[PostRA scheduling] Allow a target to do scheduling when it wants post RA.

SystemZ needs to do its scheduling after branch relaxation, which can
only happen after block placement, and therefore the standard
PostRAScheduler point in the pass sequence is too early.

TargetMachine::targetSchedulesPostRAScheduling() is a new method that
signals on returning true that target will insert the final scheduling
pass on its own.

Reviewed by Hal Finkel

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@255234 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/Target/TargetMachine.h b/include/llvm/Target/TargetMachine.h
index b7760a61806f47278ef3c9fa5941153b95395e1f..74e91b5790cba6d6ef66f87853d42dec72790184 100644 (file)
--- a/include/llvm/Target/TargetMachine.h
+++ b/include/llvm/Target/TargetMachine.h
@@ -255,6 +255,13 @@ public:
     return true;
   }
 
+  /// True if subtarget inserts the final scheduling pass on its own.
+  ///
+  /// Branch relaxation, which must happen after block placement, can
+  /// on some targets (e.g. SystemZ) expose additional post-RA
+  /// scheduling opportunities.
+  virtual bool targetSchedulesPostRAScheduling() const { return false; };
+
   void getNameWithPrefix(SmallVectorImpl<char> &Name, const GlobalValue *GV,
                          Mangler &Mang, bool MayAlwaysUsePrivate = false) const;
   MCSymbol *getSymbol(const GlobalValue *GV, Mangler &Mang) const;

diff --git a/lib/CodeGen/Passes.cpp b/lib/CodeGen/Passes.cpp
index 9d473fdb6cd72131b80ec5581daa7d71e75efecf..4d7adcbbfe7761710d153ad5a11700f2ec27d2cd 100644 (file)
--- a/lib/CodeGen/Passes.cpp
+++ b/lib/CodeGen/Passes.cpp
@@ -96,10 +96,10 @@ PrintMachineInstrs("print-machineinstrs", cl::ValueOptional,
 
 // Temporary option to allow experimenting with MachineScheduler as a post-RA
 // scheduler. Targets can "properly" enable this with
-// substitutePass(&PostRASchedulerID, &PostMachineSchedulerID); Ideally it
-// wouldn't be part of the standard pass pipeline, and the target would just add
-// a PostRA scheduling pass wherever it wants.
-static cl::opt<bool> MISchedPostRA("misched-postra", cl::Hidden,
+// substitutePass(&PostRASchedulerID, &PostMachineSchedulerID).
+// Targets can return true in targetSchedulesPostRAScheduling() and
+// insert a PostRA scheduling pass wherever it wants.
+cl::opt<bool> MISchedPostRA("misched-postra", cl::Hidden,
   cl::desc("Run MachineScheduler post regalloc (independent of preRA sched)"));
 
 // Experimental option to run live interval analysis early.
@@ -575,7 +575,10 @@ void TargetPassConfig::addMachinePasses() {
     addPass(&ImplicitNullChecksID);
 
   // Second pass scheduler.
-  if (getOptLevel() != CodeGenOpt::None) {
+  // Let Target optionally insert this pass by itself at some other
+  // point.
+  if (getOptLevel() != CodeGenOpt::None &&
+      !TM->targetSchedulesPostRAScheduling()) {
     if (MISchedPostRA)
       addPass(&PostMachineSchedulerID);
     else

diff --git a/lib/Target/SystemZ/SystemZTargetMachine.cpp b/lib/Target/SystemZ/SystemZTargetMachine.cpp
index 22beaad2ab73899b3324836f7b5f6165fb600207..f305e85f6cfee90be1872e86204f094ccc48c0bf 100644 (file)
--- a/lib/Target/SystemZ/SystemZTargetMachine.cpp
+++ b/lib/Target/SystemZ/SystemZTargetMachine.cpp
@@ -16,6 +16,7 @@
 
 using namespace llvm;
 
+extern cl::opt<bool> MISchedPostRA;
 extern "C" void LLVMInitializeSystemZTarget() {
   // Register the target.
   RegisterTargetMachine<SystemZTargetMachine> X(TheSystemZTarget);
@@ -163,6 +164,16 @@ void SystemZPassConfig::addPreEmitPass() {
   if (getOptLevel() != CodeGenOpt::None)
     addPass(createSystemZElimComparePass(getSystemZTargetMachine()), false);
   addPass(createSystemZLongBranchPass(getSystemZTargetMachine()));
+
+  // Do final scheduling after all other optimizations, to get an
+  // optimal input for the decoder (branch relaxation must happen
+  // after block placement).
+  if (getOptLevel() != CodeGenOpt::None) {
+    if (MISchedPostRA)
+      addPass(&PostMachineSchedulerID);
+    else
+      addPass(&PostRASchedulerID);
+  }
 }
 
 TargetPassConfig *SystemZTargetMachine::createPassConfig(PassManagerBase &PM) {

diff --git a/lib/Target/SystemZ/SystemZTargetMachine.h b/lib/Target/SystemZ/SystemZTargetMachine.h
index 0a81e1f9fdf99e9ef983e59cf0e11d5bde95e2a1..1a8f1f7f3aaa083b4593e3f7f5bf5dbf68983e3c 100644 (file)
--- a/lib/Target/SystemZ/SystemZTargetMachine.h
+++ b/lib/Target/SystemZ/SystemZTargetMachine.h
@@ -43,6 +43,9 @@ public:
   TargetLoweringObjectFile *getObjFileLowering() const override {
     return TLOF.get();
   }
+
+  bool targetSchedulesPostRAScheduling() const override { return true; };
+
 };
 
 } // end namespace llvm