nir/algebraic: Be more careful converting ushr to extract_u8/16

If it's not the right bit-size, it may not actually be the correct
extraction.  For now, we'll only worry about 32-bit versions.

Fixes: 905ff8619824 "nir: Recognize open-coded extract_u16"
Fixes: 76289fbfa84a "nir: Recognize open-coded extract_u8"
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

diff --git a/src/compiler/nir/nir_opt_algebraic.py b/src/compiler/nir/nir_opt_algebraic.py
index e770a61d9ff4216d55658ecde944a46211952c72..9c890c0eb249d4253e4d99f9c1bb1e745b4020b3 100644 (file)
--- a/src/compiler/nir/nir_opt_algebraic.py
+++ b/src/compiler/nir/nir_opt_algebraic.py
@@ -543,13 +543,13 @@ optimizations = [
                            ('unpack_64_2x32_split_y', a)), a),
 
    # Byte extraction
-   (('ushr', a, 24), ('extract_u8', a, 3), '!options->lower_extract_byte'),
+   (('ushr', 'a@32', 24), ('extract_u8', a, 3), '!options->lower_extract_byte'),
    (('iand', 0xff, ('ushr', a, 16)), ('extract_u8', a, 2), '!options->lower_extract_byte'),
    (('iand', 0xff, ('ushr', a,  8)), ('extract_u8', a, 1), '!options->lower_extract_byte'),
    (('iand', 0xff, a), ('extract_u8', a, 0), '!options->lower_extract_byte'),
 
     # Word extraction
-   (('ushr', a, 16), ('extract_u16', a, 1), '!options->lower_extract_word'),
+   (('ushr', 'a@32', 16), ('extract_u16', a, 1), '!options->lower_extract_word'),
    (('iand', 0xffff, a), ('extract_u16', a, 0), '!options->lower_extract_word'),
 
    # Subtracts