forked from OSchip/llvm-project
[X86] Avoid SFB - Skip meta instructions
This patch generalizes the fix in D61680 to ignore all meta instructions, not just debug info. Patch by Chris Dawson. Differential Revision: https://reviews.llvm.org/D62605 llvm-svn: 365061
This commit is contained in:
Robert Lougher
parent
4e8b99a5c3
commit
720baf0416
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@ -947,6 +947,28 @@ inline IterT skipDebugInstructionsBackward(IterT It, IterT Begin) {
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return It;
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}
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/// Increment \p It until it points to a non-meta instruction or to \p End
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/// and return the resulting iterator. This function should only be used
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/// MachineBasicBlock::{iterator, const_iterator, instr_iterator,
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/// const_instr_iterator} and the respective reverse iterators.
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template <typename IterT>
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inline IterT skipMetaInstructionsForward(IterT It, IterT End) {
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while (It != End && It->isMetaInstruction())
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It++;
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return It;
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}
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/// Decrement \p It until it points to a non-meta instruction or to \p Begin
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/// and return the resulting iterator. This function should only be used
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/// MachineBasicBlock::{iterator, const_iterator, instr_iterator,
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/// const_instr_iterator} and the respective reverse iterators.
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template <class IterT>
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inline IterT skipMetaInstructionsBackward(IterT It, IterT Begin) {
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while (It != Begin && It->isMetaInstruction())
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It--;
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return It;
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}
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} // end namespace llvm
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#endif // LLVM_CODEGEN_MACHINEBASICBLOCK_H
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@ -408,7 +408,7 @@ void X86AvoidSFBPass::buildCopy(MachineInstr *LoadInst, unsigned NLoadOpcode,
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// If the load and store are consecutive, use the loadInst location to
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// reduce register pressure.
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MachineInstr *StInst = StoreInst;
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auto PrevInstrIt = skipDebugInstructionsBackward(
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auto PrevInstrIt = skipMetaInstructionsBackward(
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std::prev(MachineBasicBlock::instr_iterator(StoreInst)),
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MBB->instr_begin());
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if (PrevInstrIt.getNodePtr() == LoadInst)
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@ -496,7 +496,7 @@ void X86AvoidSFBPass::buildCopies(int Size, MachineInstr *LoadInst,
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static void updateKillStatus(MachineInstr *LoadInst, MachineInstr *StoreInst) {
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MachineOperand &LoadBase = getBaseOperand(LoadInst);
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MachineOperand &StoreBase = getBaseOperand(StoreInst);
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auto StorePrevNonDbgInstr = skipDebugInstructionsBackward(
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auto StorePrevNonMetaInstr = skipMetaInstructionsBackward(
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std::prev(MachineBasicBlock::instr_iterator(StoreInst)),
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LoadInst->getParent()->instr_begin()).getNodePtr();
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if (LoadBase.isReg()) {
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@ -505,13 +505,13 @@ static void updateKillStatus(MachineInstr *LoadInst, MachineInstr *StoreInst) {
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// then the partial copies were also created in
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// a consecutive order to reduce register pressure,
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// and the location of the last load is before the last store.
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if (StorePrevNonDbgInstr == LoadInst)
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if (StorePrevNonMetaInstr == LoadInst)
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LastLoad = LoadInst->getPrevNode()->getPrevNode();
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getBaseOperand(LastLoad).setIsKill(LoadBase.isKill());
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}
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if (StoreBase.isReg()) {
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MachineInstr *StInst = StoreInst;
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if (StorePrevNonDbgInstr == LoadInst)
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if (StorePrevNonMetaInstr == LoadInst)
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StInst = LoadInst;
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getBaseOperand(StInst->getPrevNode()).setIsKill(StoreBase.isKill());
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}
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@ -0,0 +1,155 @@
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# RUN: llc %s -run-pass x86-avoid-SFB -mtriple=x86_64-unknown-linux-gnu -o - | FileCheck %s
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#
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# This was generated from:
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#
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# using alpha = float __attribute__((ext_vector_type(4)));
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#
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# void bravo(alpha * __restrict__ p1, alpha * __restrict__ p2) {
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# char *p3 = (char *)p1;
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# *p3 = 0;
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# alpha t = *p1;
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# *p2 = t;
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# }
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#
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# Using the command line:
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# clang -g -c 1.cpp -O2 -S -emit-llvm -fno-strict-aliasing --target=x86_64-unknown-unknown -o test.ll
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# llc -stop-before=x86-avoid-SFB test.ll -o before.mir
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#
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# The debug instruction between the load and the store has been manually replaced with a CFI meta instruction.
