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504e8fb74e
testcase test/Regression/Assembler/ConstantExprFold.llx Note that these kinds of things only rarely show up in source code, but are exceedingly common in the intermediate stages of algorithms like SCCP. By folding things (especially relational operators) that use symbolic constants, we are able to speculatively fold more conditional branches, which can lead to some big simplifications. It would be easy to add a lot more special cases here, so if you notice SCCP missing anything "obvious", you know what to make smarter. :) git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@10812 91177308-0d34-0410-b5e6-96231b3b80d8
977 lines
42 KiB
C++
977 lines
42 KiB
C++
//===- ConstantFolding.cpp - LLVM constant folder -------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by the LLVM research group and is distributed under
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// the University of Illinois Open Source License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements folding of constants for LLVM. This implements the
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// (internal) ConstantFolding.h interface, which is used by the
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// ConstantExpr::get* methods to automatically fold constants when possible.
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//
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// The current constant folding implementation is implemented in two pieces: the
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// template-based folder for simple primitive constants like ConstantInt, and
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// the special case hackery that we use to symbolically evaluate expressions
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// that use ConstantExprs.
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//
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//===----------------------------------------------------------------------===//
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#include "ConstantFolding.h"
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#include "llvm/Constants.h"
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#include "llvm/iPHINode.h"
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#include "llvm/iOperators.h"
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#include "llvm/InstrTypes.h"
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#include "llvm/DerivedTypes.h"
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#include "llvm/Support/GetElementPtrTypeIterator.h"
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#include <cmath>
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using namespace llvm;
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namespace {
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struct ConstRules {
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ConstRules() {}
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// Binary Operators...
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virtual Constant *add(const Constant *V1, const Constant *V2) const = 0;
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virtual Constant *sub(const Constant *V1, const Constant *V2) const = 0;
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virtual Constant *mul(const Constant *V1, const Constant *V2) const = 0;
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virtual Constant *div(const Constant *V1, const Constant *V2) const = 0;
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virtual Constant *rem(const Constant *V1, const Constant *V2) const = 0;
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virtual Constant *op_and(const Constant *V1, const Constant *V2) const = 0;
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virtual Constant *op_or (const Constant *V1, const Constant *V2) const = 0;
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virtual Constant *op_xor(const Constant *V1, const Constant *V2) const = 0;
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virtual Constant *shl(const Constant *V1, const Constant *V2) const = 0;
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virtual Constant *shr(const Constant *V1, const Constant *V2) const = 0;
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virtual Constant *lessthan(const Constant *V1, const Constant *V2) const =0;
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virtual Constant *equalto(const Constant *V1, const Constant *V2) const = 0;
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// Casting operators.
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virtual Constant *castToBool (const Constant *V) const = 0;
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virtual Constant *castToSByte (const Constant *V) const = 0;
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virtual Constant *castToUByte (const Constant *V) const = 0;
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virtual Constant *castToShort (const Constant *V) const = 0;
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virtual Constant *castToUShort(const Constant *V) const = 0;
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virtual Constant *castToInt (const Constant *V) const = 0;
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virtual Constant *castToUInt (const Constant *V) const = 0;
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virtual Constant *castToLong (const Constant *V) const = 0;
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virtual Constant *castToULong (const Constant *V) const = 0;
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virtual Constant *castToFloat (const Constant *V) const = 0;
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virtual Constant *castToDouble(const Constant *V) const = 0;
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virtual Constant *castToPointer(const Constant *V,
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const PointerType *Ty) const = 0;
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// ConstRules::get - Return an instance of ConstRules for the specified
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// constant operands.
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//
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static ConstRules &get(const Constant *V1, const Constant *V2);
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private:
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ConstRules(const ConstRules &); // Do not implement
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ConstRules &operator=(const ConstRules &); // Do not implement
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};
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}
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//===----------------------------------------------------------------------===//
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// TemplateRules Class
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//===----------------------------------------------------------------------===//
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//
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// TemplateRules - Implement a subclass of ConstRules that provides all
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// operations as noops. All other rules classes inherit from this class so
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// that if functionality is needed in the future, it can simply be added here
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// and to ConstRules without changing anything else...
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//
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// This class also provides subclasses with typesafe implementations of methods
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// so that don't have to do type casting.
