ac/nir: implement 64-bit packing and unpacking

We implement the split opcodes, and tell NIR to lower the original ones.
The lowering to LLVM is a little more complicated, but NIR can optimize
the split ones a little better, and some NIR lowering passes that we
might want to use (particularly for doubles) emit the split ones.

This should fix pack/unpackDouble2x32, which seems like a bug since when
we enabled the Float64 capability. It will also fix pack/unpackInt2x32
when we enable the Int64 capability.

Fixes: 798ae37c ("radv: Enable Float64 support.")
Signed-off-by: Connor Abbott <cwabbott0@gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>

src/amd/common/ac_nir_to_llvm.c

@@ -1866,6 +1866,37 @@ static void visit_alu(struct nir_to_llvm_context *ctx, const nir_alu_instr *inst
 	case nir_op_fddy_coarse:
 		result = emit_ddxy(ctx, instr->op, src[0]);
 		break;
+
+	case nir_op_unpack_64_2x32_split_x: {
+		assert(instr->src[0].src.ssa->num_components == 1);
+		LLVMValueRef tmp = LLVMBuildBitCast(ctx->builder, src[0],
+						    LLVMVectorType(ctx->i32, 2),
+						    "");
+		result = LLVMBuildExtractElement(ctx->builder, tmp,
+						 ctx->i32zero, "");
+		break;
+	}
+
+	case nir_op_unpack_64_2x32_split_y: {
+		assert(instr->src[0].src.ssa->num_components == 1);
+		LLVMValueRef tmp = LLVMBuildBitCast(ctx->builder, src[0],
+						    LLVMVectorType(ctx->i32, 2),
+						    "");
+		result = LLVMBuildExtractElement(ctx->builder, tmp,
+						 ctx->i32one, "");
+		break;
+	}
+
+	case nir_op_pack_64_2x32_split: {
+		LLVMValueRef tmp = LLVMGetUndef(LLVMVectorType(ctx->i32, 2));
+		tmp = LLVMBuildInsertElement(ctx->builder, tmp,
+					     src[0], ctx->i32zero, "");
+		tmp = LLVMBuildInsertElement(ctx->builder, tmp,
+					     src[1], ctx->i32one, "");
+		result = LLVMBuildBitCast(ctx->builder, tmp, ctx->i64, "");
+		break;
+	}
+
 	default:
 		fprintf(stderr, "Unknown NIR alu instr: ");
 		nir_print_instr(&instr->instr, stderr);

src/amd/vulkan/radv_pipeline.c

@@ -151,6 +151,7 @@ radv_optimize_nir(struct nir_shader *shader)
                 progress = false;
 
                 NIR_PASS_V(shader, nir_lower_vars_to_ssa);
+		NIR_PASS_V(shader, nir_lower_64bit_pack);
                 NIR_PASS_V(shader, nir_lower_alu_to_scalar);
                 NIR_PASS_V(shader, nir_lower_phis_to_scalar);