コード例 #1
0
        // This is before the expression is processed, so ILValue's and constants havn't been assigned

        public bool SimplifyTernaryOperator(IList <ILNode> body, ILBasicBlock head, int pos)
        {
            Debug.Assert(body.Contains(head));
            //    Debug.Assert((head.Body[0] as ILLabel).Name != "Block_54");
            //     Debug.Assert((head.Body[0] as ILLabel).Name != "L1257");
            ILExpression condExpr;
            ILLabel      trueLabel;
            ILLabel      falseLabel;

            ILExpression trueExpr;
            ILLabel      trueFall;

            ILExpression falseExpr;
            ILLabel      falseFall;


            ILLabel finalFalseFall;
            ILLabel finalTrueFall;

            if (head.MatchLastAndBr(GMCode.Bt, out trueLabel, out condExpr, out falseLabel) &&
                labelGlobalRefCount[trueLabel] == 1 &&
                labelGlobalRefCount[falseLabel] == 1 &&
                labelToBasicBlock[trueLabel].MatchSingleAndBr(GMCode.Push, out trueExpr, out trueFall) &&
                labelToBasicBlock[falseLabel].MatchSingleAndBr(GMCode.Push, out falseExpr, out falseFall) &&
                trueFall == falseFall &&
                body.Contains(labelToBasicBlock[trueFall])
                // finalFall.Code == GMCode.Pop
                ) // (finalFall == null || finalFall.Code == GMCode.Pop)
            {
                ILBasicBlock trueBlock  = labelToBasicBlock[trueLabel];
                ILBasicBlock falseBlock = labelToBasicBlock[falseLabel];
                ILBasicBlock fallBlock  = labelToBasicBlock[trueFall];
                ILExpression newExpr    = ResolveTernaryExpression(condExpr, trueExpr, falseExpr);

                head.Body.RemoveTail(GMCode.Bt, GMCode.B);
                body.RemoveOrThrow(trueBlock);
                body.RemoveOrThrow(falseBlock);
                IList <ILExpression> finalFall;
                // figure out if its a wierd short or not
                if (fallBlock.MatchSingleAndBr(GMCode.Bt, out finalTrueFall, out finalFall, out finalFalseFall) &&
                    finalFall.Count == 0)
                {
                    head.Body.Add(new ILExpression(GMCode.Bt, finalTrueFall, newExpr));
                    if (labelGlobalRefCount[trueFall] == 2)
                    {
                        body.RemoveOrThrow(fallBlock);
                    }
                }
                else if (fallBlock.Body.Count == 2)  // wierd break,
                {
                    finalFalseFall = fallBlock.GotoLabel();
                    head.Body.Add(new ILExpression(GMCode.Push, null, newExpr)); // we want to push it for next pass
                    if (labelGlobalRefCount[trueFall] == 2)
                    {
                        body.RemoveOrThrow(fallBlock);
                    }
                }
                else if (fallBlock.MatchAt(1, GMCode.Pop))  // generated? wierd instance?
                {
                    finalFalseFall = fallBlock.EntryLabel();
                    error.Info("Wierd Generated Pop here", newExpr);
                    head.Body.Add(new ILExpression(GMCode.Push, null, newExpr));
                    // It should be combined in JoinBasicBlocks function
                    // so don't remove failblock
                }
                else if (fallBlock.MatchAt(1, GMCode.Assign, out finalFall)) // This is an assignment case and unsure what its for
                {
                    finalFall.Add(newExpr);
                    finalFalseFall = fallBlock.EntryLabel();
                }
                if (finalFalseFall == null && fallBlock.MatchLastAt(1, GMCode.Ret))
                {
                    head.Body.Add(new ILExpression(GMCode.Ret, null));
                }
                else
                {
                    Debug.Assert(finalFalseFall != null);
                    head.Body.Add(new ILExpression(GMCode.B, finalFalseFall));
                }
                return(true);
            }
            return(false);
        }