This simple patch allows the i386 backend to generate pandn instructions

for V1TI mode.  Currently, the testcase:

 

typedef unsigned __int128 v1ti __attribute__ ((__vector_size__ (16)));

v1ti andnot1(v1ti x, v1ti y) { return ~x & y; }

 

generates with -O2

 

        pcmpeqd %xmm2, %xmm2

        pxor    %xmm2, %xmm0

        pand    %xmm1, %xmm0

        ret

 

with this patch, we now generate:

 

        pandn   %xmm1, %xmm0

        ret

 

It turns out that there are currently three (near) duplicates of the

logic for andn/pandn/vandn/vpandn in i386/sse.md: one for floating point

vectors (MODEF), one for integer vectors (VI) and a third for TFmode.

Rather than introduce a fourth copy, this patch introduces a new mode

iterator to share/reuse the TFmode define_insn to also handle V1TI.

 

This patch has been tested on x86_64-pc-linux-gnu with make bootstrap

and make -k check with no new failures.  Ok for mainline?

 

 

2022-04-05  Roger Sayle  <roger@nextmovesoftware.com>

 

gcc/ChangeLog

* config/i386/sse.md (ANDNOT_MODE): New mode iterator for TF and V1TI.

(*andnottf3): Replace with...

(*andnot<mode>3): New define_insn using ANDNOT_MODE.

 

gcc/testsuite/ChangeLog

* gcc.target/i386/sse2-v1ti-andnot.c: New test case.

 

 

Thanks in advance,

Roger

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