Bug Summary

File:lib/Target/X86/X86CmovConversion.cpp
Warning:line 308, column 37
The right operand of '!=' is a garbage value

Annotated Source Code

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clang -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name X86CmovConversion.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mthread-model posix -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -dwarf-column-info -debugger-tuning=gdb -momit-leaf-frame-pointer -ffunction-sections -fdata-sections -resource-dir /usr/lib/llvm-9/lib/clang/9.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-9~svn361465/build-llvm/lib/Target/X86 -I /build/llvm-toolchain-snapshot-9~svn361465/lib/Target/X86 -I /build/llvm-toolchain-snapshot-9~svn361465/build-llvm/include -I /build/llvm-toolchain-snapshot-9~svn361465/include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0/backward -internal-isystem /usr/include/clang/9.0.0/include/ -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-9/lib/clang/9.0.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-comment -std=c++11 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-9~svn361465/build-llvm/lib/Target/X86 -fdebug-prefix-map=/build/llvm-toolchain-snapshot-9~svn361465=. -ferror-limit 19 -fmessage-length 0 -fvisibility-inlines-hidden -stack-protector 2 -fobjc-runtime=gcc -fdiagnostics-show-option -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -o /tmp/scan-build-2019-05-24-031927-21217-1 -x c++ /build/llvm-toolchain-snapshot-9~svn361465/lib/Target/X86/X86CmovConversion.cpp -faddrsig
1//====- X86CmovConversion.cpp - Convert Cmov to Branch --------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9/// \file
10/// This file implements a pass that converts X86 cmov instructions into
11/// branches when profitable. This pass is conservative. It transforms if and
12/// only if it can guarantee a gain with high confidence.
13///
14/// Thus, the optimization applies under the following conditions:
15/// 1. Consider as candidates only CMOVs in innermost loops (assume that
16/// most hotspots are represented by these loops).
17/// 2. Given a group of CMOV instructions that are using the same EFLAGS def
18/// instruction:
19/// a. Consider them as candidates only if all have the same code condition
20/// or the opposite one to prevent generating more than one conditional
21/// jump per EFLAGS def instruction.
22/// b. Consider them as candidates only if all are profitable to be
23/// converted (assume that one bad conversion may cause a degradation).
24/// 3. Apply conversion only for loops that are found profitable and only for
25/// CMOV candidates that were found profitable.
26/// a. A loop is considered profitable only if conversion will reduce its
27/// depth cost by some threshold.
28/// b. CMOV is considered profitable if the cost of its condition is higher
29/// than the average cost of its true-value and false-value by 25% of
30/// branch-misprediction-penalty. This assures no degradation even with
31/// 25% branch misprediction.
32///
33/// Note: This pass is assumed to run on SSA machine code.
34//
35//===----------------------------------------------------------------------===//
36//
37// External interfaces:
38// FunctionPass *llvm::createX86CmovConverterPass();
39// bool X86CmovConverterPass::runOnMachineFunction(MachineFunction &MF);
40//
41//===----------------------------------------------------------------------===//
42
43#include "X86.h"
44#include "X86InstrInfo.h"
45#include "llvm/ADT/ArrayRef.h"
46#include "llvm/ADT/DenseMap.h"
47#include "llvm/ADT/STLExtras.h"
48#include "llvm/ADT/SmallPtrSet.h"
49#include "llvm/ADT/SmallVector.h"
50#include "llvm/ADT/Statistic.h"
51#include "llvm/CodeGen/MachineBasicBlock.h"
52#include "llvm/CodeGen/MachineFunction.h"
53#include "llvm/CodeGen/MachineFunctionPass.h"
54#include "llvm/CodeGen/MachineInstr.h"
55#include "llvm/CodeGen/MachineInstrBuilder.h"
56#include "llvm/CodeGen/MachineLoopInfo.h"
57#include "llvm/CodeGen/MachineOperand.h"
58#include "llvm/CodeGen/MachineRegisterInfo.h"
59#include "llvm/CodeGen/TargetInstrInfo.h"
60#include "llvm/CodeGen/TargetRegisterInfo.h"
61#include "llvm/CodeGen/TargetSchedule.h"
62#include "llvm/CodeGen/TargetSubtargetInfo.h"
63#include "llvm/IR/DebugLoc.h"
64#include "llvm/MC/MCSchedule.h"
65#include "llvm/Pass.h"
66#include "llvm/Support/CommandLine.h"
67#include "llvm/Support/Debug.h"
68#include "llvm/Support/raw_ostream.h"
69#include <algorithm>
70#include <cassert>
71#include <iterator>
72#include <utility>
73
74using namespace llvm;
75
76#define DEBUG_TYPE"x86-cmov-conversion" "x86-cmov-conversion"
77
78STATISTIC(NumOfSkippedCmovGroups, "Number of unsupported CMOV-groups")static llvm::Statistic NumOfSkippedCmovGroups = {"x86-cmov-conversion"
, "NumOfSkippedCmovGroups", "Number of unsupported CMOV-groups"
, {0}, {false}};
79STATISTIC(NumOfCmovGroupCandidate, "Number of CMOV-group candidates")static llvm::Statistic NumOfCmovGroupCandidate = {"x86-cmov-conversion"
, "NumOfCmovGroupCandidate", "Number of CMOV-group candidates"
, {0}, {false}};
80STATISTIC(NumOfLoopCandidate, "Number of CMOV-conversion profitable loops")static llvm::Statistic NumOfLoopCandidate = {"x86-cmov-conversion"
, "NumOfLoopCandidate", "Number of CMOV-conversion profitable loops"
, {0}, {false}};
81STATISTIC(NumOfOptimizedCmovGroups, "Number of optimized CMOV-groups")static llvm::Statistic NumOfOptimizedCmovGroups = {"x86-cmov-conversion"
, "NumOfOptimizedCmovGroups", "Number of optimized CMOV-groups"
, {0}, {false}};
82
83// This internal switch can be used to turn off the cmov/branch optimization.
