From a0348809b63def1733af55fd1a9af6bf2540d83f Mon Sep 17 00:00:00 2001 From: Dan Gohman Date: Thu, 18 Jun 2009 16:54:06 +0000 Subject: [PATCH] Remove the code from IVUsers that attempted to handle casted induction variables in cases where the cast isn't foldable. It ended up being a pessimization in many cases. This could be fixed, but it would require a bunch of complicated code in IVUsers' clients. The advantages of this approach aren't visible enough to justify it at this time. llvm-svn: 73706 --- llvm/include/llvm/Analysis/IVUsers.h | 23 ++++---------- llvm/lib/Analysis/IVUsers.cpp | 30 ++----------------- .../Transforms/Scalar/LoopStrengthReduce.cpp | 18 ++--------- .../CodeGen/X86/iv-users-in-other-loops.ll | 10 +++---- .../Transforms/IndVarSimplify/masked-iv.ll | 4 ++- .../IndVarSimplify/shrunk-constant.ll | 3 +- 6 files changed, 20 insertions(+), 68 deletions(-) diff --git a/llvm/include/llvm/Analysis/IVUsers.h b/llvm/include/llvm/Analysis/IVUsers.h index 36ff07b678e6..ac785d5c54a9 100644 --- a/llvm/include/llvm/Analysis/IVUsers.h +++ b/llvm/include/llvm/Analysis/IVUsers.h @@ -35,9 +35,9 @@ class IVStrideUse : public CallbackVH, public ilist_node { public: IVStrideUse(IVUsersOfOneStride *parent, const SCEVHandle &offset, - Instruction* U, Value *O, bool issigned) + Instruction* U, Value *O) : CallbackVH(U), Parent(parent), Offset(offset), - OperandValToReplace(O), IsSigned(issigned), + OperandValToReplace(O), IsUseOfPostIncrementedValue(false) { } @@ -57,8 +57,7 @@ public: /// getOffset - Return the offset to add to a theoeretical induction /// variable that starts at zero and counts up by the stride to compute - /// the value for the use. This always has the same type as the stride, - /// which may need to be casted to match the type of the use. + /// the value for the use. This always has the same type as the stride. SCEVHandle getOffset() const { return Offset; } /// setOffset - Assign a new offset to this use. @@ -78,13 +77,6 @@ public: OperandValToReplace = Op; } - /// isSigned - The stride (and thus also the Offset) of this use may be in - /// a narrower type than the use itself (OperandValToReplace->getType()). - /// When this is the case, isSigned() indicates whether the IV expression - /// should be signed-extended instead of zero-extended to fit the type of - /// the use. - bool isSigned() const { return IsSigned; } - /// isUseOfPostIncrementedValue - True if this should use the /// post-incremented version of this IV, not the preincremented version. /// This can only be set in special cases, such as the terminating setcc @@ -110,10 +102,6 @@ private: /// that this IVStrideUse is representing. WeakVH OperandValToReplace; - /// IsSigned - Determines whether the replacement value is sign or - /// zero extended to the type of the use. - bool IsSigned; - /// IsUseOfPostIncrementedValue - True if this should use the /// post-incremented version of this IV, not the preincremented version. bool IsUseOfPostIncrementedValue; @@ -170,9 +158,8 @@ public: /// initial value and the operand that uses the IV. ilist Users; - void addUser(const SCEVHandle &Offset,Instruction *User, Value *Operand, - bool isSigned) { - Users.push_back(new IVStrideUse(this, Offset, User, Operand, isSigned)); + void addUser(const SCEVHandle &Offset, Instruction *User, Value *Operand) { + Users.push_back(new IVStrideUse(this, Offset, User, Operand)); } }; diff --git a/llvm/lib/Analysis/IVUsers.cpp b/llvm/lib/Analysis/IVUsers.cpp index 4f77641151f7..0bacc3944365 100644 --- a/llvm/lib/Analysis/IVUsers.cpp +++ b/llvm/lib/Analysis/IVUsers.cpp @@ -82,11 +82,8 @@ static bool containsAddRecFromDifferentLoop(SCEVHandle S, Loop *L) { /// outer loop of the current loop. static bool getSCEVStartAndStride(const