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authorQuentin Colombet <qcolombet@apple.com>2013-05-31 21:29:03 +0000
committerQuentin Colombet <qcolombet@apple.com>2013-05-31 21:29:03 +0000
commit06f5ebc5a1604b01689cf2d482dd05f956538af6 (patch)
tree052709f167b5eaa2b9cd8b704361e6f8c92b5236 /lib/Transforms
parente17388fd34a12dd0ecb8e347645b945db91d90a7 (diff)
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Loop Strength Reduce: Scaling factor cost.
Account for the cost of scaling factor in Loop Strength Reduce when rating the formulae. This uses a target hook. The default implementation of the hook is: if the addressing mode is legal, the scaling factor is free. <rdar://problem/13806271> git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183045 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Transforms')
-rw-r--r--lib/Transforms/Scalar/LoopStrengthReduce.cpp46
1 files changed, 43 insertions, 3 deletions
diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index ecc96ae..b107fef 100644
--- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -779,6 +779,9 @@ class LSRUse;
// Check if it is legal to fold 2 base registers.
static bool isLegal2RegAMUse(const TargetTransformInfo &TTI, const LSRUse &LU,
const Formula &F);
+// Get the cost of the scaling factor used in F for LU.
+static unsigned getScalingFactorCost(const TargetTransformInfo &TTI,
+ const LSRUse &LU, const Formula &F);
namespace {
@@ -792,11 +795,12 @@ class Cost {
unsigned NumBaseAdds;
unsigned ImmCost;
unsigned SetupCost;
+ unsigned ScaleCost;
public:
Cost()
: NumRegs(0), AddRecCost(0), NumIVMuls(0), NumBaseAdds(0), ImmCost(0),
- SetupCost(0) {}
+ SetupCost(0), ScaleCost(0) {}
bool operator<(const Cost &Other) const;
@@ -806,9 +810,9 @@ public:
// Once any of the metrics loses, they must all remain losers.
bool isValid() {
return ((NumRegs | AddRecCost | NumIVMuls | NumBaseAdds
- | ImmCost | SetupCost) != ~0u)
+ | ImmCost | SetupCost | ScaleCost) != ~0u)
|| ((NumRegs & AddRecCost & NumIVMuls & NumBaseAdds
- & ImmCost & SetupCost) == ~0u);
+ & ImmCost & SetupCost & ScaleCost) == ~0u);
}
#endif
@@ -947,6 +951,9 @@ void Cost::RateFormula(const TargetTransformInfo &TTI,
// allows to fold 2 registers.
NumBaseAdds += NumBaseParts - (1 + isLegal2RegAMUse(TTI, LU, F));
+ // Accumulate non-free scaling amounts.
+ ScaleCost += getScalingFactorCost(TTI, LU, F);
+
// Tally up the non-zero immediates.
for (SmallVectorImpl<int64_t>::const_iterator I = Offsets.begin(),
E = Offsets.end(); I != E; ++I) {
@@ -968,6 +975,7 @@ void Cost::Loose() {
NumBaseAdds = ~0u;
ImmCost = ~0u;
SetupCost = ~0u;
+ ScaleCost = ~0u;
}
/// operator< - Choose the lower cost.
@@ -980,6 +988,8 @@ bool Cost::operator<(const Cost &Other) const {
return NumIVMuls < Other.NumIVMuls;
if (NumBaseAdds != Other.NumBaseAdds)
return NumBaseAdds < Other.NumBaseAdds;
+ if (ScaleCost != Other.ScaleCost)
+ return ScaleCost < Other.ScaleCost;
if (ImmCost != Other.ImmCost)
return ImmCost < Other.ImmCost;
if (SetupCost != Other.SetupCost)
@@ -996,6 +1006,8 @@ void Cost::print(raw_ostream &OS) const {
if (NumBaseAdds != 0)
OS << ", plus " << NumBaseAdds << " base add"
<< (NumBaseAdds == 1 ? "" : "s");
+ if (ScaleCost != 0)
+ OS << ", plus " << ScaleCost << " scale cost";
if (ImmCost != 0)
OS << ", plus " << ImmCost << " imm cost";
if (SetupCost != 0)
@@ -1396,6 +1408,34 @@ static bool isLegal2RegAMUse(const TargetTransformInfo &TTI, const LSRUse &LU,
F.BaseGV, F.BaseOffset, F.HasBaseReg, 1);
}
+static unsigned getScalingFactorCost(const TargetTransformInfo &TTI,
+ const LSRUse &LU, const Formula &F) {
+ if (!F.Scale)
+ return 0;
+ assert(isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind,
+ LU.AccessTy, F) && "Illegal formula in use.");
+
+ switch (LU.Kind) {
+ case LSRUse::Address: {
+ int CurScaleCost = TTI.getScalingFactorCost(LU.AccessTy, F.BaseGV,
+ F.BaseOffset, F.HasBaseReg,
+ F.Scale);
+ assert(CurScaleCost >= 0 && "Legal addressing mode has an illegal cost!");
+ return CurScaleCost;
+ }
+ case LSRUse::ICmpZero:
+ // ICmpZero BaseReg + -1*ScaleReg => ICmp BaseReg, ScaleReg.
+ // Therefore, return 0 in case F.Scale == -1.
+ return F.Scale != -1;
+
+ case LSRUse::Basic:
+ case LSRUse::Special:
+ return 0;
+ }
+
+ llvm_unreachable("Invalid LSRUse Kind!");
+}
+
static bool isAlwaysFoldable(const TargetTransformInfo &TTI,
LSRUse::KindType Kind, Type *AccessTy,
GlobalValue *BaseGV, int64_t BaseOffset,