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This pass identifies expensive constants to hoist and coalesces them to better prepare it for SelectionDAG-based code generation. This works around the limitations of the basic-block-at-a-time approach. First it scans all instructions for integer constants and calculates its cost. If the constant can be folded into the instruction (the cost is TCC_Free) or the cost is just a simple operation (TCC_BASIC), then we don't consider it expensive and leave it alone. This is the default behavior and the default implementation of getIntImmCost will always return TCC_Free. If the cost is more than TCC_BASIC, then the integer constant can't be folded into the instruction and it might be beneficial to hoist the constant. Similar constants are coalesced to reduce register pressure and materialization code. When a constant is hoisted, it is also hidden behind a bitcast to force it to be live-out of the basic block. Otherwise the constant would be just duplicated and each basic block would have its own copy in the SelectionDAG. The SelectionDAG recognizes such constants as opaque and doesn't perform certain transformations on them, which would create a new expensive constant. This optimization is only applied to integer constants in instructions and simple (this means not nested) constant cast experessions. For example: %0 = load i64* inttoptr (i64 big_constant to i64*) Reviewed by Eric git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@200022 91177308-0d34-0410-b5e6-96231b3b80d8
206 lines
6.2 KiB
C++
206 lines
6.2 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/PassManager.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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initializeSampleProfileLoaderPass(Registry);
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initializeCodeGenPreparePass(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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initializeEarlyCSEPass(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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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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}
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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 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 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 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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}
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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 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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