LLVM 20.0.0git
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#include "llvm/Transforms/Scalar/CallSiteSplitting.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/DomTreeUpdater.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Transforms/Utils/Local.h"
Go to the source code of this file.
Macros | |
#define | DEBUG_TYPE "callsite-splitting" |
Typedefs | |
using | ConditionTy = std::pair< ICmpInst *, unsigned > |
using | ConditionsTy = SmallVector< ConditionTy, 2 > |
using | PredsWithCondsTy = SmallVector< std::pair< BasicBlock *, ConditionsTy >, 2 > |
Functions | |
STATISTIC (NumCallSiteSplit, "Number of call-site split") | |
static void | addNonNullAttribute (CallBase &CB, Value *Op) |
static void | setConstantInArgument (CallBase &CB, Value *Op, Constant *ConstValue) |
static bool | isCondRelevantToAnyCallArgument (ICmpInst *Cmp, CallBase &CB) |
static void | recordCondition (CallBase &CB, BasicBlock *From, BasicBlock *To, ConditionsTy &Conditions) |
If From has a conditional jump to To, add the condition to Conditions, if it is relevant to any argument at CB. | |
static void | recordConditions (CallBase &CB, BasicBlock *Pred, ConditionsTy &Conditions, BasicBlock *StopAt) |
Record ICmp conditions relevant to any argument in CB following Pred's single predecessors. | |
static void | addConditions (CallBase &CB, const ConditionsTy &Conditions) |
static SmallVector< BasicBlock *, 2 > | getTwoPredecessors (BasicBlock *BB) |
static bool | canSplitCallSite (CallBase &CB, TargetTransformInfo &TTI) |
static Instruction * | cloneInstForMustTail (Instruction *I, Instruction *Before, Value *V) |
static void | copyMustTailReturn (BasicBlock *SplitBB, Instruction *CI, Instruction *NewCI) |
Copy mandatory musttail return sequence that follows original CI , and link it up to NewCI value instead: | |
static void | splitCallSite (CallBase &CB, ArrayRef< std::pair< BasicBlock *, ConditionsTy > > Preds, DomTreeUpdater &DTU) |
For each (predecessor, conditions from predecessors) pair, it will split the basic block containing the call site, hook it up to the predecessor and replace the call instruction with new call instructions, which contain constraints based on the conditions from their predecessors. | |
static bool | isPredicatedOnPHI (CallBase &CB) |
static PredsWithCondsTy | shouldSplitOnPHIPredicatedArgument (CallBase &CB) |
static PredsWithCondsTy | shouldSplitOnPredicatedArgument (CallBase &CB, DomTreeUpdater &DTU) |
static bool | tryToSplitCallSite (CallBase &CB, TargetTransformInfo &TTI, DomTreeUpdater &DTU) |
static bool | doCallSiteSplitting (Function &F, TargetLibraryInfo &TLI, TargetTransformInfo &TTI, DominatorTree &DT) |
Variables | |
static cl::opt< unsigned > | DuplicationThreshold ("callsite-splitting-duplication-threshold", cl::Hidden, cl::desc("Only allow instructions before a call, if " "their cost is below DuplicationThreshold"), cl::init(5)) |
Only allow instructions before a call, if their CodeSize cost is below DuplicationThreshold. | |
#define DEBUG_TYPE "callsite-splitting" |
Definition at line 73 of file CallSiteSplitting.cpp.
using ConditionsTy = SmallVector<ConditionTy, 2> |
Definition at line 125 of file CallSiteSplitting.cpp.
Definition at line 124 of file CallSiteSplitting.cpp.
using PredsWithCondsTy = SmallVector<std::pair<BasicBlock *, ConditionsTy>, 2> |
Definition at line 439 of file CallSiteSplitting.cpp.
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Definition at line 165 of file CallSiteSplitting.cpp.
References addNonNullAttribute(), assert(), Cond, llvm::Value::getType(), llvm::Constant::isNullValue(), llvm::Type::isPointerTy(), and setConstantInArgument().
Referenced by splitCallSite().
