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Diffstat (limited to 'gcc-4.9/libgcc/config/cris/mulsi3.S')
| -rw-r--r-- | gcc-4.9/libgcc/config/cris/mulsi3.S | 269 |
1 files changed, 269 insertions, 0 deletions
diff --git a/gcc-4.9/libgcc/config/cris/mulsi3.S b/gcc-4.9/libgcc/config/cris/mulsi3.S new file mode 100644 index 000000000..240895df0 --- /dev/null +++ b/gcc-4.9/libgcc/config/cris/mulsi3.S @@ -0,0 +1,269 @@ +;; Copyright (C) 2001-2014 Free Software Foundation, Inc. +;; +;; 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. +;; +;; Under Section 7 of GPL version 3, you are granted additional +;; permissions described in the GCC Runtime Library Exception, version +;; 3.1, as published by the Free Software Foundation. +;; +;; You should have received a copy of the GNU General Public License and +;; a copy of the GCC Runtime Library Exception along with this program; +;; see the files COPYING3 and COPYING.RUNTIME respectively. If not, see +;; <http://www.gnu.org/licenses/>. +;; +;; This code used to be expanded through interesting expansions in +;; the machine description, compiled from this code: +;; +;; #ifdef L_mulsi3 +;; long __Mul (unsigned long a, unsigned long b) __attribute__ ((__const__)); +;; +;; /* This must be compiled with the -mexpand-mul flag, to synthesize the +;; multiplication from the mstep instructions. The check for +;; smaller-size multiplication pays off in the order of .5-10%; +;; estimated median 1%, depending on application. +;; FIXME: It can be further optimized if we go to assembler code, as +;; gcc 2.7.2 adds a few unnecessary instructions and does not put the +;; basic blocks in optimal order. */ +;; long +;; __Mul (unsigned long a, unsigned long b) +;; { +;; #if defined (__CRIS_arch_version) && __CRIS_arch_version >= 10 +;; /* In case other code is compiled without -march=v10, they will +;; contain calls to __Mul, regardless of flags at link-time. The +;; "else"-code below will work, but is unnecessarily slow. This +;; sometimes cuts a few minutes off from simulation time by just +;; returning a "mulu.d". */ +;; return a * b; +;; #else +;; unsigned long min; +;; +;; /* Get minimum via the bound insn. */ +;; min = a < b ? a : b; +;; +;; /* Can we omit computation of the high part? */ +;; if (min > 65535) +;; /* No. Perform full multiplication. */ +;; return a * b; +;; else +;; { +;; /* Check if both operands are within 16 bits. */ +;; unsigned long max; +;; +;; /* Get maximum, by knowing the minimum. +;; This will partition a and b into max and min. +;; This is not currently something GCC understands, +;; so do this trick by asm. */ +;; __asm__ ("xor %1,%0\n\txor %2,%0" +;; : "=r" (max) +;; : "r" (b), "r" (a), "0" (min)); +;; +;; if (max > 65535) +;; /* Make GCC understand that only the low part of "min" will be +;; used. */ +;; return max * (unsigned short) min; +;; else +;; /* Only the low parts of both operands are necessary. */ +;; return ((unsigned short) max) * (unsigned short) min; +;; } +;; #endif /* not __CRIS_arch_version >= 10 */ +;; } +;; #endif /* L_mulsi3 */ +;; +;; That approach was abandoned since the caveats outweighted the +;; benefits. The expand-multiplication machinery is also removed, so you +;; can't do this anymore. +;; +;; For doubters of there being any benefits, some where: insensitivity to: +;; - ABI changes (mostly for experimentation) +;; - assembler syntax differences (mostly debug format). +;; - insn scheduling issues. +;; Most ABI experiments will presumably happen with arches with mul insns, +;; so that argument doesn't really hold anymore, and it's unlikely there +;; being new arch variants needing