Re: target/5107: ICE when building an ARM/Thumb cross compiler for/on HP-UX.

[Richard Earnshaw <rearnsha@arm.com>]

The following reply was made to PR target/5107; it has been noted by GNATS.

From: Richard Earnshaw <rearnsha@arm.com>
To: Klaus Pedersen <klaus.k.pedersen@nokia.com>
Cc: Richard.Earnshaw@arm.com, gcc-gnats@gcc.gnu.org
Subject: Re: target/5107: ICE when building an ARM/Thumb cross compiler 
 for/on HP-UX.
Date: Sat, 15 Dec 2001 16:37:36 +0000

 Right, I've tracked this down to what I believe is the mis-compiled 
 function.
 
 The arm.md file defines the split pattern
 
 (define_split 
   [(set (match_operand:SI 0 "register_operand" "")
         (match_operand:SI 1 "const_int_operand" ""))]
   "TARGET_THUMB && CONST_OK_FOR_THUMB_LETTER (INTVAL (operands[1]), 'K')"
   [(set (match_dup 0) (match_dup 1))
    (set (match_dup 0) (ashift:SI (match_dup 0) (match_dup 2)))]
   "
   {
     unsigned HOST_WIDE_INT val = INTVAL (operands[1]);
     unsigned HOST_WIDE_INT mask = 0xff;
     int i;
     
     for (i = 0; i < 25; i++)
       if ((val & (mask << i)) == val)
         break;
 
     if (i == 0)
       FAIL;
 
     operands[1] = GEN_INT (val >> i);
     operands[2] = GEN_INT (i);
   }"
 ...
 
 
 With the current sources (as of 15/12/2001) this is gen_split_415().
 
 The body of the for() loop in this pattern is never executing.  
 Consequently the "if (i == 0)" clause is true and the pattern fails.  
 Clearly this is incorrect behaviour when val is 65536.
 
 You might be able to work around this problem by building the compiler 
 with a lower optimization level.  Try
 	make all CFLAGS="-g".
 
 
 So over the the pa maintainers.  Sorry, I don't know pa code well enough 
 to even begin to work out why this is failing.
 
 R.