84static cl::opt<bool>
85 EnableCmovConverter("x86-cmov-converter",
86 cl::desc("Enable the X86 cmov-to-branch optimization."),
87 cl::init(true), cl::Hidden);
88
89static cl::opt<unsigned>
90 GainCycleThreshold("x86-cmov-converter-threshold",
91 cl::desc("Minimum gain per loop (in cycles) threshold."),
92 cl::init(4), cl::Hidden);
93
94static cl::opt<bool> ForceMemOperand(
95 "x86-cmov-converter-force-mem-operand",
96 cl::desc("Convert cmovs to branches whenever they have memory operands."),
97 cl::init(true), cl::Hidden);
98
99namespace {
100
101/// Converts X86 cmov instructions into branches when profitable.
102class X86CmovConverterPass : public MachineFunctionPass {
103public:
104 X86CmovConverterPass() : MachineFunctionPass(ID) {
105 initializeX86CmovConverterPassPass(*PassRegistry::getPassRegistry());
106 }
107
108 StringRef getPassName() const override { return "X86 cmov Conversion"; }
109 bool runOnMachineFunction(MachineFunction &MF) override;
110 void getAnalysisUsage(AnalysisUsage &AU) const override;
111
112 /// Pass identification, replacement for typeid.
113 static char ID;
114
115private:
116 MachineRegisterInfo *MRI;
117 const TargetInstrInfo *TII;
118 const TargetRegisterInfo *TRI;
119 TargetSchedModel TSchedModel;
120
121 /// List of consecutive CMOV instructions.
122 using CmovGroup = SmallVector<MachineInstr *, 2>;
123 using CmovGroups = SmallVector<CmovGroup, 2>;
124
125 /// Collect all CMOV-group-candidates in \p CurrLoop and update \p
126 /// CmovInstGroups accordingly.
127 ///
128 /// \param Blocks List of blocks to process.
129 /// \param CmovInstGroups List of consecutive CMOV instructions in CurrLoop.
130 /// \returns true iff it found any CMOV-group-candidate.
131 bool collectCmovCandidates(ArrayRef<MachineBasicBlock *> Blocks,
132 CmovGroups &CmovInstGroups,
133 bool IncludeLoads = false);
134
135 /// Check if it is profitable to transform each CMOV-group-candidates into
136 /// branch. Remove all groups that are not profitable from \p CmovInstGroups.
137 ///
138 /// \param Blocks List of blocks to process.
139 /// \param CmovInstGroups List of consecutive CMOV instructions in CurrLoop.
140 /// \returns true iff any CMOV-group-candidate remain.
141 bool checkForProfitableCmovCandidates(ArrayRef<MachineBasicBlock *> Blocks,
142 CmovGroups &CmovInstGroups);
143
144 /// Convert the given list of consecutive CMOV instructions into a branch.
145 ///
146 /// \param Group Consecutive CMOV instructions to be converted into branch.
147 void convertCmovInstsToBranches(SmallVectorImpl<MachineInstr *> &Group) const;
148};
149
150} // end anonymous namespace
151
152char X86CmovConverterPass::ID = 0;
153
154void X86CmovConverterPass::getAnalysisUsage(AnalysisUsage &AU) const {
155 MachineFunctionPass::getAnalysisUsage(AU);
156 AU.addRequired<MachineLoopInfo>();
157}
158
159bool X86CmovConverterPass::runOnMachineFunction(MachineFunction &MF) {
160 if (skipFunction(MF.getFunction()))
1
Assuming the condition is false
→
2
←
Taking false branch
→
161 return false;
162 if (!EnableCmovConverter)
3
←
Assuming the condition is false
→
4
←
Taking false branch
→
163 return false;
164
165 LLVM_DEBUG(dbgs() << "********** " << getPassName() << " : " << MF.getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("x86-cmov-conversion")) { dbgs() << "********** " <<
getPassName() << " : " << MF.getName() << "**********\n"
; } } while (false)
5
←
Assuming 'DebugFlag' is 0
→
6
←
Loop condition is false. Exiting loop
→
166 << "**********\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("x86-cmov-conversion")) { dbgs() << "********** " <<
getPassName() << " : " << MF.getName() << "**********\n"
; } } while (false);
167
168 bool Changed = false;
169 MachineLoopInfo &MLI = getAnalysis<MachineLoopInfo>();
170 const TargetSubtargetInfo &STI = MF.getSubtarget();
171 MRI = &MF.getRegInfo();
172 TII = STI.getInstrInfo();
173 TRI = STI.getRegisterInfo();
174 TSchedModel.init(&STI);
175
176 // Before we handle the more subtle cases of register-register CMOVs inside
177 // of potentially hot loops, we want to quickly remove all CMOVs with
178 // a memory operand. The CMOV will risk a stall waiting for the load to
179 // complete that speculative execution behind a branch is better suited to
180 // handle on modern x86 chips.
181 if (ForceMemOperand) {
7
←
Assuming the condition is true
→
8
←
Taking true branch
→
182 CmovGroups AllCmovGroups;
183 SmallVector<MachineBasicBlock *, 4> Blocks;
184 for (auto &MBB : MF)
185 Blocks.push_back(&MBB);
186 if (collectCmovCandidates(Blocks, AllCmovGroups, /*IncludeLoads*/ true)) {
9
←
Calling 'X86CmovConverterPass::collectCmovCandidates'
→
187 for (auto &Group : AllCmovGroups) {
188 // Skip any group that doesn't do at least one memory operand cmov.
189 if (!llvm::any_of(Group, [&](MachineInstr *I) { return I->mayLoad(); }))
190 continue;
191
192 // For CMOV groups which we can rewrite and which contain a memory load,
193 // always rewrite them. On x86, a CMOV will dramatically amplify any
194 // memory latency by blocking speculative execution.
195 Changed = true;
196 convertCmovInstsToBranches(Group);
197 }
198 }
199 }
200
201 //===--------------------------------------------------------------------===//
202 // Register-operand Conversion Algorithm
203 // ---------
204 // For each inner most loop
205 // collectCmovCandidates() {
206 // Find all CMOV-group-candidates.
207 // }
208 //
209 // checkForProfitableCmovCandidates() {
210 // * Calculate both loop-depth and optimized-loop-depth.
