[CodeGen] Split -enable-global-merge into ARM and AArch64 options.

Currently, there's a single flag, checked by the pass itself.
It can't force-enable the pass (and is on by default), because it
might not even have been created, as that's the targets decision.
Instead, have separate explicit flags, so that the decision is
consistently made in the target.

Keep the flag as a last-resort "force-disable GlobalMerge" for now,
for backwards compatibility.

llvm-svn: 234666

1 files changed, 8 insertions, 1 deletions

diff --git a/llvm/lib/Target/ARM/ARMTargetMachine.cpp b/llvm/lib/Target/ARM/ARMTargetMachine.cpp
index 1bee1b077f7..ae333401915 100644
--- a/llvm/lib/Target/ARM/ARMTargetMachine.cpp
+++ b/llvm/lib/Target/ARM/ARMTargetMachine.cpp
@@ -42,6 +42,11 @@ EnableARMLoadStoreOpt("arm-load-store-opt", cl::Hidden,
                       cl::desc("Enable ARM load/store optimization pass"),
                       cl::init(true));
 
+// FIXME: Unify control over GlobalMerge.
+static cl::opt<cl::boolOrDefault>
+EnableGlobalMerge("arm-global-merge", cl::Hidden,
+                  cl::desc("Enable the global merge pass"));
+
 extern "C" void LLVMInitializeARMTarget() {
   // Register the target.
   RegisterTargetMachine<ARMLETargetMachine> X(TheARMLETarget);
@@ -332,7 +337,9 @@ void ARMPassConfig::addIRPasses() {
 }
 
 bool ARMPassConfig::addPreISel() {
-  if (TM->getOptLevel() == CodeGenOpt::Aggressive)
+  if ((TM->getOptLevel() == CodeGenOpt::Aggressive &&
+       EnableGlobalMerge == cl::BOU_UNSET) ||
+      EnableGlobalMerge == cl::BOU_TRUE)
     // FIXME: This is using the thumb1 only constant value for
     // maximal global offset for merging globals. We may want
     // to look into using the old value for non-thumb1 code of