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Flag -show-encoding enables the printing of instruction encodings as part of the the instruction info view. Example (with flags -mtriple=x86_64-- -mcpu=btver2): Instruction Info: [1]: #uOps [2]: Latency [3]: RThroughput [4]: MayLoad [5]: MayStore [6]: HasSideEffects (U) [7]: Encoding Size [1] [2] [3] [4] [5] [6] [7] Encodings: Instructions: 1 2 1.00 4 c5 f0 59 d0 vmulps %xmm0, %xmm1, %xmm2 1 4 1.00 4 c5 eb 7c da vhaddps %xmm2, %xmm2, %xmm3 1 4 1.00 4 c5 e3 7c e3 vhaddps %xmm3, %xmm3, %xmm4 In this example, column Encoding Size is the size in bytes of the instruction encoding. Column Encodings reports the actual instruction encodings as byte sequences in hex (objdump style). The computation of encodings is done by a utility class named mca::CodeEmitter. In future, I plan to expose the CodeEmitter to the instruction builder, so that information about instruction encoding sizes can be used by the simulator. That would be a first step towards simulating the throughput from the decoders in the hardware frontend. Differential Revision: https://reviews.llvm.org/D65948 llvm-svn: 368432
38 lines
1.1 KiB
C++
38 lines
1.1 KiB
C++
//===--------------------- CodeEmitter.cpp ----------------------*- C++ -*-===//
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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 file implements the CodeEmitter API.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/MCA/CodeEmitter.h"
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namespace llvm {
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namespace mca {
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CodeEmitter::EncodingInfo
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CodeEmitter::getOrCreateEncodingInfo(unsigned MCID) {
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EncodingInfo &EI = Encodings[MCID];
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if (EI.second)
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return EI;
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SmallVector<llvm::MCFixup, 2> Fixups;
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const MCInst &Inst = Sequence[MCID];
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MCInst Relaxed(Sequence[MCID]);
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if (MAB.mayNeedRelaxation(Inst, STI))
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MAB.relaxInstruction(Inst, STI, Relaxed);
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EI.first = Code.size();
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MCE.encodeInstruction(Relaxed, VecOS, Fixups, STI);
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EI.second = Code.size() - EI.first;
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return EI;
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}
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} // namespace mca
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} // namespace llvm
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