#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/LoopPass.h"
#include "llvm/Analysis/ScalarEvolutionExpressions.h"
-#include "llvm/Support/CommandLine.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Assembly/Writer.h"
#include "llvm/ADT/STLExtras.h"
INITIALIZE_PASS_END(IVUsers, "iv-users",
"Induction Variable Users", false, true)
-// IVUsers behavior currently depends on this temporary indvars mode. The
-// option must be defined upstream from its uses.
-namespace llvm {
- bool DisableIVRewrite = false;
-}
-cl::opt<bool, true> DisableIVRewriteOpt(
- "disable-iv-rewrite", cl::Hidden, cl::location(llvm::DisableIVRewrite),
- cl::desc("Disable canonical induction variable rewriting"));
-
Pass *llvm::createIVUsersPass() {
return new IVUsers();
}
/// used by the given expression, within the context of analyzing the
/// given loop.
static bool isInteresting(const SCEV *S, const Instruction *I, const Loop *L,
- ScalarEvolution *SE) {
+ ScalarEvolution *SE, LoopInfo *LI) {
// An addrec is interesting if it's affine or if it has an interesting start.
if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
- // Keep things simple. Don't touch loop-variant strides.
+ // Keep things simple. Don't touch loop-variant strides unless they're
+ // only used outside the loop and we can simplify them.
if (AR->getLoop() == L)
- return AR->isAffine() || !L->contains(I);
+ return AR->isAffine() ||
+ (!L->contains(I) &&
+ SE->getSCEVAtScope(AR, LI->getLoopFor(I->getParent())) != AR);
// Otherwise recurse to see if the start value is interesting, and that
// the step value is not interesting, since we don't yet know how to
// do effective SCEV expansions for addrecs with interesting steps.
- return isInteresting(AR->getStart(), I, L, SE) &&
- !isInteresting(AR->getStepRecurrence(*SE), I, L, SE);
+ return isInteresting(AR->getStart(), I, L, SE, LI) &&
+ !isInteresting(AR->getStepRecurrence(*SE), I, L, SE, LI);
}
// An add is interesting if exactly one of its operands is interesting.
bool AnyInterestingYet = false;
for (SCEVAddExpr::op_iterator OI = Add->op_begin(), OE = Add->op_end();
OI != OE; ++OI)
- if (isInteresting(*OI, I, L, SE)) {
+ if (isInteresting(*OI, I, L, SE, LI)) {
if (AnyInterestingYet)
return false;
AnyInterestingYet = true;
/// AddUsersIfInteresting - Inspect the specified instruction. If it is a
/// reducible SCEV, recursively add its users to the IVUsesByStride set and
/// return true. Otherwise, return false.
-bool IVUsers::AddUsersIfInteresting(Instruction *I, PHINode *Phi) {
+bool IVUsers::AddUsersIfInteresting(Instruction *I) {
if (!SE->isSCEVable(I->getType()))
return false; // Void and FP expressions cannot be reduced.
if (Width > 64 || (TD && !TD->isLegalInteger(Width)))
return false;
- // We expect Sign/Zero extension to be eliminated from the IR before analyzing
- // any downstream uses.
- if (DisableIVRewrite && (isa<SExtInst>(I) || isa<ZExtInst>(I)))
- return false;
-
if (!Processed.insert(I))
return true; // Instruction already handled.
// If we've come to an uninteresting expression, stop the traversal and
// call this a user.
- if (!isInteresting(ISE, I, L, SE))
+ if (!isInteresting(ISE, I, L, SE, LI))
return false;
SmallPtrSet<Instruction *, 4> UniqueUsers;
bool AddUserToIVUsers = false;
if (LI->getLoopFor(User->getParent()) != L) {
if (isa<PHINode>(User) || Processed.count(User) ||
- !AddUsersIfInteresting(User, Phi)) {
+ !AddUsersIfInteresting(User)) {
DEBUG(dbgs() << "FOUND USER in other loop: " << *User << '\n'
<< " OF SCEV: " << *ISE << '\n');
AddUserToIVUsers = true;
}
- } else if (Processed.count(User) ||
- !AddUsersIfInteresting(User, Phi)) {
+ } else if (Processed.count(User) || !AddUsersIfInteresting(User)) {
DEBUG(dbgs() << "FOUND USER: " << *User << '\n'
<< " OF SCEV: " << *ISE << '\n');
AddUserToIVUsers = true;
if (AddUserToIVUsers) {
// Okay, we found a user that we cannot reduce.
- IVUses.push_back(new IVStrideUse(this, User, I, Phi));
+ IVUses.push_back(new IVStrideUse(this, User, I));
IVStrideUse &NewUse = IVUses.back();
- // Transform the expression into a normalized form.
+ // Autodetect the post-inc loop set, populating NewUse.PostIncLoops.
+ // The regular return value here is discarded; instead of recording
+ // it, we just recompute it when we need it.
ISE = TransformForPostIncUse(NormalizeAutodetect,
ISE, User, I,
NewUse.PostIncLoops,
return true;
}
-IVStrideUse &IVUsers::AddUser(Instruction *User, Value *Operand, PHINode *Phi) {
- IVUses.push_back(new IVStrideUse(this, User, Operand, Phi));
+IVStrideUse &IVUsers::AddUser(Instruction *User, Value *Operand) {
+ IVUses.push_back(new IVStrideUse(this, User, Operand));
return IVUses.back();
}
// them by stride. Start by finding all of the PHI nodes in the header for
// this loop. If they are induction variables, inspect their uses.
for (BasicBlock::iterator I = L->getHeader()->begin(); isa<PHINode>(I); ++I)
- (void)AddUsersIfInteresting(I, cast<PHINode>(I));
+ (void)AddUsersIfInteresting(I);
return false;
}