[llvm-commits] [llvm] r73794 - in /llvm/trunk: include/llvm/Analysis/ScalarEvolution.h lib/Analysis/ScalarEvolution.cpp
Dan Gohman
gohman at apple.com
Fri Jun 19 16:29:04 PDT 2009
Author: djg
Date: Fri Jun 19 18:29:04 2009
New Revision: 73794
URL: http://llvm.org/viewvc/llvm-project?rev=73794&view=rev
Log:
Make GetMinTrailingZeros a member function of ScalarEvolution,
so that it can access the TargetData member (when available) and
use ValueTracking.h information to compute information for
SCEVUnknown Values.
Also add GetMinLeadingZeros and GetMinSignBits functions,
with minimal implementations.
Modified:
llvm/trunk/include/llvm/Analysis/ScalarEvolution.h
llvm/trunk/lib/Analysis/ScalarEvolution.cpp
Modified: llvm/trunk/include/llvm/Analysis/ScalarEvolution.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/ScalarEvolution.h?rev=73794&r1=73793&r2=73794&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Analysis/ScalarEvolution.h (original)
+++ llvm/trunk/include/llvm/Analysis/ScalarEvolution.h Fri Jun 19 18:29:04 2009
@@ -571,6 +571,20 @@
/// is deleted.
void forgetLoopBackedgeTakenCount(const Loop *L);
+ /// GetMinTrailingZeros - Determine the minimum number of zero bits that S is
+ /// guaranteed to end in (at every loop iteration). It is, at the same time,
+ /// the minimum number of times S is divisible by 2. For example, given {4,+,8}
+ /// it returns 2. If S is guaranteed to be 0, it returns the bitwidth of S.
+ uint32_t GetMinTrailingZeros(const SCEVHandle &S);
+
+ /// GetMinLeadingZeros - Determine the minimum number of zero bits that S is
+ /// guaranteed to begin with (at every loop iteration).
+ uint32_t GetMinLeadingZeros(const SCEVHandle &S);
+
+ /// GetMinSignBits - Determine the minimum number of sign bits that S is
+ /// guaranteed to begin with.
+ uint32_t GetMinSignBits(const SCEVHandle &S);
+
virtual bool runOnFunction(Function &F);
virtual void releaseMemory();
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=73794&r1=73793&r2=73794&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
+++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Fri Jun 19 18:29:04 2009
@@ -2294,73 +2294,134 @@
/// guaranteed to end in (at every loop iteration). It is, at the same time,
/// the minimum number of times S is divisible by 2. For example, given {4,+,8}
/// it returns 2. If S is guaranteed to be 0, it returns the bitwidth of S.
-static uint32_t GetMinTrailingZeros(SCEVHandle S, const ScalarEvolution &SE) {
+uint32_t
+ScalarEvolution::GetMinTrailingZeros(const SCEVHandle &S) {
if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S))
return C->getValue()->getValue().countTrailingZeros();
if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(S))
- return std::min(GetMinTrailingZeros(T->getOperand(), SE),
- (uint32_t)SE.getTypeSizeInBits(T->getType()));
+ return std::min(GetMinTrailingZeros(T->getOperand()),
+ (uint32_t)getTypeSizeInBits(T->getType()));
if (const SCEVZeroExtendExpr *E = dyn_cast<SCEVZeroExtendExpr>(S)) {
- uint32_t OpRes = GetMinTrailingZeros(E->getOperand(), SE);
- return OpRes == SE.getTypeSizeInBits(E->getOperand()->getType()) ?
- SE.getTypeSizeInBits(E->getType()) : OpRes;
+ uint32_t OpRes = GetMinTrailingZeros(E->getOperand());
+ return OpRes == getTypeSizeInBits(E->getOperand()->getType()) ?
+ getTypeSizeInBits(E->getType()) : OpRes;
}
if (const SCEVSignExtendExpr *E = dyn_cast<SCEVSignExtendExpr>(S)) {
- uint32_t OpRes = GetMinTrailingZeros(E->getOperand(), SE);
- return OpRes == SE.getTypeSizeInBits(E->getOperand()->getType()) ?
- SE.getTypeSizeInBits(E->getType()) : OpRes;
+ uint32_t OpRes = GetMinTrailingZeros(E->getOperand());
+ return OpRes == getTypeSizeInBits(E->getOperand()->getType()) ?
+ getTypeSizeInBits(E->getType()) : OpRes;
}
if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(S)) {
// The result is the min of all operands results.
- uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0), SE);
+ uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0));
for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i)
- MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i), SE));
+ MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i)));
return MinOpRes;
}
if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S)) {
// The result is the sum of all operands results.
