intel-graphics-compiler/IGC/Compiler/CISACodeGen/getCacheOpts.cpp

/*========================== begin_copyright_notice ============================

Copyright (C) 2021 Intel Corporation

SPDX-License-Identifier: MIT

============================= end_copyright_notice ===========================*/

/**
 * @file getCacheOpts.cpp
 *
 * @section DESCRIPTION
 *
 * This file contains definitions of utility functions which return the cache options
 * for a given load or store instruction.
 */

#include "visa_igc_common_header.h"                     // for LSC_L1_L3_CC
#include "common/igc_regkeys.hpp"                       // for IGC_IS_FLAG_ENABLED, IGC_GET_FLAG_VALUE
#include "Probe/Assertion.h"                            // for IGC_ASSERT_MESSAGE
#include "AdaptorCommon/RayTracing/MemRegionAnalysis.h" // for getRTRegion(), RTMemRegion

#include "common/LLVMWarningsPush.hpp" // for suppressing LLVM warnings
#include "llvm/IR/Instructions.h"      // for llvm::StoreInst, llvm::LoadInst
#include "common/LLVMWarningsPop.hpp"  // for suppressing LLVM warnings

#include "getCacheOpts.h"
#include <optional>

using namespace llvm;

namespace IGC {
/**
 * @return the store cache policy for the RTStack
 */
LSC_L1_L3_CC RTStackStorePolicy(const CodeGenContext &Ctx) {
  LSC_L1_L3_CC cacheOpts = LSC_L1IAR_WB_L3C_WB;
  // Ctx.platform.preferLSCCache() also prefers LSC_L1IAR_WB_L3C_WB
  if (IGC_IS_FLAG_ENABLED(ForceRTStackStoreCacheCtrl)) {
    cacheOpts = (LSC_L1_L3_CC)IGC_GET_FLAG_VALUE(RTStackStoreCacheCtrl);

    IGC_ASSERT_MESSAGE(cacheOpts < LSC_CC_INVALID, "Invalid Custom LSC Cache Control Set");
  }

  return cacheOpts;
}

/**
 * @return the store cache policy for the SWHotZone
 */
LSC_L1_L3_CC SWHotZoneStorePolicy(const CodeGenContext &Ctx) {
  LSC_L1_L3_CC cacheOpts = LSC_L1IAR_WB_L3C_WB;
  if (IGC_IS_FLAG_ENABLED(ForceSWHotZoneStoreCacheCtrl)) {
    cacheOpts = (LSC_L1_L3_CC)IGC_GET_FLAG_VALUE(SWHotZoneStoreCacheCtrl);

    IGC_ASSERT_MESSAGE(cacheOpts < LSC_CC_INVALID, "Invalid Custom LSC Cache Control Set");
  }

  return cacheOpts;
}

/**
 * @return the store cache policy for the SWStack
 */
LSC_L1_L3_CC SWStackStorePolicy(const CodeGenContext &Ctx) {
  LSC_L1_L3_CC cacheOpts = Ctx.platform.NeedsLSCFenceUGMBeforeEOT()
                               ? LSC_L1S_L3C_WB
                               : (Ctx.platform.preferLSCCache() ? LSC_L1IAR_WB_L3C_WB : LSC_L1UC_L3C_WB);
  if (IGC_IS_FLAG_ENABLED(ForceSWStackStoreCacheCtrl)) {
    cacheOpts = (LSC_L1_L3_CC)IGC_GET_FLAG_VALUE(SWStackStoreCacheCtrl);

    IGC_ASSERT_MESSAGE(cacheOpts < LSC_CC_INVALID, "Invalid Custom LSC Cache Control Set");
  }

  return cacheOpts;
}

/**
 * @return the load cache policy for the RTStack
 */
LSC_L1_L3_CC RTStackLoadPolicy(const CodeGenContext &Ctx) {
  LSC_L1_L3_CC cacheOpts = LSC_L1C_WT_L3C_WB;
  // Ctx.platform.preferLSCCache() also prefers LSC_L1C_WT_L3C_WB
  if (IGC_IS_FLAG_ENABLED(ForceRTStackLoadCacheCtrl)) {
    cacheOpts = (LSC_L1_L3_CC)IGC_GET_FLAG_VALUE(RTStackLoadCacheCtrl);

