[AArch64] Enable global merge pass.

llvm-svn: 206861

lib/Target/AArch64/AArch64ISelLowering.cpp

@@ -5538,3 +5538,10 @@ int AArch64TargetLowering::getScalingFactorCost(const AddrMode &AM,
     return AM.Scale != 0 && AM.Scale != 1;
   return -1;
 }
+
+/// getMaximalGlobalOffset - Returns the maximal possible offset which can
+/// be used for loads / stores from the global.
+unsigned AArch64TargetLowering::getMaximalGlobalOffset() const {
+  return 4095;
+}
+

lib/Target/AArch64/AArch64ISelLowering.h

@@ -376,6 +376,10 @@ public:
   virtual bool getTgtMemIntrinsic(IntrinsicInfo &Info, const CallInst &I,
                                   unsigned Intrinsic) const override;
 
+  /// getMaximalGlobalOffset - Returns the maximal possible offset which can
+  /// be used for loads / stores from the global.
+  unsigned getMaximalGlobalOffset() const override;
+
 protected:
   std::pair<const TargetRegisterClass*, uint8_t>
   findRepresentativeClass(MVT VT) const;

lib/Target/AArch64/AArch64TargetMachine.cpp

@@ -19,6 +19,7 @@
 #include "llvm/CodeGen/Passes.h"
 #include "llvm/PassManager.h"
 #include "llvm/Support/TargetRegistry.h"
+#include "llvm/Transforms/Scalar.h"
 
 using namespace llvm;
 
@@ -86,11 +87,19 @@ public:
     return *getAArch64TargetMachine().getSubtargetImpl();
   }
 
+  bool addPreISel() override;
   virtual bool addInstSelector();
   virtual bool addPreEmitPass();
 };
 } // namespace
 
+bool AArch64PassConfig::addPreISel() {
+  if (TM->getOptLevel() != CodeGenOpt::None)
+    addPass(createGlobalMergePass(TM));
+
+  return false;
+}
+
 TargetPassConfig *AArch64TargetMachine::createPassConfig(PassManagerBase &PM) {
   return new AArch64PassConfig(this, PM);
 }

test/CodeGen/AArch64/global_merge_1.ll

@@ -0,0 +1,17 @@
+; RUN: llc < %s -mtriple=aarch64-none-linux-gnu | FileCheck %s
+
+@m = internal global i32 0, align 4
+@n = internal global i32 0, align 4
+
+define void @f1(i32 %a1, i32 %a2) {
+; CHECK-LABEL: f1:
+; CHECK: adrp x{{[0-9]+}}, _MergedGlobals
+; CHECK-NOT: adrp
+  store i32 %a1, i32* @m, align 4
+  store i32 %a2, i32* @n, align 4
+  ret void
+}
+
+; CHECK:        .local _MergedGlobals
+; CHECK:        .comm  _MergedGlobals,8,8
+