Follow returned pointer aliases when deciding whether runtime.alloc calls can
be lowered to stack allocations. A returned parameter is not the same as
nocapture: it still flows back to the caller and must be checked as an alias
of the original allocation.
Keep the analysis conservative for recursive returned-parameter chains and
unknown operands. The existing golden test now shows that the non-escaping
returned pointer cases no longer require heap allocation.
Add allocation diagnostics coverage for pointer-returning helpers, aggregate
slice returns, and conditional pointer returns before changing the allocation
optimizer.
The golden files record the current heap-allocation behavior so later commits
show exactly which diagnostics each optimizer improvement removes.
PR #5220 changed -print-allocs output to the go coverage tool format, which
replaced the original human-readable explanation of why each object had to be
heap allocated. That explanation is useful on its own, so this restores it as
the default behavior of -print-allocs and moves the coverage format behind a
-print-allocs-cover flag.
Signed-off-by: Piotr Bocheński <piotr@bochen.ski>
Jake Bailey
Piotr Bocheński