[SLC] Add an alignment to CreateGlobalString

Previously the alignment on the newly created global strings was not set,
meaning that DataLayout::getPreferredAlignment was free to overalign it
to 16 bytes. This caused unnecessary code bloat with the padding between
variables.

The main example of this happening was the printf->puts optimisation in
SimplifyLibCalls, but as the change here is made in
IRBuilderBase::CreateGlobalString, other globals using this will now be
aligned too.

Differential Revision: https://reviews.llvm.org/D51410

llvm-svn: 341527

1 files changed, 1 insertions, 0 deletions

diff --git a/llvm/lib/IR/IRBuilder.cpp b/llvm/lib/IR/IRBuilder.cpp
index 405a56bfb31..91c950da71b 100644
--- a/llvm/lib/IR/IRBuilder.cpp
+++ b/llvm/lib/IR/IRBuilder.cpp
@@ -50,6 +50,7 @@ GlobalVariable *IRBuilderBase::CreateGlobalString(StringRef Str,
                                 nullptr, GlobalVariable::NotThreadLocal,
                                 AddressSpace);
   GV->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
+  GV->setAlignment(1);
   return GV;
 }