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5b43c8551e
BDCE is a bit-tracking dead code elimination pass. It is based on ADCE (the "aggressive DCE" pass), with the added capability to track dead bits of integer valued instructions and remove those instructions when all of the bits are dead. Currently, it does not actually do this all-bits-dead removal, but rather replaces the instruction's uses with a constant zero, and lets instcombine (and the later run of ADCE) do the rest. Because we essentially get a run of ADCE "for free" while tracking the dead bits, we also do what ADCE does and removes actually-dead instructions as well (this includes instructions newly trivially dead because all bits were dead, but not all such instructions can be removed). The motivation for this is a case like: int __attribute__((const)) foo(int i); int bar(int x) { x |= (4 & foo(5)); x |= (8 & foo(3)); x |= (16 & foo(2)); x |= (32 & foo(1)); x |= (64 & foo(0)); x |= (128& foo(4)); return x >> 4; } As it turns out, if you order the bit-field insertions so that all of the dead ones come last, then instcombine will remove them. However, if you pick some other order (such as the one above), the fact that some of the calls to foo() are useless is not locally obvious, and we don't remove them (without this pass). I did a quick compile-time overhead check using sqlite from the test suite (Release+Asserts). BDCE took ~0.4% of the compilation time (making it about twice as expensive as ADCE). I've not looked at why yet, but we eliminate instructions due to having all-dead bits in: External/SPEC/CFP2006/447.dealII/447.dealII External/SPEC/CINT2006/400.perlbench/400.perlbench External/SPEC/CINT2006/403.gcc/403.gcc MultiSource/Applications/ClamAV/clamscan MultiSource/Benchmarks/7zip/7zip-benchmark git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229462 91177308-0d34-0410-b5e6-96231b3b80d8
236 lines
7.2 KiB
C++
236 lines
7.2 KiB
C++
//===-- Scalar.cpp --------------------------------------------------------===//
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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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//
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// This file implements common infrastructure for libLLVMScalarOpts.a, which
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// implements several scalar transformations over the LLVM intermediate
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// representation, including the C bindings for that library.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/Scalar.h"
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#include "llvm-c/Initialization.h"
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#include "llvm-c/Transforms/Scalar.h"
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#include "llvm/Analysis/Passes.h"
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#include "llvm/IR/DataLayout.h"
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#include "llvm/IR/Verifier.h"
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#include "llvm/InitializePasses.h"
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#include "llvm/IR/LegacyPassManager.h"
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using namespace llvm;
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/// initializeScalarOptsPasses - Initialize all passes linked into the
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/// ScalarOpts library.
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void llvm::initializeScalarOpts(PassRegistry &Registry) {
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initializeADCEPass(Registry);
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initializeBDCEPass(Registry);
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initializeAlignmentFromAssumptionsPass(Registry);
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initializeSampleProfileLoaderPass(Registry);
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initializeConstantHoistingPass(Registry);
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initializeConstantPropagationPass(Registry);
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initializeCorrelatedValuePropagationPass(Registry);
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initializeDCEPass(Registry);
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initializeDeadInstEliminationPass(Registry);
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initializeScalarizerPass(Registry);
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initializeDSEPass(Registry);
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initializeGVNPass(Registry);
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initializeEarlyCSELegacyPassPass(Registry);
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initializeFlattenCFGPassPass(Registry);
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initializeInductiveRangeCheckEliminationPass(Registry);
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initializeIndVarSimplifyPass(Registry);
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initializeJumpThreadingPass(Registry);
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initializeLICMPass(Registry);
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initializeLoopDeletionPass(Registry);
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initializeLoopInstSimplifyPass(Registry);
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initializeLoopRotatePass(Registry);
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initializeLoopStrengthReducePass(Registry);
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initializeLoopRerollPass(Registry);
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initializeLoopUnrollPass(Registry);
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initializeLoopUnswitchPass(Registry);
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initializeLoopIdiomRecognizePass(Registry);
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initializeLowerAtomicPass(Registry);
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initializeLowerExpectIntrinsicPass(Registry);
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initializeMemCpyOptPass(Registry);
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initializeMergedLoadStoreMotionPass(Registry);
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initializePartiallyInlineLibCallsPass(Registry);
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initializeReassociatePass(Registry);
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initializeRegToMemPass(Registry);
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initializeSCCPPass(Registry);
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initializeIPSCCPPass(Registry);
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initializeSROAPass(Registry);
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initializeSROA_DTPass(Registry);
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initializeSROA_SSAUpPass(Registry);
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initializeCFGSimplifyPassPass(Registry);
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initializeStructurizeCFGPass(Registry);
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initializeSinkingPass(Registry);
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initializeTailCallElimPass(Registry);
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initializeSeparateConstOffsetFromGEPPass(Registry);
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initializeStraightLineStrengthReducePass(Registry);
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initializeLoadCombinePass(Registry);
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initializePlaceBackedgeSafepointsImplPass(Registry);
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initializePlaceSafepointsPass(Registry);
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}
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void LLVMInitializeScalarOpts(LLVMPassRegistryRef R) {
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initializeScalarOpts(*unwrap(R));
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}
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void LLVMAddAggressiveDCEPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createAggressiveDCEPass());
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}
