| ;; 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 |
| move.d $r10,$r12 |
| move.d $r11,$r9 |
| bound.d $r12,$r9 |
| cmpu.w 65535,$r9 |
| bls L(L3) |
| move.d $r12,$r13 |
| |
| movu.w $r11,$r9 |
| lslq 16,$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 |
| mstep $r9,$r13 |
| mstep $r9,$r13 |
| clear.w $r10 |
| test.d $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 |
| mstep $r9,$r10 |
| mstep $r9,$r10 |
| movu.w $r12,$r12 |
| move.d $r11,$r9 |
| clear.w $r9 |
| test.d $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 |
| mstep $r12,$r9 |
| mstep $r12,$r9 |
| add.w $r9,$r10 |
| lslq 16,$r10 |
| ret |
| add.d $r13,$r10 |
| |
| L(L3): |
| move.d $r9,$r10 |
| xor $r11,$r10 |
| xor $r12,$r10 |
| cmpu.w 65535,$r10 |
| bls L(L5) |
| movu.w $r9,$r13 |
| |
| movu.w $r13,$r13 |
| move.d $r10,$r9 |
| lslq 16,$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 |
| mstep $r13,$r9 |
| mstep $r13,$r9 |
| clear.w $r10 |
| test.d $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 |
| mstep $r13,$r10 |
| lslq 16,$r10 |
| ret |
| add.d $r9,$r10 |
| |
| L(L5): |
| movu.w $r9,$r9 |
| lslq 16,$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 |
| mstep $r9,$r10 |
| ret |
| mstep $r9,$r10 |
| #endif |
| L(Lfe1): |
| .size ___Mul,L(Lfe1)-___Mul |
