Re: [Pharo-dev] [Spy] How to inject code *inside* a method

On 06 Dec 2013, at 10:01, Roberto Minelli <roberto.minelli@usi.ch> wrote:

Hi guys,

I am using Spy for my project, and I need to do something which, on top of my knowledge, is not supported.

Here is the point: Spy allows to insert code before (#beforeRun:with:in:) and after (#afterRun:with:in:) and works perfectly.

Now suppose I want to inject some code *inside* the method, e.g.,

aMethodToBeProfiled

do something

"Injected code accessing some fields of the current instance of this object” Transcript show: self field asString.

Is there any support for this?

Here is how to do it on the IR level: A class TestMy with test ^x + 1 + x byte code is: 13 <00> pushRcvr: 0 14 <76> pushConstant: 1 15 <B0> send: + 16 <00> pushRcvr: 0 17 <B0> send: + 18 <7C> returnTop “get a copy of the IR tree" irMethod := (TestMy>>#test) ir copy. “get all instance variable access IR instructions” allIvarAccesses := irMethod allInstructionsMatching: [ :ir |ir isInstVarAccess]. “insert code for “1 halt” before all of them" allIvarAccesses do: [ :each | each addInstructionsBefore: { IRInstruction pushLiteral: 1. IRInstruction send: #halt. IRInstruction popTop }]. “generate a new compiledMethod" cm := irMethod generate: (TestMy>>#test) trailer. “install in the class" TestMy addSelector: #test withMethod: cm. 17 <76> pushConstant: 1 18 <D0> send: halt 19 <87> pop 20 <00> pushRcvr: 0 21 <76> pushConstant: 1 22 <B0> send: + 23 <76> pushConstant: 1 24 <D0> send: halt 25 <87> pop 26 <00> pushRcvr: 0 27 <B0> send: + 28 <7C> returnTop —> TestMy new test What is now yet wiring is quick return methods —> need to clear the primitive in that case, should not be hard to do.