[globalisel] Add a combiner helpers for extending loads and use them in a pre-legalize combiner for AArch64

Summary: Depends on D45541

Reviewers: ab, aditya_nandakumar, bogner, rtereshin, volkan, rovka, javed.absar, aemerson

Subscribers: aemerson, rengolin, mgorny, javed.absar, kristof.beyls, llvm-commits

Differential Revision: https://reviews.llvm.org/D45543

llvm-svn: 343521

4 files changed, 117 insertions, 0 deletions

diff --git a/llvm/lib/Target/AArch64/AArch64.h b/llvm/lib/Target/AArch64/AArch64.h
index edda13ce97e..74f22e287f8 100644
--- a/llvm/lib/Target/AArch64/AArch64.h
+++ b/llvm/lib/Target/AArch64/AArch64.h
@@ -53,6 +53,7 @@ FunctionPass *createAArch64CollectLOHPass();
 InstructionSelector *
 createAArch64InstructionSelector(const AArch64TargetMachine &,
                                  AArch64Subtarget &, AArch64RegisterBankInfo &);
+FunctionPass *createAArch64PreLegalizeCombiner();
 
 void initializeAArch64A53Fix835769Pass(PassRegistry&);
 void initializeAArch64A57FPLoadBalancingPass(PassRegistry&);
@@ -65,6 +66,7 @@ void initializeAArch64DeadRegisterDefinitionsPass(PassRegistry&);
 void initializeAArch64ExpandPseudoPass(PassRegistry&);
 void initializeAArch64LoadStoreOptPass(PassRegistry&);
 void initializeAArch64SIMDInstrOptPass(PassRegistry&);
+void initializeAArch64PreLegalizerCombinerPass(PassRegistry&);
 void initializeAArch64PromoteConstantPass(PassRegistry&);
 void initializeAArch64RedundantCopyEliminationPass(PassRegistry&);
 void initializeAArch64StorePairSuppressPass(PassRegistry&);
diff --git a/llvm/lib/Target/AArch64/AArch64PreLegalizerCombiner.cpp b/llvm/lib/Target/AArch64/AArch64PreLegalizerCombiner.cpp
new file mode 100644
index 00000000000..32487b9ccc3
--- /dev/null
+++ b/llvm/lib/Target/AArch64/AArch64PreLegalizerCombiner.cpp
@@ -0,0 +1,108 @@
+//=== lib/CodeGen/GlobalISel/AArch64PreLegalizerCombiner.cpp --------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass does combining of machine instructions at the generic MI level,
+// before the legalizer.
+//
+//===----------------------------------------------------------------------===//
+
+#include "AArch64TargetMachine.h"
+#include "llvm/CodeGen/GlobalISel/Combiner.h"
+#include "llvm/CodeGen/GlobalISel/CombinerHelper.h"
+#include "llvm/CodeGen/GlobalISel/CombinerInfo.h"
+#include "llvm/CodeGen/GlobalISel/MIPatternMatch.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/TargetPassConfig.h"
+#include "llvm/Support/Debug.h"
+
+#define DEBUG_TYPE "aarch64-prelegalizer-combiner"
+
+using namespace llvm;
+using namespace MIPatternMatch;
+
+namespace {
+class AArch64PreLegalizerCombinerInfo : public CombinerInfo {
+public:
+  AArch64PreLegalizerCombinerInfo()
+      : CombinerInfo(/*AllowIllegalOps*/ true, /*ShouldLegalizeIllegal*/ false,
+                     /*LegalizerInfo*/ nullptr) {}
+  virtual bool combine(CombinerChangeObserver &Observer, MachineInstr &MI,
+                       MachineIRBuilder &B) const override;
+};
+
+bool AArch64PreLegalizerCombinerInfo::combine(CombinerChangeObserver &Observer,
+                                              MachineInstr &MI,
+                                              MachineIRBuilder &B) const {
+  CombinerHelper Helper(Observer, B);
+
+  switch (MI.getOpcode()) {
+  default:
+    return false;
+  case TargetOpcode::G_LOAD:
+  case TargetOpcode::G_SEXTLOAD:
+  case TargetOpcode::G_ZEXTLOAD:
+    return Helper.tryCombineExtendingLoads(MI);
+  }
+
+  return false;
+}
+