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//
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template<class ArgType, class SubClassName>
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class TemplateRules : public ConstRules {
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//===--------------------------------------------------------------------===//
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// Redirecting functions that cast to the appropriate types
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//===--------------------------------------------------------------------===//
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virtual Constant *add(const Constant *V1, const Constant *V2) const {
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return SubClassName::Add((const ArgType *)V1, (const ArgType *)V2);
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}
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virtual Constant *sub(const Constant *V1, const Constant *V2) const {
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return SubClassName::Sub((const ArgType *)V1, (const ArgType *)V2);
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}
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virtual Constant *mul(const Constant *V1, const Constant *V2) const {
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return SubClassName::Mul((const ArgType *)V1, (const ArgType *)V2);
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}
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virtual Constant *div(const Constant *V1, const Constant *V2) const {
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return SubClassName::Div((const ArgType *)V1, (const ArgType *)V2);
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}
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virtual Constant *rem(const Constant *V1, const Constant *V2) const {
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return SubClassName::Rem((const ArgType *)V1, (const ArgType *)V2);
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}
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virtual Constant *op_and(const Constant *V1, const Constant *V2) const {
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return SubClassName::And((const ArgType *)V1, (const ArgType *)V2);
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}
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virtual Constant *op_or(const Constant *V1, const Constant *V2) const {
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return SubClassName::Or((const ArgType *)V1, (const ArgType *)V2);
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}
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virtual Constant *op_xor(const Constant *V1, const Constant *V2) const {
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return SubClassName::Xor((const ArgType *)V1, (const ArgType *)V2);
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}
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virtual Constant *shl(const Constant *V1, const Constant *V2) const {
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return SubClassName::Shl((const ArgType *)V1, (const ArgType *)V2);
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}
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virtual Constant *shr(const Constant *V1, const Constant *V2) const {
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return SubClassName::Shr((const ArgType *)V1, (const ArgType *)V2);
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}
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virtual Constant *lessthan(const Constant *V1, const Constant *V2) const {
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return SubClassName::LessThan((const ArgType *)V1, (const ArgType *)V2);
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}
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virtual Constant *equalto(const Constant *V1, const Constant *V2) const {
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return SubClassName::EqualTo((const ArgType *)V1, (const ArgType *)V2);
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}
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// Casting operators. ick
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virtual Constant *castToBool(const Constant *V) const {
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return SubClassName::CastToBool((const ArgType*)V);
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}
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virtual Constant *castToSByte(const Constant *V) const {
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return SubClassName::CastToSByte((const ArgType*)V);
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}
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virtual Constant *castToUByte(const Constant *V) const {
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return SubClassName::CastToUByte((const ArgType*)V);
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}
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virtual Constant *castToShort(const Constant *V) const {
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return SubClassName::CastToShort((const ArgType*)V);
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}
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virtual Constant *castToUShort(const Constant *V) const {
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return SubClassName::CastToUShort((const ArgType*)V);
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}
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virtual Constant *castToInt(const Constant *V) const {
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return SubClassName::CastToInt((const ArgType*)V);
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}
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virtual Constant *castToUInt(const Constant *V) const {
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return SubClassName::CastToUInt((const ArgType*)V);
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}
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virtual Constant *castToLong(const Constant *V) const {
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return SubClassName::CastToLong((const ArgType*)V);
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}
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virtual Constant *castToULong(const Constant *V) const {
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return SubClassName::CastToULong((const ArgType*)V);
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}
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virtual Constant *castToFloat(const Constant *V) const {
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return SubClassName::CastToFloat((const ArgType*)V);
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}
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virtual Constant *castToDouble(const Constant *V) const {
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return SubClassName::CastToDouble((const ArgType*)V);
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}
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virtual Constant *castToPointer(const Constant *V,
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const PointerType *Ty) const {
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return SubClassName::CastToPointer((const ArgType*)V, Ty);
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}
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//===--------------------------------------------------------------------===//
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// Default "noop" implementations
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//===--------------------------------------------------------------------===//
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static Constant *Add(const ArgType *V1, const ArgType *V2) { return 0; }
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static Constant *Sub(const ArgType *V1, const ArgType *V2) { return 0; }
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static Constant *Mul(const ArgType *V1, const ArgType *V2) { return 0; }
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static Constant *Div(const ArgType *V1, const ArgType *V2) { return 0; }
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static Constant *Rem(const ArgType *V1, const ArgType *V2) { return 0; }
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static Constant *And(const ArgType *V1, const ArgType *V2) { return 0; }
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static Constant *Or (const ArgType *V1, const ArgType *V2) { return 0; }
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static Constant *Xor(const ArgType *V1, const ArgType *V2) { return 0; }
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static Constant *Shl(const ArgType *V1, const ArgType *V2) { return 0; }
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static Constant *Shr(const ArgType *V1, const ArgType *V2) { return 0; }
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static Constant *LessThan(const ArgType *V1, const ArgType *V2) {
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return 0;
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}
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static Constant *EqualTo(const ArgType *V1, const ArgType *V2) {
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return 0;
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}
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// Casting operators. ick
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static Constant *CastToBool (const Constant *V) { return 0; }
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static Constant *CastToSByte (const Constant *V) { return 0; }
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static Constant *CastToUByte (const Constant *V) { return 0; }
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static Constant *CastToShort (const Constant *V) { return 0; }
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static Constant *CastToUShort(const Constant *V) { return 0; }
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static Constant *CastToInt (const Constant *V) { return 0; }
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static Constant *CastToUInt (const Constant *V) { return 0; }
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static Constant *CastToLong (const Constant *V) { return 0; }
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static Constant *CastToULong (const Constant *V) { return 0; }
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static Constant *CastToFloat (const Constant *V) { return 0; }
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static Constant *CastToDouble(const Constant *V) { return 0; }
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static Constant *CastToPointer(const Constant *,
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const PointerType *) {return 0;}
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};
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//===----------------------------------------------------------------------===//
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// EmptyRules Class
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//===----------------------------------------------------------------------===//
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//
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// EmptyRules provides a concrete base class of ConstRules that does nothing
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//
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struct EmptyRules : public TemplateRules<Constant, EmptyRules> {
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static Constant *EqualTo(const Constant *V1, const Constant *V2) {
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if (V1 == V2) return ConstantBool::True;
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return 0;
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}
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};
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//===----------------------------------------------------------------------===//
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// BoolRules Class
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//===----------------------------------------------------------------------===//
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//
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// BoolRules provides a concrete base class of ConstRules for the 'bool' type.
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//
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struct BoolRules : public TemplateRules<ConstantBool, BoolRules> {
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static Constant *LessThan(const ConstantBool *V1, const ConstantBool *V2){
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return ConstantBool::get(V1->getValue() < V2->getValue());
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}
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static Constant *EqualTo(const Constant *V1, const Constant *V2) {
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return ConstantBool::get(V1 == V2);
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}
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static Constant *And(const ConstantBool *V1, const ConstantBool *V2) {
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return ConstantBool::get(V1->getValue() & V2->getValue());
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}
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static Constant *Or(const ConstantBool *V1, const ConstantBool *V2) {
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return ConstantBool::get(V1->getValue() | V2->getValue());
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}
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static Constant *Xor(const ConstantBool *V1, const ConstantBool *V2) {
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return ConstantBool::get(V1->getValue() ^ V2->getValue());
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}
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// Casting operators. ick
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#define DEF_CAST(TYPE, CLASS, CTYPE) \
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static Constant *CastTo##TYPE (const ConstantBool *V) { \
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return CLASS::get(Type::TYPE##Ty, (CTYPE)(bool)V->getValue()); \
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}
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DEF_CAST(Bool , ConstantBool, bool)
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DEF_CAST(SByte , ConstantSInt, signed char)
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DEF_CAST(UByte , ConstantUInt, unsigned char)
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DEF_CAST(Short , ConstantSInt, signed short)
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DEF_CAST(UShort, ConstantUInt, unsigned short)
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DEF_CAST(Int , ConstantSInt, signed int)
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DEF_CAST(UInt , ConstantUInt, unsigned int)
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DEF_CAST(Long , ConstantSInt, int64_t)
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DEF_CAST(ULong , ConstantUInt, uint64_t)
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DEF_CAST(Float , ConstantFP , float)
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DEF_CAST(Double, ConstantFP , double)
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#undef DEF_CAST
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};
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//===----------------------------------------------------------------------===//
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// NullPointerRules Class
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//===----------------------------------------------------------------------===//
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//
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// NullPointerRules provides a concrete base class of ConstRules for null
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// pointers.
