Re: [GHC] #14222: Simple text fusion example results in rather duplicative code

12 Sep 2017

      #14222: Simple text fusion example results in rather duplicative code
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        Reporter:  bgamari           |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.2.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by bgamari):

 By contrast, a relatively naive translation to C compiled with `gcc -O0`
 requires less than half the code,
 {{{#!c
 #include <stdint.h>
 #include <stdbool.h>

 bool isNumber(uint16_t c) {
   return '0' <= c && c <= '9';
 }

 bool isNumeric(uint16_t c) {
   if (isNumber(c)) return true;
   switch (c) {
   case 'e':
   case 'E':
   case '.':
   case '-':
   case '+':
     return true;
   default:
     return false;
   }
 }

 bool test(uint16_t *buf, int len) {
   for (int i=0; i<len; i++) {
     if (!isNumeric(buf[i])) return false;
   }
   for (int i=0; i<len; i++) {
     if (isNumber(buf[i])) return true;
   }
   return false;
 }
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14222#comment:1>
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