+// Pass boilerplate
+// ================
+
+class AArch64PreLegalizerCombiner : public MachineFunctionPass {
+public:
+  static char ID;
+
+  AArch64PreLegalizerCombiner();
+
+  StringRef getPassName() const override { return "AArch64PreLegalizerCombiner"; }
+
+  bool runOnMachineFunction(MachineFunction &MF) override;
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override;
+};
+}
+
+void AArch64PreLegalizerCombiner::getAnalysisUsage(AnalysisUsage &AU) const {
+  AU.addRequired<TargetPassConfig>();
+  AU.setPreservesCFG();
+  getSelectionDAGFallbackAnalysisUsage(AU);
+  MachineFunctionPass::getAnalysisUsage(AU);
+}
+
+AArch64PreLegalizerCombiner::AArch64PreLegalizerCombiner() : MachineFunctionPass(ID) {
+  initializeAArch64PreLegalizerCombinerPass(*PassRegistry::getPassRegistry());
+}
+
+bool AArch64PreLegalizerCombiner::runOnMachineFunction(MachineFunction &MF) {
+  if (MF.getProperties().hasProperty(
+          MachineFunctionProperties::Property::FailedISel))
+    return false;
+  auto *TPC = &getAnalysis<TargetPassConfig>();
+  AArch64PreLegalizerCombinerInfo PCInfo;
+  Combiner C(PCInfo, TPC);
+  return C.combineMachineInstrs(MF);
+}
+
+char AArch64PreLegalizerCombiner::ID = 0;
+INITIALIZE_PASS_BEGIN(AArch64PreLegalizerCombiner, DEBUG_TYPE,
+                      "Combine AArch64 machine instrs before legalization",
+                      false, false)
+INITIALIZE_PASS_DEPENDENCY(TargetPassConfig)
+INITIALIZE_PASS_END(AArch64PreLegalizerCombiner, DEBUG_TYPE,
+                    "Combine AArch64 machine instrs before legalization", false,
+                    false)
+
+
+namespace llvm {
+FunctionPass *createAArch64PreLegalizeCombiner() {
+  return new AArch64PreLegalizerCombiner();
+}
+} // end namespace llvm
diff --git a/llvm/lib/Target/AArch64/AArch64TargetMachine.cpp b/llvm/lib/Target/AArch64/AArch64TargetMachine.cpp
index c4b9b45f67b..a66f5277f24 100644
--- a/llvm/lib/Target/AArch64/AArch64TargetMachine.cpp
+++ b/llvm/lib/Target/AArch64/AArch64TargetMachine.cpp
@@ -158,6 +158,7 @@ extern "C" void LLVMInitializeAArch64Target() {
   initializeAArch64ExpandPseudoPass(*PR);
   initializeAArch64LoadStoreOptPass(*PR);
   initializeAArch64SIMDInstrOptPass(*PR);
+  initializeAArch64PreLegalizerCombinerPass(*PR);
   initializeAArch64PromoteConstantPass(*PR);
   initializeAArch64RedundantCopyEliminationPass(*PR);
   initializeAArch64StorePairSuppressPass(*PR);
@@ -348,6 +349,7 @@ public:
   bool addPreISel() override;
   bool addInstSelector() override;
   bool addIRTranslator() override;
+  void addPreLegalizeMachineIR() override;
   bool addLegalizeMachineIR() override;
   bool addRegBankSelect() override;
   void addPreGlobalInstructionSelect() override;
@@ -449,6 +451,10 @@ bool AArch64PassConfig::addIRTranslator() {
   return false;
 }
 
+void AArch64PassConfig::addPreLegalizeMachineIR() {
+  addPass(createAArch64PreLegalizeCombiner());
+}
+
 bool AArch64PassConfig::addLegalizeMachineIR() {
   addPass(new Legalizer());
   return false;
diff --git a/llvm/lib/Target/AArch64/CMakeLists.txt b/llvm/lib/Target/AArch64/CMakeLists.txt
index d9a00512f71..e6ca69c1971 100644
--- a/llvm/lib/Target/AArch64/CMakeLists.txt
+++ b/llvm/lib/Target/AArch64/CMakeLists.txt
@@ -43,6 +43,7 @@ add_llvm_target(AArch64CodeGen
   AArch64LoadStoreOptimizer.cpp
   AArch64MacroFusion.cpp
   AArch64MCInstLower.cpp
+  AArch64PreLegalizerCombiner.cpp
   AArch64PromoteConstant.cpp
   AArch64PBQPRegAlloc.cpp
   AArch64RegisterBankInfo.cpp