llvm-6502/lib/Support/ConstantRange.cpp
2007-02-11 00:58:49 +00:00

373 lines
13 KiB
C++

//===-- ConstantRange.cpp - ConstantRange implementation ------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Represent a range of possible values that may occur when the program is run
// for an integral value. This keeps track of a lower and upper bound for the
// constant, which MAY wrap around the end of the numeric range. To do this, it
// keeps track of a [lower, upper) bound, which specifies an interval just like
// STL iterators. When used with boolean values, the following are important
// ranges (other integral ranges use min/max values for special range values):
//
// [F, F) = {} = Empty set
// [T, F) = {T}
// [F, T) = {F}
// [T, T) = {F, T} = Full set
//
//===----------------------------------------------------------------------===//
#include "llvm/Support/ConstantRange.h"
#include "llvm/Constants.h"
#include "llvm/Instruction.h"
#include "llvm/Instructions.h"
#include "llvm/Type.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Support/Streams.h"
#include <ostream>
using namespace llvm;
static ConstantInt *getMaxValue(const Type *Ty, bool isSigned = false) {
if (Ty->isInteger()) {
if (isSigned) {
// Calculate 011111111111111...
unsigned TypeBits = Ty->getPrimitiveSizeInBits();
int64_t Val = INT64_MAX; // All ones
Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
return ConstantInt::get(Ty, Val);
}
return ConstantInt::getAllOnesValue(Ty);
}
return 0;
}
// Static constructor to create the minimum constant for an integral type...
static ConstantInt *getMinValue(const Type *Ty, bool isSigned = false) {
if (Ty->isInteger()) {
if (isSigned) {
// Calculate 1111111111000000000000
unsigned TypeBits = Ty->getPrimitiveSizeInBits();
int64_t Val = -1; // All ones
Val <<= TypeBits-1; // Shift over to the right spot
return ConstantInt::get(Ty, Val);
}
return ConstantInt::get(Ty, 0);
}
return 0;
}
static ConstantInt *Next(ConstantInt *CI) {
Constant *Result = ConstantExpr::getAdd(CI,
ConstantInt::get(CI->getType(), 1));
return cast<ConstantInt>(Result);
}
static bool LT(ConstantInt *A, ConstantInt *B, bool isSigned) {
Constant *C = ConstantExpr::getICmp(
(isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT), A, B);
assert(isa<ConstantInt>(C) && "Constant folding of integrals not impl??");
return cast<ConstantInt>(C)->getZExtValue();
}
static bool LTE(ConstantInt *A, ConstantInt *B, bool isSigned) {
Constant *C = ConstantExpr::getICmp(
(isSigned ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE), A, B);
assert(isa<ConstantInt>(C) && "Constant folding of integrals not impl??");
return cast<ConstantInt>(C)->getZExtValue();
}
static bool GT(ConstantInt *A, ConstantInt *B, bool isSigned) {
return LT(B, A, isSigned); }
static ConstantInt *Min(ConstantInt *A, ConstantInt *B,
bool isSigned) {
return LT(A, B, isSigned) ? A : B;
}
static ConstantInt *Max(ConstantInt *A, ConstantInt *B,
bool isSigned) {
return GT(A, B, isSigned) ? A : B;
}
/// Initialize a full (the default) or empty set for the specified type.
///
ConstantRange::ConstantRange(const Type *Ty, bool Full) {
assert(Ty->isInteger() &&
"Cannot make constant range of non-integral type!");
if (Full)
Lower = Upper = getMaxValue(Ty);
else
Lower = Upper = getMinValue(Ty);
}
/// Initialize a range to hold the single specified value.
///
ConstantRange::ConstantRange(Constant *V)
: Lower(cast<ConstantInt>(V)), Upper(Next(cast<ConstantInt>(V))) { }
/// Initialize a range of values explicitly... this will assert out if
/// Lower==Upper and Lower != Min or Max for its type (or if the two constants
/// have different types)
///
ConstantRange::ConstantRange(Constant *L, Constant *U)
: Lower(cast<ConstantInt>(L)), Upper(cast<ConstantInt>(U)) {
assert(Lower->getType() == Upper->getType() &&
"Incompatible types for ConstantRange!");
// Make sure that if L & U are equal that they are either Min or Max...
assert((L != U || (L == getMaxValue(L->getType()) ||
L == getMinValue(L->getType())))
&& "Lower == Upper, but they aren't min or max for type!");
}
/// Initialize a set of values that all satisfy the condition with C.
