Implement global merge optimization for global variables.

This commit implements two command line switches -global-merge-on-external
and -global-merge-aligned, and both of them are false by default, so this
optimization is disabled by default for all targets.

For ARM64, some back-end behaviors need to be tuned to get this optimization
further enabled.

llvm-svn: 208934

1 files changed, 1 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Scalar/Scalar.cpp b/llvm/lib/Transforms/Scalar/Scalar.cpp
index f8f828c8405..2cca7254806 100644
--- a/llvm/lib/Transforms/Scalar/Scalar.cpp
+++ b/llvm/lib/Transforms/Scalar/Scalar.cpp
@@ -38,6 +38,7 @@ void llvm::initializeScalarOpts(PassRegistry &Registry) {
   initializeDSEPass(Registry);
   initializeGVNPass(Registry);
   initializeEarlyCSEPass(Registry);
+  initializeGlobalMergePass(Registry);
   initializeIndVarSimplifyPass(Registry);
   initializeJumpThreadingPass(Registry);
   initializeLICMPass(Registry);