mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2025-11-04 05:17:07 +00:00
36b699f2b1
This requires a number of steps. 1) Move value_use_iterator into the Value class as an implementation detail 2) Change it to actually be a *Use* iterator rather than a *User* iterator. 3) Add an adaptor which is a User iterator that always looks through the Use to the User. 4) Wrap these in Value::use_iterator and Value::user_iterator typedefs. 5) Add the range adaptors as Value::uses() and Value::users(). 6) Update *all* of the callers to correctly distinguish between whether they wanted a use_iterator (and to explicitly dig out the User when needed), or a user_iterator which makes the Use itself totally opaque. Because #6 requires churning essentially everything that walked the Use-Def chains, I went ahead and added all of the range adaptors and switched them to range-based loops where appropriate. Also because the renaming requires at least churning every line of code, it didn't make any sense to split these up into multiple commits -- all of which would touch all of the same lies of code. The result is still not quite optimal. The Value::use_iterator is a nice regular iterator, but Value::user_iterator is an iterator over User*s rather than over the User objects themselves. As a consequence, it fits a bit awkwardly into the range-based world and it has the weird extra-dereferencing 'operator->' that so many of our iterators have. I think this could be fixed by providing something which transforms a range of T&s into a range of T*s, but that *can* be separated into another patch, and it isn't yet 100% clear whether this is the right move. However, this change gets us most of the benefit and cleans up a substantial amount of code around Use and User. =] git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203364 91177308-0d34-0410-b5e6-96231b3b80d8
103 lines
4.1 KiB
C++
103 lines
4.1 KiB
C++
//===------ SimplifyInstructions.cpp - Remove redundant instructions ------===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This is a utility pass used for testing the InstructionSimplify analysis.
|
|
// The analysis is applied to every instruction, and if it simplifies then the
|
|
// instruction is replaced by the simplification. If you are looking for a pass
|
|
// that performs serious instruction folding, use the instcombine pass instead.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#define DEBUG_TYPE "instsimplify"
|
|
#include "llvm/Transforms/Scalar.h"
|
|
#include "llvm/ADT/DepthFirstIterator.h"
|
|
#include "llvm/ADT/SmallPtrSet.h"
|
|
#include "llvm/ADT/Statistic.h"
|
|
#include "llvm/Analysis/InstructionSimplify.h"
|
|
#include "llvm/IR/DataLayout.h"
|
|
#include "llvm/IR/Dominators.h"
|
|
#include "llvm/IR/Function.h"
|
|
#include "llvm/IR/Type.h"
|
|
#include "llvm/Pass.h"
|
|
#include "llvm/Target/TargetLibraryInfo.h"
|
|
#include "llvm/Transforms/Utils/Local.h"
|
|
using namespace llvm;
|
|
|
|
STATISTIC(NumSimplified, "Number of redundant instructions removed");
|
|
|
|
namespace {
|
|
struct InstSimplifier : public FunctionPass {
|
|
static char ID; // Pass identification, replacement for typeid
|
|
InstSimplifier() : FunctionPass(ID) {
|
|
initializeInstSimplifierPass(*PassRegistry::getPassRegistry());
|
|
}
|
|
|
|
void getAnalysisUsage(AnalysisUsage &AU) const override {
|
|
AU.setPreservesCFG();
|
|
AU.addRequired<TargetLibraryInfo>();
|
|
}
|
|
|
|
/// runOnFunction - Remove instructions that simplify.
|
|
bool runOnFunction(Function &F) override {
|
|
const DominatorTreeWrapperPass *DTWP =
|
|
getAnalysisIfAvailable<DominatorTreeWrapperPass>();
|
|
const DominatorTree *DT = DTWP ? &DTWP->getDomTree() : 0;
|
|
DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
|
|
const DataLayout *DL = DLP ? &DLP->getDataLayout() : 0;
|
|
const TargetLibraryInfo *TLI = &getAnalysis<TargetLibraryInfo>();
|
|
SmallPtrSet<const Instruction*, 8> S1, S2, *ToSimplify = &S1, *Next = &S2;
|
|
bool Changed = false;
|
|
|
|
do {
|
|
for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
|
|
DE = df_end(&F.getEntryBlock()); DI != DE; ++DI)
|
|
for (BasicBlock::iterator BI = DI->begin(), BE = DI->end(); BI != BE;) {
|
|
Instruction *I = BI++;
|
|
// The first time through the loop ToSimplify is empty and we try to
|
|
// simplify all instructions. On later iterations ToSimplify is not
|
|
// empty and we only bother simplifying instructions that are in it.
|
|
if (!ToSimplify->empty() && !ToSimplify->count(I))
|
|
continue;
|
|
// Don't waste time simplifying unused instructions.
|
|
if (!I->use_empty())
|
|
if (Value *V = SimplifyInstruction(I, DL, TLI, DT)) {
|
|
// Mark all uses for resimplification next time round the loop.
|
|
for (User *U : I->users())
|
|
Next->insert(cast<Instruction>(U));
|
|
I->replaceAllUsesWith(V);
|
|
++NumSimplified;
|
|
Changed = true;
|
|
}
|
|
Changed |= RecursivelyDeleteTriviallyDeadInstructions(I, TLI);
|
|
}
|
|
|
|
// Place the list of instructions to simplify on the next loop iteration
|
|
// into ToSimplify.
|
|
std::swap(ToSimplify, Next);
|
|
Next->clear();
|
|
} while (!ToSimplify->empty());
|
|
|
|
return Changed;
|
|
}
|
|
};
|
|
}
|
|
|
|
char InstSimplifier::ID = 0;
|
|
INITIALIZE_PASS_BEGIN(InstSimplifier, "instsimplify",
|
|
"Remove redundant instructions", false, false)
|
|
INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo)
|
|
INITIALIZE_PASS_END(InstSimplifier, "instsimplify",
|
|
"Remove redundant instructions", false, false)
|
|
char &llvm::InstructionSimplifierID = InstSimplifier::ID;
|
|
|
|
// Public interface to the simplify instructions pass.
|
|
FunctionPass *llvm::createInstructionSimplifierPass() {
|
|
return new InstSimplifier();
|
|
}
|