DwarfDebug: Don't drop the DIExpression just because a variable is

described by an immediate.

Found via http://reviews.llvm.org/D16867
Thanks to Paul Robinson for pointing this out.

<rdar://problem/24456528>

llvm-svn: 261168

1 files changed, 14 insertions, 3 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index 5febd9fb380..56856c7ee3f 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -504,9 +504,20 @@ DIE *DwarfCompileUnit::constructVariableDIEImpl(const DbgVariable &DV,
         addVariableAddress(DV, *VariableDie, Location);
       } else if (RegOp.getReg())
         addVariableAddress(DV, *VariableDie, MachineLocation(RegOp.getReg()));
-    } else if (DVInsn->getOperand(0).isImm())
-      addConstantValue(*VariableDie, DVInsn->getOperand(0), DV.getType());
-    else if (DVInsn->getOperand(0).isFPImm())
+    } else if (DVInsn->getOperand(0).isImm()) {
+      // This variable is described by a single constant.
+      // Check whether it has a DIExpression.
+      auto *Expr = DV.getSingleExpression();
+      if (Expr && Expr->getNumElements()) {
+        DIELoc *Loc = new (DIEValueAllocator) DIELoc;
+        DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
+        // If there is an expression, emit raw unsigned bytes.
+        DwarfExpr.AddUnsignedConstant(DVInsn->getOperand(0).getImm());
+        DwarfExpr.AddExpression(Expr->expr_op_begin(), Expr->expr_op_end());
+        addBlock(*VariableDie, dwarf::DW_AT_location, Loc);
+      } else
+        addConstantValue(*VariableDie, DVInsn->getOperand(0), DV.getType());
+    } else if (DVInsn->getOperand(0).isFPImm())
       addConstantFPValue(*VariableDie, DVInsn->getOperand(0));
     else if (DVInsn->getOperand(0).isCImm())
       addConstantValue(*VariableDie, DVInsn->getOperand(0).getCImm(),