[Mesa-dev] [PATCH v2 2/2] spirv: fix OpUConvert when the source is signed

[Samuel Iglesias Gonsálvez]

From: Iago Toral Quiroga <itoral at igalia.com>

In this case we don't want to do sign-extension, since the value is
interpreted as unsigned. If we want sign-extension, OpSConvert should
be used.
---
 src/compiler/spirv/vtn_alu.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/compiler/spirv/vtn_alu.c b/src/compiler/spirv/vtn_alu.c
index a5cefc35773..0b279fe7e54 100644
--- a/src/compiler/spirv/vtn_alu.c
+++ b/src/compiler/spirv/vtn_alu.c
@@ -349,7 +349,6 @@ vtn_nir_alu_op_for_spirv_opcode(struct vtn_builder *b,
 
    /* Conversions: */
    case SpvOpQuantizeToF16:         return nir_op_fquantize2f16;
-   case SpvOpUConvert:
    case SpvOpConvertFToU:
    case SpvOpConvertFToS:
    case SpvOpConvertSToF:
@@ -374,6 +373,25 @@ vtn_nir_alu_op_for_spirv_opcode(struct vtn_builder *b,
       }
       return nir_type_conversion_op(src, dst, nir_rounding_mode_undef);
    }
+
+   case SpvOpUConvert: {
+      nir_alu_type src_base = (nir_alu_type) nir_alu_type_get_base_type(src);
+      if (src_base == nir_type_int) {
+         /* SPIR-V expects to interpret the signed value as unsigned and
+          * not sign extend. Return the opcode accordingly.
+          */
+         unsigned dst_bit_size = nir_alu_type_get_type_size(dst);
+         switch (dst_bit_size) {
+         case 16:   return nir_op_u2u16;
+         case 32:   return nir_op_u2u32;
+         case 64:   return nir_op_u2u64;
+         default:
+            vtn_fail("Invalid nir alu bit size");
+         }
+      }
+      return nir_type_conversion_op(src, dst, nir_rounding_mode_undef);
+   }
+
    /* Derivatives: */
    case SpvOpDPdx:         return nir_op_fddx;
    case SpvOpDPdy:         return nir_op_fddy;
-- 
2.14.1