/* Definitions of target machine for GNU compiler, for IBM S/390 Copyright (C) 2002, 2003, 2004, 2005, 2007 Free Software Foundation, Inc. Contributed by Hartmut Penner (hpenner@de.ibm.com) and Ulrich Weigand (uweigand@de.ibm.com). This file is part of GCC. GCC is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version. GCC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GCC; see the file COPYING3. If not see . */ /* 256-bit integer mode is needed for STACK_SAVEAREA_MODE. */ INT_MODE (OI, 32); /* Define TFmode to work around reload problem PR 20927. */ FLOAT_MODE (TF, 16, ieee_quad_format); /* Add any extra modes needed to represent the condition code. */ /* Condition Codes Check for zero CCZ: EQ NE NE NE CCZ1: EQ NE (CS) Unsigned compares CCU: EQ LTU GTU NE (CLG/R, CL/R/Y, CLM/Y, CLI/Y) CCUR: EQ GTU LTU NE (CLGF/R) Signed compares CCS: EQ LT GT UNORDERED (LTGFR, LTGR, LTR, ICM/Y, LTDBR, LTDR, LTEBR, LTER, CG/R, C/R/Y, CGHI, CHI, CDB/R, CD/R, CEB/R, CE/R, ADB/R, AEB/R, SDB/R, SEB/R, SRAG, SRA, SRDA) CCSR: EQ GT LT UNORDERED (CGF/R, CH/Y) Condition codes resulting from add with overflow CCA: EQ LT GT Overflow CCAP: EQ LT GT LT (AGHI, AHI) CCAN: EQ LT GT GT (AGHI, AHI) Condition codes of unsigned adds and subs CCL: EQ NE EQ NE (ALGF/R, ALG/R, AL/R/Y, ALCG/R, ALC/R, SLGF/R, SLG/R, SL/R/Y, SLBG/R, SLB/R) CCL1: GEU GEU LTU LTU (ALG/R, AL/R/Y) CCL2: GTU GTU LEU LEU (SLG/R, SL/R/Y) CCL3: EQ LTU EQ GTU (SLG/R, SL/R/Y) Test under mask checks CCT: EQ NE NE NE (ICM/Y, TML, CG/R, CGHI, C/R/Y, CHI, NG/R, N/R/Y, OG/R, O/R/Y, XG/R, X/R/Y) CCT1: NE EQ NE NE (TMH, TML) CCT2: NE NE EQ NE (TMH, TML) CCT3: NE NE NE EQ (TMH, TML) CCA and CCT modes are request only modes. These modes are never returned by s390_select_cc_mode. They are only intended to match other modes. Requested mode -> Destination CC register mode CCS, CCU, CCT, CCSR, CCUR -> CCZ CCA -> CCAP, CCAN *** Comments *** CCAP, CCAN The CC obtained from add instruction usually can't be used for comparisons because its coupling with overflow flag. In case of an overflow the less than/greater than data are lost. Nevertheless a comparison can be done whenever immediate values are involved because they are known at compile time. If you know whether the used constant is positive or negative you can predict the sign of the result even in case of an overflow. CCT, CCT1, CCT2, CCT3 If bits of an integer masked with an AND instruction are checked, the test under mask instructions turn out to be very handy for a set of special cases. The simple cases are checks whether all masked bits are zero or ones: int a; if ((a & (16 + 128)) == 0) -> CCT/CCZ if ((a & (16 + 128)) == 16 + 128) -> CCT3 Using two extra modes makes it possible to do complete checks on two bits of an integer (This is possible on register operands only. TM does not provide the information necessary for CCT1 and CCT2 modes.): int a; if ((a & (16 + 128)) == 16) -> CCT1 if ((a & (16 + 128)) == 128) -> CCT2 CCSR, CCUR There are several instructions comparing 32 bit with 64-bit unsigned/signed values. Such instructions can be considered to have a builtin zero/sign_extend. The problem is that in the RTL (to be canonical) the zero/sign extended operand has to be the first one but the machine instructions like it the other way around. The following both modes can be considered as CCS and CCU modes with exchanged operands. CCL1, CCL2 These modes represent the result of overflow checks. if (a + b < a) -> CCL1 state of the carry bit (CC2 | CC3) if (a - b > a) -> CCL2 state of the borrow bit (CC0 | CC1) They are used when multi word numbers are computed dealing one SImode part after another or whenever manual overflow checks like the examples above are compiled. CCL3 A logical subtract instruction sets the borrow bit in case of an overflow. The resulting condition code of those instructions is represented by the CCL3 mode. Together with the CCU mode this mode is used for jumpless implementations of several if-constructs - see s390_expand_addcc for more details. CCZ1 The compare and swap instructions sets the condition code to 0/1 if the operands were equal/unequal. The CCZ1 mode ensures the result can be effectively placed into a register. */ CC_MODE (CCZ); CC_MODE (CCZ1); CC_MODE (CCA); CC_MODE (CCAP); CC_MODE (CCAN); CC_MODE (CCL); CC_MODE (CCL1); CC_MODE (CCL2); CC_MODE (CCL3); CC_MODE (CCU); CC_MODE (CCUR); CC_MODE (CCS); CC_MODE (CCSR); CC_MODE (CCT); CC_MODE (CCT1); CC_MODE (CCT2); CC_MODE (CCT3);