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void LLVMAddBitTrackingDCEPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createBitTrackingDCEPass());
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}
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void LLVMAddAlignmentFromAssumptionsPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createAlignmentFromAssumptionsPass());
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}
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void LLVMAddCFGSimplificationPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createCFGSimplificationPass());
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}
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void LLVMAddDeadStoreEliminationPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createDeadStoreEliminationPass());
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}
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void LLVMAddScalarizerPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createScalarizerPass());
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}
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void LLVMAddGVNPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createGVNPass());
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}
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void LLVMAddMergedLoadStoreMotionPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createMergedLoadStoreMotionPass());
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}
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void LLVMAddIndVarSimplifyPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createIndVarSimplifyPass());
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}
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void LLVMAddInstructionCombiningPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createInstructionCombiningPass());
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}
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void LLVMAddJumpThreadingPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createJumpThreadingPass());
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}
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void LLVMAddLICMPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createLICMPass());
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}
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void LLVMAddLoopDeletionPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createLoopDeletionPass());
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}
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void LLVMAddLoopIdiomPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createLoopIdiomPass());
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}
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void LLVMAddLoopRotatePass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createLoopRotatePass());
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}
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void LLVMAddLoopRerollPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createLoopRerollPass());
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}
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void LLVMAddLoopUnrollPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createLoopUnrollPass());
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}
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void LLVMAddLoopUnswitchPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createLoopUnswitchPass());
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}
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void LLVMAddMemCpyOptPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createMemCpyOptPass());
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}
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void LLVMAddPartiallyInlineLibCallsPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createPartiallyInlineLibCallsPass());
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}
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void LLVMAddLowerSwitchPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createLowerSwitchPass());
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}
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void LLVMAddPromoteMemoryToRegisterPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createPromoteMemoryToRegisterPass());
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}
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void LLVMAddReassociatePass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createReassociatePass());
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}
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void LLVMAddSCCPPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createSCCPPass());
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}
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void LLVMAddScalarReplAggregatesPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createScalarReplAggregatesPass());
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}
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void LLVMAddScalarReplAggregatesPassSSA(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createScalarReplAggregatesPass(-1, false));
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}
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void LLVMAddScalarReplAggregatesPassWithThreshold(LLVMPassManagerRef PM,
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int Threshold) {
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unwrap(PM)->add(createScalarReplAggregatesPass(Threshold));
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}
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void LLVMAddSimplifyLibCallsPass(LLVMPassManagerRef PM) {
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// NOTE: The simplify-libcalls pass has been removed.
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}
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void LLVMAddTailCallEliminationPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createTailCallEliminationPass());
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}
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void LLVMAddConstantPropagationPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createConstantPropagationPass());
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}
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void LLVMAddDemoteMemoryToRegisterPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createDemoteRegisterToMemoryPass());
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}
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void LLVMAddVerifierPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createVerifierPass());
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// FIXME: should this also add createDebugInfoVerifierPass()?
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}
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void LLVMAddCorrelatedValuePropagationPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createCorrelatedValuePropagationPass());
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}
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void LLVMAddEarlyCSEPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createEarlyCSEPass());
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}
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void LLVMAddTypeBasedAliasAnalysisPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createTypeBasedAliasAnalysisPass());
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}
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void LLVMAddScopedNoAliasAAPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createScopedNoAliasAAPass());
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}
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void LLVMAddBasicAliasAnalysisPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createBasicAliasAnalysisPass());
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}
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void LLVMAddLowerExpectIntrinsicPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createLowerExpectIntrinsicPass());
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}
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