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//
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struct NullPointerRules : public TemplateRules<ConstantPointerNull,
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NullPointerRules> {
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static Constant *EqualTo(const Constant *V1, const Constant *V2) {
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return ConstantBool::True; // Null pointers are always equal
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}
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static Constant *CastToBool(const Constant *V) {
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return ConstantBool::False;
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}
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static Constant *CastToSByte (const Constant *V) {
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return ConstantSInt::get(Type::SByteTy, 0);
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}
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static Constant *CastToUByte (const Constant *V) {
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return ConstantUInt::get(Type::UByteTy, 0);
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}
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static Constant *CastToShort (const Constant *V) {
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return ConstantSInt::get(Type::ShortTy, 0);
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}
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static Constant *CastToUShort(const Constant *V) {
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return ConstantUInt::get(Type::UShortTy, 0);
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}
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static Constant *CastToInt (const Constant *V) {
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return ConstantSInt::get(Type::IntTy, 0);
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}
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static Constant *CastToUInt (const Constant *V) {
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return ConstantUInt::get(Type::UIntTy, 0);
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}
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static Constant *CastToLong (const Constant *V) {
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return ConstantSInt::get(Type::LongTy, 0);
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}
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static Constant *CastToULong (const Constant *V) {
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return ConstantUInt::get(Type::ULongTy, 0);
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}
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static Constant *CastToFloat (const Constant *V) {
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return ConstantFP::get(Type::FloatTy, 0);
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}
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static Constant *CastToDouble(const Constant *V) {
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return ConstantFP::get(Type::DoubleTy, 0);
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}
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static Constant *CastToPointer(const ConstantPointerNull *V,
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const PointerType *PTy) {
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return ConstantPointerNull::get(PTy);
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}
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};
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//===----------------------------------------------------------------------===//
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// DirectRules Class
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//===----------------------------------------------------------------------===//
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//
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// DirectRules provides a concrete base classes of ConstRules for a variety of
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// different types. This allows the C++ compiler to automatically generate our
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// constant handling operations in a typesafe and accurate manner.
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//
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template<class ConstantClass, class BuiltinType, Type **Ty, class SuperClass>
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struct DirectRules : public TemplateRules<ConstantClass, SuperClass> {
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static Constant *Add(const ConstantClass *V1, const ConstantClass *V2) {
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BuiltinType R = (BuiltinType)V1->getValue() + (BuiltinType)V2->getValue();
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return ConstantClass::get(*Ty, R);
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}
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static Constant *Sub(const ConstantClass *V1, const ConstantClass *V2) {
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BuiltinType R = (BuiltinType)V1->getValue() - (BuiltinType)V2->getValue();
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return ConstantClass::get(*Ty, R);
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}
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static Constant *Mul(const ConstantClass *V1, const ConstantClass *V2) {
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BuiltinType R = (BuiltinType)V1->getValue() * (BuiltinType)V2->getValue();
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return ConstantClass::get(*Ty, R);
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}
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static Constant *Div(const ConstantClass *V1, const ConstantClass *V2) {
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if (V2->isNullValue()) return 0;
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BuiltinType R = (BuiltinType)V1->getValue() / (BuiltinType)V2->getValue();
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return ConstantClass::get(*Ty, R);
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}
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static Constant *LessThan(const ConstantClass *V1, const ConstantClass *V2) {
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bool R = (BuiltinType)V1->getValue() < (BuiltinType)V2->getValue();
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return ConstantBool::get(R);
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}
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static Constant *EqualTo(const ConstantClass *V1, const ConstantClass *V2) {
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bool R = (BuiltinType)V1->getValue() == (BuiltinType)V2->getValue();
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return ConstantBool::get(R);
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}
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static Constant *CastToPointer(const ConstantClass *V,
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const PointerType *PTy) {
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if (V->isNullValue()) // Is it a FP or Integral null value?
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return ConstantPointerNull::get(PTy);
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return 0; // Can't const prop other types of pointers
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}
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// Casting operators. ick
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#define DEF_CAST(TYPE, CLASS, CTYPE) \
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static Constant *CastTo##TYPE (const ConstantClass *V) { \
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return CLASS::get(Type::TYPE##Ty, (CTYPE)(BuiltinType)V->getValue()); \
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}
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DEF_CAST(Bool , ConstantBool, bool)
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DEF_CAST(SByte , ConstantSInt, signed char)
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DEF_CAST(UByte , ConstantUInt, unsigned char)
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DEF_CAST(Short , ConstantSInt, signed short)
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DEF_CAST(UShort, ConstantUInt, unsigned short)
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DEF_CAST(Int , ConstantSInt, signed int)
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DEF_CAST(UInt , ConstantUInt, unsigned int)
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DEF_CAST(Long , ConstantSInt, int64_t)
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DEF_CAST(ULong , ConstantUInt, uint64_t)
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DEF_CAST(Float , ConstantFP , float)
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DEF_CAST(Double, ConstantFP , double)
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#undef DEF_CAST
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};
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//===----------------------------------------------------------------------===//
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// DirectIntRules Class
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//===----------------------------------------------------------------------===//
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//
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// DirectIntRules provides implementations of functions that are valid on
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// integer types, but not all types in general.
