* Be a lot more accurate about what the effects will be when inlining a call
to a function when an argument is an alloca.
* Dramatically reduce the penalty for inlining a call in a large function.
This heuristic made it almost impossible to inline a function into a large
function, no matter how small the callee is.
llvm-svn: 12363
This allows pointers to aggregate objects, whose elements are only read, to
be promoted and passed in by element instead of by reference. This can
enable a LOT of subsequent optimizations in the caller function.
It's worth pointing out that this stuff happens a LOT of C++ programs, because
objects in templates are generally passed around by reference. When these
templates are instantiated on small aggregate or scalar types, however, it is
more efficient to pass them in by value than by reference.
This transformation triggers most on C++ codes (e.g. 334 times on eon), but
does happen on C codes as well. For example, on mesa it triggers 72 times,
and on gcc it triggers 35 times. this is amazingly good considering that
we are using 'basicaa' so far.
llvm-svn: 12202
assume that if they don't intend to write to a global variable, that they
would mark it as constant. However, there are people that don't understand
that the compiler can do nice things for them if they give it the information
it needs.
This pass looks for blatently obvious globals that are only ever read from.
Though it uses a trivially simple "alias analysis" of sorts, it is still able
to do amazing things to important benchmarks. 253.perlbmk, for example,
contains several ***GIANT*** function pointer tables that are not marked
constant and should be. Marking them constant allows the optimizer to turn
a whole bunch of indirect calls into direct calls. Note that only a link-time
optimizer can do this transformation, but perlbmk does have several strings
and other minor globals that can be marked constant by this pass when run
from GCCAS.
176.gcc has a ton of strings and large tables that are marked constant, both
at compile time (38 of them) and at link time (48 more). Other benchmarks
give similar results, though it seems like big ones have disproportionally
more than small ones.
This pass is extremely quick and does good things. I'm going to enable it
in gccas & gccld. Not bad for 50 SLOC.
llvm-svn: 11836
* Make the cost metric for passing constants in as arguments to functions MUCH
more accurate, by actually estimating the amount of code that will be constant
propagated away.
llvm-svn: 10136
* Implement FuncResolve/2003-11-20-BogusResolveWarning.ll
... which eliminates a large number of annoying warnings. I know misha
will miss them though!
llvm-svn: 10123
pool allocator no end of trouble, and doesn't make a lot of sense anyway. This
does not solve the problem with mutually recursive functions, but they are much less common.
llvm-svn: 9828
as well as arguments. Now it can delete arguments and return values which are
only passed into other arguments or are returned, if they are dead. This causes
it to delete several hundred extra args/retvals from the C++ hello world program,
shrinking it by about 2K.
llvm-svn: 9398
Only transform call sites in a setjmp'ing function which are reachable from
the setjmp. If the call dominates the setjmp (for example), the called
function cannot longjmp to the setjmp.
This dramatically reduces the number of invoke instructions created in some
large testcases.
llvm-svn: 9066
of callees between executions.
On eon, in release mode, this changes the inliner from taking 11.5712s
to taking 2.2066s. In debug mode, it went from taking 14.4148s to
taking 7.0745s. In release mode, this is a 24.7% speedup of gccas, in
debug mode, it's a total speedup of 11.7%.
This also makes it slightly more aggressive. This could be because we
are not judging the size of the functions quite as accurately as before.
When we start looking at the performance of the generated code, this can
be investigated further.
llvm-svn: 8893
in it being both shorter and more effective. It no longer depends on the
callgraph, so one FIXME has been fixed.
Additionally, this pass was not able to delete recursive (but dead) functions
if they were pointed to by global variables which were also dead. In fact
this pass had a lot of problems deleting functions which were only pointed
to by dead globals and other stuff.
Fixing this means that the entire EH library should be stripped away now from
programs that don't use sjlj or exceptions.
llvm-svn: 8567
This makes it more efficient: it doesn't have to scan the whole program, so
it performs work proportional to the number of malloc/free calls in the
program, not the size of the program.
llvm-svn: 8280
* Separate the policy decisions into a derived class [InlineSimple]
* Move the inlining mechanics into a base class [Inliner]
* Change the inliner to be an SCCPass, making it more structured and
eventually pipelinable with other SCC passes
llvm-svn: 8257
Chris Lattner