llvm-6502/lib/IR/LLVMContext.cpp
Hal Finkel 16fd27b2c3 Add scoped-noalias metadata
This commit adds scoped noalias metadata. The primary motivations for this
feature are:
  1. To preserve noalias function attribute information when inlining
  2. To provide the ability to model block-scope C99 restrict pointers

Neither of these two abilities are added here, only the necessary
infrastructure. In fact, there should be no change to existing functionality,
only the addition of new features. The logic that converts noalias function
parameters into this metadata during inlining will come in a follow-up commit.

What is added here is the ability to generally specify noalias memory-access
sets. Regarding the metadata, alias-analysis scopes are defined similar to TBAA
nodes:

!scope0 = metadata !{ metadata !"scope of foo()" }
!scope1 = metadata !{ metadata !"scope 1", metadata !scope0 }
!scope2 = metadata !{ metadata !"scope 2", metadata !scope0 }
!scope3 = metadata !{ metadata !"scope 2.1", metadata !scope2 }
!scope4 = metadata !{ metadata !"scope 2.2", metadata !scope2 }

Loads and stores can be tagged with an alias-analysis scope, and also, with a
noalias tag for a specific scope:

... = load %ptr1, !alias.scope !{ !scope1 }
... = load %ptr2, !alias.scope !{ !scope1, !scope2 }, !noalias !{ !scope1 }

When evaluating an aliasing query, if one of the instructions is associated
with an alias.scope id that is identical to the noalias scope associated with
the other instruction, or is a descendant (in the scope hierarchy) of the
noalias scope associated with the other instruction, then the two memory
accesses are assumed not to alias.

Note that is the first element of the scope metadata is a string, then it can
be combined accross functions and translation units. The string can be replaced
by a self-reference to create globally unqiue scope identifiers.

[Note: This overview is slightly stylized, since the metadata nodes really need
to just be numbers (!0 instead of !scope0), and the scope lists are also global
unnamed metadata.]

Existing noalias metadata in a callee is "cloned" for use by the inlined code.
This is necessary because the aliasing scopes are unique to each call site
(because of possible control dependencies on the aliasing properties). For
example, consider a function: foo(noalias a, noalias b) { *a = *b; } that gets
inlined into bar() { ... if (...) foo(a1, b1); ... if (...) foo(a2, b2); } --
now just because we know that a1 does not alias with b1 at the first call site,
and a2 does not alias with b2 at the second call site, we cannot let inlining
these functons have the metadata imply that a1 does not alias with b2.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213864 91177308-0d34-0410-b5e6-96231b3b80d8
2014-07-24 14:25:39 +00:00

