mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2025-10-26 18:20:39 +00:00
b5c82c079a
This patch folds fcmp in some cases of interest in Julia. The patch adds a function CannotBeOrderedLessThanZero that returns true if a value is provably not less than zero. I.e. the function returns true if the value is provably -0, +0, positive, or a NaN. The patch extends InstructionSimplify.cpp to fold instances of fcmp where: - the predicate is olt or uge - the first operand is provably not less than zero - the second operand is zero The motivation for handling these cases optimizing away domain checks for sqrt in Julia for common idioms such as sqrt(x*x+y*y).. http://reviews.llvm.org/D6972 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@227298 91177308-0d34-0410-b5e6-96231b3b80d8
237 lines
12 KiB
C++
237 lines
12 KiB
C++
//===- llvm/Analysis/ValueTracking.h - Walk computations --------*- C++ -*-===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This file contains routines that help analyze properties that chains of
|
|
// computations have.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#ifndef LLVM_ANALYSIS_VALUETRACKING_H
|
|
#define LLVM_ANALYSIS_VALUETRACKING_H
|
|
|
|
#include "llvm/ADT/ArrayRef.h"
|
|
#include "llvm/Support/DataTypes.h"
|
|
|
|
namespace llvm {
|
|
class Value;
|
|
class Instruction;
|
|
class APInt;
|
|
class DataLayout;
|
|
class StringRef;
|
|
class MDNode;
|
|
class AssumptionCache;
|
|
class DominatorTree;
|
|
class TargetLibraryInfo;
|
|
|
|
/// Determine which bits of V are known to be either zero or one and return
|
|
/// them in the KnownZero/KnownOne bit sets.
|
|
///
|
|
/// This function is defined on values with integer type, values with pointer
|
|
/// type (but only if TD is non-null), and vectors of integers. In the case
|
|
/// where V is a vector, the known zero and known one values are the
|
|
/// same width as the vector element, and the bit is set only if it is true
|
|
/// for all of the elements in the vector.
|
|
void computeKnownBits(Value *V, APInt &KnownZero, APInt &KnownOne,
|
|
const DataLayout *TD = nullptr, unsigned Depth = 0,
|
|
AssumptionCache *AC = nullptr,
|
|
const Instruction *CxtI = nullptr,
|
|
const DominatorTree *DT = nullptr);
|
|
/// Compute known bits from the range metadata.
|
|
/// \p KnownZero the set of bits that are known to be zero
|
|
void computeKnownBitsFromRangeMetadata(const MDNode &Ranges,
|
|
APInt &KnownZero);
|
|
|
|
/// ComputeSignBit - Determine whether the sign bit is known to be zero or
|
|
/// one. Convenience wrapper around computeKnownBits.
|
|
void ComputeSignBit(Value *V, bool &KnownZero, bool &KnownOne,
|
|
const DataLayout *TD = nullptr, unsigned Depth = 0,
|
|
AssumptionCache *AC = nullptr,
|
|
const Instruction *CxtI = nullptr,
|
|
const DominatorTree *DT = nullptr);
|
|
|
|
/// isKnownToBeAPowerOfTwo - Return true if the given value is known to have
|
|
/// exactly one bit set when defined. For vectors return true if every
|
|
/// element is known to be a power of two when defined. Supports values with
|
|
/// integer or pointer type and vectors of integers. If 'OrZero' is set then
|
|
/// returns true if the given value is either a power of two or zero.
|
|
bool isKnownToBeAPowerOfTwo(Value *V, bool OrZero = false, unsigned Depth = 0,
|
|
AssumptionCache *AC = nullptr,
|
|
const Instruction *CxtI = nullptr,
|
|
const DominatorTree *DT = nullptr);
|
|
|
|
/// isKnownNonZero - Return true if the given value is known to be non-zero
|
|
/// when defined. For vectors return true if every element is known to be
|
|
/// non-zero when defined. Supports values with integer or pointer type and
|
|
/// vectors of integers.
|
|
bool isKnownNonZero(Value *V, const DataLayout *TD = nullptr,
|
|
unsigned Depth = 0, AssumptionCache *AC = nullptr,
|
|
const Instruction *CxtI = nullptr,
|
|
const DominatorTree *DT = nullptr);
|
|
|
|
/// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use
|
|
/// this predicate to simplify operations downstream. Mask is known to be
|
|
/// zero for bits that V cannot have.
