06f22c9ae5
This attribute makes the `enable_arm_streaming` pass ignore a function (i.e. not add the enable streaming/za attributes). The main use case for this is to prevent helper functions within tests being made streaming functions.
94 lines
3.5 KiB
C++
94 lines
3.5 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/Transforms/Passes.h"
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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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static constexpr char kArmStreamingAttr[] = "arm_streaming";
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static constexpr char kArmLocallyStreamingAttr[] = "arm_locally_streaming";
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static constexpr char kArmZAAttr[] = "arm_za";
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static constexpr char kEnableArmStreamingIgnoreAttr[] =
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"enable_arm_streaming_ignore";
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namespace {
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struct EnableArmStreamingPass
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: public arm_sme::impl::EnableArmStreamingBase<EnableArmStreamingPass> {
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EnableArmStreamingPass(ArmStreaming mode, bool enableZA) {
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this->mode = mode;
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this->enableZA = enableZA;
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}
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void runOnOperation() override {
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if (getOperation()->getAttr(kEnableArmStreamingIgnoreAttr))
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return;
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StringRef attr;
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switch (mode) {
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case ArmStreaming::Default:
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attr = kArmStreamingAttr;
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break;
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case ArmStreaming::Locally:
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attr = kArmLocallyStreamingAttr;
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break;
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}
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getOperation()->setAttr(attr, UnitAttr::get(&getContext()));
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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 (enableZA)
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getOperation()->setAttr(kArmZAAttr, UnitAttr::get(&getContext()));
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}
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};
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} // namespace
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std::unique_ptr<Pass>
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mlir::arm_sme::createEnableArmStreamingPass(const ArmStreaming mode,
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const bool enableZA) {
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return std::make_unique<EnableArmStreamingPass>(mode, enableZA);
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}
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