[AMDGPU] Disable FillMFMAShadowMutation by default

Disable amdgpu mfma power sched.

Reviewed By: rampitec

Differential Revision: https://reviews.llvm.org/D129172

Author: kerbowa

llvm/lib/Target/AMDGPU/AMDGPUSubtarget.cpp

@@ -40,9 +40,9 @@ using namespace llvm;
 #include "AMDGPUGenSubtargetInfo.inc"
 #undef AMDGPUSubtarget
 
-static cl::opt<bool> DisablePowerSched(
-  "amdgpu-disable-power-sched",
-  cl::desc("Disable scheduling to minimize mAI power bursts"),
+static cl::opt<bool> EnablePowerSched(
+  "amdgpu-enable-power-sched",
+  cl::desc("Enable scheduling to minimize mAI power bursts"),
   cl::init(false));
 
 static cl::opt<bool> EnableVGPRIndexMode(
@@ -916,7 +916,7 @@ struct FillMFMAShadowMutation : ScheduleDAGMutation {
 
   void apply(ScheduleDAGInstrs *DAGInstrs) override {
     const GCNSubtarget &ST = DAGInstrs->MF.getSubtarget<GCNSubtarget>();
-    if (!ST.hasMAIInsts() || DisablePowerSched)
+    if (!ST.hasMAIInsts())
       return;
     DAG = static_cast<ScheduleDAGMI*>(DAGInstrs);
     const TargetSchedModel *TSchedModel = DAGInstrs->getSchedModel();
@@ -966,7 +966,8 @@ void GCNSubtarget::getPostRAMutations(
 
 std::unique_ptr<ScheduleDAGMutation>
 GCNSubtarget::createFillMFMAShadowMutation(const TargetInstrInfo *TII) const {
-  return std::make_unique<FillMFMAShadowMutation>(&InstrInfo);
+  return EnablePowerSched ? std::make_unique<FillMFMAShadowMutation>(&InstrInfo)
+                          : nullptr;
 }
 
 const AMDGPUSubtarget &AMDGPUSubtarget::get(const MachineFunction &MF) {

llvm/test/CodeGen/AMDGPU/sched-prefer-non-mfma.mir

@@ -1,4 +1,4 @@
-# RUN: llc -march=amdgcn -mcpu=gfx908 -run-pass post-RA-sched -amdgpu-disable-power-sched -verify-machineinstrs -o - %s | FileCheck -check-prefix=GCN %s
+# RUN: llc -march=amdgcn -mcpu=gfx908 -run-pass post-RA-sched -verify-machineinstrs -o - %s | FileCheck -check-prefix=GCN %s
 
 # GCN-LABEL: name: unrelated_mfma
 # GCN: V_MFMA_F32_32X32X1F32