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--- |
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; ModuleID = 'test.ll'
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source_filename = "1.cpp"
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target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-unknown-unknown"
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; Function Attrs: norecurse nounwind uwtable
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define dso_local void @debug(<4 x float>* noalias nocapture %p1, <4 x float>* noalias nocapture %p2) local_unnamed_addr !dbg !10 {
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entry:
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call void @llvm.dbg.value(metadata <4 x float>* %p1, metadata !21, metadata !DIExpression()), !dbg !25
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call void @llvm.dbg.value(metadata <4 x float>* %p2, metadata !22, metadata !DIExpression()), !dbg !25
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%0 = bitcast <4 x float>* %p1 to i8*, !dbg !26
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call void @llvm.dbg.value(metadata i8* %0, metadata !23, metadata !DIExpression()), !dbg !25
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store i8 0, i8* %0, align 1, !dbg !27
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%1 = load <4 x float>, <4 x float>* %p1, align 16, !dbg !28
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call void @llvm.dbg.value(metadata <4 x float> %1, metadata !24, metadata !DIExpression()), !dbg !25
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store <4 x float> %1, <4 x float>* %p2, align 16, !dbg !29
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ret void, !dbg !30
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}
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; Function Attrs: nounwind readnone speculatable
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declare void @llvm.dbg.value(metadata, metadata, metadata)
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; Function Attrs: nounwind
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declare void @llvm.stackprotector(i8*, i8**)
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!llvm.dbg.cu = !{!0}
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!llvm.module.flags = !{!6, !7, !8}
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!llvm.ident = !{!9}
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!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 9.0.0 (https://github.com/llvm/llvm-project.git 9afc4764dd24bd2f23c44e51ad33f8e58234a8b6)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, retainedTypes: !3, nameTableKind: None)
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!1 = !DIFile(filename: "1.cpp", directory: "C:\5CUsers\5Cgbdawsoc\5CDocuments\5Cllvm\5Cbg40969")
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!2 = !{}
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!3 = !{!4}
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!4 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !5, size: 64)
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!5 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
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!6 = !{i32 2, !"Dwarf Version", i32 4}
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!7 = !{i32 2, !"Debug Info Version", i32 3}
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!8 = !{i32 1, !"wchar_size", i32 4}
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!9 = !{!"clang version 9.0.0 (https://github.com/llvm/llvm-project.git 9afc4764dd24bd2f23c44e51ad33f8e58234a8b6)"}
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!10 = distinct !DISubprogram(name: "bravo", linkageName: "_Z5bravoPDv4_fS0_", scope: !1, file: !1, line: 4, type: !11, scopeLine: 4, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !20)
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!11 = !DISubroutineType(types: !12)
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!12 = !{null, !13, !13}
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!13 = !DIDerivedType(tag: DW_TAG_restrict_type, baseType: !14)
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!14 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !15, size: 64)
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!15 = !DIDerivedType(tag: DW_TAG_typedef, name: "alpha", file: !1, line: 2, baseType: !16)
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!16 = !DICompositeType(tag: DW_TAG_array_type, baseType: !17, size: 128, flags: DIFlagVector, elements: !18)
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!17 = !DIBasicType(name: "float", size: 32, encoding: DW_ATE_float)
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!18 = !{!19}
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!19 = !DISubrange(count: 4)
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!20 = !{!21, !22, !23, !24}
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!21 = !DILocalVariable(name: "p1", arg: 1, scope: !10, file: !1, line: 4, type: !13)
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!22 = !DILocalVariable(name: "p2", arg: 2, scope: !10, file: !1, line: 4, type: !13)
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!23 = !DILocalVariable(name: "p3", scope: !10, file: !1, line: 5, type: !4)
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!24 = !DILocalVariable(name: "t", scope: !10, file: !1, line: 7, type: !15)
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!25 = !DILocation(line: 0, scope: !10)
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!26 = !DILocation(line: 5, column: 14, scope: !10)
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!27 = !DILocation(line: 6, column: 7, scope: !10)
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!28 = !DILocation(line: 7, column: 13, scope: !10)
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!29 = !DILocation(line: 8, column: 7, scope: !10)
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!30 = !DILocation(line: 9, column: 1, scope: !10)
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...