211 // * Use these depth to check for loop transformation profitability.
212 // * Check for CMOV-group-candidate transformation profitability.
213 // }
214 //
215 // For each profitable CMOV-group-candidate
216 // convertCmovInstsToBranches() {
217 // * Create FalseBB, SinkBB, Conditional branch to SinkBB.
218 // * Replace each CMOV instruction with a PHI instruction in SinkBB.
219 // }
220 //
221 // Note: For more details, see each function description.
222 //===--------------------------------------------------------------------===//
223
224 // Build up the loops in pre-order.
225 SmallVector<MachineLoop *, 4> Loops(MLI.begin(), MLI.end());
226 // Note that we need to check size on each iteration as we accumulate child
227 // loops.
228 for (int i = 0; i < (int)Loops.size(); ++i)
229 for (MachineLoop *Child : Loops[i]->getSubLoops())
230 Loops.push_back(Child);
231
232 for (MachineLoop *CurrLoop : Loops) {
233 // Optimize only inner most loops.
234 if (!CurrLoop->getSubLoops().empty())
235 continue;
236
237 // List of consecutive CMOV instructions to be processed.
238 CmovGroups CmovInstGroups;
239
240 if (!collectCmovCandidates(CurrLoop->getBlocks(), CmovInstGroups))
241 continue;
242
243 if (!checkForProfitableCmovCandidates(CurrLoop->getBlocks(),
244 CmovInstGroups))
245 continue;
246
247 Changed = true;
248 for (auto &Group : CmovInstGroups)
249 convertCmovInstsToBranches(Group);
250 }
251
252 return Changed;
253}
254
255bool X86CmovConverterPass::collectCmovCandidates(
256 ArrayRef<MachineBasicBlock *> Blocks, CmovGroups &CmovInstGroups,
257 bool IncludeLoads) {
258 //===--------------------------------------------------------------------===//
259 // Collect all CMOV-group-candidates and add them into CmovInstGroups.
260 //
261 // CMOV-group:
262 // CMOV instructions, in same MBB, that uses same EFLAGS def instruction.
263 //
264 // CMOV-group-candidate:
265 // CMOV-group where all the CMOV instructions are
266 // 1. consecutive.
267 // 2. have same condition code or opposite one.
268 // 3. have only operand registers (X86::CMOVrr).
269 //===--------------------------------------------------------------------===//
270 // List of possible improvement (TODO's):
271 // --------------------------------------
272 // TODO: Add support for X86::CMOVrm instructions.
273 // TODO: Add support for X86::SETcc instructions.
274 // TODO: Add support for CMOV-groups with non consecutive CMOV instructions.
275 //===--------------------------------------------------------------------===//
276
277 // Current processed CMOV-Group.
278 CmovGroup Group;
279 for (auto *MBB : Blocks) {
10
←
Assuming '__begin1' is not equal to '__end1'
→
280 Group.clear();
281 // Condition code of first CMOV instruction current processed range and its
282 // opposite condition code.
283 X86::CondCode FirstCC, FirstOppCC, MemOpCC;
11
←
'FirstCC' declared without an initial value
→
284 // Indicator of a non CMOVrr instruction in the current processed range.
285 bool FoundNonCMOVInst = false;
286 // Indicator for current processed CMOV-group if it should be skipped.
287 bool SkipGroup = false;
288
289 for (auto &I : *MBB) {
290 // Skip debug instructions.
291 if (I.isDebugInstr())
12
←
Taking false branch
→
292 continue;
293 X86::CondCode CC = X86::getCondFromCMov(I);
294 // Check if we found a X86::CMOVrr instruction.
295 if (CC != X86::COND_INVALID && (IncludeLoads || !I.mayLoad())) {
13
←
Assuming 'CC' is not equal to COND_INVALID
→
296 if (Group.empty()) {
14
←
Taking false branch
→
297 // We found first CMOV in the range, reset flags.
298 FirstCC = CC;
299 FirstOppCC = X86::GetOppositeBranchCondition(CC);
300 // Clear out the prior group's memory operand CC.
301 MemOpCC = X86::COND_INVALID;
302 FoundNonCMOVInst = false;
303 SkipGroup = false;
304 }
305 Group.push_back(&I);
306 // Check if it is a non-consecutive CMOV instruction or it has different
307 // condition code than FirstCC or FirstOppCC.
308 if (FoundNonCMOVInst || (CC != FirstCC && CC != FirstOppCC))
15
←
The right operand of '!=' is a garbage value
309 // Mark the SKipGroup indicator to skip current processed CMOV-Group.
310 SkipGroup = true;
311 if (I.mayLoad()) {
312 if (MemOpCC == X86::COND_INVALID)
313 // The first memory operand CMOV.
314 MemOpCC = CC;
315 else if (CC != MemOpCC)
316 // Can't handle mixed conditions with memory operands.
317 SkipGroup = true;
318 }
319 // Check if we were relying on zero-extending behavior of the CMOV.
320 if (!SkipGroup &&
321 llvm::any_of(
322 MRI->use_nodbg_instructions(I.defs().begin()->getReg()),
323 [&](MachineInstr &UseI) {
324 return UseI.getOpcode() == X86::SUBREG_TO_REG;
325 }))
326 // FIXME: We should model the cost of using an explicit MOV to handle
327 // the zero-extension rather than just refusing to handle this.
328 SkipGroup = true;
329 continue;
330 }
331 // If Group is empty, keep looking for first CMOV in the range.
332 if (Group.empty())
333 continue;
334
335 // We found a non X86::CMOVrr instruction.
336 FoundNonCMOVInst = true;
337 // Check if this instruction define EFLAGS, to determine end of processed
338 // range, as there would be no more instructions using current EFLAGS def.
339 if (I.definesRegister(X86::EFLAGS)) {
340 // Check if current processed CMOV-group should not be skipped and add
341 // it as a CMOV-group-candidate.
342 if (!SkipGroup)
343 CmovInstGroups.push_back(Group);
344 else
345 ++NumOfSkippedCmovGroups;
346 Group.clear();
347 }
348 }
349 // End of basic block is considered end of range, check if current processed
350 // CMOV-group should not be skipped and add it as a CMOV-group-candidate.
