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[IndVars] Remove -liv-reduce
It is an off-by-default option that no one seems to use[0], and given that SCEV directly understands the overflow instrinsics there is no real need for it anymore. [0]: http://lists.llvm.org/pipermail/llvm-dev/2016-April/098181.html llvm-svn: 271845
This commit is contained in:
Sanjoy Das
parent
1709e61793
commit
8562f7e8b8
@ -33,24 +33,14 @@ class ScalarEvolution;
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class IVVisitor {
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protected:
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const DominatorTree *DT;
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bool ShouldSplitOverflowIntrinsics;
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virtual void anchor();
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public:
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IVVisitor(): DT(nullptr), ShouldSplitOverflowIntrinsics(false) {}
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IVVisitor() : DT(nullptr) {}
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virtual ~IVVisitor() {}
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const DominatorTree *getDomTree() const { return DT; }
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bool shouldSplitOverflowInstrinsics() const {
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return ShouldSplitOverflowIntrinsics;
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}
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void setSplitOverflowIntrinsics() {
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ShouldSplitOverflowIntrinsics = true;
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assert(DT && "Splitting overflow intrinsics requires a DomTree.");
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}
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virtual void visitCast(CastInst *Cast) = 0;
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};
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@ -68,9 +68,6 @@ static cl::opt<bool> VerifyIndvars(
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"verify-indvars", cl::Hidden,
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cl::desc("Verify the ScalarEvolution result after running indvars"));
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static cl::opt<bool> ReduceLiveIVs("liv-reduce", cl::Hidden,
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cl::desc("Reduce live induction variables."));
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enum ReplaceExitVal { NeverRepl, OnlyCheapRepl, AlwaysRepl };
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static cl::opt<ReplaceExitVal> ReplaceExitValue(
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@ -1489,8 +1486,6 @@ public:
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: SE(SCEV), TTI(TTI), IVPhi(IV) {
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DT = DTree;
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WI.NarrowIV = IVPhi;
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if (ReduceLiveIVs)
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setSplitOverflowIntrinsics();
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}
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// Implement the interface used by simplifyUsersOfIV.
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@ -76,9 +76,6 @@ namespace {
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void eliminateIVRemainder(BinaryOperator *Rem, Value *IVOperand,
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bool IsSigned);
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bool strengthenOverflowingOperation(BinaryOperator *OBO, Value *IVOperand);
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Instruction *splitOverflowIntrinsic(Instruction *IVUser,
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const DominatorTree *DT);
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};
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}
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@ -552,69 +549,6 @@ bool SimplifyIndvar::strengthenOverflowingOperation(BinaryOperator *BO,
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return Changed;
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}
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/// \brief Split sadd.with.overflow into add + sadd.with.overflow to allow
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/// analysis and optimization.
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///
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/// \return A new value representing the non-overflowing add if possible,
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/// otherwise return the original value.
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Instruction *SimplifyIndvar::splitOverflowIntrinsic(Instruction *IVUser,
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const DominatorTree *DT) {
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IntrinsicInst *II = dyn_cast<IntrinsicInst>(IVUser);
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if (!II || II->getIntrinsicID() != Intrinsic::sadd_with_overflow)
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return IVUser;
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// Find a branch guarded by the overflow check.
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BranchInst *Branch = nullptr;
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Instruction *AddVal = nullptr;
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for (User *U : II->users()) {
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if (ExtractValueInst *ExtractInst = dyn_cast<ExtractValueInst>(U)) {
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if (ExtractInst->getNumIndices() != 1)
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continue;
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if (ExtractInst->getIndices()[0] == 0)
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AddVal = ExtractInst;
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else if (ExtractInst->getIndices()[0] == 1 && ExtractInst->hasOneUse())
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Branch = dyn_cast<BranchInst>(ExtractInst->user_back());
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}
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}
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if (!AddVal || !Branch)
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return IVUser;
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BasicBlock *ContinueBB = Branch->getSuccessor(1);
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if (std::next(pred_begin(ContinueBB)) != pred_end(ContinueBB))
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return IVUser;
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// Check if all users of the add are provably NSW.