|
|
///
|
|
/// This function is defined on values with integer type, values with pointer
|
|
/// type (but only if TD is non-null), and vectors of integers. In the case
|
|
/// where V is a vector, the mask, known zero, and known one values are the
|
|
/// same width as the vector element, and the bit is set only if it is true
|
|
/// for all of the elements in the vector.
|
|
bool MaskedValueIsZero(Value *V, const APInt &Mask,
|
|
const DataLayout *TD = nullptr, unsigned Depth = 0,
|
|
AssumptionCache *AC = nullptr,
|
|
const Instruction *CxtI = nullptr,
|
|
const DominatorTree *DT = nullptr);
|
|
|
|
/// ComputeNumSignBits - Return the number of times the sign bit of the
|
|
/// register is replicated into the other bits. We know that at least 1 bit
|
|
/// is always equal to the sign bit (itself), but other cases can give us
|
|
/// information. For example, immediately after an "ashr X, 2", we know that
|
|
/// the top 3 bits are all equal to each other, so we return 3.
|
|
///
|
|
/// 'Op' must have a scalar integer type.
|
|
///
|
|
unsigned ComputeNumSignBits(Value *Op, const DataLayout *TD = nullptr,
|
|
unsigned Depth = 0, AssumptionCache *AC = nullptr,
|
|
const Instruction *CxtI = nullptr,
|
|
const DominatorTree *DT = nullptr);
|
|
|
|
/// ComputeMultiple - This function computes the integer multiple of Base that
|
|
/// equals V. If successful, it returns true and returns the multiple in
|
|
/// Multiple. If unsuccessful, it returns false. Also, if V can be
|
|
/// simplified to an integer, then the simplified V is returned in Val. Look
|
|
/// through sext only if LookThroughSExt=true.
|
|
bool ComputeMultiple(Value *V, unsigned Base, Value *&Multiple,
|
|
bool LookThroughSExt = false,
|
|
unsigned Depth = 0);
|
|
|
|
/// CannotBeNegativeZero - Return true if we can prove that the specified FP
|
|
/// value is never equal to -0.0.
|
|
///
|
|
bool CannotBeNegativeZero(const Value *V, unsigned Depth = 0);
|
|
|
|
/// CannotBeOrderedLessThanZero - Return true if we can prove that the
|
|
/// specified FP value is either a NaN or never less than 0.0.
|
|
///
|
|
bool CannotBeOrderedLessThanZero(const Value *V, unsigned Depth = 0);
|
|
|
|
/// isBytewiseValue - If the specified value can be set by repeating the same
|
|
/// byte in memory, return the i8 value that it is represented with. This is
|
|
/// true for all i8 values obviously, but is also true for i32 0, i32 -1,
|
|
/// i16 0xF0F0, double 0.0 etc. If the value can't be handled with a repeated
|
|
/// byte store (e.g. i16 0x1234), return null.
|
|
Value *isBytewiseValue(Value *V);
|
|
|
|
/// FindInsertedValue - Given an aggregrate and an sequence of indices, see if
|
|
/// the scalar value indexed is already around as a register, for example if
|
|
/// it were inserted directly into the aggregrate.
|
|
///
|
|
/// If InsertBefore is not null, this function will duplicate (modified)
|
|
/// insertvalues when a part of a nested struct is extracted.
|
|
Value *FindInsertedValue(Value *V,
|
|
ArrayRef<unsigned> idx_range,
|
|
Instruction *InsertBefore = nullptr);
|
|
|
|
/// GetPointerBaseWithConstantOffset - Analyze the specified pointer to see if
|
|
/// it can be expressed as a base pointer plus a constant offset. Return the
|
|
/// base and offset to the caller.
|
|
Value *GetPointerBaseWithConstantOffset(Value *Ptr, int64_t &Offset,
|
|
const DataLayout *TD);
|
|
static inline const Value *
|
|
GetPointerBaseWithConstantOffset(const Value *Ptr, int64_t &Offset,
|
|
const DataLayout *TD) {
|
|
return GetPointerBaseWithConstantOffset(const_cast<Value*>(Ptr), Offset,TD);
|
|
}
|
|
|
|
/// getConstantStringInfo - This function computes the length of a
|
|
/// null-terminated C string pointed to by V. If successful, it returns true
|
|
/// and returns the string in Str. If unsuccessful, it returns false. This
|
|
/// does not include the trailing nul character by default. If TrimAtNul is
|
|
/// set to false, then this returns any trailing nul characters as well as any
|
|
/// other characters that come after it.