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//
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template <class ConstantClass, class BuiltinType, Type **Ty>
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struct DirectIntRules
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: public DirectRules<ConstantClass, BuiltinType, Ty,
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DirectIntRules<ConstantClass, BuiltinType, Ty> > {
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static Constant *Div(const ConstantClass *V1, const ConstantClass *V2) {
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if (V2->isNullValue()) return 0;
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if (V2->isAllOnesValue() && // MIN_INT / -1
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(BuiltinType)V1->getValue() == -(BuiltinType)V1->getValue())
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return 0;
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BuiltinType R = (BuiltinType)V1->getValue() / (BuiltinType)V2->getValue();
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return ConstantClass::get(*Ty, R);
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}
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static Constant *Rem(const ConstantClass *V1,
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const ConstantClass *V2) {
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if (V2->isNullValue()) return 0; // X / 0
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if (V2->isAllOnesValue() && // MIN_INT / -1
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(BuiltinType)V1->getValue() == -(BuiltinType)V1->getValue())
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return 0;
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BuiltinType R = (BuiltinType)V1->getValue() % (BuiltinType)V2->getValue();
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return ConstantClass::get(*Ty, R);
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}
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static Constant *And(const ConstantClass *V1, const ConstantClass *V2) {
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BuiltinType R = (BuiltinType)V1->getValue() & (BuiltinType)V2->getValue();
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return ConstantClass::get(*Ty, R);
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}
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static Constant *Or(const ConstantClass *V1, const ConstantClass *V2) {
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BuiltinType R = (BuiltinType)V1->getValue() | (BuiltinType)V2->getValue();
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return ConstantClass::get(*Ty, R);
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}
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static Constant *Xor(const ConstantClass *V1, const ConstantClass *V2) {
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BuiltinType R = (BuiltinType)V1->getValue() ^ (BuiltinType)V2->getValue();
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return ConstantClass::get(*Ty, R);
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}
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static Constant *Shl(const ConstantClass *V1, const ConstantClass *V2) {
|
|
BuiltinType R = (BuiltinType)V1->getValue() << (BuiltinType)V2->getValue();
|
|
return ConstantClass::get(*Ty, R);
|
|
}
|
|
|
|
static Constant *Shr(const ConstantClass *V1, const ConstantClass *V2) {
|
|
BuiltinType R = (BuiltinType)V1->getValue() >> (BuiltinType)V2->getValue();
|
|
return ConstantClass::get(*Ty, R);
|
|
}
|
|
};
|
|
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// DirectFPRules Class
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
/// DirectFPRules provides implementations of functions that are valid on
|
|
/// floating point types, but not all types in general.
|
|
///
|
|
template <class ConstantClass, class BuiltinType, Type **Ty>
|
|
struct DirectFPRules
|
|
: public DirectRules<ConstantClass, BuiltinType, Ty,
|
|
DirectFPRules<ConstantClass, BuiltinType, Ty> > {
|
|
static Constant *Rem(const ConstantClass *V1, const ConstantClass *V2) {
|
|
if (V2->isNullValue()) return 0;
|
|
BuiltinType Result = std::fmod((BuiltinType)V1->getValue(),
|
|
(BuiltinType)V2->getValue());
|
|
return ConstantClass::get(*Ty, Result);
|
|
}
|
|
};
|
|
|
|
|
|
/// ConstRules::get - This method returns the constant rules implementation that
|
|
/// implements the semantics of the two specified constants.
|
|
ConstRules &ConstRules::get(const Constant *V1, const Constant *V2) {
|
|
static EmptyRules EmptyR;
|
|
static BoolRules BoolR;
|
|
static NullPointerRules NullPointerR;
|
|
static DirectIntRules<ConstantSInt, signed char , &Type::SByteTy> SByteR;
|
|
static DirectIntRules<ConstantUInt, unsigned char , &Type::UByteTy> UByteR;
|
|
static DirectIntRules<ConstantSInt, signed short, &Type::ShortTy> ShortR;
|
|
static DirectIntRules<ConstantUInt, unsigned short, &Type::UShortTy> UShortR;
|
|
static DirectIntRules<ConstantSInt, signed int , &Type::IntTy> IntR;
|
|
static DirectIntRules<ConstantUInt, unsigned int , &Type::UIntTy> UIntR;
|
|
static DirectIntRules<ConstantSInt, int64_t , &Type::LongTy> LongR;
|
|
static DirectIntRules<ConstantUInt, uint64_t , &Type::ULongTy> ULongR;
|
|
static DirectFPRules <ConstantFP , float , &Type::FloatTy> FloatR;
|
|
static DirectFPRules <ConstantFP , double , &Type::DoubleTy> DoubleR;
|
|
|
|
if (isa<ConstantExpr>(V1) || isa<ConstantExpr>(V2) ||
|
|
isa<ConstantPointerRef>(V1) || isa<ConstantPointerRef>(V2))
|
|
return EmptyR;
|
|
|
|
switch (V1->getType()->getPrimitiveID()) {
|
|
default: assert(0 && "Unknown value type for constant folding!");
|
|
case Type::BoolTyID: return BoolR;
|
|
case Type::PointerTyID: return NullPointerR;
|
|
case Type::SByteTyID: return SByteR;
|
|
case Type::UByteTyID: return UByteR;
|
|
case Type::ShortTyID: return ShortR;
|
|
case Type::UShortTyID: return UShortR;
|
|
case Type::IntTyID: return IntR;
|
|
case Type::UIntTyID: return UIntR;
|
|
case Type::LongTyID: return LongR;
|
|
case Type::ULongTyID: return ULongR;
|
|
case Type::FloatTyID: return FloatR;
|
|
case Type::DoubleTyID: return DoubleR;
|
|
}
|
|
}
|
|
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// ConstantFold*Instruction Implementations
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// These methods contain the special case hackery required to symbolically
|
|
// evaluate some constant expression cases, and use the ConstantRules class to
|
|
// evaluate normal constants.