///
ConstantRange::ConstantRange(unsigned short ICmpOpcode, ConstantInt *C) {
switch (ICmpOpcode) {
default: assert(0 && "Invalid ICmp opcode to ConstantRange ctor!");
case ICmpInst::ICMP_EQ: Lower = C; Upper = Next(C); return;
case ICmpInst::ICMP_NE: Upper = C; Lower = Next(C); return;
case ICmpInst::ICMP_ULT:
Lower = getMinValue(C->getType());
Upper = C;
return;
case ICmpInst::ICMP_SLT:
Lower = getMinValue(C->getType(), true);
Upper = C;
return;
case ICmpInst::ICMP_UGT:
Lower = Next(C);
Upper = getMinValue(C->getType()); // Min = Next(Max)
return;
case ICmpInst::ICMP_SGT:
Lower = Next(C);
Upper = getMinValue(C->getType(), true); // Min = Next(Max)
return;
case ICmpInst::ICMP_ULE:
Lower = getMinValue(C->getType());
Upper = Next(C);
return;
case ICmpInst::ICMP_SLE:
Lower = getMinValue(C->getType(), true);
Upper = Next(C);
return;
case ICmpInst::ICMP_UGE:
Lower = C;
Upper = getMinValue(C->getType()); // Min = Next(Max)
return;
case ICmpInst::ICMP_SGE:
Lower = C;
Upper = getMinValue(C->getType(), true); // Min = Next(Max)
return;
}
}
/// getType - Return the LLVM data type of this range.
///
const Type *ConstantRange::getType() const { return Lower->getType(); }
/// isFullSet - Return true if this set contains all of the elements possible
/// for this data-type
bool ConstantRange::isFullSet() const {
return Lower == Upper && Lower == getMaxValue(getType());
}
/// isEmptySet - Return true if this set contains no members.
///
bool ConstantRange::isEmptySet() const {
return Lower == Upper && Lower == getMinValue(getType());
}
/// isWrappedSet - Return true if this set wraps around the top of the range,
/// for example: [100, 8)
///
bool ConstantRange::isWrappedSet(bool isSigned) const {
return GT(Lower, Upper, isSigned);
}
/// getSingleElement - If this set contains a single element, return it,
/// otherwise return null.
ConstantInt *ConstantRange::getSingleElement() const {
if (Upper == Next(Lower)) // Is it a single element range?
return Lower;
return 0;
}
/// getSetSize - Return the number of elements in this set.
///
uint64_t ConstantRange::getSetSize() const {
if (isEmptySet()) return 0;
if (getType() == Type::Int1Ty) {
if (Lower != Upper) // One of T or F in the set...
return 1;
return 2; // Must be full set...
}
// Simply subtract the bounds...
Constant *Result = ConstantExpr::getSub(Upper, Lower);
return cast<ConstantInt>(Result)->getZExtValue();
}
/// contains - Return true if the specified value is in the set.
///
bool ConstantRange::contains(ConstantInt *Val, bool isSigned) const {
if (Lower == Upper) {
if (isFullSet()) return true;
return false;
}
if (!isWrappedSet(isSigned))
return LTE(Lower, Val, isSigned) && LT(Val, Upper, isSigned);
return LTE(Lower, Val, isSigned) || LT(Val, Upper, isSigned);
}
/// subtract - Subtract the specified constant from the endpoints of this
/// constant range.
ConstantRange ConstantRange::subtract(ConstantInt *CI) const {
assert(CI->getType() == getType() && getType()->isInteger() &&
"Cannot subtract from different type range or non-integer!");
// If the set is empty or full, don't modify the endpoints.
if (Lower == Upper) return *this;
return ConstantRange(ConstantExpr::getSub(Lower, CI),
ConstantExpr::getSub(Upper, CI));
}
// intersect1Wrapped - This helper function is used to intersect two ranges when
// it is known that LHS is wrapped and RHS isn't.
//
static ConstantRange intersect1Wrapped(const ConstantRange &LHS,
const ConstantRange &RHS,
bool isSigned) {
assert(LHS.isWrappedSet(isSigned) && !RHS.isWrappedSet(isSigned));
// Check to see if we overlap on the Left side of RHS...
//
if (LT(RHS.getLower(), LHS.getUpper(), isSigned)) {
// We do overlap on the left side of RHS, see if we overlap on the right of
// RHS...
if (GT(RHS.getUpper(), LHS.getLower(), isSigned)) {
// Ok, the result overlaps on both the left and right sides. See if the
// resultant interval will be smaller if we wrap or not...
