It's not necessary to do rounding for alloca operations when the requested
alignment is equal to the stack alignment.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40004 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ScalarEvolutionExpander.cpp b/lib/Analysis/ScalarEvolutionExpander.cpp
new file mode 100644
index 0000000..3e590d6
--- /dev/null
+++ b/lib/Analysis/ScalarEvolutionExpander.cpp
@@ -0,0 +1,209 @@
+//===- ScalarEvolutionExpander.cpp - Scalar Evolution Analysis --*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains the implementation of the scalar evolution expander,
+// which is used to generate the code corresponding to a given scalar evolution
+// expression.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Analysis/ScalarEvolutionExpander.h"
+#include "llvm/Analysis/LoopInfo.h"
+using namespace llvm;
+
+/// InsertCastOfTo - Insert a cast of V to the specified type, doing what
+/// we can to share the casts.
+Value *SCEVExpander::InsertCastOfTo(Instruction::CastOps opcode, Value *V,
+ const Type *Ty) {
+ // FIXME: keep track of the cast instruction.
+ if (Constant *C = dyn_cast<Constant>(V))
+ return ConstantExpr::getCast(opcode, C, Ty);
+
+ if (Argument *A = dyn_cast<Argument>(V)) {
+ // Check to see if there is already a cast!
+ for (Value::use_iterator UI = A->use_begin(), E = A->use_end();
+ UI != E; ++UI) {
+ if ((*UI)->getType() == Ty)
+ if (CastInst *CI = dyn_cast<CastInst>(cast<Instruction>(*UI))) {
+ // If the cast isn't the first instruction of the function, move it.
+ if (BasicBlock::iterator(CI) !=
+ A->getParent()->getEntryBlock().begin()) {
+ CI->moveBefore(A->getParent()->getEntryBlock().begin());
+ }
+ return CI;
+ }
+ }
+ return CastInst::create(opcode, V, Ty, V->getName(),
+ A->getParent()->getEntryBlock().begin());
+ }
+
+ Instruction *I = cast<Instruction>(V);
+
+ // Check to see if there is already a cast. If there is, use it.
+ for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
+ UI != E; ++UI) {
+ if ((*UI)->getType() == Ty)
+ if (CastInst *CI = dyn_cast<CastInst>(cast<Instruction>(*UI))) {
+ BasicBlock::iterator It = I; ++It;
+ if (isa<InvokeInst>(I))
+ It = cast<InvokeInst>(I)->getNormalDest()->begin();
+ while (isa<PHINode>(It)) ++It;
+ if (It != BasicBlock::iterator(CI)) {
+ // Splice the cast immediately after the operand in question.
+ CI->moveBefore(It);
+ }
+ return CI;
+ }
+ }
+ BasicBlock::iterator IP = I; ++IP;
+ if (InvokeInst *II = dyn_cast<InvokeInst>(I))
+ IP = II->getNormalDest()->begin();
+ while (isa<PHINode>(IP)) ++IP;
+ return CastInst::create(opcode, V, Ty, V->getName(), IP);
+}
+
+/// InsertBinop - Insert the specified binary operator, doing a small amount
+/// of work to avoid inserting an obviously redundant operation.
+Value *SCEVExpander::InsertBinop(Instruction::BinaryOps Opcode, Value *LHS,
+ Value *RHS, Instruction *&InsertPt) {
+ // Fold a binop with constant operands.
+ if (Constant *CLHS = dyn_cast<Constant>(LHS))
+ if (Constant *CRHS = dyn_cast<Constant>(RHS))
+ return ConstantExpr::get(Opcode, CLHS, CRHS);
+
+ // Do a quick scan to see if we have this binop nearby. If so, reuse it.
+ unsigned ScanLimit = 6;
+ for (BasicBlock::iterator IP = InsertPt, E = InsertPt->getParent()->begin();
+ ScanLimit; --IP, --ScanLimit) {
+ if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(IP))
+ if (BinOp->getOpcode() == Opcode && BinOp->getOperand(0) == LHS &&
+ BinOp->getOperand(1) == RHS) {
+ // If we found the instruction *at* the insert point, insert later
+ // instructions after it.
+ if (BinOp == InsertPt)
+ InsertPt = ++IP;
+ return BinOp;
+ }
+ if (IP == E) break;
+ }
+
+ // If we don't have
+ return BinaryOperator::create(Opcode, LHS, RHS, "tmp.", InsertPt);
+}
+
+Value *SCEVExpander::visitMulExpr(SCEVMulExpr *S) {
+ int FirstOp = 0; // Set if we should emit a subtract.
