Mesa (main): nir: add fisnormal lowering

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Module: Mesa
Branch: main
Commit: ad92c2b253d8e122d0f01ab72ccbdfa37efde538
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=ad92c2b253d8e122d0f01ab72ccbdfa37efde538

Author: Dave Airlie <airlied at redhat.com>
Date:   Fri Aug  6 07:19:27 2021 +1000

nir: add fisnormal lowering

just lower the 32-bit version for now.

Thanks to alyssa for this suggested lowering.

Reviewed-by: Jesse Natalie <jenatali at microsoft.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12207>

---

 src/compiler/nir/nir.h                | 2 ++
 src/compiler/nir/nir_opt_algebraic.py | 4 ++++
 2 files changed, 6 insertions(+)

diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
index 2789080d1df..006a25debc9 100644
--- a/src/compiler/nir/nir.h
+++ b/src/compiler/nir/nir.h
@@ -3427,6 +3427,8 @@ typedef struct nir_shader_compiler_options {
    bool lower_fneg;
    /** lowers ineg to isub. Driver must call nir_opt_algebraic_late(). */
    bool lower_ineg;
+   /** lowers fisnormal to alu ops. */
+   bool lower_fisnormal;
 
    /* lower {slt,sge,seq,sne} to {flt,fge,feq,fneu} + b2f: */
    bool lower_scmp;
diff --git a/src/compiler/nir/nir_opt_algebraic.py b/src/compiler/nir/nir_opt_algebraic.py
index 6bb9884acbd..f2bf852ea8b 100644
--- a/src/compiler/nir/nir_opt_algebraic.py
+++ b/src/compiler/nir/nir_opt_algebraic.py
@@ -2143,6 +2143,10 @@ for op in ['ineg', 'iabs', 'inot', 'isign']:
         ((op, ('bcsel', c, '#a', '#b')), ('bcsel', c, (op, a), (op, b))),
     ]
 
+optimizations.extend([
+    (('fisnormal', 'a at 32'), ('ult', 0x1ffffff, ('iadd', ('ishl', a, 1), 0x1000000)), 'options->lower_fisnormal')
+    ])
+
 # This section contains optimizations to propagate downsizing conversions of
 # constructed vectors into vectors of downsized components. Whether this is
 # useful depends on the SIMD semantics of the backend. On a true SIMD machine,