basic block. This is amazingly common in code generated by the C/C++ front-ends.
This change makes it not have to insert ANY phi nodes, whereas before it would insert
a ton of dead ones which DCE would have to clean up.
Thus, this fix improves compile-time performance of these trivial allocas in two ways:
1. It doesn't have to do the walking and book-keeping for renaming
2. It does not insert dead phi nodes for them which would have to
subsequently be cleaned up.
On my favorite testcase from 252.eon, this special case handles 305 out of
356 promoted allocas in the function. It speeds up the mem2reg pass from 7.5256s
to 1.2505s. It inserts 677 fewer dead PHI nodes, which speeds up a subsequent
-dce pass from 18.7524s to 2.4806s.
There are still 120 trivially dead PHI nodes being inserted for variables used
in multiple basic blocks, but they are not handled by this patch.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@8881 91177308-0d34-0410-b5e6-96231b3b80d8
*** Revamp the code which handled unreachable code in the function. Now the
code is much more efficient for high-degree basic blocks, such as those
that occur in the 252.eon SPEC benchmark.
For the interested, the time to promote a SINGLE alloca in _ZN7mrScene4ReadERSi
function used to be > 3.5s. Now it is < .075s. The function has a LOT of
allocas in it, so it appeared to be infinite looping, this should make it much
nicer. :)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@8863 91177308-0d34-0410-b5e6-96231b3b80d8
work-list of value definitions. This allows elimination of the explicit
'iterative' step of the algorithm, and also reuses temporary memory better.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@8861 91177308-0d34-0410-b5e6-96231b3b80d8
* Do not insert a new entry into NewPhiNodes during the rename pass if there are no PHIs in a block.
* Do not compute WriteSets in parallel
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@8858 91177308-0d34-0410-b5e6-96231b3b80d8
* Eliminate the KillList instance variable, instead, just delete loads and
stores as they are "renamed", and delete allocas when they are done
* Make the 'visited' set an instance variable to avoid passing it on the stack.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@8857 91177308-0d34-0410-b5e6-96231b3b80d8
... by making sure to update PHI nodes to take into consideration the
extra edges we get if we inline a call instruction through an invoke.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@8664 91177308-0d34-0410-b5e6-96231b3b80d8
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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@8567 91177308-0d34-0410-b5e6-96231b3b80d8
Instead, check all uses.
This fixes bug: ScalarRepl/2003-09-12-IncorrectPromote.ll
This also fixes the miscompilation of Ptrdist/bc
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@8493 91177308-0d34-0410-b5e6-96231b3b80d8
