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-rw-r--r--llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp99
1 files changed, 82 insertions, 17 deletions
diff --git a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index d18a008fef0..2099ceace51 100644
--- a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -26,19 +26,19 @@
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/LoopPass.h"
#include "llvm/Analysis/ScalarEvolutionExpander.h"
-#include "llvm/Support/CFG.h"
-#include "llvm/Support/GetElementPtrTypeIterator.h"
+#include "llvm/Transforms/Utils/AddrModeMatcher.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Target/TargetData.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/Statistic.h"
+#include "llvm/Support/CFG.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Target/TargetLowering.h"
#include <algorithm>
-#include <set>
using namespace llvm;
STATISTIC(NumReduced , "Number of GEPs strength reduced");
@@ -46,6 +46,7 @@ STATISTIC(NumInserted, "Number of PHIs inserted");
STATISTIC(NumVariable, "Number of PHIs with variable strides");
STATISTIC(NumEliminated, "Number of strides eliminated");
STATISTIC(NumShadow, "Number of Shadow IVs optimized");
+STATISTIC(NumImmSunk, "Number of common expr immediates sunk into uses");
static cl::opt<bool> EnableFullLSRMode("enable-full-lsr",
cl::init(false),
@@ -954,21 +955,17 @@ static void MoveLoopVariantsToImmediateField(SCEVHandle &Val, SCEVHandle &Imm,
/// that can fit into the immediate field of instructions in the target.
/// Accumulate these immediate values into the Imm value.
static void MoveImmediateValues(const TargetLowering *TLI,
- Instruction *User,
+ const Type *UseTy,
SCEVHandle &Val, SCEVHandle &Imm,
bool isAddress, Loop *L,
ScalarEvolution *SE) {
- const Type *UseTy = User->getType();
- if (StoreInst *SI = dyn_cast<StoreInst>(User))
- UseTy = SI->getOperand(0)->getType();
-
if (SCEVAddExpr *SAE = dyn_cast<SCEVAddExpr>(Val)) {
std::vector<SCEVHandle> NewOps;
NewOps.reserve(SAE->getNumOperands());
for (unsigned i = 0; i != SAE->getNumOperands(); ++i) {
SCEVHandle NewOp = SAE->getOperand(i);
- MoveImmediateValues(TLI, User, NewOp, Imm, isAddress, L, SE);
+ MoveImmediateValues(TLI, UseTy, NewOp, Imm, isAddress, L, SE);
if (!NewOp->isLoopInvariant(L)) {
// If this is a loop-variant expression, it must stay in the immediate
@@ -987,7 +984,7 @@ static void MoveImmediateValues(const TargetLowering *TLI,
} else if (SCEVAddRecExpr *SARE = dyn_cast<SCEVAddRecExpr>(Val)) {
// Try to pull immediates out of the start value of nested addrec's.
SCEVHandle Start = SARE->getStart();
- MoveImmediateValues(TLI, User, Start, Imm, isAddress, L, SE);
+ MoveImmediateValues(TLI, UseTy, Start, Imm, isAddress, L, SE);
if (Start != SARE->getStart()) {
std::vector<SCEVHandle> Ops(SARE->op_begin(), SARE->op_end());
@@ -1002,7 +999,7 @@ static void MoveImmediateValues(const TargetLowering *TLI,
SCEVHandle SubImm = SE->getIntegerSCEV(0, Val->getType());
SCEVHandle NewOp = SME->getOperand(1);
- MoveImmediateValues(TLI, User, NewOp, SubImm, isAddress, L, SE);
+ MoveImmediateValues(TLI, UseTy, NewOp, SubImm, isAddress, L, SE);
// If we extracted something out of the subexpressions, see if we can
// simplify this!
@@ -1034,6 +1031,16 @@ static void MoveImmediateValues(const TargetLowering *TLI,
// Otherwise, no immediates to move.
}
+static void MoveImmediateValues(const TargetLowering *TLI,
+ Instruction *User,
+ SCEVHandle &Val, SCEVHandle &Imm,
+ bool isAddress, Loop *L,
+ ScalarEvolution *SE) {
+ const Type *UseTy = User->getType();
+ if (StoreInst *SI = dyn_cast<StoreInst>(User))
+ UseTy = SI->getOperand(0)->getType();
+ MoveImmediateValues(TLI, UseTy, Val, Imm, isAddress, L, SE);
+}
/// SeparateSubExprs - Decompose Expr into all of the subexpressions that are
/// added together. This is used to reassociate common addition subexprs
@@ -1450,6 +1457,9 @@ SCEVHandle LoopStrengthReduce::CollectIVUsers(const SCEVHandle &Stride,
UsersToProcess[i].Base =
SE->getIntegerSCEV(0, UsersToProcess[i].Base->getType());
} else {
+ // Not all uses are outside the loop.
