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//===- AssumptionCache.cpp - Cache finding @llvm.assume calls -------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains a pass that keeps track of @llvm.assume intrinsics in
// the functions of a module.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/Support/Debug.h"
using namespace llvm;
using namespace llvm::PatternMatch;
void AssumptionCache::scanFunction() {
assert(!Scanned && "Tried to scan the function twice!");
assert(AssumeHandles.empty() && "Already have assumes when scanning!");
// Go through all instructions in all blocks, add all calls to @llvm.assume
// to this cache.
for (BasicBlock &B : F)
for (Instruction &II : B)
if (match(&II, m_Intrinsic<Intrinsic::assume>()))
AssumeHandles.push_back(&II);
// Mark the scan as complete.
Scanned = true;
}
void AssumptionCache::registerAssumption(CallInst *CI) {
assert(match(CI, m_Intrinsic<Intrinsic::assume>()) &&
"Registered call does not call @llvm.assume");
// If we haven't scanned the function yet, just drop this assumption. It will
// be found when we scan later.
if (!Scanned)
return;
AssumeHandles.push_back(CI);
#ifndef NDEBUG
assert(CI->getParent() &&
"Cannot register @llvm.assume call not in a basic block");
assert(&F == CI->getParent()->getParent() &&
"Cannot register @llvm.assume call not in this function");
// We expect the number of assumptions to be small, so in an asserts build
// check that we don't accumulate duplicates and that all assumptions point
// to the same function.
SmallPtrSet<Value *, 16> AssumptionSet;
for (auto &VH : AssumeHandles) {
if (!VH)
continue;
assert(&F == cast<Instruction>(VH)->getParent()->getParent() &&
"Cached assumption not inside this function!");
assert(match(cast<CallInst>(VH), m_Intrinsic<Intrinsic::assume>()) &&
"Cached something other than a call to @llvm.assume!");
assert(AssumptionSet.insert(VH).second &&
"Cache contains multiple copies of a call!");
}
#endif
}
void AssumptionCacheTracker::FunctionCallbackVH::deleted() {
auto I = ACT->AssumptionCaches.find_as(cast<Function>(getValPtr()));
if (I != ACT->AssumptionCaches.end())
ACT->AssumptionCaches.erase(I);
// 'this' now dangles!
}
AssumptionCache &AssumptionCacheTracker::getAssumptionCache(Function &F) {
// We probe the function map twice to try and avoid creating a value handle
// around the function in common cases. This makes insertion a bit slower,
// but if we have to insert we're going to scan the whole function so that
// shouldn't matter.
auto I = AssumptionCaches.find_as(&F);
if (I != AssumptionCaches.end())
return *I->second;
// Ok, build a new cache by scanning the function, insert it and the value
// handle into our map, and return the newly populated cache.
auto IP = AssumptionCaches.insert(std::make_pair(
FunctionCallbackVH(&F, this), llvm::make_unique<AssumptionCache>(F)));
assert(IP.second && "Scanning function already in the map?");
return *IP.first->second;
}
void AssumptionCacheTracker::verifyAnalysis() const {
#ifndef NDEBUG
SmallPtrSet<const CallInst *, 4> AssumptionSet;
for (const auto &I : AssumptionCaches) {
for (auto &VH : I.second->assumptions())
if (VH)
AssumptionSet.insert(cast<CallInst>(VH));
for (const BasicBlock &B : cast<Function>(*I.first))
for (const Instruction &II : B)
if (match(&II, m_Intrinsic<Intrinsic::assume>()))
assert(AssumptionSet.count(cast<CallInst>(&II)) &&
"Assumption in scanned function not in cache");
}
#endif
}
AssumptionCacheTracker::AssumptionCacheTracker() : ImmutablePass(ID) {
initializeAssumptionCacheTrackerPass(*PassRegistry::getPassRegistry());
}
AssumptionCacheTracker::~AssumptionCacheTracker() {}
INITIALIZE_PASS(AssumptionCacheTracker, "assumption-cache-tracker",
"Assumption Cache Tracker", false, true)
char AssumptionCacheTracker::ID = 0;
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