105 lines
3.9 KiB
C++
105 lines
3.9 KiB
C++
//===- EnableArmStreaming.cpp - Enable Armv9 Streaming SVE mode -----------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This pass enables the Armv9 Scalable Matrix Extension (SME) Streaming SVE
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// (SSVE) mode [1][2] by adding either of the following attributes to
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// 'func.func' ops:
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//
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// * 'arm_streaming' (default)
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// * 'arm_locally_streaming'
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//
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// It can also optionally enable the ZA storage array.
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//
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// Streaming-mode is part of the interface (ABI) for functions with the
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// first attribute and it's the responsibility of the caller to manage
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// PSTATE.SM on entry/exit to functions with this attribute [3]. The LLVM
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// backend will emit 'smstart sm' / 'smstop sm' [4] around calls to
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// streaming functions.
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//
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// In locally streaming functions PSTATE.SM is kept internal and managed by
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// the callee on entry/exit. The LLVM backend will emit 'smstart sm' /
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// 'smstop sm' in the prologue / epilogue for functions with this
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// attribute.
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//
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// [1] https://developer.arm.com/documentation/ddi0616/aa
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// [2] https://llvm.org/docs/AArch64SME.html
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// [3] https://github.com/ARM-software/abi-aa/blob/main/aapcs64/aapcs64.rst#671pstatesm-interfaces
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// [4] https://developer.arm.com/documentation/ddi0602/2023-03/Base-Instructions/SMSTART--Enables-access-to-Streaming-SVE-mode-and-SME-architectural-state--an-alias-of-MSR--immediate--
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//
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//===----------------------------------------------------------------------===//
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#include "mlir/Dialect/ArmSME/IR/ArmSME.h"
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#include "mlir/Dialect/ArmSME/Transforms/Passes.h"
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#include "mlir/Dialect/ArmSME/Transforms/PassesEnums.cpp.inc"
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#include "mlir/Dialect/Func/IR/FuncOps.h"
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#define DEBUG_TYPE "enable-arm-streaming"
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namespace mlir {
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namespace arm_sme {
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#define GEN_PASS_DEF_ENABLEARMSTREAMING
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#include "mlir/Dialect/ArmSME/Transforms/Passes.h.inc"
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} // namespace arm_sme
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} // namespace mlir
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using namespace mlir;
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using namespace mlir::arm_sme;
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namespace {
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constexpr StringLiteral
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kEnableArmStreamingIgnoreAttr("enable_arm_streaming_ignore");
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struct EnableArmStreamingPass
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: public arm_sme::impl::EnableArmStreamingBase<EnableArmStreamingPass> {
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EnableArmStreamingPass(ArmStreamingMode streamingMode, ArmZaMode zaMode,
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bool onlyIfRequiredByOps) {
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this->streamingMode = streamingMode;
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this->zaMode = zaMode;
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this->onlyIfRequiredByOps = onlyIfRequiredByOps;
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}
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void runOnOperation() override {
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auto op = getOperation();
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if (onlyIfRequiredByOps) {
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bool foundTileOp = false;
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op.walk([&](Operation *op) {
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if (llvm::isa<ArmSMETileOpInterface>(op)) {
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foundTileOp = true;
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return WalkResult::interrupt();
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}
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return WalkResult::advance();
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});
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if (!foundTileOp)
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return;
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}
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if (op->getAttr(kEnableArmStreamingIgnoreAttr) ||
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streamingMode == ArmStreamingMode::Disabled)
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return;
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auto unitAttr = UnitAttr::get(&getContext());
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op->setAttr(stringifyArmStreamingMode(streamingMode), unitAttr);
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// The pass currently only supports enabling ZA when in streaming-mode, but
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// ZA can be accessed by the SME LDR, STR and ZERO instructions when not in
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// streaming-mode (see section B1.1.1, IDGNQM of spec [1]). It may be worth
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// supporting this later.
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if (zaMode != ArmZaMode::Disabled)
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op->setAttr(stringifyArmZaMode(zaMode), unitAttr);
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}
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};
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} // namespace
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std::unique_ptr<Pass> mlir::arm_sme::createEnableArmStreamingPass(
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const ArmStreamingMode streamingMode, const ArmZaMode zaMode,
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bool onlyIfRequiredByOps) {
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return std::make_unique<EnableArmStreamingPass>(streamingMode, zaMode,
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onlyIfRequiredByOps);
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}
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