+ if (SCEVConstant *SC = dyn_cast<SCEVConstant>(S->getOperand(0)))
+ if (SC->getValue()->isAllOnesValue())
+ FirstOp = 1;
+
+ int i = S->getNumOperands()-2;
+ Value *V = expand(S->getOperand(i+1));
+
+ // Emit a bunch of multiply instructions
+ for (; i >= FirstOp; --i)
+ V = InsertBinop(Instruction::Mul, V, expand(S->getOperand(i)),
+ InsertPt);
+ // -1 * ... ---> 0 - ...
+ if (FirstOp == 1)
+ V = InsertBinop(Instruction::Sub, Constant::getNullValue(V->getType()), V,
+ InsertPt);
+ return V;
+}
+
+Value *SCEVExpander::visitAddRecExpr(SCEVAddRecExpr *S) {
+ const Type *Ty = S->getType();
+ const Loop *L = S->getLoop();
+ // We cannot yet do fp recurrences, e.g. the xform of {X,+,F} --> X+{0,+,F}
+ assert(Ty->isInteger() && "Cannot expand fp recurrences yet!");
+
+ // {X,+,F} --> X + {0,+,F}
+ if (!isa<SCEVConstant>(S->getStart()) ||
+ !cast<SCEVConstant>(S->getStart())->getValue()->isZero()) {
+ Value *Start = expand(S->getStart());
+ std::vector<SCEVHandle> NewOps(S->op_begin(), S->op_end());
+ NewOps[0] = SCEVUnknown::getIntegerSCEV(0, Ty);
+ Value *Rest = expand(SCEVAddRecExpr::get(NewOps, L));
+
+ // FIXME: look for an existing add to use.
+ return InsertBinop(Instruction::Add, Rest, Start, InsertPt);
+ }
+
+ // {0,+,1} --> Insert a canonical induction variable into the loop!
+ if (S->getNumOperands() == 2 &&
+ S->getOperand(1) == SCEVUnknown::getIntegerSCEV(1, Ty)) {
+ // Create and insert the PHI node for the induction variable in the
+ // specified loop.
+ BasicBlock *Header = L->getHeader();
+ PHINode *PN = new PHINode(Ty, "indvar", Header->begin());
+ PN->addIncoming(Constant::getNullValue(Ty), L->getLoopPreheader());
+
+ pred_iterator HPI = pred_begin(Header);
+ assert(HPI != pred_end(Header) && "Loop with zero preds???");
+ if (!L->contains(*HPI)) ++HPI;
+ assert(HPI != pred_end(Header) && L->contains(*HPI) &&
+ "No backedge in loop?");
+
+ // Insert a unit add instruction right before the terminator corresponding
+ // to the back-edge.
+ Constant *One = ConstantInt::get(Ty, 1);
+ Instruction *Add = BinaryOperator::createAdd(PN, One, "indvar.next",
+ (*HPI)->getTerminator());
+
+ pred_iterator PI = pred_begin(Header);
+ if (*PI == L->getLoopPreheader())
+ ++PI;
+ PN->addIncoming(Add, *PI);
+ return PN;
+ }
+
+ // Get the canonical induction variable I for this loop.
+ Value *I = getOrInsertCanonicalInductionVariable(L, Ty);
+
+ // If this is a simple linear addrec, emit it now as a special case.
+ if (S->getNumOperands() == 2) { // {0,+,F} --> i*F
+ Value *F = expand(S->getOperand(1));
+
+ // IF the step is by one, just return the inserted IV.
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(F))
+ if (CI->getValue() == 1)
+ return I;
+
+ // If the insert point is directly inside of the loop, emit the multiply at
+ // the insert point. Otherwise, L is a loop that is a parent of the insert
+ // point loop. If we can, move the multiply to the outer most loop that it
+ // is safe to be in.
+ Instruction *MulInsertPt = InsertPt;
+ Loop *InsertPtLoop = LI.getLoopFor(MulInsertPt->getParent());
+ if (InsertPtLoop != L && InsertPtLoop &&
+ L->contains(InsertPtLoop->getHeader())) {
+ while (InsertPtLoop != L) {
+ // If we cannot hoist the multiply out of this loop, don't.
+ if (!InsertPtLoop->isLoopInvariant(F)) break;
+
+ // Otherwise, move the insert point to the preheader of the loop.
+ MulInsertPt = InsertPtLoop->getLoopPreheader()->getTerminator();
+ InsertPtLoop = InsertPtLoop->getParentLoop();
+ }
+ }
+
+ return InsertBinop(Instruction::Mul, I, F, MulInsertPt);
+ }
+
+ // If this is a chain of recurrences, turn it into a closed form, using the
+ // folders, then expandCodeFor the closed form. This allows the folders to
+ // simplify the expression without having to build a bunch of special code
+ // into this folder.
+ SCEVHandle IH = SCEVUnknown::get(I); // Get I as a "symbolic" SCEV.
+
+ SCEVHandle V = S->evaluateAtIteration(IH);
+ //cerr << "Evaluated: " << *this << "\n to: " << *V << "\n";
+
+ return expand(V);
+}