Fix resetting the DataLayout in a Module.

No tool does this currently, but as everything else in a module we should be
able to change its DataLayout.

Most of the fix is in DataLayout to make sure it can be reset properly.

The test uses Module::setDataLayout since the fact that we mutate a DataLayout
is an implementation detail. The module could hold a OwningPtr<DataLayout> and
the DataLayout itself could be immutable.

Thanks to Philip Reames for pushing me in the right direction.

llvm-svn: 202198

1 files changed, 5 insertions, 1 deletions

diff --git a/llvm/lib/IR/Module.cpp b/llvm/lib/IR/Module.cpp
index 739f888..4204c8e 100644
--- a/llvm/lib/IR/Module.cpp
+++ b/llvm/lib/IR/Module.cpp
@@ -339,17 +339,21 @@ void Module::addModuleFlag(MDNode *Node) {
 }
 
 void Module::setDataLayout(StringRef Desc) {
+  DL.reset(Desc);
+
   if (Desc.empty()) {
     DataLayoutStr = "";
   } else {
-    DL.init(Desc);
     DataLayoutStr = DL.getStringRepresentation();
+    // DataLayoutStr is now equivalent to Desc, but since the representation
+    // is not unique, they may not be identical.
   }
 }
 
 void Module::setDataLayout(const DataLayout *Other) {
   if (!Other) {
     DataLayoutStr = "";
+    DL.reset("");
   } else {
     DL = *Other;
     DataLayoutStr = DL.getStringRepresentation();