351 if (Group.empty())
352 continue;
353 if (!SkipGroup)
354 CmovInstGroups.push_back(Group);
355 else
356 ++NumOfSkippedCmovGroups;
357 }
358
359 NumOfCmovGroupCandidate += CmovInstGroups.size();
360 return !CmovInstGroups.empty();
361}
362
363/// \returns Depth of CMOV instruction as if it was converted into branch.
364/// \param TrueOpDepth depth cost of CMOV true value operand.
365/// \param FalseOpDepth depth cost of CMOV false value operand.
366static unsigned getDepthOfOptCmov(unsigned TrueOpDepth, unsigned FalseOpDepth) {
367 //===--------------------------------------------------------------------===//
368 // With no info about branch weight, we assume 50% for each value operand.
369 // Thus, depth of optimized CMOV instruction is the rounded up average of
370 // its True-Operand-Value-Depth and False-Operand-Value-Depth.
371 //===--------------------------------------------------------------------===//
372 return (TrueOpDepth + FalseOpDepth + 1) / 2;
373}
374
375bool X86CmovConverterPass::checkForProfitableCmovCandidates(
376 ArrayRef<MachineBasicBlock *> Blocks, CmovGroups &CmovInstGroups) {
377 struct DepthInfo {
378 /// Depth of original loop.
379 unsigned Depth;
380 /// Depth of optimized loop.
381 unsigned OptDepth;
382 };
383 /// Number of loop iterations to calculate depth for ?!
384 static const unsigned LoopIterations = 2;
385 DenseMap<MachineInstr *, DepthInfo> DepthMap;
386 DepthInfo LoopDepth[LoopIterations] = {{0, 0}, {0, 0}};
387 enum { PhyRegType = 0, VirRegType = 1, RegTypeNum = 2 };
388 /// For each register type maps the register to its last def instruction.
389 DenseMap<unsigned, MachineInstr *> RegDefMaps[RegTypeNum];
390 /// Maps register operand to its def instruction, which can be nullptr if it
391 /// is unknown (e.g., operand is defined outside the loop).
392 DenseMap<MachineOperand *, MachineInstr *> OperandToDefMap;
393
394 // Set depth of unknown instruction (i.e., nullptr) to zero.
395 DepthMap[nullptr] = {0, 0};
396
397 SmallPtrSet<MachineInstr *, 4> CmovInstructions;
398 for (auto &Group : CmovInstGroups)
399 CmovInstructions.insert(Group.begin(), Group.end());
400
401 //===--------------------------------------------------------------------===//
402 // Step 1: Calculate instruction depth and loop depth.
403 // Optimized-Loop:
404 // loop with CMOV-group-candidates converted into branches.
405 //
406 // Instruction-Depth:
407 // instruction latency + max operand depth.
408 // * For CMOV instruction in optimized loop the depth is calculated as:
409 // CMOV latency + getDepthOfOptCmov(True-Op-Depth, False-Op-depth)
410 // TODO: Find a better way to estimate the latency of the branch instruction
411 // rather than using the CMOV latency.
412 //
413 // Loop-Depth:
414 // max instruction depth of all instructions in the loop.
415 // Note: instruction with max depth represents the critical-path in the loop.
416 //
417 // Loop-Depth[i]:
418 // Loop-Depth calculated for first `i` iterations.
419 // Note: it is enough to calculate depth for up to two iterations.
420 //
421 // Depth-Diff[i]:
422 // Number of cycles saved in first 'i` iterations by optimizing the loop.
423 //===--------------------------------------------------------------------===//
424 for (unsigned I = 0; I < LoopIterations; ++I) {
425 DepthInfo &MaxDepth = LoopDepth[I];
426 for (auto *MBB : Blocks) {
427 // Clear physical registers Def map.
428 RegDefMaps[PhyRegType].clear();
429 for (MachineInstr &MI : *MBB) {
430 // Skip debug instructions.
431 if (MI.isDebugInstr())
432 continue;
433 unsigned MIDepth = 0;
434 unsigned MIDepthOpt = 0;
435 bool IsCMOV = CmovInstructions.count(&MI);
436 for (auto &MO : MI.uses()) {
437 // Checks for "isUse()" as "uses()" returns also implicit definitions.
438 if (!MO.isReg() || !MO.isUse())
439 continue;
440 unsigned Reg = MO.getReg();
441 auto &RDM = RegDefMaps[TargetRegisterInfo::isVirtualRegister(Reg)];
442 if (MachineInstr *DefMI = RDM.lookup(Reg)) {
443 OperandToDefMap[&MO] = DefMI;
444 DepthInfo Info = DepthMap.lookup(DefMI);
445 MIDepth = std::max(MIDepth, Info.Depth);
446 if (!IsCMOV)
447 MIDepthOpt = std::max(MIDepthOpt, Info.OptDepth);
448 }
449 }
450
451 if (IsCMOV)
452 MIDepthOpt = getDepthOfOptCmov(
453 DepthMap[OperandToDefMap.lookup(&MI.getOperand(1))].OptDepth,
454 DepthMap[OperandToDefMap.lookup(&MI.getOperand(2))].OptDepth);
455
456 // Iterates over all operands to handle implicit definitions as well.
457 for (auto &MO : MI.operands()) {
458 if (!MO.isReg() || !MO.isDef())
459 continue;
460 unsigned Reg = MO.getReg();
461 RegDefMaps[TargetRegisterInfo::isVirtualRegister(Reg)][Reg] = &MI;
462 }
463
464 unsigned Latency = TSchedModel.computeInstrLatency(&MI);
465 DepthMap[&MI] = {MIDepth += Latency, MIDepthOpt += Latency};
466 MaxDepth.Depth = std::max(MaxDepth.Depth, MIDepth);
467 MaxDepth.OptDepth = std::max(MaxDepth.OptDepth, MIDepthOpt);
468 }
469 }
470 }
471
472 unsigned Diff[LoopIterations] = {LoopDepth[0].Depth - LoopDepth[0].OptDepth,
473 LoopDepth[1].Depth - LoopDepth[1].OptDepth};
474
475 //===--------------------------------------------------------------------===//
476 // Step 2: Check if Loop worth to be optimized.