SCEVHandle &SH, Loop *L, Loop *UseLoop, SCEVHandle &Start, SCEVHandle &Stride, - bool &isSigned, ScalarEvolution *SE, DominatorTree *DT) { SCEVHandle TheAddRec = Start; // Initialize to zero. - bool isSExt = false; - bool isZExt = false; // If the outer level is an AddExpr, the operands are all start values except // for a nested AddRecExpr. @@ -101,13 +98,6 @@ static bool getSCEVStartAndStride(const SCEVHandle &SH, Loop *L, Loop *UseLoop, } else { Start = SE->getAddExpr(Start, AE->getOperand(i)); } - - } else if (const SCEVZeroExtendExpr *Z = dyn_cast(SH)) { - TheAddRec = Z->getOperand(); - isZExt = true; - } else if (const SCEVSignExtendExpr *S = dyn_cast(SH)) { - TheAddRec = S->getOperand(); - isSExt = true; } else if (isa(SH)) { TheAddRec = SH; } else { @@ -131,9 +121,6 @@ static bool getSCEVStartAndStride(const SCEVHandle &SH, Loop *L, Loop *UseLoop, if (containsAddRecFromDifferentLoop(AddRecStart, L)) return false; - if (isSExt || isZExt) - Start = SE->getTruncateExpr(Start, AddRec->getType()); - Start = SE->getAddExpr(Start, AddRecStart); // If stride is an instruction, make sure it dominates the loop preheader. @@ -148,7 +135,6 @@ static bool getSCEVStartAndStride(const SCEVHandle &SH, Loop *L, Loop *UseLoop, } Stride = AddRecStride; - isSigned = isSExt; return true; } @@ -218,9 +204,8 @@ bool IVUsers::AddUsersIfInteresting(Instruction *I) { Loop *UseLoop = LI->getLoopFor(I->getParent()); SCEVHandle Start = SE->getIntegerSCEV(0, ISE->getType()); SCEVHandle Stride = Start; - bool isSigned = false; // Arbitrary initial value - pacifies compiler. - if (!getSCEVStartAndStride(ISE, L, UseLoop, Start, Stride, isSigned, SE, DT)) + if (!getSCEVStartAndStride(ISE, L, UseLoop, Start, Stride, SE, DT)) return false; // Non-reducible symbolic expression, bail out. SmallPtrSet UniqueUsers; @@ -271,11 +256,11 @@ bool IVUsers::AddUsersIfInteresting(Instruction *I) { // The value used will be incremented by the stride more than we are // expecting, so subtract this off. SCEVHandle NewStart = SE->getMinusSCEV(Start, Stride); - StrideUses->addUser(NewStart, User, I, isSigned); + StrideUses->addUser(NewStart, User, I); StrideUses->Users.back().setIsUseOfPostIncrementedValue(true); DOUT << " USING POSTINC SCEV, START=" << *NewStart<< "\n"; } else { - StrideUses->addUser(Start, User, I, isSigned); + StrideUses->addUser(Start, User, I); } } } @@ -312,7 +297,6 @@ bool IVUsers::runOnLoop(Loop *l, LPPassManager &LPM) { /// getReplacementExpr - Return a SCEV expression which computes the /// value of the OperandValToReplace of the given IVStrideUse. SCEVHandle IVUsers::getReplacementExpr(const IVStrideUse &U) const { - const Type *UseTy = U.getOperandValToReplace()->getType(); // Start with zero. SCEVHandle RetVal = SE->getIntegerSCEV(0, U.getParent()->Stride->getType()); // Create the basic add recurrence. @@ -329,14 +313,6 @@ SCEVHandle IVUsers::getReplacementExpr(const IVStrideUse &U) const { if (ExitVal->isLoopInvariant(L)) RetVal = ExitVal; } - // Promote the result to the type of the use. - if (SE->getTypeSizeInBits(RetVal->getType()) != - SE->getTypeSizeInBits(UseTy)) { - if (U.isSigned()) - RetVal = SE->getSignExtendExpr(RetVal, UseTy); - else - RetVal = SE->getZeroExtendExpr(RetVal, UseTy); - } return RetVal; } diff --git a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp index 894eb4a1673b..03966672d623 100644 --- a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp +++ b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp @@ -336,13 +336,6 @@ namespace { /// EmittedBase. Value *OperandValToReplace; - /// isSigned - The stride (and thus also the Base) of this use may be in - /// a narrower type than the use itself (OperandValToReplace->getType()). - /// When