ZJIT: Refactor gen_new_hash (ruby#14293)

We can use the `gen_push_opnds` and `gen_pop_opnds` helpers added in ruby#14200 to simplify the code.

Author: st0012

zjit/src/codegen.rs

@@ -1005,35 +1005,11 @@ fn gen_new_hash(
             pairs.push(val);
         }
 
-        let n = pairs.len();
-
-        // Calculate the compile-time NATIVE_STACK_PTR offset from NATIVE_BASE_PTR
-        // At this point, frame_setup(&[], jit.c_stack_slots) has been called,
-        // which allocated aligned_stack_bytes(jit.c_stack_slots) on the stack
-        let frame_size = aligned_stack_bytes(jit.c_stack_slots);
-        let allocation_size = aligned_stack_bytes(n);
-
-        asm_comment!(asm, "allocate {} bytes on C stack for {} hash elements", allocation_size, n);
-        asm.sub_into(NATIVE_STACK_PTR, allocation_size.into());
-
-        // Calculate the total offset from NATIVE_BASE_PTR to our buffer
-        let total_offset_from_base = (frame_size + allocation_size) as i32;
-
-        for (idx, &pair_opnd) in pairs.iter().enumerate() {
-            let slot_offset = -total_offset_from_base + (idx as i32 * SIZEOF_VALUE_I32);
-            asm.mov(
-                Opnd::mem(VALUE_BITS, NATIVE_BASE_PTR, slot_offset),
-                pair_opnd
-            );
-        }
-
-        let argv = asm.lea(Opnd::mem(64, NATIVE_BASE_PTR, -total_offset_from_base));
-
+        let argv = gen_push_opnds(jit, asm, &pairs);
         let argc = (elements.len() * 2) as ::std::os::raw::c_long;
         asm_ccall!(asm, rb_hash_bulk_insert, lir::Opnd::Imm(argc), argv, new_hash);
 
-        asm_comment!(asm, "restore C stack pointer");
-        asm.add_into(NATIVE_STACK_PTR, allocation_size.into());
+        gen_pop_opnds(asm, &pairs);
     }
 
     new_hash