477 // Worth-Optimize-Loop:
478 // case 1: Diff[1] == Diff[0]
479 // Critical-path is iteration independent - there is no dependency
480 // of critical-path instructions on critical-path instructions of
481 // previous iteration.
482 // Thus, it is enough to check gain percent of 1st iteration -
483 // To be conservative, the optimized loop need to have a depth of
484 // 12.5% cycles less than original loop, per iteration.
485 //
486 // case 2: Diff[1] > Diff[0]
487 // Critical-path is iteration dependent - there is dependency of
488 // critical-path instructions on critical-path instructions of
489 // previous iteration.
490 // Thus, check the gain percent of the 2nd iteration (similar to the
491 // previous case), but it is also required to check the gradient of
492 // the gain - the change in Depth-Diff compared to the change in
493 // Loop-Depth between 1st and 2nd iterations.
494 // To be conservative, the gradient need to be at least 50%.
495 //
496 // In addition, In order not to optimize loops with very small gain, the
497 // gain (in cycles) after 2nd iteration should not be less than a given
498 // threshold. Thus, the check (Diff[1] >= GainCycleThreshold) must apply.
499 //
500 // If loop is not worth optimizing, remove all CMOV-group-candidates.
501 //===--------------------------------------------------------------------===//
502 if (Diff[1] < GainCycleThreshold)
503 return false;
504
505 bool WorthOptLoop = false;
506 if (Diff[1] == Diff[0])
507 WorthOptLoop = Diff[0] * 8 >= LoopDepth[0].Depth;
508 else if (Diff[1] > Diff[0])
509 WorthOptLoop =
510 (Diff[1] - Diff[0]) * 2 >= (LoopDepth[1].Depth - LoopDepth[0].Depth) &&
511 (Diff[1] * 8 >= LoopDepth[1].Depth);
512
513 if (!WorthOptLoop)
514 return false;
515
516 ++NumOfLoopCandidate;
517
518 //===--------------------------------------------------------------------===//
519 // Step 3: Check for each CMOV-group-candidate if it worth to be optimized.
520 // Worth-Optimize-Group:
521 // Iff it worths to optimize all CMOV instructions in the group.
522 //
523 // Worth-Optimize-CMOV:
524 // Predicted branch is faster than CMOV by the difference between depth of
525 // condition operand and depth of taken (predicted) value operand.
526 // To be conservative, the gain of such CMOV transformation should cover at
527 // at least 25% of branch-misprediction-penalty.
528 //===--------------------------------------------------------------------===//
529 unsigned MispredictPenalty = TSchedModel.getMCSchedModel()->MispredictPenalty;
530 CmovGroups TempGroups;
531 std::swap(TempGroups, CmovInstGroups);
532 for (auto &Group : TempGroups) {
533 bool WorthOpGroup = true;
534 for (auto *MI : Group) {
535 // Avoid CMOV instruction which value is used as a pointer to load from.
536 // This is another conservative check to avoid converting CMOV instruction
537 // used with tree-search like algorithm, where the branch is unpredicted.
538 auto UIs = MRI->use_instructions(MI->defs().begin()->getReg());
539 if (UIs.begin() != UIs.end() && ++UIs.begin() == UIs.end()) {
540 unsigned Op = UIs.begin()->getOpcode();
541 if (Op == X86::MOV64rm || Op == X86::MOV32rm) {
542 WorthOpGroup = false;
543 break;
544 }
545 }
546
547 unsigned CondCost =
548 DepthMap[OperandToDefMap.lookup(&MI->getOperand(4))].Depth;
549 unsigned ValCost = getDepthOfOptCmov(
550 DepthMap[OperandToDefMap.lookup(&MI->getOperand(1))].Depth,
551 DepthMap[OperandToDefMap.lookup(&MI->getOperand(2))].Depth);
552 if (ValCost > CondCost || (CondCost - ValCost) * 4 < MispredictPenalty) {
553 WorthOpGroup = false;
554 break;
555 }
556 }
557
558 if (WorthOpGroup)
559 CmovInstGroups.push_back(Group);
560 }
561
562 return !CmovInstGroups.empty();
563}
564
565static bool checkEFLAGSLive(MachineInstr *MI) {
566 if (MI->killsRegister(X86::EFLAGS))
567 return false;
568
569 // The EFLAGS operand of MI might be missing a kill marker.
570 // Figure out whether EFLAGS operand should LIVE after MI instruction.
571 MachineBasicBlock *BB = MI->getParent();
572 MachineBasicBlock::iterator ItrMI = MI;
573
574 // Scan forward through BB for a use/def of EFLAGS.
575 for (auto I = std::next(ItrMI), E = BB->end(); I != E; ++I) {
576 if (I->readsRegister(X86::EFLAGS))
577 return true;
578 if (I->definesRegister(X86::EFLAGS))
579 return false;
580 }
581
582 // We hit the end of the block, check whether EFLAGS is live into a successor.
583 for (auto I = BB->succ_begin(), E = BB->succ_end(); I != E; ++I) {
584 if ((*I)->isLiveIn(X86::EFLAGS))
585 return true;
586 }
587
588 return false;
589}
590
591/// Given /p First CMOV instruction and /p Last CMOV instruction representing a
592/// group of CMOV instructions, which may contain debug instructions in between,
593/// move all debug instructions to after the last CMOV instruction, making the
594/// CMOV group consecutive.