Definition at line 86 of file CallSiteSplitting.cpp.
References llvm::CallBase::addParamAttr(), llvm::CallBase::args(), and I.
Referenced by addConditions().
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Definition at line 184 of file CallSiteSplitting.cpp.
References llvm::BasicBlock::begin(), llvm::CallBase::cannotDuplicate(), llvm::BasicBlock::canSplitPredecessors(), DuplicationThreshold, llvm::TargetTransformInfo::getInstructionCost(), llvm::ilist_node_impl< OptionsT >::getIterator(), llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), llvm::CallBase::isConvergent(), llvm::BasicBlock::isEHPad(), llvm::make_range(), llvm::predecessors(), llvm::SmallVectorBase< Size_T >::size(), and llvm::TargetTransformInfo::TCK_CodeSize.
Referenced by tryToSplitCallSite().
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Definition at line 221 of file CallSiteSplitting.cpp.
Referenced by copyMustTailReturn().
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Copy mandatory musttail
return sequence that follows original CI
, and link it up to NewCI
value instead:
bitcast NewCI to ...
ret bitcast or NewCI
Insert this sequence right before SplitBB
's terminator, which will be cleaned up later in splitCallSite
below.
Definition at line 239 of file CallSiteSplitting.cpp.
References assert(), cloneInstForMustTail(), llvm::ilist_node_impl< OptionsT >::getIterator(), llvm::BasicBlock::getParent(), llvm::Function::getReturnType(), llvm::BasicBlock::getTerminator(), II, and llvm::Type::isVoidTy().
Referenced by splitCallSite().
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Definition at line 502 of file CallSiteSplitting.cpp.
References F, llvm::CallBase::getCalledFunction(), II, llvm::isInstructionTriviallyDead(), llvm::CallBase::isMustTailCall(), llvm::make_early_inc_range(), and tryToSplitCallSite().
Referenced by llvm::CallSiteSplittingPass::run().
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Definition at line 178 of file CallSiteSplitting.cpp.
References assert(), llvm::predecessors(), and llvm::SmallVectorBase< Size_T >::size().
Referenced by shouldSplitOnPHIPredicatedArgument(), and shouldSplitOnPredicatedArgument().
Definition at line 109 of file CallSiteSplitting.cpp.
References llvm::CallBase::arg_begin(), llvm::CallBase::arg_end(), assert(), I, and llvm::CallBase::paramHasAttr().
Referenced by recordCondition().
Definition at line 416 of file CallSiteSplitting.cpp.
References llvm::CallBase::args(), assert(), llvm::BasicBlock::getFirstNonPHIOrDbg(), llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), and llvm::BasicBlock::phis().
Referenced by shouldSplitOnPHIPredicatedArgument().
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If From has a conditional jump to To, add the condition to Conditions, if it is relevant to any argument at CB.
Definition at line 129 of file CallSiteSplitting.cpp.
References Cond, From, isCondRelevantToAnyCallArgument(), llvm::PatternMatch::m_Constant(), llvm::PatternMatch::m_ICmp(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::match(), and llvm::SmallVectorTemplateBase< T, bool >::push_back().
Referenced by recordConditions(), and shouldSplitOnPredicatedArgument().
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Record ICmp conditions relevant to any argument in CB following Pred's single predecessors.
If there are conflicting conditions along a path, like x == 1 and x == 0, the first condition will be used. We stop once we reach an edge to StopAt.
Definition at line 152 of file CallSiteSplitting.cpp.
References llvm::SmallPtrSetImpl< PtrType >::count(), From, llvm::SmallPtrSetImpl< PtrType >::insert(), and recordCondition().
Referenced by shouldSplitOnPredicatedArgument().
Definition at line 95 of file CallSiteSplitting.cpp.
References llvm::CallBase::args(), I, llvm::CallBase::removeParamAttr(), and llvm::CallBase::setArgOperand().
Referenced by addConditions().
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Definition at line 443 of file CallSiteSplitting.cpp.
References llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), getTwoPredecessors(), and isPredicatedOnPHI().