//
if (LHS.getSetSize() < RHS.getSetSize())
return LHS;
else
return RHS;
} else {
// No overlap on the right, just on the left.
return ConstantRange(RHS.getLower(), LHS.getUpper());
}
} else {
// We don't overlap on the left side of RHS, see if we overlap on the right
// of RHS...
if (GT(RHS.getUpper(), LHS.getLower(), isSigned)) {
// Simple overlap...
return ConstantRange(LHS.getLower(), RHS.getUpper());
} else {
// No overlap...
return ConstantRange(LHS.getType(), false);
}
}
}
/// intersectWith - Return the range that results from the intersection of this
/// range with another range.
///
ConstantRange ConstantRange::intersectWith(const ConstantRange &CR,
bool isSigned) const {
assert(getType() == CR.getType() && "ConstantRange types don't agree!");
// Handle common special cases
if (isEmptySet() || CR.isFullSet()) return *this;
if (isFullSet() || CR.isEmptySet()) return CR;
if (!isWrappedSet(isSigned)) {
if (!CR.isWrappedSet(isSigned)) {
ConstantInt *L = Max(Lower, CR.Lower, isSigned);
ConstantInt *U = Min(Upper, CR.Upper, isSigned);
if (LT(L, U, isSigned)) // If range isn't empty...
return ConstantRange(L, U);
else
return ConstantRange(getType(), false); // Otherwise, return empty set
} else
return intersect1Wrapped(CR, *this, isSigned);
} else { // We know "this" is wrapped...
if (!CR.isWrappedSet(isSigned))
return intersect1Wrapped(*this, CR, isSigned);
else {
// Both ranges are wrapped...
ConstantInt *L = Max(Lower, CR.Lower, isSigned);
ConstantInt *U = Min(Upper, CR.Upper, isSigned);
return ConstantRange(L, U);
}
}
return *this;
}
/// unionWith - Return the range that results from the union of this range with
/// another range. The resultant range is guaranteed to include the elements of
/// both sets, but may contain more. For example, [3, 9) union [12,15) is [3,
/// 15), which includes 9, 10, and 11, which were not included in either set
/// before.
///
ConstantRange ConstantRange::unionWith(const ConstantRange &CR,
bool isSigned) const {
assert(getType() == CR.getType() && "ConstantRange types don't agree!");
assert(0 && "Range union not implemented yet!");
return *this;
}
/// zeroExtend - Return a new range in the specified integer type, which must
/// be strictly larger than the current type. The returned range will
/// correspond to the possible range of values as if the source range had been
/// zero extended.
ConstantRange ConstantRange::zeroExtend(const Type *Ty) const {
unsigned SrcTySize = getLower()->getType()->getPrimitiveSizeInBits();
assert(SrcTySize < Ty->getPrimitiveSizeInBits() && "Not a value extension");
if (isFullSet()) {
// Change a source full set into [0, 1 << 8*numbytes)
return ConstantRange(Constant::getNullValue(Ty),
ConstantInt::get(Ty, 1ULL << SrcTySize));
}
Constant *Lower = getLower();
Constant *Upper = getUpper();
return ConstantRange(ConstantExpr::getZExt(Lower, Ty),
ConstantExpr::getZExt(Upper, Ty));
}
/// truncate - Return a new range in the specified integer type, which must be
/// strictly smaller than the current type. The returned range will
/// correspond to the possible range of values as if the source range had been
/// truncated to the specified type.
ConstantRange ConstantRange::truncate(const Type *Ty) const {
unsigned SrcTySize = getLower()->getType()->getPrimitiveSizeInBits();
assert(SrcTySize > Ty->getPrimitiveSizeInBits() && "Not a value truncation");
uint64_t Size = 1ULL << Ty->getPrimitiveSizeInBits();
if (isFullSet() || getSetSize() >= Size)
return ConstantRange(getType());
return ConstantRange(
ConstantExpr::getTrunc(getLower(), Ty),
ConstantExpr::getTrunc(getUpper(), Ty));
}
/// print - Print out the bounds to a stream...
///
void ConstantRange::print(std::ostream &OS) const {
OS << "[" << *Lower << "," << *Upper << " )";
}
/// dump - Allow printing from a debugger easily...
///
void ConstantRange::dump() const {
print(cerr);
}