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llvm-mirror/lib/Analysis/PtrUseVisitor.cpp
Matt Arsenault 731346ec27 SROA: Allow eliminating addrspacecasted allocas
There is a circular dependency between SROA and InferAddressSpaces
today that requires running both multiple times in order to be able to
eliminate all simple allocas and addrspacecasts. InferAddressSpaces
can't remove addrspacecasts when written to memory, and SROA helps
move pointers out of memory.

This should avoid inserting new commuting addrspacecasts with GEPs,
since there are unresolved questions about pointer wrapping between
different address spaces.

For now, don't replace volatile operations that don't match the alloca
addrspace, as it would change the address space of the access. It may
be still OK to insert an addrspacecast from the new alloca, but be
more conservative for now.

llvm-svn: 363462
2019-06-14 21:38:31 +00:00

45 lines
1.3 KiB
C++

//===- PtrUseVisitor.cpp - InstVisitors over a pointers uses --------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
/// \file
/// Implementation of the pointer use visitors.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/PtrUseVisitor.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include <algorithm>
using namespace llvm;
void detail::PtrUseVisitorBase::enqueueUsers(Instruction &I) {
for (Use &U : I.uses()) {
if (VisitedUses.insert(&U).second) {
UseToVisit NewU = {
UseToVisit::UseAndIsOffsetKnownPair(&U, IsOffsetKnown),
Offset
};
Worklist.push_back(std::move(NewU));
}
}
}
bool detail::PtrUseVisitorBase::adjustOffsetForGEP(GetElementPtrInst &GEPI) {
if (!IsOffsetKnown)
return false;
APInt TmpOffset(DL.getIndexTypeSizeInBits(GEPI.getType()), 0);
if (GEPI.accumulateConstantOffset(DL, TmpOffset)) {
Offset += TmpOffset.sextOrTrunc(Offset.getBitWidth());
return true;
}
return false;
}