595static void packCmovGroup(MachineInstr *First, MachineInstr *Last) {
596 assert(X86::getCondFromCMov(*Last) != X86::COND_INVALID &&((X86::getCondFromCMov(*Last) != X86::COND_INVALID &&
"Last instruction in a CMOV group must be a CMOV instruction"
) ? static_cast<void> (0) : __assert_fail ("X86::getCondFromCMov(*Last) != X86::COND_INVALID && \"Last instruction in a CMOV group must be a CMOV instruction\""
, "/build/llvm-toolchain-snapshot-9~svn361465/lib/Target/X86/X86CmovConversion.cpp"
, 597, __PRETTY_FUNCTION__))
597 "Last instruction in a CMOV group must be a CMOV instruction")((X86::getCondFromCMov(*Last) != X86::COND_INVALID &&
"Last instruction in a CMOV group must be a CMOV instruction"
) ? static_cast<void> (0) : __assert_fail ("X86::getCondFromCMov(*Last) != X86::COND_INVALID && \"Last instruction in a CMOV group must be a CMOV instruction\""
, "/build/llvm-toolchain-snapshot-9~svn361465/lib/Target/X86/X86CmovConversion.cpp"
, 597, __PRETTY_FUNCTION__));
598
599 SmallVector<MachineInstr *, 2> DBGInstructions;
600 for (auto I = First->getIterator(), E = Last->getIterator(); I != E; I++) {
601 if (I->isDebugInstr())
602 DBGInstructions.push_back(&*I);
603 }
604
605 // Splice the debug instruction after the cmov group.
606 MachineBasicBlock *MBB = First->getParent();
607 for (auto *MI : DBGInstructions)
608 MBB->insertAfter(Last, MI->removeFromParent());
609}
610
611void X86CmovConverterPass::convertCmovInstsToBranches(
612 SmallVectorImpl<MachineInstr *> &Group) const {
613 assert(!Group.empty() && "No CMOV instructions to convert")((!Group.empty() && "No CMOV instructions to convert"
) ? static_cast<void> (0) : __assert_fail ("!Group.empty() && \"No CMOV instructions to convert\""
, "/build/llvm-toolchain-snapshot-9~svn361465/lib/Target/X86/X86CmovConversion.cpp"
, 613, __PRETTY_FUNCTION__));
614 ++NumOfOptimizedCmovGroups;
615
616 // If the CMOV group is not packed, e.g., there are debug instructions between
617 // first CMOV and last CMOV, then pack the group and make the CMOV instruction
618 // consecutive by moving the debug instructions to after the last CMOV.
619 packCmovGroup(Group.front(), Group.back());
620
621 // To convert a CMOVcc instruction, we actually have to insert the diamond
622 // control-flow pattern. The incoming instruction knows the destination vreg
623 // to set, the condition code register to branch on, the true/false values to
624 // select between, and a branch opcode to use.
625
626 // Before
627 // -----
628 // MBB:
629 // cond = cmp ...
630 // v1 = CMOVge t1, f1, cond
631 // v2 = CMOVlt t2, f2, cond
632 // v3 = CMOVge v1, f3, cond
633 //
634 // After
635 // -----
636 // MBB:
637 // cond = cmp ...
638 // jge %SinkMBB
639 //
640 // FalseMBB:
641 // jmp %SinkMBB
642 //
643 // SinkMBB:
644 // %v1 = phi[%f1, %FalseMBB], [%t1, %MBB]
645 // %v2 = phi[%t2, %FalseMBB], [%f2, %MBB] ; For CMOV with OppCC switch
646 // ; true-value with false-value
647 // %v3 = phi[%f3, %FalseMBB], [%t1, %MBB] ; Phi instruction cannot use
648 // ; previous Phi instruction result
649
650 MachineInstr &MI = *Group.front();
651 MachineInstr *LastCMOV = Group.back();
652 DebugLoc DL = MI.getDebugLoc();
653
654 X86::CondCode CC = X86::CondCode(X86::getCondFromCMov(MI));
655 X86::CondCode OppCC = X86::GetOppositeBranchCondition(CC);
656 // Potentially swap the condition codes so that any memory operand to a CMOV
657 // is in the *false* position instead of the *true* position. We can invert
658 // any non-memory operand CMOV instructions to cope with this and we ensure
659 // memory operand CMOVs are only included with a single condition code.
660 if (llvm::any_of(Group, [&](MachineInstr *I) {
661 return I->mayLoad() && X86::getCondFromCMov(*I) == CC;
662 }))
663 std::swap(CC, OppCC);
664
665 MachineBasicBlock *MBB = MI.getParent();
666 MachineFunction::iterator It = ++MBB->getIterator();
667 MachineFunction *F = MBB->getParent();
668 const BasicBlock *BB = MBB->getBasicBlock();
669
670 MachineBasicBlock *FalseMBB = F->CreateMachineBasicBlock(BB);
671 MachineBasicBlock *SinkMBB = F->CreateMachineBasicBlock(BB);
672 F->insert(It, FalseMBB);
673 F->insert(It, SinkMBB);
674
675 // If the EFLAGS register isn't dead in the terminator, then claim that it's
676 // live into the sink and copy blocks.
677 if (checkEFLAGSLive(LastCMOV)) {
678 FalseMBB->addLiveIn(X86::EFLAGS);
679 SinkMBB->addLiveIn(X86::EFLAGS);
680 }
681
682 // Transfer the remainder of BB and its successor edges to SinkMBB.
683 SinkMBB->splice(SinkMBB->begin(), MBB,
684 std::next(MachineBasicBlock::iterator(LastCMOV)), MBB->end());
685 SinkMBB->transferSuccessorsAndUpdatePHIs(MBB);
686
687 // Add the false and sink blocks as its successors.
688 MBB->addSuccessor(FalseMBB);
689 MBB->addSuccessor(SinkMBB);
690
691 // Create the conditional branch instruction.
692 BuildMI(MBB, DL, TII->get(X86::JCC_1)).addMBB(SinkMBB).addImm(CC);
693
694 // Add the sink block to the false block successors.
695 FalseMBB->addSuccessor(SinkMBB);
696
697 MachineInstrBuilder MIB;
698 MachineBasicBlock::iterator MIItBegin = MachineBasicBlock::iterator(MI);
699 MachineBasicBlock::iterator MIItEnd =
700 std::next(MachineBasicBlock::iterator(LastCMOV));
701 MachineBasicBlock::iterator FalseInsertionPoint = FalseMBB->begin();
702 MachineBasicBlock::iterator SinkInsertionPoint = SinkMBB->begin();
703
704 // First we need to insert an explicit load on the false path for any memory
705 // operand. We also need to potentially do register rewriting here, but it is
706 // simpler as the memory operands are always on the false path so we can
707 // simply take that input, whatever it is.
