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//===- llvm/Analysis/Expressions.h - Expression Analysis Utils ---*- C++ -*--=//
//
// This file defines a package of expression analysis utilties:
//
// ClassifyExpression: Analyze an expression to determine the complexity of the
// expression, and which other variables it depends on.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ANALYSIS_EXPRESSIONS_H
#define LLVM_ANALYSIS_EXPRESSIONS_H
#include <assert.h>
class Value;
class ConstPoolInt;
struct ExprAnalysisResult;
// ClassifyExpression: Analyze an expression to determine the complexity of the
// expression, and which other values it depends on.
//
ExprAnalysisResult ClassifyExpression(Value *Expr);
// ExprAnalysisResult - Represent an expression of the form CONST*VAR+CONST
// or simpler. The expression form that yields the least information about the
// expression is just the Linear form with no offset.
//
struct ExprAnalysisResult {
enum ExpressionType {
Constant, // Expr is a simple constant, Offset is value
Linear, // Expr is linear expr, Value is Var+Offset
ScaledLinear, // Expr is scaled linear exp, Value is Scale*Var+Offset
} ExprType;
const ConstPoolInt *Offset; // Offset of expr, or null if 0
Value *Var; // Var referenced, if Linear or above (null if 0)
const ConstPoolInt *Scale; // Scale of var if ScaledLinear expr (null if 1)
inline ExprAnalysisResult(const ConstPoolInt *CPV = 0) {
Offset = CPV; Var = 0; Scale = 0;
ExprType = Constant;
}
inline ExprAnalysisResult(Value *Val) {
Var = Val; Offset = Scale = 0;
ExprType = Var ? Linear : Constant;
}
inline ExprAnalysisResult(const ConstPoolInt *scale, Value *var,
const ConstPoolInt *offset) {
assert(!(Scale && !Var) && "Can't have scaled nonvariable!");
Scale = scale; Var = var; Offset = offset;
ExprType = Scale ? ScaledLinear : (Var ? Linear : Constant);
}
private:
friend ExprAnalysisResult ClassifyExpression(Value *);
inline ExprAnalysisResult operator+(const ConstPoolInt *Offset);
};
#endif
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