------- Comment #2 from rguenth at gcc dot gnu dot org 2010-01-03 11:45 -------
With
Index: tree-ssa-math-opts.c
===================================================================
--- tree-ssa-math-opts.c (revision 155576)
+++ tree-ssa-math-opts.c (working copy)
@@ -1111,8 +1111,9 @@ execute_optimize_bswap (void)
&& optab_handler (bswap_optab, SImode)->insn_code !=
CODE_FOR_nothing);
bswap64_p = (built_in_decls[BUILT_IN_BSWAP64]
- && optab_handler (bswap_optab, DImode)->insn_code !=
- CODE_FOR_nothing);
+ && (optab_handler (bswap_optab, DImode)->insn_code !=
+ CODE_FOR_nothing
+ || bswap32_p));
if (!bswap32_p && !bswap64_p)
return 0;
and thus generic expansion for 64bit bswap we produce
- movl %edx, %edi
- movl %ecx, %esi
- andl $-16711936, %edi
- andl $-16711936, %esi
- movl %edi, -36(%ebp)
- movl %esi, -40(%ebp)
- movl -36(%ebp), %edi
- movl -40(%ebp), %esi
- andl $16711935, %ecx
- shrdl $8, %edi, %esi
- movl %ecx, -48(%ebp)
- movl %esi, -32(%ebp)
- shrl $8, %edi
- movl -48(%ebp), %esi
- movl %edi, -28(%ebp)
- andl $16711935, %edx
- movl -28(%ebp), %ecx
- movl %edx, -44(%ebp)
- movl -32(%ebp), %edx
- movl -44(%ebp), %edi
- shldl $8, %esi, %edi
- sall $8, %esi
- orl %edi, %ecx
- orl %esi, %edx
- movzwl %cx, %esi
- movzwl %dx, %edi
- movl %esi, -52(%ebp)
- movl %edi, -56(%ebp)
- xorw %dx, %dx
- movl -56(%ebp), %esi
- movl %edx, -64(%ebp)
- movl -52(%ebp), %edi
- xorw %cx, %cx
- shldl $16, %esi, %edi
- movl %ecx, -60(%ebp)
- movl %edi, -28(%ebp)
- sall $16, %esi
- movl -60(%ebp), %edi
- movl %esi, -32(%ebp)
- movl -28(%ebp), %ecx
- movl -64(%ebp), %esi
- movl -32(%ebp), %edx
- shrdl $16, %edi, %esi
- shrl $16, %edi
- orl %esi, %edx
- orl %edi, %ecx
- movl %edx, (%ebx,%eax,8)
- movl %ecx, 4(%ebx,%eax,8)
- movl 8(%ebp), %edi
- movl %edx, (%edi,%eax,8)
- movl %ecx, 4(%edi,%eax,8)
+ bswap %edx
+ bswap %ecx
+ movl %edx, 4(%ebx,%eax,8)
+ movl %ecx, (%ebx,%eax,8)
+ movl %ecx, (%esi,%eax,8)
+ movl %edx, 4(%esi,%eax,8)
No idea if it is generally a good idea to do this on all targets though.
At least we'd go through expand_doubleword_bswap which should be pretty
much optimal.
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
AssignedTo|unassigned at gcc dot gnu |rguenth at gcc dot gnu dot
|dot org |org
Status|WAITING |ASSIGNED
Ever Confirmed|0 |1
Last reconfirmed|0000-00-00 00:00:00 |2010-01-03 11:45:57
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42589