708 DenseMap<unsigned, unsigned> FalseBBRegRewriteTable;
709 for (MachineBasicBlock::iterator MIIt = MIItBegin; MIIt != MIItEnd;) {
710 auto &MI = *MIIt++;
711 // Skip any CMOVs in this group which don't load from memory.
712 if (!MI.mayLoad()) {
713 // Remember the false-side register input.
714 unsigned FalseReg =
715 MI.getOperand(X86::getCondFromCMov(MI) == CC ? 1 : 2).getReg();
716 // Walk back through any intermediate cmovs referenced.
717 while (true) {
718 auto FRIt = FalseBBRegRewriteTable.find(FalseReg);
719 if (FRIt == FalseBBRegRewriteTable.end())
720 break;
721 FalseReg = FRIt->second;
722 }
723 FalseBBRegRewriteTable[MI.getOperand(0).getReg()] = FalseReg;
724 continue;
725 }
726
727 // The condition must be the *opposite* of the one we've decided to branch
728 // on as the branch will go *around* the load and the load should happen
729 // when the CMOV condition is false.
730 assert(X86::getCondFromCMov(MI) == OppCC &&((X86::getCondFromCMov(MI) == OppCC && "Can only handle memory-operand cmov instructions with a condition "
"opposite to the selected branch direction.") ? static_cast<
void> (0) : __assert_fail ("X86::getCondFromCMov(MI) == OppCC && \"Can only handle memory-operand cmov instructions with a condition \" \"opposite to the selected branch direction.\""
, "/build/llvm-toolchain-snapshot-9~svn361465/lib/Target/X86/X86CmovConversion.cpp"
, 732, __PRETTY_FUNCTION__))
731 "Can only handle memory-operand cmov instructions with a condition "((X86::getCondFromCMov(MI) == OppCC && "Can only handle memory-operand cmov instructions with a condition "
"opposite to the selected branch direction.") ? static_cast<
void> (0) : __assert_fail ("X86::getCondFromCMov(MI) == OppCC && \"Can only handle memory-operand cmov instructions with a condition \" \"opposite to the selected branch direction.\""
, "/build/llvm-toolchain-snapshot-9~svn361465/lib/Target/X86/X86CmovConversion.cpp"
, 732, __PRETTY_FUNCTION__))
732 "opposite to the selected branch direction.")((X86::getCondFromCMov(MI) == OppCC && "Can only handle memory-operand cmov instructions with a condition "
"opposite to the selected branch direction.") ? static_cast<
void> (0) : __assert_fail ("X86::getCondFromCMov(MI) == OppCC && \"Can only handle memory-operand cmov instructions with a condition \" \"opposite to the selected branch direction.\""
, "/build/llvm-toolchain-snapshot-9~svn361465/lib/Target/X86/X86CmovConversion.cpp"
, 732, __PRETTY_FUNCTION__));
733
734 // The goal is to rewrite the cmov from:
735 //
736 // MBB:
737 // %A = CMOVcc %B (tied), (mem)
738 //
739 // to
740 //
741 // MBB:
742 // %A = CMOVcc %B (tied), %C
743 // FalseMBB:
744 // %C = MOV (mem)
745 //
746 // Which will allow the next loop to rewrite the CMOV in terms of a PHI:
747 //
748 // MBB:
749 // JMP!cc SinkMBB
750 // FalseMBB:
751 // %C = MOV (mem)
752 // SinkMBB:
753 // %A = PHI [ %C, FalseMBB ], [ %B, MBB]
754
755 // Get a fresh register to use as the destination of the MOV.
756 const TargetRegisterClass *RC = MRI->getRegClass(MI.getOperand(0).getReg());
757 unsigned TmpReg = MRI->createVirtualRegister(RC);
758
759 SmallVector<MachineInstr *, 4> NewMIs;
760 bool Unfolded = TII->unfoldMemoryOperand(*MBB->getParent(), MI, TmpReg,
761 /*UnfoldLoad*/ true,
762 /*UnfoldStore*/ false, NewMIs);
763 (void)Unfolded;
764 assert(Unfolded && "Should never fail to unfold a loading cmov!")((Unfolded && "Should never fail to unfold a loading cmov!"
) ? static_cast<void> (0) : __assert_fail ("Unfolded && \"Should never fail to unfold a loading cmov!\""
, "/build/llvm-toolchain-snapshot-9~svn361465/lib/Target/X86/X86CmovConversion.cpp"
, 764, __PRETTY_FUNCTION__));
765
766 // Move the new CMOV to just before the old one and reset any impacted
767 // iterator.
768 auto *NewCMOV = NewMIs.pop_back_val();
769 assert(X86::getCondFromCMov(*NewCMOV) == OppCC &&((X86::getCondFromCMov(*NewCMOV) == OppCC && "Last new instruction isn't the expected CMOV!"
) ? static_cast<void> (0) : __assert_fail ("X86::getCondFromCMov(*NewCMOV) == OppCC && \"Last new instruction isn't the expected CMOV!\""
, "/build/llvm-toolchain-snapshot-9~svn361465/lib/Target/X86/X86CmovConversion.cpp"
, 770, __PRETTY_FUNCTION__))
770 "Last new instruction isn't the expected CMOV!")((X86::getCondFromCMov(*NewCMOV) == OppCC && "Last new instruction isn't the expected CMOV!"
) ? static_cast<void> (0) : __assert_fail ("X86::getCondFromCMov(*NewCMOV) == OppCC && \"Last new instruction isn't the expected CMOV!\""
, "/build/llvm-toolchain-snapshot-9~svn361465/lib/Target/X86/X86CmovConversion.cpp"
, 770, __PRETTY_FUNCTION__));
771 LLVM_DEBUG(dbgs() << "\tRewritten cmov: "; NewCMOV->dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("x86-cmov-conversion")) { dbgs() << "\tRewritten cmov: "
; NewCMOV->dump(); } } while (false);
772 MBB->insert(MachineBasicBlock::iterator(MI), NewCMOV);
773 if (&*MIItBegin == &MI)
774 MIItBegin = MachineBasicBlock::iterator(NewCMOV);
775
776 // Sink whatever instructions were needed to produce the unfolded operand
777 // into the false block.