    IGC_ASSERT_MESSAGE(cacheOpts < LSC_CC_INVALID, "Invalid Custom LSC Cache Control Set");
  }

  return cacheOpts;
}

/**
 * @return the load cache policy for the SWHotZone
 */
LSC_L1_L3_CC SWHotZoneLoadPolicy(const CodeGenContext &Ctx) {
  LSC_L1_L3_CC cacheOpts = LSC_L1C_WT_L3C_WB;
  if (IGC_IS_FLAG_ENABLED(ForceSWHotZoneLoadCacheCtrl)) {
    cacheOpts = (LSC_L1_L3_CC)IGC_GET_FLAG_VALUE(SWHotZoneLoadCacheCtrl);

    IGC_ASSERT_MESSAGE(cacheOpts < LSC_CC_INVALID, "Invalid Custom LSC Cache Control Set");
  }

  return cacheOpts;
}

/**
 * @return the load cache policy for the SWStack
 */
LSC_L1_L3_CC SWStackLoadPolicy(const CodeGenContext &Ctx) {
  LSC_L1_L3_CC cacheOpts = Ctx.platform.preferLSCCache() ? LSC_L1C_WT_L3C_WB : LSC_L1UC_L3C_WB;
  if (IGC_IS_FLAG_ENABLED(ForceSWStackLoadCacheCtrl)) {
    cacheOpts = (LSC_L1_L3_CC)IGC_GET_FLAG_VALUE(SWStackLoadCacheCtrl);

    IGC_ASSERT_MESSAGE(cacheOpts < LSC_CC_INVALID, "Invalid Custom LSC Cache Control Set");
  }

  return cacheOpts;
}

std::optional<LSC_L1_L3_CC> getCacheOptsStorePolicy(const Value *Ptr, const CodeGenContext &Ctx) {
  auto Region = getRTRegion(Ptr, *Ctx.getModuleMetaData());

  if (!Region)
    return std::nullopt;

  std::optional<LSC_L1_L3_CC> cacheOpts;

  switch (*Region) {
  case RTMemRegion::RTAsyncStack:
  case RTMemRegion::RTSyncStack:
    cacheOpts = RTStackStorePolicy(Ctx);
    break;
  case RTMemRegion::SWStack:
    cacheOpts = SWStackStorePolicy(Ctx);
    break;
  case RTMemRegion::SWHotZone:
    cacheOpts = SWHotZoneStorePolicy(Ctx);
    break;
  default:
    break;
  }

  return cacheOpts;
}

std::optional<LSC_L1_L3_CC> getCacheOptsStorePolicy(const StoreInst &storeInst, const CodeGenContext &Ctx) {
  return getCacheOptsStorePolicy(storeInst.getPointerOperand(), Ctx);
}

std::optional<LSC_L1_L3_CC> getCacheOptsLoadPolicy(const Value *Ptr, const CodeGenContext &Ctx) {
  auto Region = getRTRegion(Ptr, *Ctx.getModuleMetaData());

  if (!Region)
    return std::nullopt;

  std::optional<LSC_L1_L3_CC> cacheOpts;

  switch (*Region) {
  case RTMemRegion::RTAsyncStack:
  case RTMemRegion::RTSyncStack:
    cacheOpts = RTStackLoadPolicy(Ctx);
    break;
  case RTMemRegion::SWStack:
    cacheOpts = SWStackLoadPolicy(Ctx);
    break;
  case RTMemRegion::SWHotZone:
    cacheOpts = SWHotZoneLoadPolicy(Ctx);
    break;
  default:
    break;
  }

  return cacheOpts;
}

std::optional<LSC_L1_L3_CC> getCacheOptsLoadPolicy(const LoadInst &loadInst, const CodeGenContext &Ctx) {
  return getCacheOptsLoadPolicy(loadInst.getPointerOperand(), Ctx);
}

} // namespace IGC