Cleanup and document MachineLocation.

Clarify documentation and API to make the difference between register and
register-indirect addressed locations more explicit. Put in a comment
to point out that with the current implementation we cannot specify
a register-indirect location with offset 0 (a breg 0 in DWARF).
No functionality change intended.

rdar://problem/13658587

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@180641 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 7 insertions, 1 deletions

diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 270a10ad37..c4e77aafab 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -1131,7 +1131,13 @@ static DotDebugLocEntry getDebugLocEntry(AsmPrinter *Asm,
   }
   if (MI->getOperand(0).isReg() && MI->getOperand(1).isImm()) {
     MachineLocation MLoc;
-    MLoc.set(MI->getOperand(0).getReg(), MI->getOperand(1).getImm());
+    // TODO: Currently an offset of 0 in a DBG_VALUE means
+    // we need to generate a direct register value.
+    // There is no way to specify an indirect value with offset 0.
+    if (MI->getOperand(1).getImm() == 0)
+      MLoc.set(MI->getOperand(0).getReg());
+    else
+      MLoc.set(MI->getOperand(0).getReg(), MI->getOperand(1).getImm());
     return DotDebugLocEntry(FLabel, SLabel, MLoc, Var);
   }
   if (MI->getOperand(0).isImm())