AMDGPU/SI: Pass whether to use the SI scheduler via Target Attribute

Summary:
Currently the SI scheduler can be selected via command line option,
but it turned out it would be better if it was selectable via a Target Attribute.

This patch adds "si-scheduler" attribute to the backend.

Reviewers: tstellarAMD, echristo

Subscribers: echristo, arsenm

Differential Revision: http://reviews.llvm.org/D16192

llvm-svn: 258386

llvm/lib/Target/AMDGPU/AMDGPU.td

@@ -144,6 +144,11 @@ def FeatureEnableHugeScratchBuffer : SubtargetFeature<"huge-scratch-buffer",
         "true",
         "Enable scratch buffer sizes greater than 128 GB">;
 
+def FeatureEnableSIScheduler : SubtargetFeature<"si-scheduler",
+        "EnableSIScheduler",
+        "true",
+        "Enable SI Machine Scheduler">;
+
 class SubtargetFeatureFetchLimit <string Value> :
                           SubtargetFeature <"fetch"#Value,
         "TexVTXClauseSize",

llvm/lib/Target/AMDGPU/AMDGPUSubtarget.cpp

@@ -81,7 +81,7 @@ AMDGPUSubtarget::AMDGPUSubtarget(const Triple &TT, StringRef GPU, StringRef FS,
       EnableVGPRSpilling(false), SGPRInitBug(false), IsGCN(false),
       GCN1Encoding(false), GCN3Encoding(false), CIInsts(false), LDSBankCount(0),
       IsaVersion(ISAVersion0_0_0), EnableHugeScratchBuffer(false),
-      FrameLowering(nullptr),
+      EnableSIScheduler(false), FrameLowering(nullptr),
       InstrItins(getInstrItineraryForCPU(GPU)), TargetTriple(TT) {
 
   initializeSubtargetDependencies(TT, GPU, FS);

llvm/lib/Target/AMDGPU/AMDGPUSubtarget.h

@@ -92,6 +92,7 @@ private:
   int LDSBankCount;
   unsigned IsaVersion;
   bool EnableHugeScratchBuffer;
+  bool EnableSIScheduler;
 
   std::unique_ptr<AMDGPUFrameLowering> FrameLowering;
   std::unique_ptr<AMDGPUTargetLowering> TLInfo;
@@ -286,6 +287,10 @@ public:
     return EnableHugeScratchBuffer;
   }
 
+  bool enableSIScheduler() const {
+    return EnableSIScheduler;
+  }
+
   bool dumpCode() const {
     return DumpCode;
   }

llvm/lib/Target/AMDGPU/AMDGPUTargetMachine.cpp

@@ -148,6 +148,8 @@ public:
     const AMDGPUSubtarget &ST = *getAMDGPUTargetMachine().getSubtargetImpl();
     if (ST.getGeneration() <= AMDGPUSubtarget::NORTHERN_ISLANDS)
       return createR600MachineScheduler(C);
+    else if (ST.enableSIScheduler())
+      return createSIMachineScheduler(C);
     return nullptr;
   }