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bool AllNSW = true;
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for (Use &U : AddVal->uses()) {
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if (Instruction *UseInst = dyn_cast<Instruction>(U.getUser())) {
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BasicBlock *UseBB = UseInst->getParent();
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if (PHINode *PHI = dyn_cast<PHINode>(UseInst))
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UseBB = PHI->getIncomingBlock(U);
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if (!DT->dominates(ContinueBB, UseBB)) {
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AllNSW = false;
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break;
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}
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}
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}
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if (!AllNSW)
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return IVUser;
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// Go for it...
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IRBuilder<> Builder(IVUser);
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Instruction *AddInst = dyn_cast<Instruction>(
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Builder.CreateNSWAdd(II->getOperand(0), II->getOperand(1)));
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// The caller expects the new add to have the same form as the intrinsic. The
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// IV operand position must be the same.
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assert((AddInst->getOpcode() == Instruction::Add &&
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AddInst->getOperand(0) == II->getOperand(0)) &&
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"Bad add instruction created from overflow intrinsic.");
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AddVal->replaceAllUsesWith(AddInst);
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DeadInsts.emplace_back(AddVal);
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return AddInst;
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}
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/// Add all uses of Def to the current IV's worklist.
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static void pushIVUsers(
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Instruction *Def,
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@ -689,12 +623,6 @@ void SimplifyIndvar::simplifyUsers(PHINode *CurrIV, IVVisitor *V) {
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// Bypass back edges to avoid extra work.
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if (UseInst == CurrIV) continue;
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if (V && V->shouldSplitOverflowInstrinsics()) {
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UseInst = splitOverflowIntrinsic(UseInst, V->getDomTree());
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if (!UseInst)
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continue;
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}
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Instruction *IVOperand = UseOper.second;
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for (unsigned N = 0; IVOperand; ++N) {
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assert(N <= Simplified.size() && "runaway iteration");
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@ -1,56 +0,0 @@
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; RUN: opt < %s -indvars -liv-reduce -S | FileCheck %s
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target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
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target triple = "x86_64-apple-macosx"
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; CHECK-LABEL: @addwithoverflow
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; CHECK-LABEL: loop1:
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; CHECK-NOT: zext
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; CHECK: add nsw
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; CHECK: @llvm.sadd.with.overflow
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; CHECK-LABEL: loop2:
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; CHECK-NOT: extractvalue
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; CHECK: add nuw
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; CHECK: @llvm.sadd.with.overflow
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; CHECK-LABEL: loop3:
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; CHECK-NOT: extractvalue
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; CHECK: ret
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define i64 @addwithoverflow(i32 %n, i64* %a) {
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entry:
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br label %loop0
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loop0:
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%i = phi i32 [ 0, %entry ], [ %i1val, %loop3 ]
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%s = phi i32 [ 0, %entry ], [ %addsval, %loop3 ]
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%bc = icmp ult i32 %i, %n
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br i1 %bc, label %loop1, label %exit
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loop1:
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%zxt = zext i32 %i to i64
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%ofs = shl nuw nsw i64 %zxt, 3
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%gep = getelementptr i64, i64* %a, i64 %zxt
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%v = load i64, i64* %gep, align 8
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%truncv = trunc i64 %v to i32
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%adds = call { i32, i1 } @llvm.sadd.with.overflow.i32(i32 %s, i32 %truncv)
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%ovflows = extractvalue { i32, i1 } %adds, 1
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br i1 %ovflows, label %exit, label %loop2
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loop2:
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%addsval = extractvalue { i32, i1 } %adds, 0
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%i1 = call { i32, i1 } @llvm.sadd.with.overflow.i32(i32 %i, i32 1)
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%i1check = extractvalue { i32, i1 } %i1, 1
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br i1 %i1check, label %exit, label %loop3
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loop3:
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%i1val = extractvalue { i32, i1 } %i1, 0
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%test = icmp slt i32 %i1val, %n
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br i1 %test, label %return, label %loop0
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return:
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%ret = zext i32 %addsval to i64
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ret i64 %ret
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exit:
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unreachable
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}
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declare { i32, i1 } @llvm.sadd.with.overflow.i32(i32, i32)
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