On Jul 28, 2007, at 11:52 AM, Christopher Lamb <[EMAIL PROTECTED] > wrote:


On Jul 28, 2007, at 1:48 AM, Evan Cheng wrote:

Very cool! I need to read it more carefully.

But I see you are lowering zext to a single insert_subreg. Is that right? It won't zero out the top part, no?

It's only lowering (zext i32 to i64) to an insert_subreg on x86-64 where all writes to 32-bit registers implicitly zero-extend into the upper 32-bits.


I know. But thy mismatch semantically. A insert_subreg to the lower part should not change the upper half. I think this is only legal for anyext.

Evan

--
Chris

Sent from my iPhone

On Jul 28, 2007, at 12:17 AM, Christopher Lamb <[EMAIL PROTECTED] > wrote:

This patch changes the X86 back end to use the new subreg operations for appropriate truncate and extend operations. This should allow regression testing of the subreg feature going forward, as it's now used in a public target.

The patch passed DejaGnu and all of SingleSource on my x86 machine, but there are changes for x86-64 as well which I haven't been able to test. Output assembly for x86-64 appears sane, but I'd appreciate someone giving the patch a try on their x86-64 system. Other 32-bit x86 testing is also appreciated.

Thanks
--
Christopher Lamb

<x86_subregs.patch>


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Christopher Lamb



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