llvm-6502/lib/Support/ConstantRange.cpp
Reid Spencer d977d8651a Replace inferred getCast(V,Ty) calls with more strict variants.
Rename getZeroExtend and getSignExtend to getZExt and getSExt to match
the the casting mnemonics in the rest of LLVM.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@32514 91177308-0d34-0410-b5e6-96231b3b80d8
2006-12-12 23:36:14 +00:00

375 lines
12 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/Type.h"
#include "llvm/Support/Streams.h"
#include <ostream>
using namespace llvm;
static ConstantIntegral *getMaxValue(const Type *Ty) {
switch (Ty->getTypeID()) {
case Type::BoolTyID: return ConstantBool::getTrue();
case Type::SByteTyID:
case Type::ShortTyID:
case Type::IntTyID:
case Type::LongTyID: {
// Calculate 011111111111111...
unsigned TypeBits = Ty->getPrimitiveSize()*8;
int64_t Val = INT64_MAX; // All ones
Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
return ConstantInt::get(Ty, Val);
}
case Type::UByteTyID:
case Type::UShortTyID:
case Type::UIntTyID:
case Type::ULongTyID: return ConstantInt::getAllOnesValue(Ty);
default: return 0;
}
}
// Static constructor to create the minimum constant for an integral type...
static ConstantIntegral *getMinValue(const Type *Ty) {
switch (Ty->getTypeID()) {
case Type::BoolTyID: return ConstantBool::getFalse();
case Type::SByteTyID:
case Type::ShortTyID:
case Type::IntTyID:
case Type::LongTyID: {
// Calculate 1111111111000000000000
unsigned TypeBits = Ty->getPrimitiveSize()*8;
int64_t Val = -1; // All ones
Val <<= TypeBits-1; // Shift over to the right spot
return ConstantInt::get(Ty, Val);
}
case Type::UByteTyID:
case Type::UShortTyID:
case Type::UIntTyID:
case Type::ULongTyID: return ConstantInt::get(Ty, 0);
default: return 0;
}
}
static ConstantIntegral *Next(ConstantIntegral *CI) {
if (ConstantBool *CB = dyn_cast<ConstantBool>(CI))
return ConstantBool::get(!CB->getValue());
Constant *Result = ConstantExpr::getAdd(CI,
ConstantInt::get(CI->getType(), 1));
return cast<ConstantIntegral>(Result);
}
static bool LT(ConstantIntegral *A, ConstantIntegral *B) {
Constant *C = ConstantExpr::getSetLT(A, B);
assert(isa<ConstantBool>(C) && "Constant folding of integrals not impl??");
return cast<ConstantBool>(C)->getValue();
}
static bool LTE(ConstantIntegral *A, ConstantIntegral *B) {
Constant *C = ConstantExpr::getSetLE(A, B);
assert(isa<ConstantBool>(C) && "Constant folding of integrals not impl??");
return cast<ConstantBool>(C)->getValue();
}
static bool GT(ConstantIntegral *A, ConstantIntegral *B) { return LT(B, A); }
static ConstantIntegral *Min(ConstantIntegral *A, ConstantIntegral *B) {
return LT(A, B) ? A : B;
}
static ConstantIntegral *Max(ConstantIntegral *A, ConstantIntegral *B) {
return GT(A, B) ? A : B;
}
/// Initialize a full (the default) or empty set for the specified type.
///
ConstantRange::ConstantRange(const Type *Ty, bool Full) {
assert(Ty->isIntegral() &&
"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<ConstantIntegral>(V)), Upper(Next(cast<ConstantIntegral>(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<ConstantIntegral>(L)), Upper(cast<ConstantIntegral>(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 SetCCOpcode, ConstantIntegral *C) {
switch (SetCCOpcode) {
default: assert(0 && "Invalid SetCC opcode to ConstantRange ctor!");
case Instruction::SetEQ: Lower = C; Upper = Next(C); return;
case Instruction::SetNE: Upper = C; Lower = Next(C); return;
case Instruction::SetLT:
Lower = getMinValue(C->getType());
Upper = C;
return;
case Instruction::SetGT:
Lower = Next(C);
Upper = getMinValue(C->getType()); // Min = Next(Max)
return;
case Instruction::SetLE:
Lower = getMinValue(C->getType());
Upper = Next(C);
return;
case Instruction::SetGE:
Lower = C;
Upper = getMinValue(C->getType()); // 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() const {
return GT(Lower, Upper);
}
/// getSingleElement - If this set contains a single element, return it,
/// otherwise return null.
ConstantIntegral *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::BoolTy) {
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) const {
if (Lower == Upper) {
if (isFullSet()) return true;
return false;
}
if (!isWrappedSet())
return LTE(Lower, Val) && LT(Val, Upper);
return LTE(Lower, Val) || LT(Val, Upper);
}
/// 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) {
assert(LHS.isWrappedSet() && !RHS.isWrappedSet());
// Check to see if we overlap on the Left side of RHS...
//
if (LT(RHS.getLower(), LHS.getUpper())) {
// We do overlap on the left side of RHS, see if we overlap on the right of
// RHS...
if (GT(RHS.getUpper(), LHS.getLower())) {
// 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())) {
// Simple overlap...
return ConstantRange(LHS.getLower(), RHS.getUpper());
} else {
// No overlap...
return ConstantRange(LHS.getType(), false);
}
}
}
/// intersect - Return the range that results from the intersection of this
/// range with another range.
///
ConstantRange ConstantRange::intersectWith(const ConstantRange &CR) 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()) {
if (!CR.isWrappedSet()) {
ConstantIntegral *L = Max(Lower, CR.Lower);
ConstantIntegral *U = Min(Upper, CR.Upper);
if (LT(L, U)) // If range isn't empty...
return ConstantRange(L, U);
else
return ConstantRange(getType(), false); // Otherwise, return empty set
} else
return intersect1Wrapped(CR, *this);
} else { // We know "this" is wrapped...
if (!CR.isWrappedSet())
return intersect1Wrapped(*this, CR);
else {
// Both ranges are wrapped...
ConstantIntegral *L = Max(Lower, CR.Lower);
ConstantIntegral *U = Min(Upper, CR.Upper);
return ConstantRange(L, U);
}
}
return *this;
}
/// union - 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) 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 if the source range had been
/// zero extended.
ConstantRange ConstantRange::zeroExtend(const Type *Ty) const {
assert(getLower()->getType()->getPrimitiveSize() < Ty->getPrimitiveSize() &&
"Not a value extension");
if (isFullSet()) {
// Change a source full set into [0, 1 << 8*numbytes)
unsigned SrcTySize = getLower()->getType()->getPrimitiveSize();
return ConstantRange(Constant::getNullValue(Ty),
ConstantInt::get(Ty, 1ULL << SrcTySize*8));
}
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 if the source range had been
/// truncated to the specified type.
ConstantRange ConstantRange::truncate(const Type *Ty) const {
assert(getLower()->getType()->getPrimitiveSize() > Ty->getPrimitiveSize() &&
"Not a value truncation");
uint64_t Size = 1ULL << Ty->getPrimitiveSize()*8;
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);
}