+ AllUsesAreOutsideLoop = false;
+
// Addressing modes can be folded into loads and stores. Be careful that
// the store is through the expression, not of the expression though.
bool isPHI = false;
@@ -1460,9 +1470,6 @@ SCEVHandle LoopStrengthReduce::CollectIVUsers(const SCEVHandle &Stride,
++NumPHI;
}
- // Not all uses are outside the loop.
- AllUsesAreOutsideLoop = false;
-
if (isAddress)
HasAddress = true;
@@ -1475,12 +1482,12 @@ SCEVHandle LoopStrengthReduce::CollectIVUsers(const SCEVHandle &Stride,
}
}
- // If one of the use if a PHI node and all other uses are addresses, still
+ // If one of the use is a PHI node and all other uses are addresses, still
// allow iv reuse. Essentially we are trading one constant multiplication
// for one fewer iv.
if (NumPHI > 1)
AllUsesAreAddresses = false;
-
+
// There are no in-loop address uses.
if (AllUsesAreAddresses && (!HasAddress && !AllUsesAreOutsideLoop))
AllUsesAreAddresses = false;
@@ -1754,6 +1761,28 @@ LoopStrengthReduce::PrepareToStrengthReduceFromSmallerStride(
"commonbase", PreInsertPt);
}
+static bool IsImmFoldedIntoAddrMode(GlobalValue *GV, int64_t Offset,
+ const Type *ReplacedTy,
+ std::vector<BasedUser> &UsersToProcess,
+ const TargetLowering *TLI) {
+ SmallVector<Instruction*, 16> AddrModeInsts;
+ for (unsigned i = 0, e = UsersToProcess.size(); i != e; ++i) {
+ if (UsersToProcess[i].isUseOfPostIncrementedValue)
+ continue;
+ ExtAddrMode AddrMode =
+ AddressingModeMatcher::Match(UsersToProcess[i].OperandValToReplace,
+ ReplacedTy, UsersToProcess[i].Inst,
+ AddrModeInsts, *TLI);
+ if (GV && GV != AddrMode.BaseGV)
+ return false;
+ if (Offset && !AddrMode.BaseOffs)
+ // FIXME: How to accurate check it's immediate offset is folded.
+ return false;
+ AddrModeInsts.clear();
+ }
+ return true;
+}
+
/// StrengthReduceStridedIVUsers - Strength reduce all of the users of a single
/// stride of IV. All of the users may have different starting values, and this
/// may not be the only stride (we know it is if isOnlyStride is true).
@@ -1797,6 +1826,41 @@ void LoopStrengthReduce::StrengthReduceStridedIVUsers(const SCEVHandle &Stride,
const Type *ReplacedTy = CommonExprs->getType();
+ // If all uses are addresses, consider sinking the immediate part of the
+ // common expression back into uses if they can fit in the immediate fields.
+ if (HaveCommonExprs && AllUsesAreAddresses) {
+ SCEVHandle NewCommon = CommonExprs;
+ SCEVHandle Imm = SE->getIntegerSCEV(0, ReplacedTy);
+ MoveImmediateValues(TLI, ReplacedTy, NewCommon, Imm, true, L, SE);
+ if (!Imm->isZero()) {
+ bool DoSink = true;
+
+ // If the immediate part of the common expression is a GV, check if it's
+ // possible to fold it into the target addressing mode.
+ GlobalValue *GV = 0;
+ if (SCEVUnknown *SU = dyn_cast<SCEVUnknown>(Imm)) {
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(SU->getValue()))
+ if (CE->getOpcode() == Instruction::PtrToInt)
+ GV = dyn_cast<GlobalValue>(CE->getOperand(0));
+ }
+ int64_t Offset = 0;
+ if (SCEVConstant *SC = dyn_cast<SCEVConstant>(Imm))
+ Offset = SC->getValue()->getSExtValue();
+ if (GV || Offset)
+ DoSink = IsImmFoldedIntoAddrMode(GV, Offset, ReplacedTy,
+ UsersToProcess, TLI);
+
+ if (DoSink) {
+ DOUT << " Sinking " << *Imm << " back down into uses\n";
+ for (unsigned i = 0, e = UsersToProcess.size(); i != e; ++i)
+ UsersToProcess[i].Imm = SE->getAddExpr(UsersToProcess[i].Imm, Imm);
+ CommonExprs = NewCommon;
+ HaveCommonExprs = !CommonExprs->isZero();
+ ++NumImmSunk;
+ }
+ }
+ }
+
// Now that we know what we need to do, insert the PHI node itself.
//
DOUT << "LSR: Examining IVs of TYPE " << *ReplacedTy << " of STRIDE "
@@ -2556,7 +2620,8 @@ bool LoopStrengthReduce::runOnLoop(Loop *L, LPPassManager &LPM) {
bool HasOneStride = IVUsesByStride.size() == 1;
#ifndef NDEBUG
- DOUT << "\nLSR on ";
+ DOUT << "\nLSR on \"" << L->getHeader()->getParent()->getNameStart()
+ << "\" ";
DEBUG(L->dump());
#endif
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