gccjitd.examples.square source code

1 
2 //  This examples creates and runs the equivalent of this C function:
3 //
4 //  int square(int i)
5 //  {
6 //      return i * i;
7 //  }
8 
9 module gccjitd.examples.square;
10 
11 import gccjit.d;
12 
13 JITResult create_fn()
14 {
15     // Create a compilation context
16     JITContext ctxt = new JITContext();
17 
18     // Turn these on to get various kinds of debugging
19     version(none)
20     {
21         ctxt.setOption(JITBoolOption.DUMP_INITIAL_TREE, true);
22         ctxt.setOption(JITBoolOption.DUMP_INITIAL_GIMPLE, true);
23         ctxt.setOption(JITBoolOption.DUMP_GENERATED_CODE, true);
24     }
25 
26     // Adjust this to control optimization level of the generated code
27     version(none)
28         ctxt.setOption(JITIntOption.OPTIMIZATION_LEVEL, 3);
29 
30     // Create parameter "i"
31     JITParam param_i = ctxt.newParam(JITTypeKind.INT, "i");
32     // Create the function
33     JITFunction fn = ctxt.newFunction(JITFunctionKind.EXPORTED,
34                                       JITTypeKind.INT,
35                                       "square", false, param_i);
36 
37     // Create a basic block within the function
38     JITBlock block = fn.newBlock("entry");
39 
40     // This basic block is relatively simple
41     block.endWithReturn(ctxt.newBinaryOp(JITBinaryOp.MULT,
42                                          ctxt.getType(JITTypeKind.INT),
43                                          param_i, param_i));
44 
45     // Having populated the context, compile it
46     JITResult result = ctxt.compile();
47     return result;
48 }
49 
50 int square(int i)
51 {
52     JITResult result = create_fn();
53 
54     // Look up a specific machine code routine within the JITResult,
55     // in this case, the function we created above.
56     void *void_ptr = result.getCode("square");
57 
58     // Now turn it into something we can call from D.
59     auto code = cast(int function(int))(void_ptr);
60 
61     // Now try running the code
62     return code(i);
63 }
64 
65 void main()
66 {
67     import std.stdio : writeln;
68     writeln(square(5));
69 }