|
|
bool getConstantStringInfo(const Value *V, StringRef &Str,
|
|
uint64_t Offset = 0, bool TrimAtNul = true);
|
|
|
|
/// GetStringLength - If we can compute the length of the string pointed to by
|
|
/// the specified pointer, return 'len+1'. If we can't, return 0.
|
|
uint64_t GetStringLength(Value *V);
|
|
|
|
/// GetUnderlyingObject - This method strips off any GEP address adjustments
|
|
/// and pointer casts from the specified value, returning the original object
|
|
/// being addressed. Note that the returned value has pointer type if the
|
|
/// specified value does. If the MaxLookup value is non-zero, it limits the
|
|
/// number of instructions to be stripped off.
|
|
Value *GetUnderlyingObject(Value *V, const DataLayout *TD = nullptr,
|
|
unsigned MaxLookup = 6);
|
|
static inline const Value *
|
|
GetUnderlyingObject(const Value *V, const DataLayout *TD = nullptr,
|
|
unsigned MaxLookup = 6) {
|
|
return GetUnderlyingObject(const_cast<Value *>(V), TD, MaxLookup);
|
|
}
|
|
|
|
/// GetUnderlyingObjects - This method is similar to GetUnderlyingObject
|
|
/// except that it can look through phi and select instructions and return
|
|
/// multiple objects.
|
|
void GetUnderlyingObjects(Value *V,
|
|
SmallVectorImpl<Value *> &Objects,
|
|
const DataLayout *TD = nullptr,
|
|
unsigned MaxLookup = 6);
|
|
|
|
/// onlyUsedByLifetimeMarkers - Return true if the only users of this pointer
|
|
/// are lifetime markers.
|
|
bool onlyUsedByLifetimeMarkers(const Value *V);
|
|
|
|
/// isSafeToSpeculativelyExecute - Return true if the instruction does not
|
|
/// have any effects besides calculating the result and does not have
|
|
/// undefined behavior.
|
|
///
|
|
/// This method never returns true for an instruction that returns true for
|
|
/// mayHaveSideEffects; however, this method also does some other checks in
|
|
/// addition. It checks for undefined behavior, like dividing by zero or
|
|
/// loading from an invalid pointer (but not for undefined results, like a
|
|
/// shift with a shift amount larger than the width of the result). It checks
|
|
/// for malloc and alloca because speculatively executing them might cause a
|
|
/// memory leak. It also returns false for instructions related to control
|
|
/// flow, specifically terminators and PHI nodes.
|
|
///
|
|
/// This method only looks at the instruction itself and its operands, so if
|
|
/// this method returns true, it is safe to move the instruction as long as
|
|
/// the correct dominance relationships for the operands and users hold.
|
|
/// However, this method can return true for instructions that read memory;
|
|
/// for such instructions, moving them may change the resulting value.
|
|
bool isSafeToSpeculativelyExecute(const Value *V,
|
|
const DataLayout *TD = nullptr);
|
|
|
|
/// isKnownNonNull - Return true if this pointer couldn't possibly be null by
|
|
/// its definition. This returns true for allocas, non-extern-weak globals
|
|
/// and byval arguments.
|
|
bool isKnownNonNull(const Value *V, const TargetLibraryInfo *TLI = nullptr);
|
|
|
|
/// Return true if it is valid to use the assumptions provided by an
|
|
/// assume intrinsic, I, at the point in the control-flow identified by the
|
|
/// context instruction, CxtI.
|
|
bool isValidAssumeForContext(const Instruction *I, const Instruction *CxtI,
|
|
const DataLayout *DL = nullptr,
|
|
const DominatorTree *DT = nullptr);
|
|
|
|
enum class OverflowResult { AlwaysOverflows, MayOverflow, NeverOverflows };
|
|
OverflowResult computeOverflowForUnsignedMul(Value *LHS, Value *RHS,
|
|
const DataLayout *DL,
|
|
AssumptionCache *AC,
|
|
const Instruction *CxtI,
|
|
const DominatorTree *DT);
|
|
OverflowResult computeOverflowForUnsignedAdd(Value *LHS, Value *RHS,
|
|
const DataLayout *DL,
|
|
AssumptionCache *AC,
|
|
const Instruction *CxtI,
|
|
const DominatorTree *DT);
|
|
} // end namespace llvm
|
|
|
|
#endif
|