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[PM] Remove the preverifier and directly compute the DominatorTree for

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the verifier after ensuring the CFG is at least usefully formed.

This fixes a number of problems:
1) The PreVerifier was missing the controls the Verifier provides over
   *how* an invalid module is handled -- it just aborted the program!
   Now it uses the same logic as the Verifier which is significantly
   more library-friendly.
2) The DominatorTree used previously could have been cached and not
   updated due to bugs in prior passes and we would silently use the
   stale tree. This could cause dominance errors to not be as quickly
   diagnosed.
3) We can now (in the next patch) pull the functionality of the verifier
   apart from the pass infrastructure so that you can verify IR without
   having any form of pass manager. This in turn frees the code to share
   logic between old and new pass manager variants.

Along the way I fixed at least one annoying bug -- the state for
'Broken' wasn't being cleared from run to run causing all functions
visited after the first broken function to be marked as broken
regardless of whether *they* were a problem. Fortunately, I don't really
know much of a way to observe this peculiarity.

In case folks are worried about the runtime cost, its negligible.
I looked at running the entire regression test suite (which should be
a relatively good use of the verifier) before and after but was unable
to even measure the time spent on the verifier and there was no
regresion from before to after. I checked both with debug builds and
optimized builds.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199487 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chandler Carruth 2014-01-17 10:56:02 +00:00
parent b9536ac581
commit 0c25726596
3 changed files with 27 additions and 55 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/llvm/InitializePasses.h
View File

@ -211,7 +211,6 @@ void initializePostDomViewerPass(PassRegistry&);
void initializePostDominatorTreePass(PassRegistry&);
void initializePostRASchedulerPass(PassRegistry&);
void initializePostMachineSchedulerPass(PassRegistry&);
void initializePreVerifierPass(PassRegistry&);
void initializePrintFunctionPassWrapperPass(PassRegistry&);
void initializePrintModulePassWrapperPass(PassRegistry&);
void initializePrintBasicBlockPassPass(PassRegistry&);

1
lib/IR/Core.cpp
View File

@ -45,7 +45,6 @@ void llvm::initializeCore(PassRegistry &Registry) {
initializePrintFunctionPassWrapperPass(Registry);
initializePrintBasicBlockPassPass(Registry);
initializeVerifierPass(Registry);
initializePreVerifierPass(Registry);
}
void LLVMInitializeCore(LLVMPassRegistryRef R) {

80
lib/IR/Verifier.cpp
View File

@ -79,46 +79,6 @@ using namespace llvm;
static cl::opt<bool> DisableDebugInfoVerifier("disable-debug-info-verifier",
cl::init(true));
namespace { // Anonymous namespace for class
struct PreVerifier : public FunctionPass {
static char ID; // Pass ID, replacement for typeid
PreVerifier() : FunctionPass(ID) {
initializePreVerifierPass(*PassRegistry::getPassRegistry());
}
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
}
// Check that the prerequisites for successful DominatorTree construction
// are satisfied.
bool runOnFunction(Function &F) {
bool Broken = false;
for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I) {
if (I->empty() || !I->back().isTerminator()) {
dbgs() << "Basic Block in function '" << F.getName()
<< "' does not have terminator!\n";
I->printAsOperand(dbgs(), true);
dbgs() << "\n";
Broken = true;
}
}
if (Broken)
report_fatal_error("Broken module, no Basic Block terminator!");
return false;
}
};
}
char PreVerifier::ID = 0;
INITIALIZE_PASS(PreVerifier, "preverify", "Preliminary module verification",
false, false)
static char &PreVerifyID = PreVerifier::ID;
namespace {
struct Verifier : public FunctionPass, public InstVisitor<Verifier> {
static char ID; // Pass ID, replacement for typeid
@ -127,7 +87,7 @@ namespace {
// What to do if verification fails.
Module *Mod; // Module we are verifying right now
LLVMContext *Context; // Context within which we are verifying
DominatorTree *DT; // Dominator Tree, caution can be null!
DominatorTree DT;
const DataLayout *DL;
std::string Messages;
@ -153,13 +113,13 @@ namespace {
Verifier()
: FunctionPass(ID), Broken(false),
action(AbortProcessAction), Mod(0), Context(0), DT(0), DL(0),
action(AbortProcessAction), Mod(0), Context(0), DL(0),
MessagesStr(Messages), PersonalityFn(0) {
initializeVerifierPass(*PassRegistry::getPassRegistry());
}
explicit Verifier(VerifierFailureAction ctn)
: FunctionPass(ID), Broken(false), action(ctn), Mod(0),
Context(0), DT(0), DL(0), MessagesStr(Messages), PersonalityFn(0) {
Context(0), DL(0), MessagesStr(Messages), PersonalityFn(0) {
initializeVerifierPass(*PassRegistry::getPassRegistry());
}
@ -175,8 +135,27 @@ namespace {
}
bool runOnFunction(Function &F) {
// Get dominator information if we are being run by PassManager
DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
Broken = false;
// First ensure the function is well-enough formed to compute dominance
// information.
for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I) {
if (I->empty() || !I->back().isTerminator()) {
dbgs() << "Basic Block in function '" << F.getName()
<< "' does not have terminator!\n";
I->printAsOperand(dbgs(), true);
dbgs() << "\n";
Broken = true;
}
}
if (Broken)
return abortIfBroken();
// Now directly compute a dominance tree. We don't rely on the pass
// manager to provide this as it isolates us from a potentially
// out-of-date dominator tree and makes it significantly more complex to
// run this code outside of a pass manager.
DT.recalculate(F);
Mod = F.getParent();
if (!Context) Context = &F.getContext();
@ -232,8 +211,6 @@ namespace {
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
AU.addRequiredID(PreVerifyID);
AU.addRequired<DominatorTreeWrapperPass>();
}
/// abortIfBroken - If the module is broken and we are supposed to abort on
@ -393,10 +370,7 @@ namespace {
} // End anonymous namespace
char Verifier::ID = 0;
INITIALIZE_PASS_BEGIN(Verifier, "verify", "Module Verifier", false, false)
INITIALIZE_PASS_DEPENDENCY(PreVerifier)
INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
INITIALIZE_PASS_END(Verifier, "verify", "Module Verifier", false, false)
INITIALIZE_PASS(Verifier, "verify", "Module Verifier", false, false)
// Assert - We know that cond should be true, if not print an error message.
#define Assert(C, M) \
@ -2026,7 +2000,7 @@ void Verifier::verifyDominatesUse(Instruction &I, unsigned i) {
}
const Use &U = I.getOperandUse(i);
Assert2(InstsInThisBlock.count(Op) || DT->dominates(Op, U),
Assert2(InstsInThisBlock.count(Op) || DT.dominates(Op, U),
"Instruction does not dominate all uses!", Op, &I);
}
@ -2039,7 +2013,7 @@ void Verifier::visitInstruction(Instruction &I) {
if (!isa<PHINode>(I)) { // Check that non-phi nodes are not self referential
for (Value::use_iterator UI = I.use_begin(), UE = I.use_end();
UI != UE; ++UI)
Assert1(*UI != (User*)&I || !DT->isReachableFromEntry(BB),
Assert1(*UI != (User*)&I || !DT.isReachableFromEntry(BB),
"Only PHI nodes may reference their own value!", &I);
}