nir/algebraic: collapse conversion opcodes (many patterns)

mediump inserts a lot of conversions. This cleans up the IR.
All other combinations are covered too.

Reviewed-by: Rob Clark <robdclark@chromium.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6283>

src/compiler/nir/nir_opt_algebraic.py

@@ -673,18 +673,63 @@ for s in [16, 32, 64]:
        (('iadd', ('b2i{}'.format(s), ('flt', 0, 'a@{}'.format(s))), ('ineg', ('b2i{}'.format(s), ('flt', 'a@{}'.format(s), 0)))), ('f2i{}'.format(s), ('fsign', a)), '!options->lower_fsign'),
     ])
 
-    # Conversions from a lower bit size to a higher bit size and back can always be removed
+    # float? -> float? -> floatS ==> float? -> floatS
-    for h in [16, 32, 64]:
+    (('~f2f{}'.format(s), ('f2f', a)), ('f2f{}'.format(s), a)),
-        if s < h:
+
+    # int? -> float? -> floatS ==> int? -> floatS
+    (('~f2f{}'.format(s), ('u2f', a)), ('u2f{}'.format(s), a)),
+    (('~f2f{}'.format(s), ('i2f', a)), ('i2f{}'.format(s), a)),
+
+    # float? -> float? -> intS ==> float? -> intS
+    (('~f2u{}'.format(s), ('f2f', a)), ('f2u{}'.format(s), a)),
+    (('~f2i{}'.format(s), ('f2f', a)), ('f2i{}'.format(s), a)),
+
+    for B in [32, 64]:
+        if s < B:
             optimizations.extend([
-               (('f2f{}'.format(s), ('f2f{}'.format(h), 'a@{}'.format(s))), a),
+               # S = smaller, B = bigger
-               (('i2i{}'.format(s), ('i2i{}'.format(h), 'a@{}'.format(s))), a),
+               # typeS -> typeB -> typeS ==> identity
-               (('u2u{}'.format(s), ('u2u{}'.format(h), 'a@{}'.format(s))), a),
+               (('f2f{}'.format(s), ('f2f{}'.format(B), 'a@{}'.format(s))), a),
-               (('f2f{}'.format(s), ('b2f{}'.format(h), 'a@1')), ('b2f{}'.format(s), a)),
+               (('i2i{}'.format(s), ('i2i{}'.format(B), 'a@{}'.format(s))), a),
-               (('i2i{}'.format(s), ('b2i{}'.format(h), 'a@1')), ('b2i{}'.format(s), a)),
+               (('u2u{}'.format(s), ('u2u{}'.format(B), 'a@{}'.format(s))), a),
-               (('u2u{}'.format(s), ('b2i{}'.format(h), 'a@1')), ('b2i{}'.format(s), a)),
+
+               # bool1 -> typeB -> typeS ==> bool1 -> typeS
+               (('f2f{}'.format(s), ('b2f{}'.format(B), 'a@1')), ('b2f{}'.format(s), a)),
+               (('i2i{}'.format(s), ('b2i{}'.format(B), 'a@1')), ('b2i{}'.format(s), a)),
+               (('u2u{}'.format(s), ('b2i{}'.format(B), 'a@1')), ('b2i{}'.format(s), a)),
+
+               # floatS -> floatB -> intB ==> floatS -> intB
+               (('f2u{}'.format(B), ('f2f{}'.format(B), 'a@{}'.format(s))), ('f2u{}'.format(B), a)),
+               (('f2i{}'.format(B), ('f2f{}'.format(B), 'a@{}'.format(s))), ('f2i{}'.format(B), a)),
+
+               # int? -> floatB -> floatS ==> int? -> floatS
+               (('f2f{}'.format(s), ('u2f{}'.format(B), a)), ('u2f{}'.format(s), a)),
+               (('f2f{}'.format(s), ('i2f{}'.format(B), a)), ('i2f{}'.format(s), a)),
+
+               # intS -> intB -> floatB ==> intS -> floatB
+               (('u2f{}'.format(B), ('u2u{}'.format(B), 'a@{}'.format(s))), ('u2f{}'.format(B), a)),
+               (('i2f{}'.format(B), ('i2i{}'.format(B), 'a@{}'.format(s))), ('i2f{}'.format(B), a)),
             ])
 
+# mediump variants of the above
+optimizations.extend([
+    # int32 -> float32 -> float16 ==> int32 -> float16
+    (('f2fmp', ('u2f32', 'a@32')), ('u2fmp', a)),
+    (('f2fmp', ('i2f32', 'a@32')), ('i2fmp', a)),
+
+    # float32 -> float16 -> int16 ==> float32 -> int16
+    (('f2u16', ('f2fmp', 'a@32')), ('f2u16', a)),
+    (('f2i16', ('f2fmp', 'a@32')), ('f2i16', a)),
+
+    # float32 -> int32 -> int16 ==> float32 -> int16
+    (('i2imp', ('f2u32', 'a@32')), ('f2ump', a)),
+    (('i2imp', ('f2i32', 'a@32')), ('f2imp', a)),
+
+    # int32 -> int16 -> float16 ==> int32 -> float16
+    (('u2f16', ('i2imp', 'a@32')), ('u2f16', a)),
+    (('i2f16', ('i2imp', 'a@32')), ('i2f16', a)),
+])
+
 # Integer sizes
 for s in [8, 16, 32, 64]:
     optimizations.extend([
@@ -968,15 +1013,32 @@ optimizations.extend([
    (('f2fmp', ('f2f32', 'a@16')), a),
    (('i2imp', ('i2i32', 'a@16')), a),
    (('i2imp', ('u2u32', 'a@16')), a),
+
+   (('f2imp', ('f2f32', 'a@16')), ('f2i16', a)),
+   (('f2ump', ('f2f32', 'a@16')), ('f2u16', a)),
+   (('i2fmp', ('i2i32', 'a@16')), ('i2f16', a)),
+   (('u2fmp', ('u2u32', 'a@16')), ('u2f16', a)),
+
    (('f2fmp', ('b2f32', 'a@1')), ('b2f16', a)),
    (('i2imp', ('b2i32', 'a@1')), ('b2i16', a)),
    (('i2imp', ('b2i32', 'a@1')), ('b2i16', a)),
+
+   (('f2imp', ('b2f32', 'a@1')), ('b2i16', a)),
+   (('f2ump', ('b2f32', 'a@1')), ('b2i16', a)),
+   (('i2fmp', ('b2i32', 'a@1')), ('b2f16', a)),
+   (('u2fmp', ('b2i32', 'a@1')), ('b2f16', a)),
+
    # Conversions to 16 bits would be lossy so they should only be removed if
    # the instruction was generated by the precision lowering pass.
    (('f2f32', ('f2fmp', 'a@32')), a),
    (('i2i32', ('i2imp', 'a@32')), a),
    (('u2u32', ('i2imp', 'a@32')), a),
 
+   (('i2i32', ('f2imp', 'a@32')), ('f2i32', a)),
+   (('u2u32', ('f2ump', 'a@32')), ('f2u32', a)),
+   (('f2f32', ('i2fmp', 'a@32')), ('i2f32', a)),
+   (('f2f32', ('u2fmp', 'a@32')), ('u2f32', a)),
+
    (('ffloor', 'a(is_integral)'), a),
    (('fceil', 'a(is_integral)'), a),
    (('ftrunc', 'a(is_integral)'), a),