|
|
//
|
|
static unsigned getSize(const Type *Ty) {
|
|
unsigned S = Ty->getPrimitiveSize();
|
|
return S ? S : 8; // Treat pointers at 8 bytes
|
|
}
|
|
|
|
Constant *llvm::ConstantFoldCastInstruction(const Constant *V,
|
|
const Type *DestTy) {
|
|
if (V->getType() == DestTy) return (Constant*)V;
|
|
|
|
if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
|
|
if (CE->getOpcode() == Instruction::Cast) {
|
|
Constant *Op = const_cast<Constant*>(CE->getOperand(0));
|
|
// Try to not produce a cast of a cast, which is almost always redundant.
|
|
if (!Op->getType()->isFloatingPoint() &&
|
|
!CE->getType()->isFloatingPoint() &&
|
|
!DestTy->getType()->isFloatingPoint()) {
|
|
unsigned S1 = getSize(Op->getType()), S2 = getSize(CE->getType());
|
|
unsigned S3 = getSize(DestTy);
|
|
if (Op->getType() == DestTy && S3 >= S2)
|
|
return Op;
|
|
if (S1 >= S2 && S2 >= S3)
|
|
return ConstantExpr::getCast(Op, DestTy);
|
|
if (S1 <= S2 && S2 >= S3 && S1 <= S3)
|
|
return ConstantExpr::getCast(Op, DestTy);
|
|
}
|
|
} else if (CE->getOpcode() == Instruction::GetElementPtr) {
|
|
// If all of the indexes in the GEP are null values, there is no pointer
|
|
// adjustment going on. We might as well cast the source pointer.
|
|
bool isAllNull = true;
|
|
for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
|
|
if (!CE->getOperand(i)->isNullValue()) {
|
|
isAllNull = false;
|
|
break;
|
|
}
|
|
if (isAllNull)
|
|
return ConstantExpr::getCast(CE->getOperand(0), DestTy);
|
|
}
|
|
|
|
ConstRules &Rules = ConstRules::get(V, V);
|
|
|
|
switch (DestTy->getPrimitiveID()) {
|
|
case Type::BoolTyID: return Rules.castToBool(V);
|
|
case Type::UByteTyID: return Rules.castToUByte(V);
|
|
case Type::SByteTyID: return Rules.castToSByte(V);
|
|
case Type::UShortTyID: return Rules.castToUShort(V);
|
|
case Type::ShortTyID: return Rules.castToShort(V);
|
|
case Type::UIntTyID: return Rules.castToUInt(V);
|
|
case Type::IntTyID: return Rules.castToInt(V);
|
|
case Type::ULongTyID: return Rules.castToULong(V);
|
|
case Type::LongTyID: return Rules.castToLong(V);
|
|
case Type::FloatTyID: return Rules.castToFloat(V);
|
|
case Type::DoubleTyID: return Rules.castToDouble(V);
|
|
case Type::PointerTyID:
|
|
return Rules.castToPointer(V, cast<PointerType>(DestTy));
|
|
default: return 0;
|
|
}
|
|
}
|
|
|
|
/// IdxCompare - Compare the two constants as though they were getelementptr
|
|
/// indices. This allows coersion of the types to be the same thing.
|
|
///
|
|
/// If the two constants are the "same" (after coersion), return 0. If the
|
|
/// first is less than the second, return -1, if the second is less than the
|
|
/// first, return 1. If the constants are not integral, return -2.
|
|
///
|
|
static int IdxCompare(Constant *C1, Constant *C2) {
|
|
if (C1 == C2) return 0;
|
|
|
|
// Ok, we found a different index. Are either of the operands
|
|
// ConstantExprs? If so, we can't do anything with them.
|
|
if (!isa<ConstantInt>(C1) || !isa<ConstantInt>(C2))
|
|
return -2; // don't know!
|
|
|
|
// Ok, we have two differing integer indices. Convert them to
|
|
// be the same type. Long is always big enough, so we use it.
|
|
C1 = ConstantExpr::getCast(C1, Type::LongTy);
|
|
C2 = ConstantExpr::getCast(C2, Type::LongTy);
|
|
if (C1 == C2) return 0; // Are they just differing types?
|
|
|
|
// If they are really different, now that they are the same type, then we
|
|
// found a difference!
|
|
if (cast<ConstantSInt>(C1)->getValue() < cast<ConstantSInt>(C2)->getValue())
|
|
return -1;
|
|
else
|
|
return 1;
|
|
}
|
|
|
|
/// evaluateRelation - This function determines if there is anything we can
|
|
/// decide about the two constants provided. This doesn't need to handle simple
|
|
/// things like integer comparisons, but should instead handle ConstantExpr's
|
|
/// and ConstantPointerRef's. If we can determine that the two constants have a
|
|
/// particular relation to each other, we should return the corresponding SetCC
|
|
/// code, otherwise return Instruction::BinaryOpsEnd.
|
|
///
|
|
/// To simplify this code we canonicalize the relation so that the first
|
|
/// operand is always the most "complex" of the two. We consider simple
|
|
/// constants (like ConstantInt) to be the simplest, followed by
|
|
/// ConstantPointerRef's, followed by ConstantExpr's (the most complex).
|
|
///
|
|
static Instruction::BinaryOps evaluateRelation(const Constant *V1,
|
|
const Constant *V2) {
|
|
assert(V1->getType() == V2->getType() &&
|
|
"Cannot compare different types of values!");
|
|
if (V1 == V2) return Instruction::SetEQ;
|
|
|
|
if (!isa<ConstantExpr>(V1) && !isa<ConstantPointerRef>(V1)) {
|
|
// If the first operand is simple, swap operands.
