[cfe-dev] Elimination of dead globals (functions/variables)

[Christopher Lamb]

With llvm-gcc the following test case

static int alive, dead;
void foo(int v) { glob_alive = v; }
int FOO() { return glob_alive; }
static void bar(int v) { gdead = v; }
static int BAR() { return dead; }

is correctly pruned down to only foo, FOO, and alive, but with the  
following warnings:

warning: 'bar' defined but not used
warning: 'BAR' defined but not used

clang with -emit-llvm currently emits everything (with no warnings)  
and opt isn't able to reduce it. What needs to be done by clang to  
get the non-visible parts of the module stripped out? In addition to  
diagnostics is clang responsible for not generating code for unused  
functions, or is it simply responsible for passing some sort of  
information so that opt can do the chopping?

--
Christopher Lamb