Function call used instead of primitive arithmetic operation

[GoogleCodeExporter]

What steps will reproduce the problem?

compile a module with content

module A where

g :: Int -> Int
g x = x * 5

inspecting produced file A.c

Int f_A (Int x_2) {
    return _sym_622_Prelude/* * */(x_2, 5);
}

compile a second module 

module B where 

f :: Int -> Int
f x = x * 5

g :: Int -> Int
g x = f (x +1)

inspecting the produced file B.c

Int f_B (Int x_3) {
    return _sym_622_Prelude/* * */(x_3, 5);
}
Int g_B (Int x_4) {
    return ((x_4 + 1) * 5);
}

What is the expected output? What do you see instead?

primitive integer multiplication is used in the second module but not in the 
first. 

What version of the product are you using? On what operating system?
HEAD from https://code.google.com/p/timberc/

Original issue reported on code.google.com by [email protected] on 20 Oct 2012 at 11:21