Referenced by tryToSplitCallSite().
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Definition at line 454 of file CallSiteSplitting.cpp.
References llvm::all_of(), assert(), llvm::GenericDomTreeUpdater< DerivedT, DomTreeT, PostDomTreeT >::getDomTree(), llvm::DominatorTreeBase< NodeT, IsPostDom >::getNode(), llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), getTwoPredecessors(), llvm::GenericDomTreeUpdater< DerivedT, DomTreeT, PostDomTreeT >::hasDomTree(), P, llvm::SmallVectorTemplateBase< T, bool >::push_back(), recordCondition(), recordConditions(), and llvm::reverse().
Referenced by tryToSplitCallSite().
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For each (predecessor, conditions from predecessors) pair, it will split the basic block containing the call site, hook it up to the predecessor and replace the call instruction with new call instructions, which contain constraints based on the conditions from their predecessors.
For example, in the IR below with an OR condition, the call-site can be split. In this case, Preds for Tail is [(Header, a == null), (TBB, a != null, b == null)]. Tail is replaced by 2 split blocks, containing CallInst1, which has constraints based on the conditions from Head and CallInst2, which has constraints based on the conditions coming from TBB.
From :
Header: c = icmp eq i32* a, null br i1 c Tail, TBB TBB: c2 = icmp eq i32* b, null br i1 c Tail, End Tail: ca = call i1 @callee (i32* a, i32* b)
to :
Header: // PredBB1 is Header c = icmp eq i32* a, null br i1 c Tail-split1, TBB TBB: // PredBB2 is TBB c2 = icmp eq i32* b, null br i1 c Tail-split2, End Tail-split1: ca1 = call @callee (i32* null, i32* b) // CallInst1 br Tail Tail-split2: ca2 = call @callee (i32* nonnull a, i32* null) // CallInst2 br Tail Tail: p = phi i1 [ca1, Tail-split1],[ca2, Tail-split2]
Note that in case any arguments at the call-site are constrained by its predecessors, new call-sites with more constrained arguments will be created in createCallSitesOnPredicatedArgument().
Definition at line 302 of file CallSiteSplitting.cpp.
References addConditions(), llvm::PHINode::addIncoming(), llvm::GenericDomTreeUpdater< DerivedT, DomTreeT, PostDomTreeT >::applyUpdatesPermissive(), llvm::CallBase::args(), assert(), llvm::BasicBlock::begin(), copyMustTailReturn(), llvm::PHINode::Create(), llvm::dbgs(), llvm::DomTreeUpdater::deleteBB(), llvm::Instruction::dropDbgRecords(), llvm::DuplicateInstructionsInSplitBetween(), llvm::Instruction::eraseFromParent(), llvm::Instruction::getDebugLoc(), llvm::ilist_node_impl< OptionsT >::getIterator(), llvm::Value::getName(), llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), getParent(), llvm::ilist_node_impl< OptionsT >::getReverseIterator(), llvm::BasicBlock::getTerminator(), llvm::Value::getType(), I, llvm::Instruction::insertBefore(), llvm::CallBase::isMustTailCall(), LLVM_DEBUG, llvm::BasicBlock::phis(), llvm::predecessors(), llvm::BasicBlock::rend(), llvm::Value::replaceAllUsesWith(), llvm::Instruction::setDebugLoc(), llvm::SmallVectorBase< Size_T >::size(), llvm::SplitBlock(), and llvm::Value::use_empty().
Referenced by tryToSplitCallSite().
STATISTIC | ( | NumCallSiteSplit | , |
"Number of call-site split" | |||
) |
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Definition at line 486 of file CallSiteSplitting.cpp.
References llvm::CallBase::arg_size(), canSplitCallSite(), shouldSplitOnPHIPredicatedArgument(), shouldSplitOnPredicatedArgument(), and splitCallSite().
Referenced by doCallSiteSplitting().
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Only allow instructions before a call, if their CodeSize cost is below DuplicationThreshold.
Those instructions need to be duplicated in all split blocks.
Referenced by canSplitCallSite().