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a7d4828a91
This patch enables redundant sign- and zero-extension elimination in PowerPC MI Peephole pass.
If the input value of a sign- or zero-extension is known to be already sign- or zero-extended, the operation is redundant and can be eliminated.
One common case is sign-extensions for a method parameter or for a method return value; they must be sign- or zero-extended as defined in PPC ELF ABI.
For example of the following simple code, two extsw instructions are generated before the invocation of int_func and before the return. With this patch, both extsw are eliminated.
void int_func(int);
void ii_test(int a) {
if (a & 1) return int_func(a);
}
Such redundant sign- or zero-extensions are quite common in many programs; e.g. I observed about 60,000 occurrences of the elimination while compiling the LLVM+CLANG.
Differential Revision: https://reviews.llvm.org/D31319
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@315888 91177308-0d34-0410-b5e6-96231b3b80d8
60 lines
2.2 KiB
C++
60 lines
2.2 KiB
C++
//===-- PPCMachineFunctionInfo.cpp - Private data used for PowerPC --------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "PPCMachineFunctionInfo.h"
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#include "llvm/ADT/Twine.h"
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#include "llvm/IR/DataLayout.h"
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#include "llvm/MC/MCContext.h"
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using namespace llvm;
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void PPCFunctionInfo::anchor() {}
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MCSymbol *PPCFunctionInfo::getPICOffsetSymbol() const {
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const DataLayout &DL = MF.getDataLayout();
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return MF.getContext().getOrCreateSymbol(Twine(DL.getPrivateGlobalPrefix()) +
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Twine(MF.getFunctionNumber()) +
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"$poff");
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}
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MCSymbol *PPCFunctionInfo::getGlobalEPSymbol() const {
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const DataLayout &DL = MF.getDataLayout();
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return MF.getContext().getOrCreateSymbol(Twine(DL.getPrivateGlobalPrefix()) +
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"func_gep" +
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Twine(MF.getFunctionNumber()));
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}
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MCSymbol *PPCFunctionInfo::getLocalEPSymbol() const {
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const DataLayout &DL = MF.getDataLayout();
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return MF.getContext().getOrCreateSymbol(Twine(DL.getPrivateGlobalPrefix()) +
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"func_lep" +
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Twine(MF.getFunctionNumber()));
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}
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MCSymbol *PPCFunctionInfo::getTOCOffsetSymbol() const {
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const DataLayout &DL = MF.getDataLayout();
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return MF.getContext().getOrCreateSymbol(Twine(DL.getPrivateGlobalPrefix()) +
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"func_toc" +
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Twine(MF.getFunctionNumber()));
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}
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bool PPCFunctionInfo::isLiveInSExt(unsigned VReg) const {
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for (const std::pair<unsigned, ISD::ArgFlagsTy> &LiveIn : LiveInAttrs)
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if (LiveIn.first == VReg)
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return LiveIn.second.isSExt();
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return false;
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}
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bool PPCFunctionInfo::isLiveInZExt(unsigned VReg) const {
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for (const std::pair<unsigned, ISD::ArgFlagsTy> &LiveIn : LiveInAttrs)
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if (LiveIn.first == VReg)
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return LiveIn.second.isZExt();
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return false;
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}
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