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[Bug tree-optimization/45685] [4.6 Regression] missed conditional move opportunity in loop
- From: "ekuznetsov at divxcorp dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Thu, 25 Nov 2010 00:19:38 +0000
- Subject: [Bug tree-optimization/45685] [4.6 Regression] missed conditional move opportunity in loop
- Auto-submitted: auto-generated
- References: <bug-45685-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45685
--- Comment #13 from Eugene K. <ekuznetsov at divxcorp dot com> 2010-11-25 00:19:19 UTC ---
Further down in that gimple code
val_3 = [cond_expr] i_19 != D.2699_25 ? prephitmp.10_40 : val_4;
prephitmp.11_43 = [cond_expr] i_19 != D.2699_25 ? prephitmp.11_41 :
prephitmp.9_39;
this is duplicate too. The only difference seems to be that the result of one
operation is stored as a 64-bit type and the other is added to a 32-bit
variable. This trickles down into the assembly shown in comment 4 in both
versions: 4.4.4 produces two cmov instructions "cmovne %r11, %r8; cmove %r9d,
%ecx" where one should be sufficient, and 4.4.4 produces a cmov and a branch.