insn scheduling and not having mul +;; insns. + +;; ELF and a.out have different syntax for local labels: the "wrong" +;; one may not be omitted from the object. +#undef L +#ifdef __AOUT__ +# define L(x) x +#else +# define L(x) .x +#endif + + .global ___Mul + .type ___Mul,@function +___Mul: +#if defined (__CRIS_arch_version) && __CRIS_arch_version >= 10 +;; Can't have the mulu.d last on a cache-line (in the delay-slot of the +;; "ret"), due to hardware bug. See documentation for -mmul-bug-workaround. +;; Not worthwhile to conditionalize here. + .p2alignw 2,0x050f + mulu.d $r11,$r10 + ret + nop +#else +;; See if we can avoid multiplying some of the parts, knowing +;; they're zero. + + move.d $r11,$r9 + bound.d $r10,$r9 + cmpu.w 65535,$r9 + bls L(L3) + move.d $r10,$r12 + +;; Nope, have to do all the parts of a 32-bit multiplication. +;; See head comment in optabs.c:expand_doubleword_mult. + + move.d $r10,$r13 + movu.w $r11,$r9 ; ab*cd = (a*d + b*c)<<16 + b*d + lslq 16,$r13 + mstep $r9,$r13 ; d*b + mstep $r9,$r13 + mstep $r9,$r13 + mstep $r9,$r13 + mstep $r9,$r13 + mstep $r9,$r13 + mstep $r9,$r13 + mstep $r9,$r13 + mstep $r9,$r13 + mstep $r9,$r13 + mstep $r9,$r13 + mstep $r9,$r13 + mstep $r9,$r13 + mstep $r9,$r13 + mstep $r9,$r13 + mstep $r9,$r13 + clear.w $r10 + test.d $r10 + mstep $r9,$r10 ; d*a + mstep $r9,$r10 + mstep $r9,$r10 + mstep $r9,$r10 + mstep $r9,$r10 + mstep $r9,$r10 + mstep $r9,$r10 + mstep $r9,$r10 + mstep $r9,$r10 + mstep $r9,$r10 + mstep $r9,$r10 + mstep $r9,$r10 + mstep $r9,$r10 + mstep $r9,$r10 + mstep $r9,$r10 + mstep $r9,$r10 + movu.w $r12,$r12 + clear.w $r11 + move.d $r11,$r9 ; Doubles as a "test.d" preparing for the mstep. + mstep $r12,$r9 ; b*c + mstep $r12,$r9 + mstep $r12,$r9 + mstep $r12,$r9 + mstep $r12,$r9 + mstep $r12,$r9 + mstep $r12,$r9 + mstep $r12,$r9 + mstep $r12,$r9 + mstep $r12,$r9 + mstep $r12,$r9 + mstep $r12,$r9 + mstep $r12,$r9 + mstep $r12,$r9 + mstep $r12,$r9 + mstep $r12,$r9 + add.w $r9,$r10 + lslq 16,$r10 + ret + add.d $r13,$r10 + +L(L3): +;; Form the maximum in $r10, by knowing the minimum, $r9. +;; (We don't know which one of $r10 or $r11 it is.) +;; Check if the largest operand is still just 16 bits. + + xor $r9,$r10 + xor $r11,$r10 + cmpu.w 65535,$r10 + bls L(L5) + movu.w $r9,$r13 + +;; We have ab*cd = (a*c)<<32 + (a*d + b*c)<<16 + b*d, but c==0 +;; so we only need (a*d)<<16 + b*d with d = $r13, ab = $r10. +;; We drop the upper part of (a*d)<<16 as we're only doing a +;; 32-bit-result multiplication. + + move.d $r10,$r9 + lslq 16,$r9 + mstep $r13,$r9 ; b*d + mstep $r13,$r9 + mstep $r13,$r9 + mstep $r13,$r9 + mstep $r13,$r9 + mstep $r13,$r9 + mstep $r13,$r9 + mstep $r13,$r9 + mstep $r13,$r9 + mstep $r13,$r9 + mstep $r13,$r9 + mstep $r13,$r9 + mstep $r13,$r9 + mstep $r13,$r9 + mstep $r13,$r9 + mstep $r13,$r9 + clear.w $r10 + test.d $r10 + mstep $r13,$r10 ; a*d + mstep $r13,$r10 + mstep $r13,$r10 + mstep $r13,$r10 + mstep $r13,$r10 + mstep $r13,$r10 + mstep $r13,$r10 + mstep $r13,$r10 + mstep $r13,$r10 + mstep $r13,$r10 + mstep $r13,$r10 + mstep $r13,$r10 + mstep $r13,$r10 + mstep $r13,$r10 + mstep $r13,$r10 + mstep $r13,$r10 + lslq 16,$r10 + ret + add.d $r9,$r10 + +L(L5): +;; We have ab*cd = (a*c)<<32 + (a*d + b*c)<<16 + b*d, but a and c==0 +;; so b*d (with b=$r13, a=$r10) it is. + + lslq 16,$r10 + mstep $r13,$r10 + mstep $r13,$r10 + mstep $r13,$r10 + mstep $r13,$r10 + mstep $r13,$r10 + mstep $r13,$r10 + mstep $r13,$r10 + mstep $r13,$r10 + mstep $r13,$r10 + mstep $r13,$r10 + mstep $r13,$r10 + mstep $r13,$r10 + mstep $r13,$r10 + mstep $r13,$r10 + mstep $r13,$r10 + ret + mstep $r13,$r10 +#endif +L(Lfe1): + .size ___Mul,L(Lfe1)-___Mul |