|
|
assert((isa<ConstantPointerRef>(V2) || isa<ConstantExpr>(V2)) &&
|
|
"Simple cases should have been handled by caller!");
|
|
return SetCondInst::getSwappedCondition(evaluateRelation(V2, V1));
|
|
|
|
} else if (const ConstantPointerRef *CPR1 = dyn_cast<ConstantPointerRef>(V1)){
|
|
if (isa<ConstantExpr>(V2)) // Swap as necessary.
|
|
return SetCondInst::getSwappedCondition(evaluateRelation(V2, V1));
|
|
|
|
// Now we know that the RHS is a ConstantPointerRef or simple constant,
|
|
// which (since the types must match) means that it's a ConstantPointerNull.
|
|
if (const ConstantPointerRef *CPR2 = dyn_cast<ConstantPointerRef>(V2)) {
|
|
assert(CPR1->getValue() != CPR2->getValue() &&
|
|
"CPRs for the same value exist at different addresses??");
|
|
// FIXME: If both globals are external weak, they might both be null!
|
|
return Instruction::SetNE;
|
|
} else {
|
|
assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!");
|
|
// Global can never be null. FIXME: if we implement external weak
|
|
// linkage, this is not necessarily true!
|
|
return Instruction::SetNE;
|
|
}
|
|
|
|
} else {
|
|
// Ok, the LHS is known to be a constantexpr. The RHS can be any of a
|
|
// constantexpr, a CPR, or a simple constant.
|
|
const ConstantExpr *CE1 = cast<ConstantExpr>(V1);
|
|
Constant *CE1Op0 = CE1->getOperand(0);
|
|
|
|
switch (CE1->getOpcode()) {
|
|
case Instruction::Cast:
|
|
// If the cast is not actually changing bits, and the second operand is a
|
|
// null pointer, do the comparison with the pre-casted value.
|
|
if (V2->isNullValue() &&
|
|
CE1->getType()->isLosslesslyConvertibleTo(CE1Op0->getType()))
|
|
return evaluateRelation(CE1Op0,
|
|
Constant::getNullValue(CE1Op0->getType()));
|
|
|
|
case Instruction::GetElementPtr:
|
|
// Ok, since this is a getelementptr, we know that the constant has a
|
|
// pointer type. Check the various cases.
|
|
if (isa<ConstantPointerNull>(V2)) {
|
|
// If we are comparing a GEP to a null pointer, check to see if the base
|
|
// of the GEP equals the null pointer.
|
|
if (isa<ConstantPointerRef>(CE1Op0)) {
|
|
// FIXME: this is not true when we have external weak references!
|
|
// No offset can go from a global to a null pointer.
|
|
return Instruction::SetGT;
|
|
} else if (isa<ConstantPointerNull>(CE1Op0)) {
|
|
// If we are indexing from a null pointer, check to see if we have any
|
|
// non-zero indices.
|
|
for (unsigned i = 1, e = CE1->getNumOperands(); i != e; ++i)
|
|
if (!CE1->getOperand(i)->isNullValue())
|
|
// Offsetting from null, must not be equal.
|
|
return Instruction::SetGT;
|
|
// Only zero indexes from null, must still be zero.
|
|
return Instruction::SetEQ;
|
|
}
|
|
// Otherwise, we can't really say if the first operand is null or not.
|
|
} else if (const ConstantPointerRef *CPR2 =
|
|
dyn_cast<ConstantPointerRef>(V2)) {
|
|
if (isa<ConstantPointerNull>(CE1Op0)) {
|
|
// FIXME: This is not true with external weak references.
|
|
return Instruction::SetLT;
|
|
} else if (const ConstantPointerRef *CPR1 =
|
|
dyn_cast<ConstantPointerRef>(CE1Op0)) {
|
|
if (CPR1 == CPR2) {
|
|
// If this is a getelementptr of the same global, then it must be
|
|
// different. Because the types must match, the getelementptr could
|
|
// only have at most one index, and because we fold getelementptr's
|
|
// with a single zero index, it must be nonzero.
|
|
assert(CE1->getNumOperands() == 2 &&
|
|
!CE1->getOperand(1)->isNullValue() &&
|
|
"Suprising getelementptr!");
|
|
return Instruction::SetGT;
|
|
} else {
|
|
// If they are different globals, we don't know what the value is,
|
|
// but they can't be equal.
|
|
return Instruction::SetNE;
|
|
}
|
|
}
|
|
} else {
|
|
const ConstantExpr *CE2 = cast<ConstantExpr>(V2);
|
|
const Constant *CE2Op0 = CE2->getOperand(0);
|
|
|
|
// There are MANY other foldings that we could perform here. They will
|
|
// probably be added on demand, as they seem needed.
|
|
switch (CE2->getOpcode()) {
|
|
default: break;
|
|
case Instruction::GetElementPtr:
|
|
// By far the most common case to handle is when the base pointers are
|
|
// obviously to the same or different globals.
|
|
if (isa<ConstantPointerRef>(CE1Op0) &&
|
|
isa<ConstantPointerRef>(CE2Op0)) {
|
|
if (CE1Op0 != CE2Op0) // Don't know relative ordering, but not equal
|
|
return Instruction::SetNE;
|
|
// Ok, we know that both getelementptr instructions are based on the
|
|
// same global. From this, we can precisely determine the relative
|
|
// ordering of the resultant pointers.
|
|
unsigned i = 1;
|
|
|
|
// Compare all of the operands the GEP's have in common.
|
|
for (;i != CE1->getNumOperands() && i != CE2->getNumOperands(); ++i)
|
|
switch (IdxCompare(CE1->getOperand(i), CE2->getOperand(i))) {
|
|
case -1: return Instruction::SetLT;
|
|
case 1: return Instruction::SetGT;
|
|
case -2: return Instruction::BinaryOpsEnd;
|
|
}
|
|
|
|
// Ok, we ran out of things they have in common. If any leftovers
|
|
// are non-zero then we have a difference, otherwise we are equal.