- uint32_t SumOpRes = GetMinTrailingZeros(M->getOperand(0), SE);
- uint32_t BitWidth = SE.getTypeSizeInBits(M->getType());
+ uint32_t SumOpRes = GetMinTrailingZeros(M->getOperand(0));
+ uint32_t BitWidth = getTypeSizeInBits(M->getType());
for (unsigned i = 1, e = M->getNumOperands();
SumOpRes != BitWidth && i != e; ++i)
- SumOpRes = std::min(SumOpRes + GetMinTrailingZeros(M->getOperand(i), SE),
+ SumOpRes = std::min(SumOpRes + GetMinTrailingZeros(M->getOperand(i)),
BitWidth);
return SumOpRes;
}
if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(S)) {
// The result is the min of all operands results.
- uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0), SE);
+ uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0));
for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i)
- MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i), SE));
+ MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i)));
return MinOpRes;
}
if (const SCEVSMaxExpr *M = dyn_cast<SCEVSMaxExpr>(S)) {
// The result is the min of all operands results.
- uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0), SE);
+ uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0));
for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i)
- MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i), SE));
+ MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i)));
return MinOpRes;
}
if (const SCEVUMaxExpr *M = dyn_cast<SCEVUMaxExpr>(S)) {
// The result is the min of all operands results.
- uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0), SE);
+ uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0));
for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i)
- MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i), SE));
+ MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i)));
return MinOpRes;
}
- // SCEVUDivExpr, SCEVUnknown
+ if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
+ // For a SCEVUnknown, ask ValueTracking.
+ unsigned BitWidth = getTypeSizeInBits(U->getType());
+ APInt Mask = APInt::getAllOnesValue(BitWidth);
+ APInt Zeros(BitWidth, 0), Ones(BitWidth, 0);
+ ComputeMaskedBits(U->getValue(), Mask, Zeros, Ones);
+ return Zeros.countTrailingOnes();
+ }
+
+ // SCEVUDivExpr
return 0;
}
+uint32_t
+ScalarEvolution::GetMinLeadingZeros(const SCEVHandle &S) {
+ // TODO: Handle other SCEV expression types here.
+
+ if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S))
+ return C->getValue()->getValue().countLeadingZeros();
+
+ if (const SCEVZeroExtendExpr *C = dyn_cast<SCEVZeroExtendExpr>(S)) {
+ // A zero-extension cast adds zero bits.
+ return GetMinLeadingZeros(C->getOperand()) +
+ (getTypeSizeInBits(C->getType()) -
+ getTypeSizeInBits(C->getOperand()->getType()));
+ }
+
+ if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
+ // For a SCEVUnknown, ask ValueTracking.
+ unsigned BitWidth = getTypeSizeInBits(U->getType());
+ APInt Mask = APInt::getAllOnesValue(BitWidth);
+ APInt Zeros(BitWidth, 0), Ones(BitWidth, 0);
+ ComputeMaskedBits(U->getValue(), Mask, Zeros, Ones, TD);
+ return Zeros.countLeadingOnes();
+ }
+
+ return 1;
+}
+
+uint32_t
+ScalarEvolution::GetMinSignBits(const SCEVHandle &S) {
+ // TODO: Handle other SCEV expression types here.
+
+ if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) {
+ const APInt &A = C->getValue()->getValue();
+ return A.isNegative() ? A.countLeadingOnes() :
+ A.countLeadingZeros();
+ }
+
+ if (const SCEVSignExtendExpr *C = dyn_cast<SCEVSignExtendExpr>(S)) {
+ // A sign-extension cast adds sign bits.
+ return GetMinSignBits(C->getOperand()) +
+ (getTypeSizeInBits(C->getType()) -
+ getTypeSizeInBits(C->getOperand()->getType()));
+ }
+
+ if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
+ // For a SCEVUnknown, ask ValueTracking.
+ return ComputeNumSignBits(U->getValue(), TD);
+ }
+
+ return 1;
+}
+
/// createSCEV - We know that there is no SCEV for the specified value.
/// Analyze the expression.
///
@@ -2430,7 +2491,7 @@
if (ConstantInt *CI = dyn_cast<ConstantInt>(U->getOperand(1))) {
SCEVHandle LHS = getSCEV(U->getOperand(0));
const APInt &CIVal = CI->getValue();
- if (GetMinTrailingZeros(LHS, *this) >=
+ if (GetMinTrailingZeros(LHS) >=
(CIVal.getBitWidth() - CIVal.countLeadingZeros()))
return getAddExpr(LHS, getSCEV(U->getOperand(1)));
}
More information about the llvm-commits
mailing list