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---
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name: debug
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alignment: 4
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exposesReturnsTwice: false
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legalized: false
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regBankSelected: false
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selected: false
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failedISel: false
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tracksRegLiveness: true
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hasWinCFI: false
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registers:
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- { id: 0, class: gr64, preferred-register: '' }
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- { id: 1, class: gr64, preferred-register: '' }
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- { id: 2, class: vr128, preferred-register: '' }
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liveins:
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- { reg: '$rdi', virtual-reg: '%0' }
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- { reg: '$rsi', virtual-reg: '%1' }
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frameInfo:
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isFrameAddressTaken: false
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isReturnAddressTaken: false
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hasStackMap: false
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hasPatchPoint: false
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stackSize: 0
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offsetAdjustment: 0
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maxAlignment: 0
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adjustsStack: false
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hasCalls: false
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stackProtector: ''
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maxCallFrameSize: 4294967295
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cvBytesOfCalleeSavedRegisters: 0
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hasOpaqueSPAdjustment: false
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hasVAStart: false
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hasMustTailInVarArgFunc: false
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localFrameSize: 0
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savePoint: ''
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restorePoint: ''
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fixedStack: []
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stack: []
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constants: []
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machineFunctionInfo: {}
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body: |
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bb.0.entry:
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liveins: $rdi, $rsi
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DBG_VALUE $rdi, $noreg, !21, !DIExpression(), debug-location !25
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DBG_VALUE $rsi, $noreg, !22, !DIExpression(), debug-location !25
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%1:gr64 = COPY $rsi
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DBG_VALUE %1, $noreg, !22, !DIExpression(), debug-location !25
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%0:gr64 = COPY $rdi
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DBG_VALUE %0, $noreg, !21, !DIExpression(), debug-location !25
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DBG_VALUE %0, $noreg, !23, !DIExpression(), debug-location !25
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MOV8mi %0, 1, $noreg, 0, $noreg, 0, debug-location !27 :: (store 1 into %ir.0)
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%2:vr128 = MOVAPSrm %0, 1, $noreg, 0, $noreg, debug-location !28 :: (load 16 from %ir.p1)
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CFI_INSTRUCTION offset $r13, -123
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MOVAPSmr %1, 1, $noreg, 0, $noreg, killed %2, debug-location !29 :: (store 16 into %ir.p2)
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RET 0, debug-location !30
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; CHECK-LABEL: name: debug
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; CHECK: %1:gr64 = COPY
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; CHECK: %0:gr64 = COPY
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; CHECK: MOV8mi
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; CHECK: %3:gr8 = MOV8rm
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; CHECK: MOV8mr
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; CHECK: %4:gr64 = MOV64rm
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; CHECK: MOV64mr
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; CHECK: %5:gr32 = MOV32rm
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; CHECK: MOV32mr
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; CHECK: %6:gr16 = MOV16rm
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; CHECK: MOV16mr
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; CHECK: %7:gr8 = MOV8rm
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; CHECK: MOV8mr
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; CHECK: RET 0
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...
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