778 for (auto *NewMI : NewMIs) {
779 LLVM_DEBUG(dbgs() << "\tRewritten load instr: "; NewMI->dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("x86-cmov-conversion")) { dbgs() << "\tRewritten load instr: "
; NewMI->dump(); } } while (false);
780 FalseMBB->insert(FalseInsertionPoint, NewMI);
781 // Re-map any operands that are from other cmovs to the inputs for this block.
782 for (auto &MOp : NewMI->uses()) {
783 if (!MOp.isReg())
784 continue;
785 auto It = FalseBBRegRewriteTable.find(MOp.getReg());
786 if (It == FalseBBRegRewriteTable.end())
787 continue;
788
789 MOp.setReg(It->second);
790 // This might have been a kill when it referenced the cmov result, but
791 // it won't necessarily be once rewritten.
792 // FIXME: We could potentially improve this by tracking whether the
793 // operand to the cmov was also a kill, and then skipping the PHI node
794 // construction below.
795 MOp.setIsKill(false);
796 }
797 }
798 MBB->erase(MachineBasicBlock::iterator(MI),
799 std::next(MachineBasicBlock::iterator(MI)));
800
801 // Add this PHI to the rewrite table.
802 FalseBBRegRewriteTable[NewCMOV->getOperand(0).getReg()] = TmpReg;
803 }
804
805 // As we are creating the PHIs, we have to be careful if there is more than
806 // one. Later CMOVs may reference the results of earlier CMOVs, but later
807 // PHIs have to reference the individual true/false inputs from earlier PHIs.
808 // That also means that PHI construction must work forward from earlier to
809 // later, and that the code must maintain a mapping from earlier PHI's
810 // destination registers, and the registers that went into the PHI.
811 DenseMap<unsigned, std::pair<unsigned, unsigned>> RegRewriteTable;
812
813 for (MachineBasicBlock::iterator MIIt = MIItBegin; MIIt != MIItEnd; ++MIIt) {
814 unsigned DestReg = MIIt->getOperand(0).getReg();
815 unsigned Op1Reg = MIIt->getOperand(1).getReg();
816 unsigned Op2Reg = MIIt->getOperand(2).getReg();
817
818 // If this CMOV we are processing is the opposite condition from the jump we
819 // generated, then we have to swap the operands for the PHI that is going to
820 // be generated.
821 if (X86::getCondFromCMov(*MIIt) == OppCC)
822 std::swap(Op1Reg, Op2Reg);
823
824 auto Op1Itr = RegRewriteTable.find(Op1Reg);
825 if (Op1Itr != RegRewriteTable.end())
826 Op1Reg = Op1Itr->second.first;
827
828 auto Op2Itr = RegRewriteTable.find(Op2Reg);
829 if (Op2Itr != RegRewriteTable.end())
830 Op2Reg = Op2Itr->second.second;
831
832 // SinkMBB:
833 // %Result = phi [ %FalseValue, FalseMBB ], [ %TrueValue, MBB ]
834 // ...
835 MIB = BuildMI(*SinkMBB, SinkInsertionPoint, DL, TII->get(X86::PHI), DestReg)
836 .addReg(Op1Reg)
837 .addMBB(FalseMBB)
838 .addReg(Op2Reg)
839 .addMBB(MBB);
840 (void)MIB;
841 LLVM_DEBUG(dbgs() << "\tFrom: "; MIIt->dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("x86-cmov-conversion")) { dbgs() << "\tFrom: "; MIIt->
dump(); } } while (false);
842 LLVM_DEBUG(dbgs() << "\tTo: "; MIB->dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("x86-cmov-conversion")) { dbgs() << "\tTo: "; MIB->
dump(); } } while (false);
843
844 // Add this PHI to the rewrite table.
845 RegRewriteTable[DestReg] = std::make_pair(Op1Reg, Op2Reg);
846 }
847
848 // Now remove the CMOV(s).
849 MBB->erase(MIItBegin, MIItEnd);
850}
851
852INITIALIZE_PASS_BEGIN(X86CmovConverterPass, DEBUG_TYPE, "X86 cmov Conversion",static void *initializeX86CmovConverterPassPassOnce(PassRegistry
&Registry) {
853 false, false)static void *initializeX86CmovConverterPassPassOnce(PassRegistry
&Registry) {
854INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)initializeMachineLoopInfoPass(Registry);
855INITIALIZE_PASS_END(X86CmovConverterPass, DEBUG_TYPE, "X86 cmov Conversion",PassInfo *PI = new PassInfo( "X86 cmov Conversion", "x86-cmov-conversion"
, &X86CmovConverterPass::ID, PassInfo::NormalCtor_t(callDefaultCtor
<X86CmovConverterPass>), false, false); Registry.registerPass
(*PI, true); return PI; } static llvm::once_flag InitializeX86CmovConverterPassPassFlag
; void llvm::initializeX86CmovConverterPassPass(PassRegistry &
Registry) { llvm::call_once(InitializeX86CmovConverterPassPassFlag
, initializeX86CmovConverterPassPassOnce, std::ref(Registry))
; }
856 false, false)PassInfo *PI = new PassInfo( "X86 cmov Conversion", "x86-cmov-conversion"
, &X86CmovConverterPass::ID, PassInfo::NormalCtor_t(callDefaultCtor
<X86CmovConverterPass>), false, false); Registry.registerPass
(*PI, true); return PI; } static llvm::once_flag InitializeX86CmovConverterPassPassFlag
; void llvm::initializeX86CmovConverterPassPass(PassRegistry &
Registry) { llvm::call_once(InitializeX86CmovConverterPassPassFlag
, initializeX86CmovConverterPassPassOnce, std::ref(Registry))
; }
857
858FunctionPass *llvm::createX86CmovConverterPass() {
859 return new X86CmovConverterPass();
860}