG::getFrameIndexDbgValue(MDNode *Var, MDNode *Expr,
-                                                unsigned FI, const DebugLoc &DL,
+SDDbgValue *SelectionDAG::getFrameIndexDbgValue(DIVariable *Var,
+                                                DIExpression *Expr, unsigned FI,
+                                                const DebugLoc &DL,
                                                 unsigned O) {
   assert(cast<DILocalVariable>(Var)->isValidLocationForIntrinsic(DL) &&
          "Expected inlined-at fields to agree");
@@ -7337,9 +7339,9 @@ void SelectionDAG::TransferDbgValues(SDValue From, SDValue To) {
         Dbg->getResNo() == From.getResNo() && !Dbg->isInvalidated()) {
       assert(FromNode != ToNode &&
              "Should not transfer Debug Values intranode");
-      SDDbgValue *Clone = getDbgValue(Dbg->getVariable(), Dbg->getExpression(),
-                                      ToNode, To.getResNo(), Dbg->isIndirect(),
-                                      Dbg->getDebugLoc(), Dbg->getOrder());
+      SDDbgValue *Clone = getDbgValue(
+          Dbg->getVariable(), Dbg->getExpression(), ToNode, Dbg->getResNo(),
+          Dbg->isIndirect(), Dbg->getDebugLoc(), Dbg->getOrder());
       ClonedDVs.push_back(Clone);
       Dbg->setIsInvalidated();
     }