|
|
for (; i < CE1->getNumOperands(); ++i)
|
|
if (!CE1->getOperand(i)->isNullValue())
|
|
return Instruction::SetGT;
|
|
for (; i < CE2->getNumOperands(); ++i)
|
|
if (!CE2->getOperand(i)->isNullValue())
|
|
return Instruction::SetLT;
|
|
return Instruction::SetEQ;
|
|
}
|
|
}
|
|
}
|
|
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
|
|
return Instruction::BinaryOpsEnd;
|
|
}
|
|
|
|
Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
|
|
const Constant *V1,
|
|
const Constant *V2) {
|
|
Constant *C = 0;
|
|
switch (Opcode) {
|
|
default: break;
|
|
case Instruction::Add: C = ConstRules::get(V1, V2).add(V1, V2); break;
|
|
case Instruction::Sub: C = ConstRules::get(V1, V2).sub(V1, V2); break;
|
|
case Instruction::Mul: C = ConstRules::get(V1, V2).mul(V1, V2); break;
|
|
case Instruction::Div: C = ConstRules::get(V1, V2).div(V1, V2); break;
|
|
case Instruction::Rem: C = ConstRules::get(V1, V2).rem(V1, V2); break;
|
|
case Instruction::And: C = ConstRules::get(V1, V2).op_and(V1, V2); break;
|
|
case Instruction::Or: C = ConstRules::get(V1, V2).op_or (V1, V2); break;
|
|
case Instruction::Xor: C = ConstRules::get(V1, V2).op_xor(V1, V2); break;
|
|
case Instruction::Shl: C = ConstRules::get(V1, V2).shl(V1, V2); break;
|
|
case Instruction::Shr: C = ConstRules::get(V1, V2).shr(V1, V2); break;
|
|
case Instruction::SetEQ: C = ConstRules::get(V1, V2).equalto(V1, V2); break;
|
|
case Instruction::SetLT: C = ConstRules::get(V1, V2).lessthan(V1, V2);break;
|
|
case Instruction::SetGT: C = ConstRules::get(V1, V2).lessthan(V2, V1);break;
|
|
case Instruction::SetNE: // V1 != V2 === !(V1 == V2)
|
|
C = ConstRules::get(V1, V2).equalto(V1, V2);
|
|
if (C) return ConstantExpr::get(Instruction::Xor, C, ConstantBool::True);
|
|
break;
|
|
case Instruction::SetLE: // V1 <= V2 === !(V2 < V1)
|
|
C = ConstRules::get(V1, V2).lessthan(V2, V1);
|
|
if (C) return ConstantExpr::get(Instruction::Xor, C, ConstantBool::True);
|
|
break;
|
|
case Instruction::SetGE: // V1 >= V2 === !(V1 < V2)
|
|
C = ConstRules::get(V1, V2).lessthan(V1, V2);
|
|
if (C) return ConstantExpr::get(Instruction::Xor, C, ConstantBool::True);
|
|
break;
|
|
}
|
|
|
|
// If we successfully folded the expression, return it now.
|
|
if (C) return C;
|
|
|
|
if (SetCondInst::isRelational(Opcode))
|
|
switch (evaluateRelation(V1, V2)) {
|
|
default: assert(0 && "Unknown relational!");
|
|
case Instruction::BinaryOpsEnd:
|
|
break; // Couldn't determine anything about these constants.
|
|
case Instruction::SetEQ: // We know the constants are equal!
|
|
// If we know the constants are equal, we can decide the result of this
|
|
// computation precisely.
|
|
return ConstantBool::get(Opcode == Instruction::SetEQ ||
|
|
Opcode == Instruction::SetLE ||
|
|
Opcode == Instruction::SetGE);
|
|
case Instruction::SetLT:
|
|
// If we know that V1 < V2, we can decide the result of this computation
|
|
// precisely.
|
|
return ConstantBool::get(Opcode == Instruction::SetLT ||
|
|
Opcode == Instruction::SetNE ||
|
|
Opcode == Instruction::SetLE);
|
|
case Instruction::SetGT:
|
|
// If we know that V1 > V2, we can decide the result of this computation
|
|
// precisely.
|
|
return ConstantBool::get(Opcode == Instruction::SetGT ||
|
|
Opcode == Instruction::SetNE ||
|
|
Opcode == Instruction::SetGE);
|
|
case Instruction::SetLE:
|
|
// If we know that V1 <= V2, we can only partially decide this relation.
|
|
if (Opcode == Instruction::SetGT) return ConstantBool::False;
|
|
if (Opcode == Instruction::SetLT) return ConstantBool::True;
|
|
break;
|
|
|
|
case Instruction::SetGE:
|
|
// If we know that V1 >= V2, we can only partially decide this relation.
|
|
if (Opcode == Instruction::SetLT) return ConstantBool::False;
|
|
if (Opcode == Instruction::SetGT) return ConstantBool::True;
|
|
break;
|
|
|
|
case Instruction::SetNE:
|
|
// If we know that V1 != V2, we can only partially decide this relation.
|
|
if (Opcode == Instruction::SetEQ) return ConstantBool::False;
|
|
if (Opcode == Instruction::SetNE) return ConstantBool::True;
|
|
break;
|
|
}
|
|
|
|
if (const ConstantExpr *CE1 = dyn_cast<ConstantExpr>(V1)) {
|
|
if (const ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2)) {
|
|
// There are many possible foldings we could do here. We should probably
|
|
// at least fold add of a pointer with an integer into the appropriate
|
|
// getelementptr. This will improve alias analysis a bit.
|
|
|
|
|
|
|
|
|
|
} else {
|
|
// Just implement a couple of simple identities.
