llvm/lib/Analysis/AssumptionCache.cpp
Chandler Carruth 9a78a64776 [PM] Actually add the new pass manager support for the assumption cache.
I had already factored this analysis specifically to enable doing this,
but hadn't actually committed the necessary wiring to get at this from
the new pass manager. This also nicely shows how the separate cache
object can be directly managed by the new pass manager.

This analysis didn't have any direct tests and so I've added a printer
pass and a boring test case. I chose to print the i1 value which is
being assumed rather than the call to llvm.assume as that seems much
more useful for testing... but suggestions on an even better printing
strategy welcome. My main goal was to make sure things actually work. =]

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226868 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-22 21:53:09 +00:00

141 lines
4.9 KiB
C++

//===- 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/PassManager.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
}
char AssumptionAnalysis::PassID;
PreservedAnalyses AssumptionPrinterPass::run(Function &F,
AnalysisManager<Function> *AM) {
AssumptionCache &AC = AM->getResult<AssumptionAnalysis>(F);
OS << "Cached assumptions for function: " << F.getName() << "\n";
for (auto &VH : AC.assumptions())
if (VH)
OS << " " << *cast<CallInst>(VH)->getArgOperand(0) << "\n";
return PreservedAnalyses::all();
}
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;