--- /dev/null
+/* 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
+<http://www.gnu.org/licenses/>. */
+
+/* 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);
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