[Mesa-dev] [PATCH 1/2] spirv: convert the shift operand for bitwise shift ops to uint32

[Samuel Iglesias Gonsálvez]

SPIR-V allows to define the shift operand for shift opcodes with
a bit-size different than 32 bits, but in NIR the opcodes have
that limitation. As agreed in the mailing list, this patch adds
a conversion to 32 bits to fix this.

For more info, see:

https://lists.freedesktop.org/archives/mesa-dev/2018-April/193026.html

Signed-off-by: Samuel Iglesias Gonsálvez <siglesias at igalia.com>
---
 src/compiler/spirv/vtn_alu.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/src/compiler/spirv/vtn_alu.c b/src/compiler/spirv/vtn_alu.c
index 71e743cdd1e..6f3b82cd5c3 100644
--- a/src/compiler/spirv/vtn_alu.c
+++ b/src/compiler/spirv/vtn_alu.c
@@ -640,6 +640,26 @@ vtn_handle_alu(struct vtn_builder *b, SpvOp opcode,
       break;
    }
 
+   case SpvOpShiftLeftLogical:
+   case SpvOpShiftRightArithmetic:
+   case SpvOpShiftRightLogical: {
+      bool swap;
+      unsigned src_bit_size = glsl_get_bit_size(vtn_src[0]->type);
+      unsigned dst_bit_size = glsl_get_bit_size(type);
+      nir_op op = vtn_nir_alu_op_for_spirv_opcode(b, opcode, &swap,
+                                                  src_bit_size, dst_bit_size);
+      if (src[1]->bit_size != 32) {
+         /* Convert the Shift operand to 32 bits, which is the bitsize
+          * supported by the NIR instruction. See discussion here:
+          *
+          * https://lists.freedesktop.org/archives/mesa-dev/2018-April/193026.html
+          */
+         src[1] = nir_build_alu(&b->nb, nir_op_u2u32, src[1], NULL, NULL, NULL);
+      }
+      val->ssa->def = nir_build_alu(&b->nb, op, src[0], src[1], src[2], src[3]);
+      break;
+   }
+
    default: {
       bool swap;
       unsigned src_bit_size = glsl_get_bit_size(vtn_src[0]->type);
-- 
2.14.1