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From: "kazu at cs dot umass dot edu" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/15473] New: [tree-ssa] Sibcall optimization for libcalls. Date: Mon, 17 May 2004 00:47:00 -0000 [thread overview] Message-ID: <20040516100200.15473.kazu@cs.umass.edu> (raw) Consider: long long foo (long long a, long long b) { return a / b; } I get: foo (a, b) { <bb 0>: return a_1 / b_2; } with the assembly code being foo: subl $12, %esp pushl 28(%esp) pushl 28(%esp) pushl 28(%esp) pushl 28(%esp) call __divdi3 addl $28, %esp ret Note that the sequence of 4 pushl instructions simply copy 16 bytes from one location of the stack to another. If I create a (non-libcall) function with the same arguments like so long long div64 (long long a, long long b); long long bar (long long a, long long b) { return div64 (a, b); } I get: bar (a, b) { long long int T.0; <bb 0>: T.0_3 = div64 (a_1, b_2) [tail call]; return T.0_3; } with the assembly code being bar: jmp div64 -- Summary: [tree-ssa] Sibcall optimization for libcalls. Product: gcc Version: 3.5.0 Status: UNCONFIRMED Keywords: pessimizes-code Severity: enhancement Priority: P2 Component: tree-optimization AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: kazu at cs dot umass dot edu CC: gcc-bugs at gcc dot gnu dot org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15473
next reply other threads:[~2004-05-16 10:02 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2004-05-17 0:47 kazu at cs dot umass dot edu [this message] 2004-05-17 0:57 ` [Bug tree-optimization/15473] " pinskia at gcc dot gnu dot org 2004-05-17 19:33 ` [Bug rtl-optimization/15473] " steven at gcc dot gnu dot org 2004-08-16 0:19 ` pinskia at gcc dot gnu dot org
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