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[Bug target/16532] Inefficient jump to epilogue
- From: "ebotcazou at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 19 Aug 2004 10:13:36 -0000
- Subject: [Bug target/16532] Inefficient jump to epilogue
- References: <20040713215437.16532.dann@godzilla.ics.uci.edu>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Additional Comments From ebotcazou at gcc dot gnu dot org 2004-08-19 10:13 -------
> gcc -O2 -mcpu=ultrasparc generates a "save" in the prologue,
> A "save" is not generated when compiling for v8.
> There should be no need for a "save", this is a leaf function, and the number
> of registers used is very small.
That's because -mcpu=ultrasparc enables -mv8plus, which means that the global
and out registers can be used as full 64-bit registers. For example in the .s file:
srlx %o5, 48, %o5
However, this optimization is partially defeated by the 32-bit calling
convention in the testcase, so I'm not sure it is really worth while there.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16532