|
|
switch (Opcode) {
|
|
case Instruction::Add:
|
|
if (V2->isNullValue()) return const_cast<Constant*>(V1); // X + 0 == X
|
|
break;
|
|
case Instruction::Sub:
|
|
if (V2->isNullValue()) return const_cast<Constant*>(V1); // X - 0 == X
|
|
break;
|
|
case Instruction::Mul:
|
|
if (V2->isNullValue()) return const_cast<Constant*>(V2); // X * 0 == 0
|
|
if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
|
|
if (CI->getRawValue() == 1)
|
|
return const_cast<Constant*>(V1); // X * 1 == X
|
|
break;
|
|
case Instruction::Div:
|
|
if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
|
|
if (CI->getRawValue() == 1)
|
|
return const_cast<Constant*>(V1); // X / 1 == X
|
|
break;
|
|
case Instruction::Rem:
|
|
if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
|
|
if (CI->getRawValue() == 1)
|
|
return Constant::getNullValue(CI->getType()); // X % 1 == 0
|
|
break;
|
|
case Instruction::And:
|
|
if (cast<ConstantIntegral>(V2)->isAllOnesValue())
|
|
return const_cast<Constant*>(V1); // X & -1 == X
|
|
if (V2->isNullValue()) return const_cast<Constant*>(V2); // X & 0 == 0
|
|
break;
|
|
case Instruction::Or:
|
|
if (V2->isNullValue()) return const_cast<Constant*>(V1); // X | 0 == X
|
|
if (cast<ConstantIntegral>(V2)->isAllOnesValue())
|
|
return const_cast<Constant*>(V2); // X | -1 == -1
|
|
break;
|
|
case Instruction::Xor:
|
|
if (V2->isNullValue()) return const_cast<Constant*>(V1); // X ^ 0 == X
|
|
break;
|
|
}
|
|
}
|
|
|
|
} else if (const ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2)) {
|
|
// If V2 is a constant expr and V1 isn't, flop them around and fold the
|
|
// other way if possible.
|
|
switch (Opcode) {
|
|
case Instruction::Add:
|
|
case Instruction::Mul:
|
|
case Instruction::And:
|
|
case Instruction::Or:
|
|
case Instruction::Xor:
|
|
case Instruction::SetEQ:
|
|
case Instruction::SetNE:
|
|
// No change of opcode required.
|
|
return ConstantFoldBinaryInstruction(Opcode, V2, V1);
|
|
|
|
case Instruction::SetLT:
|
|
case Instruction::SetGT:
|
|
case Instruction::SetLE:
|
|
case Instruction::SetGE:
|
|
// Change the opcode as necessary to swap the operands.
|
|
Opcode = SetCondInst::getSwappedCondition((Instruction::BinaryOps)Opcode);
|
|
return ConstantFoldBinaryInstruction(Opcode, V2, V1);
|
|
|
|
case Instruction::Shl:
|
|
case Instruction::Shr:
|
|
case Instruction::Sub:
|
|
case Instruction::Div:
|
|
case Instruction::Rem:
|
|
default: // These instructions cannot be flopped around.
|
|
break;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
Constant *llvm::ConstantFoldGetElementPtr(const Constant *C,
|
|
const std::vector<Constant*> &IdxList) {
|
|
if (IdxList.size() == 0 ||
|
|
(IdxList.size() == 1 && IdxList[0]->isNullValue()))
|
|
return const_cast<Constant*>(C);
|
|
|
|
// TODO If C is null and all idx's are null, return null of the right type.
|
|
|
|
|
|
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(const_cast<Constant*>(C))) {
|
|
// Combine Indices - If the source pointer to this getelementptr instruction
|
|
// is a getelementptr instruction, combine the indices of the two
|
|
// getelementptr instructions into a single instruction.
|
|
//
|
|
if (CE->getOpcode() == Instruction::GetElementPtr) {
|
|
const Type *LastTy = 0;
|
|
for (gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
|
|
I != E; ++I)
|
|
LastTy = *I;
|
|
|
|
if ((LastTy && isa<ArrayType>(LastTy)) || IdxList[0]->isNullValue()) {
|
|
std::vector<Constant*> NewIndices;
|
|
NewIndices.reserve(IdxList.size() + CE->getNumOperands());
|
|
for (unsigned i = 1, e = CE->getNumOperands()-1; i != e; ++i)
|
|
NewIndices.push_back(cast<Constant>(CE->getOperand(i)));
|
|
|
|
// Add the last index of the source with the first index of the new GEP.
|
|
// Make sure to handle the case when they are actually different types.
|
|
Constant *Combined = CE->getOperand(CE->getNumOperands()-1);
|
|
if (!IdxList[0]->isNullValue()) // Otherwise it must be an array
|
|
Combined =
|
|
ConstantExpr::get(Instruction::Add,
|
|
ConstantExpr::getCast(IdxList[0], Type::LongTy),
|
|
ConstantExpr::getCast(Combined, Type::LongTy));
|
|
|
|
NewIndices.push_back(Combined);
|
|
NewIndices.insert(NewIndices.end(), IdxList.begin()+1, IdxList.end());
|
|
return ConstantExpr::getGetElementPtr(CE->getOperand(0), NewIndices);
|
|
}
|
|
}
|
|
|
|
// Implement folding of:
|
|
// int* getelementptr ([2 x int]* cast ([3 x int]* %X to [2 x int]*),
|
|
// long 0, long 0)
|
|
// To: int* getelementptr ([3 x int]* %X, long 0, long 0)
|
|
//
|
|
if (CE->getOpcode() == Instruction::Cast && IdxList.size() > 1 &&
|
|
IdxList[0]->isNullValue())
|
|
if (const PointerType *SPT =
|
|
dyn_cast<PointerType>(CE->getOperand(0)->getType()))
|
|
if (const ArrayType *SAT = dyn_cast<ArrayType>(SPT->getElementType()))
|
|
if (const ArrayType *CAT =
|
|
dyn_cast<ArrayType>(cast<PointerType>(C->getType())->getElementType()))
|
|
if (CAT->getElementType() == SAT->getElementType())
|
|
return ConstantExpr::getGetElementPtr(
|
|
(Constant*)CE->getOperand(0), IdxList);
|
|
}
|
|
return 0;
|
|
}
|
|
|