Separate ExecutionDepsFix into 4 parts:

1. ReachingDefsAnalysis - Allows to identify for each instruction what is the “closest” reaching def of a certain register. Used by BreakFalseDeps (for clearance calculation) and ExecutionDomainFix (for arbitrating conflicting domains).
2. ExecutionDomainFix - Changes the variant of the instructions in order to minimize domain crossings.
3. BreakFalseDeps - Breaks false dependencies.
4. LoopTraversal - Creatws a traversal order of the basic blocks that is optimal for loops (introduced in revision L293571). Both ExecutionDomainFix and ReachingDefsAnalysis use this to determine the order they will traverse the basic blocks.

This also included the following changes to ExcecutionDepsFix original logic:
1. BreakFalseDeps and ReachingDefsAnalysis logic no longer restricted by a register class.
2. ReachingDefsAnalysis tracks liveness of reg units instead of reg indices into a given reg class.

Additional changes in affected files:
1. X86 and ARM targets now inherit from ExecutionDomainFix instead of ExecutionDepsFix. BreakFalseDeps also was added to the passes they activate.
2. Comments and references to ExecutionDepsFix replaced with ExecutionDomainFix and BreakFalseDeps, as appropriate.

Additional refactoring changes will follow.

This commit is (almost) NFC.
The only functional change is that now BreakFalseDeps will break dependency for all register classes.
Since no additional instructions were added to the list of instructions that have false dependencies, there is no actual change yet.
In a future commit several instructions (and tests) will be added.

This is the first of multiple patches that fix bugzilla https://bugs.llvm.org/show_bug.cgi?id=33869
Most of the patches are intended at refactoring the existent code.

Additional relevant reviews:
https://reviews.llvm.org/D40331
https://reviews.llvm.org/D40332
https://reviews.llvm.org/D40333
https://reviews.llvm.org/D40334

Differential Revision: https://reviews.llvm.org/D40330

Change-Id: Icaeb75e014eff96a8f721377783f9a3e6c679275

1 files changed, 14 insertions, 9 deletions

diff --git a/llvm/lib/Target/X86/X86TargetMachine.cpp b/llvm/lib/Target/X86/X86TargetMachine.cpp
index b3bf9269f73..ca243b5f374 100644
--- a/llvm/lib/Target/X86/X86TargetMachine.cpp
+++ b/llvm/lib/Target/X86/X86TargetMachine.cpp
@@ -60,7 +60,7 @@ void initializeWinEHStatePassPass(PassRegistry &);
 void initializeFixupLEAPassPass(PassRegistry &);
 void initializeX86CallFrameOptimizationPass(PassRegistry &);
 void initializeX86CmovConverterPassPass(PassRegistry &);
-void initializeX86ExecutionDepsFixPass(PassRegistry &);
+void initializeX86ExecutionDomainFixPass(PassRegistry &);
 void initializeX86DomainReassignmentPass(PassRegistry &);
 
 } // end namespace llvm
@@ -78,7 +78,7 @@ extern "C" void LLVMInitializeX86Target() {
   initializeFixupLEAPassPass(PR);
   initializeX86CallFrameOptimizationPass(PR);
   initializeX86CmovConverterPassPass(PR);
-  initializeX86ExecutionDepsFixPass(PR);
+  initializeX86ExecutionDomainFixPass(PR);
   initializeX86DomainReassignmentPass(PR);
 }
 
@@ -342,20 +342,23 @@ public:
   void addPreSched2() override;
 };
 
-class X86ExecutionDepsFix : public ExecutionDepsFix {
+class X86ExecutionDomainFix : public ExecutionDomainFix {
 public:
   static char ID;
-  X86ExecutionDepsFix() : ExecutionDepsFix(ID, X86::VR128XRegClass) {}
+  X86ExecutionDomainFix() : ExecutionDomainFix(ID, X86::VR128XRegClass) {}
   StringRef getPassName() const override {
     return "X86 Execution Dependency Fix";
   }
 };
-char X86ExecutionDepsFix::ID;
+char X86ExecutionDomainFix::ID;
 
 } // end anonymous namespace
 
-INITIALIZE_PASS(X86ExecutionDepsFix, "x86-execution-deps-fix",
-                "X86 Execution Dependency Fix", false, false)
+INITIALIZE_PASS_BEGIN(X86ExecutionDomainFix, "x86-execution-domain-fix",
+  "X86 Execution Domain Fix", false, false)
+INITIALIZE_PASS_DEPENDENCY(ReachingDefAnalysis)
+INITIALIZE_PASS_END(X86ExecutionDomainFix, "x86-execution-domain-fix",
+  "X86 Execution Domain Fix", false, false)
 
 TargetPassConfig *X86TargetMachine::createPassConfig(PassManagerBase &PM) {
   return new X86PassConfig(*this, PM);
@@ -441,8 +444,10 @@ void X86PassConfig::addPostRegAlloc() {
 void X86PassConfig::addPreSched2() { addPass(createX86ExpandPseudoPass()); }
 
 void X86PassConfig::addPreEmitPass() {
-  if (getOptLevel() != CodeGenOpt::None)
-    addPass(new X86ExecutionDepsFix());
+  if (getOptLevel() != CodeGenOpt::None) {
+    addPass(new X86ExecutionDomainFix());
+    addPass(new BreakFalseDeps());
+  }
 
   addPass(createX86IndirectBranchTrackingPass());