Stumbled upon the Overengineered calculator: Zig + QBE blog article when browsing reddit and thought it would be cool to run the snippets in the browser.

qbe-wasm does not have wasi support, so this demo uses a quick and dirty printf. Please remember, this is just a demo...

snippet1.qbe

      
# ld means: as long integer
data $fmt = { b "%ld\n", b 0 }
export function w $main() {
@start
    %.0 =l mul 2, 2
    %.1 =l add 2, %.0
    # call C printf function, needs linking with libc, to print the result
    call $printf(l $fmt, ..., l %.1)
    ret 0
}

qbe-wasm -o snippet1.wasm snippet1.qbe
      
    2 + 2 * 2 = 
    

qbe-wasm -t wat -o snippet1.wat snippet1.qbe
      
(module
 (type $0 (func (result i32)))
 (type $1 (func (param i64 i64)))
 (import "env" "printf" (func $printf (param i64 i64)))
 (memory $mem 1 1)
 (data $fmt_0 (i32.const 0) "%ld\n")
 (export "main" (func $main))
 (export "mem" (memory $mem))
 (func $main (result i32)
  (i64.store
   (i32.const 6)
   (i64.const 6)
  )
  (call $printf
   (i64.const 0)
   (i64.const 6)
  )
  (i32.const 0)
 )
)
      
    

snippet2.qbe

      
data $fmt = { b "%ld\n", b 0 }
export function w $main() {
@start
    %.0 =l neg 2
    %.1 =l div 4, 2
    %.2 =l mul 2, %.1
    %.3 =l add %.0, %.2
    call $printf(l $fmt, ..., l %.3)
    ret 0
}

qbe-wasm -o snippet2.wasm snippet2.qbe
      
    -2 + 2 * (4 / 2) = 
    

qbe-wasm -t wat -o snippet2.wat snippet2.qbe
      
(module
 (type $0 (func (result i32)))
 (type $1 (func (param i64 i64)))
 (import "env" "printf" (func $printf (param i64 i64)))
 (memory $mem 1 1)
 (data $fmt_0 (i32.const 0) "%ld\n")
 (export "main" (func $main))
 (export "mem" (memory $mem))
 (func $main (result i32)
  (i64.store
   (i32.const 6)
   (i64.const 2)
  )
  (call $printf
   (i64.const 0)
   (i64.const 6)
  )
  (i32.const 0)
 )
)
      
    

An interesting observation of the wat for snippet2, the blog post mentions that the assembly generated did not fold the constants. They do, however, get folded when compiling to wat/wasm via qbe-wasm.

This is because qbe-wasm uses QBE+binaryen, so I take no direct credit for this, just thought it was worth mentioning.