LargeBlockInfo, we can now dramatically simplify their implementation
and speed them up at the same time. Now the code has time proportional
to the number of uses of the alloca, not the size of the block.
This also eliminates code that tried to batch up different allocas which
are used in the same blocks, and eliminates the 'retry list' logic which
was baroque and no unneccesary. In addition to being a speedup for crazy
cases, this is also a nice cleanup:
PromoteMemoryToRegister.cpp | 270 +++++++++++++++-----------------------------
1 file changed, 96 insertions(+), 174 deletions(-)
llvm-svn: 58229
a trivial dense map. Use this in RewriteSingleStoreAlloca to
avoid aggressively rescanning blocks over and over again. This
fixes PR2925, speeding up mem2reg on the testcase in that bug
from 4.56s to 0.02s in a debug build on my machine.
llvm-svn: 58227
In the old way, we computed and inserted phi nodes for the whole IDF of
the definitions of the alloca, then computed which ones were dead and
removed them.
In the new method, we first compute the region where the value is live,
and use that information to only insert phi nodes that are live. This
eliminates the need to compute liveness later, and stops the algorithm
from inserting a bunch of phis which it then later removes.
This speeds up the testcase in PR1432 from 2.00s to 0.15s (14x) in a
release build and 6.84s->0.50s (14x) in a debug build.
llvm-svn: 40825
stored value was a non-instruction value. Doh.
This increase the # single store allocas from 8982 to 9026, and
speeds up mem2reg on the testcase in PR1432 from 2.17 to 2.13s.
llvm-svn: 40813
1. Check for revisiting a block before checking domination, which is faster.
2. If the stored value isn't an instruction, we don't have to check for domination.
3. If we have a value used in the same block more than once, make sure to remove the
block from the UsingBlocks vector. Not doing so forces us to go through the slow
path for the alloca.
The combination of these improvements increases the number of allocas on the fastpath
from 8935 to 8982 on PR1432. This speeds it up from 2.90s to 2.20s (31%)
llvm-svn: 40811
a using block from the list if we handle it. Not doing this caused us
to not be able to promote (with the fast path) allocas which have uses (whoops).
This increases the # allocas hitting this fastpath from 4042 to 8935 on the
testcase in PR1432, speeding up mem2reg by 2.6x
llvm-svn: 40809
BBNumbers. Instead of using a bi-directional mapping, just use a single
densemap. This speeds up mem2reg on 176.gcc by 8%, from 1.3489 to
1.2485s.
llvm-svn: 33940
