gcc/config/s390/s390-modes.def

   1 /* Definitions of target machine for GNU compiler, for IBM S/390
   2    Copyright (C) 2002-2014 Free Software Foundation, Inc.
   3    Contributed by Hartmut Penner (hpenner@de.ibm.com) and
   4                   Ulrich Weigand (uweigand@de.ibm.com).
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 3, or (at your option) any later
  11 version.
  12
  13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING3.  If not see
  20 <http://www.gnu.org/licenses/>.  */
  21
  22 /* 256-bit integer mode is needed for STACK_SAVEAREA_MODE.  */
  23 INT_MODE (OI, 32);
  24
  25 /* Define TFmode to work around reload problem PR 20927.  */
  26 FLOAT_MODE (TF, 16, ieee_quad_format);
  27
  28 /* Add any extra modes needed to represent the condition code.  */
  29
  30 /*
  31
  32 Condition Codes
  33
  34 Check for zero
  35
  36 CCZ:  EQ          NE           NE          NE
  37 CCZ1: EQ          NE                                  (CS)
  38
  39 Unsigned compares
  40
  41 CCU:  EQ          LTU          GTU         NE         (CLG/R, CL/R/Y, CLM/Y, CLI/Y)
  42 CCUR: EQ          GTU          LTU         NE         (CLGF/R)
  43
  44 Signed compares
  45
  46 CCS:  EQ          LT           GT          UNORDERED  (LTGFR, LTGR, LTR, ICM/Y,
  47                                                        LTDBR, LTDR, LTEBR, LTER,
  48                                                        CG/R, C/R/Y, CGHI, CHI,
  49                                                        CDB/R, CD/R, CEB/R, CE/R,
  50                                                        ADB/R, AEB/R, SDB/R, SEB/R,
  51                                                        SRAG, SRA, SRDA)
  52 CCSR: EQ          GT           LT          UNORDERED  (CGF/R, CH/Y)
  53
  54 Condition codes resulting from add with overflow
  55
  56 CCA:  EQ          LT           GT          Overflow
  57 CCAP: EQ          LT           GT          LT         (AGHI, AHI)
  58 CCAN: EQ          LT           GT          GT         (AGHI, AHI)
  59
  60 Condition codes of unsigned adds and subs
  61
  62 CCL:  EQ          NE           EQ          NE         (ALGF/R, ALG/R, AL/R/Y,
  63                                                        ALCG/R, ALC/R,
  64                                                        SLGF/R, SLG/R, SL/R/Y,
  65                                                        SLBG/R, SLB/R)
  66 CCL1: GEU         GEU          LTU         LTU        (ALG/R, AL/R/Y)
  67 CCL2: GTU         GTU          LEU         LEU        (SLG/R, SL/R/Y)
  68 CCL3: EQ          LTU          EQ          GTU        (SLG/R, SL/R/Y)
  69
  70 Test under mask checks
  71
  72 CCT:  EQ          NE           NE          NE         (ICM/Y, TML, CG/R, CGHI,
  73                                                        C/R/Y, CHI, NG/R, N/R/Y,
  74                                                        OG/R, O/R/Y, XG/R, X/R/Y)
  75 CCT1: NE          EQ           NE          NE         (TMH, TML)
  76 CCT2: NE          NE           EQ          NE         (TMH, TML)
  77 CCT3: NE          NE           NE          EQ         (TMH, TML)
  78
  79 CCA and CCT modes are request only modes. These modes are never returned by
  80 s390_select_cc_mode. They are only intended to match other modes.
  81
  82 Requested mode            -> Destination CC register mode
  83
  84 CCS, CCU, CCT, CCSR, CCUR -> CCZ
  85 CCA                       -> CCAP, CCAN
  86
  87
  88 *** Comments ***
  89
  90 CCAP, CCAN
  91
  92 The CC obtained from add instruction usually can't be used for comparisons
  93 because its coupling with overflow flag. In case of an overflow the
  94 less than/greater than data are lost. Nevertheless a comparison can be done
  95 whenever immediate values are involved because they are known at compile time.
  96 If you know whether the used constant is positive or negative you can predict
  97 the sign of the result even in case of an overflow.
  98
  99
 100 CCT, CCT1, CCT2, CCT3
 101
 102 If bits of an integer masked with an AND instruction are checked, the test under
 103 mask instructions turn out to be very handy for a set of special cases.
 104 The simple cases are checks whether all masked bits are zero or ones:
 105
 106   int a;
 107   if ((a & (16 + 128)) == 0)          -> CCT/CCZ
 108   if ((a & (16 + 128)) == 16 + 128)   -> CCT3
 109
 110 Using two extra modes makes it possible to do complete checks on two bits of an
 111 integer (This is possible on register operands only. TM does not provide the
 112 information necessary for CCT1 and CCT2 modes.):
 113
 114   int a;
 115   if ((a & (16 + 128)) == 16)         -> CCT1
 116   if ((a & (16 + 128)) == 128)        -> CCT2
 117
 118
 119 CCSR, CCUR
 120
 121 There are several instructions comparing 32 bit with 64-bit unsigned/signed
 122 values. Such instructions can be considered to have a builtin zero/sign_extend.
 123 The problem is that in the RTL (to be canonical) the zero/sign extended operand
 124 has to be the first one but the machine instructions like it the other way
 125 around. The following both modes can be considered as CCS and CCU modes with
 126 exchanged operands.
 127
 128
 129 CCL1, CCL2
 130
 131 These modes represent the result of overflow checks.
 132
 133 if (a + b < a) -> CCL1 state of the carry bit   (CC2 | CC3)
 134 if (a - b > a) -> CCL2 state of the borrow bit  (CC0 | CC1)
 135
 136 They are used when multi word numbers are computed dealing one SImode part after
 137 another or whenever manual overflow checks like the examples above are
 138 compiled.
 139
 140
 141 CCL3
 142
 143 A logical subtract instruction sets the borrow bit in case of an overflow.
 144 The resulting condition code of those instructions is represented by the
 145 CCL3 mode. Together with the CCU mode this mode is used for jumpless
 146 implementations of several if-constructs - see s390_expand_addcc for more
 147 details.
 148
 149 CCZ1
 150
 151 The compare and swap instructions sets the condition code to 0/1 if the
 152 operands were equal/unequal. The CCZ1 mode ensures the result can be
 153 effectively placed into a register.
 154
 155 CCRAW
 156
 157 The cc mode generated by a non-compare instruction.  The condition
 158 code mask for the CC consumer is determined by the comparison operator
 159 (only EQ and NE allowed) and the immediate value given as second
 160 operand to the operator.  For the other CC modes this value used to be
 161 0.
 162
 163 */
 164
 165
 166 CC_MODE (CCZ);
 167 CC_MODE (CCZ1);
 168 CC_MODE (CCA);
 169 CC_MODE (CCAP);
 170 CC_MODE (CCAN);
 171 CC_MODE (CCL);
 172 CC_MODE (CCL1);
 173 CC_MODE (CCL2);
 174 CC_MODE (CCL3);
 175 CC_MODE (CCU);
 176 CC_MODE (CCUR);
 177 CC_MODE (CCS);
 178 CC_MODE (CCSR);
 179 CC_MODE (CCT);
 180 CC_MODE (CCT1);
 181 CC_MODE (CCT2);
 182 CC_MODE (CCT3);
 183 CC_MODE (CCRAW);