this is the case, the isSigned field indicates whether the - /// IV expression should be signed-extended instead of zero-extended to - /// fit the type of the use. - bool isSigned; - /// Imm - The immediate value that should be added to the base immediately /// before Inst, because it will be folded into the imm field of the /// instruction. This is also sometimes used for loop-variant values that @@ -363,7 +356,6 @@ namespace { BasedUser(IVStrideUse &IVSU, ScalarEvolution *se) : SE(se), Base(IVSU.getOffset()), Inst(IVSU.getUser()), OperandValToReplace(IVSU.getOperandValToReplace()), - isSigned(IVSU.isSigned()), Imm(SE->getIntegerSCEV(0, Base->getType())), isUseOfPostIncrementedValue(IVSU.isUseOfPostIncrementedValue()) {} @@ -428,11 +420,6 @@ Value *BasedUser::InsertCodeForBaseAtPosition(const SCEVHandle &NewBase, NewValSCEV = SE->getAddExpr(NewValSCEV, Imm); } - if (isSigned) - NewValSCEV = SE->getTruncateOrSignExtend(NewValSCEV, Ty); - else - NewValSCEV = SE->getTruncateOrZeroExtend(NewValSCEV, Ty); - return Rewriter.expandCodeFor(NewValSCEV, Ty, IP); } @@ -2047,7 +2034,7 @@ ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond, OldCond->replaceAllUsesWith(Cond); OldCond->eraseFromParent(); - IU->IVUsesByStride[*NewStride]->addUser(NewOffset, Cond, NewCmpLHS, false); + IU->IVUsesByStride[*NewStride]->addUser(NewOffset, Cond, NewCmpLHS); CondUse = &IU->IVUsesByStride[*NewStride]->Users.back(); CondStride = NewStride; ++NumEliminated; @@ -2397,8 +2384,7 @@ void LoopStrengthReduce::OptimizeLoopTermCond(Loop *L) { // Clone the IVUse, as the old use still exists! IU->IVUsesByStride[*CondStride]->addUser(CondUse->getOffset(), Cond, - CondUse->getOperandValToReplace(), - false); + CondUse->getOperandValToReplace()); CondUse = &IU->IVUsesByStride[*CondStride]->Users.back(); } } diff --git a/llvm/test/CodeGen/X86/iv-users-in-other-loops.ll b/llvm/test/CodeGen/X86/iv-users-in-other-loops.ll index 2208b2d2e0e3..a48f0616291f 100644 --- a/llvm/test/CodeGen/X86/iv-users-in-other-loops.ll +++ b/llvm/test/CodeGen/X86/iv-users-in-other-loops.ll @@ -1,11 +1,11 @@ ; RUN: llvm-as < %s | llc -march=x86-64 -f -o %t ; RUN: grep inc %t | count 1 ; RUN: grep dec %t | count 2 -; RUN: grep addq %t | count 8 -; RUN: grep addb %t | count 2 -; RUN: grep leaq %t | count 12 -; RUN: grep leal %t | count 2 -; RUN: grep movq %t | count 4 +; RUN: grep addq %t | count 13 +; RUN: not grep addb %t +; RUN: grep leaq %t | count 8 +; RUN: grep leal %t | count 4 +; RUN: grep movq %t | count 5 ; IV users in each of the loops from other loops shouldn't cause LSR ; to insert new induction variables. Previously it would create a diff --git a/llvm/test/Transforms/IndVarSimplify/masked-iv.ll b/llvm/test/Transforms/IndVarSimplify/masked-iv.ll index c7583c9655a8..f77b9357d75a 100644 --- a/llvm/test/Transforms/IndVarSimplify/masked-iv.ll +++ b/llvm/test/Transforms/IndVarSimplify/masked-iv.ll @@ -1,4 +1,6 @@ -; RUN: llvm-as < %s | opt -indvars | llvm-dis | grep trunc | count 1 +; RUN: llvm-as < %s | opt -indvars | llvm-dis > %t +; RUN: not grep trunc %t +; RUN: grep and %t | count 1 ; Indvars should do the IV arithmetic in the canonical IV type (i64), ; and only use one truncation. diff --git a/llvm/test/Transforms/IndVarSimplify/shrunk-constant.ll b/llvm/test/Transforms/IndVarSimplify/shrunk-constant.ll index f1caf142cfc1..0b2ecaf38d77 100644 --- a/llvm/test/Transforms/IndVarSimplify/shrunk-constant.ll +++ b/llvm/test/Transforms/IndVarSimplify/shrunk-constant.ll @@ -1,4 +1,5 @@ -; RUN: llvm-as < %s | opt -iv-users -analyze -disable-output | grep store +; RUN: llvm-as < %s | opt -scalar-evolution -analyze -disable-output \ +; RUN: | grep {\\--> (zext i4 {-7,+,-8} to i32)} define fastcc void @foo() nounwind { entry: