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[Bug tree-optimization/34437] several test failures for gcc.dg/vect/no-scevccp-*
- From: "jakub at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 12 Dec 2007 17:51:34 -0000
- Subject: [Bug tree-optimization/34437] several test failures for gcc.dg/vect/no-scevccp-*
- References: <bug-34437-4503@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #6 from jakub at gcc dot gnu dot org 2007-12-12 17:51 -------
As -m32 -maltivec without -mabi=altivec has the VMX regs effectively neither
fixed, nor call saved, nor call used, it simply can't work reliably.
Registers really need to have some rules for using them, while -m32 -maltivec
means complete anarchy. The compiler is told calls won't clobber values stored
in them, but nothing saves the registers, so things work only as long as no
calls are crossed with live VMX registers, or with pure luck that the callee
clobbers different VMX registers than the parent has live accross the call.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34437