inline does not happen as expected

[Roger-luo]

MWE, need https://github.com/QuantumBFS/YaoTargetQASM.jl for the syntax, on 1.6.1

using OpenQASM
using YaoTargetQASM
using YaoCompiler
using YaoCompiler.Intrinsics
using CompilerPluginTools

qasm"""
OPENQASM 2.0;
gate cx c,t { CX c,t; }
gate u1(lambda) q { U(0,0,lambda) q; }
gate t a { u1(pi/4) a; }
gate h a { u2(0,pi) a; }
gate tdg a { u1(-pi/4) a; }

gate ccx a,b,c
{
  h c;
  cx b,c; tdg c;
  cx a,c; t c;
  cx b,c; tdg c;
  cx a,c; t b; t c; h c;
  cx a,b; t a; tdg b;
  cx a,b;
}

gate majority a,b,c 
{ 
  cx c,b; 
  cx c,a; 
  ccx a,b,c; 
}
"""

ast = code_qasm(typeof(majority()))

This gives you the following

julia> ast = code_qasm(typeof(majority()))
OPENQASM 2.0;
qreg qreg_1[3];
CX qreg_1[2], qreg_1[1];
CX qreg_1[2], qreg_1[0];
h qreg_1[2];
CX qreg_1[1], qreg_1[2];
tdg qreg_1[2];
CX qreg_1[0], qreg_1[2];
t qreg_1[2];
CX qreg_1[1], qreg_1[2];
tdg qreg_1[2];
CX qreg_1[0], qreg_1[2];
t qreg_1[1];
t qreg_1[2];
h qreg_1[2];
CX qreg_1[0], qreg_1[1];
t qreg_1[0];
tdg qreg_1[1];
CX qreg_1[0], qreg_1[1];

but h and t should be inlined instead of invoke, this seems to only happen when ccx is called inside another function, and for ccx itself it is fine

julia> code_qasm(typeof(ccx()))
OPENQASM 2.0;
qreg qreg_1[3];
h qreg_1[2];
CX qreg_1[1], qreg_1[2];
rz(0) qreg_1[2];
ry(0) qreg_1[2];
rz(-0.7853981633974483) qreg_1[2];
CX qreg_1[0], qreg_1[2];
rz(0) qreg_1[2];
ry(0) qreg_1[2];
rz(0.7853981633974483) qreg_1[2];
CX qreg_1[1], qreg_1[2];
rz(0) qreg_1[2];
ry(0) qreg_1[2];
rz(-0.7853981633974483) qreg_1[2];
CX qreg_1[0], qreg_1[2];
rz(0) qreg_1[1];
ry(0) qreg_1[1];
rz(0.7853981633974483) qreg_1[1];
rz(0) qreg_1[2];
ry(0) qreg_1[2];
rz(0.7853981633974483) qreg_1[2];
h qreg_1[2];
CX qreg_1[0], qreg_1[1];
rz(0) qreg_1[0];
ry(0) qreg_1[0];
rz(0.7853981633974483) qreg_1[0];
rz(0) qreg_1[1];
ry(0) qreg_1[1];
rz(-0.7853981633974483) qreg_1[1];
CX qreg_1[0], qreg_1[1];

the CodeInfo can be obtained via

code_typed(Intrinsics.apply, (AnyReg, typeof(majority())); interp=YaoInterpreter())

I think need some help from you @vchuravy

[Roger-luo]

When apply is called via a non-intrinsic user-defined Operation, it is forced to inline by making inlineable=true in CodeInfo

https://github.com/QuantumBFS/YaoCompiler.jl/blob/master/src/compiler/syntax.jl#L248

thus I'm not sure why inlining pass decide not to inline them.