nir: Make nir_build_alu() variants per 1-4 arg count.

This saves a bunch of generated code to pack up the extra NULLs to get to
4 args, and saves executing the conditions in nir_build_alu() to then skip
those NULLs.

Saves another 27kb on disk.

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13916>

src/compiler/nir/nir_builder.c

@@ -140,6 +140,63 @@ nir_build_alu(nir_builder *build, nir_op op, nir_ssa_def *src0,
    return nir_builder_alu_instr_finish_and_insert(build, instr);
 }
 
+nir_ssa_def *
+nir_build_alu1(nir_builder *build, nir_op op, nir_ssa_def *src0)
+{
+   nir_alu_instr *instr = nir_alu_instr_create(build->shader, op);
+   if (!instr)
+      return NULL;
+
+   instr->src[0].src = nir_src_for_ssa(src0);
+
+   return nir_builder_alu_instr_finish_and_insert(build, instr);
+}
+
+nir_ssa_def *
+nir_build_alu2(nir_builder *build, nir_op op, nir_ssa_def *src0,
+              nir_ssa_def *src1)
+{
+   nir_alu_instr *instr = nir_alu_instr_create(build->shader, op);
+   if (!instr)
+      return NULL;
+
+   instr->src[0].src = nir_src_for_ssa(src0);
+   instr->src[1].src = nir_src_for_ssa(src1);
+
+   return nir_builder_alu_instr_finish_and_insert(build, instr);
+}
+
+nir_ssa_def *
+nir_build_alu3(nir_builder *build, nir_op op, nir_ssa_def *src0,
+              nir_ssa_def *src1, nir_ssa_def *src2)
+{
+   nir_alu_instr *instr = nir_alu_instr_create(build->shader, op);
+   if (!instr)
+      return NULL;
+
+   instr->src[0].src = nir_src_for_ssa(src0);
+   instr->src[1].src = nir_src_for_ssa(src1);
+   instr->src[2].src = nir_src_for_ssa(src2);
+
+   return nir_builder_alu_instr_finish_and_insert(build, instr);
+}
+
+nir_ssa_def *
+nir_build_alu4(nir_builder *build, nir_op op, nir_ssa_def *src0,
+              nir_ssa_def *src1, nir_ssa_def *src2, nir_ssa_def *src3)
+{
+   nir_alu_instr *instr = nir_alu_instr_create(build->shader, op);
+   if (!instr)
+      return NULL;
+
+   instr->src[0].src = nir_src_for_ssa(src0);
+   instr->src[1].src = nir_src_for_ssa(src1);
+   instr->src[2].src = nir_src_for_ssa(src2);
+   instr->src[3].src = nir_src_for_ssa(src3);
+
+   return nir_builder_alu_instr_finish_and_insert(build, instr);
+}
+
 /* for the couple special cases with more than 4 src args: */
 nir_ssa_def *
 nir_build_alu_src_arr(nir_builder *build, nir_op op, nir_ssa_def **srcs)

src/compiler/nir/nir_builder.h

@@ -109,10 +109,24 @@ nir_builder_last_instr(nir_builder *build)
    return build->cursor.instr;
 }
 
+/* General nir_build_alu() taking a variable arg count with NULLs for the rest. */
 nir_ssa_def *
 nir_build_alu(nir_builder *build, nir_op op, nir_ssa_def *src0,
               nir_ssa_def *src1, nir_ssa_def *src2, nir_ssa_def *src3);
 
+/* Fixed-arg-count variants to reduce size of codegen. */
+nir_ssa_def *
+nir_build_alu1(nir_builder *build, nir_op op, nir_ssa_def *src0);
+nir_ssa_def *
+nir_build_alu2(nir_builder *build, nir_op op, nir_ssa_def *src0,
+               nir_ssa_def *src1);
+nir_ssa_def *
+nir_build_alu3(nir_builder *build, nir_op op, nir_ssa_def *src0,
+               nir_ssa_def *src1, nir_ssa_def *src2);
+nir_ssa_def *
+nir_build_alu4(nir_builder *build, nir_op op, nir_ssa_def *src0,
+               nir_ssa_def *src1, nir_ssa_def *src2, nir_ssa_def *src3);
+
 nir_ssa_def *nir_build_alu_src_arr(nir_builder *build, nir_op op, nir_ssa_def **srcs);
 
 nir_instr *nir_builder_last_instr(nir_builder *build);

src/compiler/nir/nir_builder_opcodes_h.py

@@ -29,10 +29,7 @@ def src_decl_list(num_srcs):
    return ', '.join('nir_ssa_def *src' + str(i) for i in range(num_srcs))
 
 def src_list(num_srcs):
-   if num_srcs <= 4:
+   return ', '.join('src' + str(i) for i in range(num_srcs))
-      return ', '.join('src' + str(i) if i < num_srcs else 'NULL' for i in range(4))
-   else:
-      return ', '.join('src' + str(i) for i in range(num_srcs))
 %>
 
 % for name, opcode in sorted(opcodes.items()):
@@ -40,7 +37,7 @@ static inline nir_ssa_def *
 nir_${name}(nir_builder *build, ${src_decl_list(opcode.num_inputs)})
 {
 % if opcode.num_inputs <= 4:
-   return nir_build_alu(build, nir_op_${name}, ${src_list(opcode.num_inputs)});
+   return nir_build_alu${opcode.num_inputs}(build, nir_op_${name}, ${src_list(opcode.num_inputs)});
 % else:
    nir_ssa_def *srcs[${opcode.num_inputs}] = {${src_list(opcode.num_inputs)}};
    return nir_build_alu_src_arr(build, nir_op_${name}, srcs);