Re: [PATCH], Fix PowerPC ISA 3.0 word extract/insert thinkos

[Michael Meissner <meissner at linux dot vnet dot ibm dot com>]

On Fri, Dec 23, 2016 at 04:34:10PM -0600, Segher Boessenkool wrote:
> On Fri, Dec 23, 2016 at 04:47:22PM -0500, Michael Meissner wrote:
> > I had two thinkos in my previous patches for ISA 3.0 (power9) support that both
> > relate to word extraction and insertion.
> > 
> > The first thinko was that I thought the index for the first byte in the 4 bytes
> > to be extracted should be 0..11, when it should be 0..12.  If it isn't allowed
> > to be 12, you cannot extract the 32-bit word at the bottom of the vector
> > register.
> > 
> > The second thinko is where I was doing zeo extending of a 32-bit value within
> > a vector register, I used xxextractuw with a byte offset of 1 instead of 4.
> > 
> > I have done the usual bootstrap and make check with no regressions on these
> > patches.  Can I install them into the trunk?
> 
> Yes please.  It sounds like we need a few more testcases though?

Actually, since the test case was written at the time I made the thinko, the
original test case tested if 12 was illegal instead of 13.  I have adjusted the
test case.  I also forgot to adjust the check in rs6000.c for the bounds being
0..12 instead of 0..11.  I fixed that as well.  This is the patch that was
checked in:

[gcc]
2016-12-27  Michael Meissner  <meissner@linux.vnet.ibm.com>

	* config/rs6000/predicates.md (const_0_to_12_operand): Rename
	predicate and change test from 0..11 to 0..12 to match the
	semantics of the word extract/insert instructions.  Change all
	callers.
	(const_0_to_11_operand): Likewise.
	* config/rs6000/rs6000.c (altivec_expand_builtin): Likewise.
	* config/rs6000/vsx.md (vextract4b): Likewise.
	(vextract4b_internal): Likewise.
	(vinsert4b): Likewise.
	(vinsert4b_internal): Likewise.
	(vinsert4b_di): Likewise.
	(vinsert4b_di_internal): Likewise.
	* config/rs6000/rs6000.md (zero_extendsi<mode>2): Fix offset used
	in xxextractuw to zero extend the word in the vector registers.
	(lfiwzx): Likewise.

[gcc/testsuite]
2016-12-27  Michael Meissner  <meissner@linux.vnet.ibm.com>

	* gcc.target/powerpc/p9-vinsert4b-2.c: Update test to test for 13
	being out of bounds instead of 12.

-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.vnet.ibm.com, phone: +1 (978) 899-4797

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