[Debug info] Handle endianness when moving debug info for split integer values

Summary:
Take the target's endianness into account when splitting the
debug information in DAGTypeLegalizer::SetExpandedInteger.

This patch fixes so that, for big-endian targets, the fragment
expression corresponding to the high part of a split integer
value is placed at offset 0, in order to correctly represent
the memory address order.

I have attached a PPC32 reproducer where the resulting DWARF
pieces for a 64-bit integer were incorrectly reversed.

Patch by: dstenb

Reviewers: JDevlieghere, aprantl, dblaikie

Reviewed By: JDevlieghere, aprantl, dblaikie

Subscribers: nemanjai

Differential Revision: https://reviews.llvm.org/D38172

llvm-svn: 314666

1 files changed, 7 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp
index f76363adb99..f331fc7c250 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp
@@ -864,8 +864,13 @@ void DAGTypeLegalizer::SetExpandedInteger(SDValue Op, SDValue Lo,
   AnalyzeNewValue(Hi);
 
   // Transfer debug values.
-  transferDbgValues(DAG, Op, Lo, 0);
-  transferDbgValues(DAG, Op, Hi, Lo.getValueSizeInBits());
+  if (DAG.getDataLayout().isBigEndian()) {
+    transferDbgValues(DAG, Op, Hi, 0);
+    transferDbgValues(DAG, Op, Lo, Hi.getValueSizeInBits());
+  } else {
+    transferDbgValues(DAG, Op, Lo, 0);
+    transferDbgValues(DAG, Op, Hi, Lo.getValueSizeInBits());
+  }
 
   // Remember that this is the result of the node.
   std::pair<SDValue, SDValue> &Entry = ExpandedIntegers[Op];