243 lines
7.7 KiB
C++

//===-- LLVMContext.cpp - Implement LLVMContext ---------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements LLVMContext, as a wrapper around the opaque
// class LLVMContextImpl.
//
//===----------------------------------------------------------------------===//
#include "llvm/IR/LLVMContext.h"
#include "LLVMContextImpl.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DebugLoc.h"
#include "llvm/IR/DiagnosticInfo.h"
#include "llvm/IR/DiagnosticPrinter.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Metadata.h"
#include "llvm/Support/ManagedStatic.h"
#include "llvm/Support/SourceMgr.h"
#include <cctype>
using namespace llvm;
static ManagedStatic<LLVMContext> GlobalContext;
LLVMContext& llvm::getGlobalContext() {
return *GlobalContext;
}
LLVMContext::LLVMContext() : pImpl(new LLVMContextImpl(*this)) {
// Create the fixed metadata kinds. This is done in the same order as the
// MD_* enum values so that they correspond.
// Create the 'dbg' metadata kind.
unsigned DbgID = getMDKindID("dbg");
assert(DbgID == MD_dbg && "dbg kind id drifted"); (void)DbgID;
// Create the 'tbaa' metadata kind.
unsigned TBAAID = getMDKindID("tbaa");
assert(TBAAID == MD_tbaa && "tbaa kind id drifted"); (void)TBAAID;
// Create the 'prof' metadata kind.
unsigned ProfID = getMDKindID("prof");
assert(ProfID == MD_prof && "prof kind id drifted"); (void)ProfID;
// Create the 'fpmath' metadata kind.
unsigned FPAccuracyID = getMDKindID("fpmath");
assert(FPAccuracyID == MD_fpmath && "fpmath kind id drifted");
(void)FPAccuracyID;
// Create the 'range' metadata kind.
unsigned RangeID = getMDKindID("range");
assert(RangeID == MD_range && "range kind id drifted");
(void)RangeID;
// Create the 'tbaa.struct' metadata kind.
unsigned TBAAStructID = getMDKindID("tbaa.struct");
assert(TBAAStructID == MD_tbaa_struct && "tbaa.struct kind id drifted");
(void)TBAAStructID;
// Create the 'invariant.load' metadata kind.
unsigned InvariantLdId = getMDKindID("invariant.load");
assert(InvariantLdId == MD_invariant_load && "invariant.load kind id drifted");
(void)InvariantLdId;
// Create the 'alias.scope' metadata kind.
unsigned AliasScopeID = getMDKindID("alias.scope");
assert(AliasScopeID == MD_alias_scope && "alias.scope kind id drifted");
(void)AliasScopeID;
// Create the 'noalias' metadata kind.
unsigned NoAliasID = getMDKindID("noalias");
assert(NoAliasID == MD_noalias && "noalias kind id drifted");
(void)NoAliasID;
}
LLVMContext::~LLVMContext() { delete pImpl; }
void LLVMContext::addModule(Module *M) {
pImpl->OwnedModules.insert(M);
}
void LLVMContext::removeModule(Module *M) {
pImpl->OwnedModules.erase(M);
}
//===----------------------------------------------------------------------===//
// Recoverable Backend Errors
//===----------------------------------------------------------------------===//
void LLVMContext::
setInlineAsmDiagnosticHandler(InlineAsmDiagHandlerTy DiagHandler,
void *DiagContext) {
pImpl->InlineAsmDiagHandler = DiagHandler;
pImpl->InlineAsmDiagContext = DiagContext;
}
/// getInlineAsmDiagnosticHandler - Return the diagnostic handler set by
/// setInlineAsmDiagnosticHandler.
LLVMContext::InlineAsmDiagHandlerTy
LLVMContext::getInlineAsmDiagnosticHandler() const {
return pImpl->InlineAsmDiagHandler;
}
/// getInlineAsmDiagnosticContext - Return the diagnostic context set by
/// setInlineAsmDiagnosticHandler.
void *LLVMContext::getInlineAsmDiagnosticContext() const {
return pImpl->InlineAsmDiagContext;
}
void LLVMContext::setDiagnosticHandler(DiagnosticHandlerTy DiagnosticHandler,
void *DiagnosticContext) {
pImpl->DiagnosticHandler = DiagnosticHandler;
pImpl->DiagnosticContext = DiagnosticContext;
}
LLVMContext::DiagnosticHandlerTy LLVMContext::getDiagnosticHandler() const {
return pImpl->DiagnosticHandler;
}
void *LLVMContext::getDiagnosticContext() const {
return pImpl->DiagnosticContext;
}
void LLVMContext::setYieldCallback(YieldCallbackTy Callback, void *OpaqueHandle)
{
pImpl->YieldCallback = Callback;
pImpl->YieldOpaqueHandle = OpaqueHandle;
}
void LLVMContext::yield() {
if (pImpl->YieldCallback)
pImpl->YieldCallback(this, pImpl->YieldOpaqueHandle);
}
void LLVMContext::emitError(const Twine &ErrorStr) {
diagnose(DiagnosticInfoInlineAsm(ErrorStr));
}
void LLVMContext::emitError(const Instruction *I, const Twine &ErrorStr) {
assert (I && "Invalid instruction");
diagnose(DiagnosticInfoInlineAsm(*I, ErrorStr));
}
void LLVMContext::diagnose(const DiagnosticInfo &DI) {
// If there is a report handler, use it.
if (pImpl->DiagnosticHandler) {
pImpl->DiagnosticHandler(DI, pImpl->DiagnosticContext);
return;
}
// Optimization remarks are selective. They need to check whether the regexp
// pattern, passed via one of the -pass-remarks* flags, matches the name of
// the pass that is emitting the diagnostic. If there is no match, ignore the
// diagnostic and return.
switch (DI.getKind()) {
case llvm::DK_OptimizationRemark:
if (!cast<DiagnosticInfoOptimizationRemark>(DI).isEnabled())
return;
break;
case llvm::DK_OptimizationRemarkMissed:
if (!cast<DiagnosticInfoOptimizationRemarkMissed>(DI).isEnabled())
return;
break;
case llvm::DK_OptimizationRemarkAnalysis:
if (!cast<DiagnosticInfoOptimizationRemarkAnalysis>(DI).isEnabled())
return;
break;
default:
break;
}
// Otherwise, print the message with a prefix based on the severity.
std::string MsgStorage;
raw_string_ostream Stream(MsgStorage);
DiagnosticPrinterRawOStream DP(Stream);
DI.print(DP);
Stream.flush();
switch (DI.getSeverity()) {
case DS_Error:
errs() << "error: " << MsgStorage << "\n";
exit(1);
case DS_Warning:
errs() << "warning: " << MsgStorage << "\n";
break;
case DS_Remark:
errs() << "remark: " << MsgStorage << "\n";
break;
case DS_Note:
errs() << "note: " << MsgStorage << "\n";
break;
}
}
void LLVMContext::emitError(unsigned LocCookie, const Twine &ErrorStr) {
diagnose(DiagnosticInfoInlineAsm(LocCookie, ErrorStr));
}
//===----------------------------------------------------------------------===//
// Metadata Kind Uniquing
//===----------------------------------------------------------------------===//
#ifndef NDEBUG
/// isValidName - Return true if Name is a valid custom metadata handler name.
static bool isValidName(StringRef MDName) {
if (MDName.empty())
return false;
if (!std::isalpha(static_cast<unsigned char>(MDName[0])))
return false;
for (StringRef::iterator I = MDName.begin() + 1, E = MDName.end(); I != E;
++I) {
if (!std::isalnum(static_cast<unsigned char>(*I)) && *I != '_' &&
*I != '-' && *I != '.')
return false;
}
return true;
}
#endif
/// getMDKindID - Return a unique non-zero ID for the specified metadata kind.
unsigned LLVMContext::getMDKindID(StringRef Name) const {
assert(isValidName(Name) && "Invalid MDNode name");
// If this is new, assign it its ID.
return
pImpl->CustomMDKindNames.GetOrCreateValue(
Name, pImpl->CustomMDKindNames.size()).second;
}
/// getHandlerNames - Populate client supplied smallvector using custome
/// metadata name and ID.
void LLVMContext::getMDKindNames(SmallVectorImpl<StringRef> &Names) const {
Names.resize(pImpl->CustomMDKindNames.size());
for (StringMap<unsigned>::const_iterator I = pImpl->CustomMDKindNames.begin(),
E = pImpl->CustomMDKindNames.end(); I != E; ++I)
Names[I->second] = I->first();
}