new instructions it simplifies. Because we're threading jumps on edges
with constants coming in from PHI's, we inherently are exposing a lot more
constants to the new block. Folding them and deleting dead conditions
allows the cost model in jump threading to be more accurate as it iterates.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60327 91177308-0d34-0410-b5e6-96231b3b80d8
elimination: when finding dependent load/stores, realize that
they are the same if aliasing claims must alias instead of relying
on the pointers to be exactly equal. This makes load elimination
more aggressive. For example, on 403.gcc, we had:
< 68 gvn - Number of instructions PRE'd
< 152718 gvn - Number of instructions deleted
< 49699 gvn - Number of loads deleted
< 6153 memdep - Number of dirty cached non-local responses
< 169336 memdep - Number of fully cached non-local responses
< 162428 memdep - Number of uncached non-local responses
now we have:
> 64 gvn - Number of instructions PRE'd
> 153623 gvn - Number of instructions deleted
> 49856 gvn - Number of loads deleted
> 5022 memdep - Number of dirty cached non-local responses
> 159030 memdep - Number of fully cached non-local responses
> 162443 memdep - Number of uncached non-local responses
That's an extra 157 loads deleted and extra 905 other instructions nuked.
This slows down GVN very slightly, from 3.91 to 3.96s.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60314 91177308-0d34-0410-b5e6-96231b3b80d8
vector instead of a densemap. This shrinks the memory usage of this thing
substantially (the high water mark) as well as making operations like
scanning it faster. This speeds up memdep slightly, gvn goes from
3.9376 to 3.9118s on 403.gcc
This also splits out the statistics for the cached non-local case to
differentiate between the dirty and clean cached case. Here's the stats
for 403.gcc:
6153 memdep - Number of dirty cached non-local responses
169336 memdep - Number of fully cached non-local responses
162428 memdep - Number of uncached non-local responses
yay for caching :)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60313 91177308-0d34-0410-b5e6-96231b3b80d8
Note that the FoldOpIntoPhi call is dead because it's impossible for the
first operand of a subtraction to be both a ConstantInt and a PHINode.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60306 91177308-0d34-0410-b5e6-96231b3b80d8
"For signed integers, the determination of overflow of x*y is not so simple. If
x and y have the same sign, then overflow occurs iff xy > 2**31 - 1. If they
have opposite signs, then overflow occurs iff xy < -2**31."
In this case, x == -1.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60278 91177308-0d34-0410-b5e6-96231b3b80d8
overflowed on negation. This commit checks to make sure that neithe C nor X
overflows. This requires that the RHS of X (a subtract instruction) be a
constant integer.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60275 91177308-0d34-0410-b5e6-96231b3b80d8
If we see that a load depends on the allocation of its memory with no
intervening stores, we now return a 'None' depedency instead of "Normal".
This tweaks GVN to do its optimization with the new result.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60267 91177308-0d34-0410-b5e6-96231b3b80d8
former does caching, the later doesn't. This dramatically simplifies
the logic in getDependency and getDependencyFrom.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60234 91177308-0d34-0410-b5e6-96231b3b80d8
query. This makes it crystal clear what cases can escape from MemDep that
the clients have to handle. This also gives the clients a nice simplified
interface to it that is easy to poke at.
This patch also makes DepResultTy and MemoryDependenceAnalysis::DepType
private, yay.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60231 91177308-0d34-0410-b5e6-96231b3b80d8
of a pointer/int pair instead of a manually bitmangled pointer.
This forces clients to think a little more about checking the
appropriate pieces and will be useful for internal
implementation improvements later.
I'm not particularly happy with this. After going through this
I don't think that the clients of memdep should be exposed to
the internal type at all. I'll fix this in a subsequent commit.
This has no functionality change.
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wrappers around the interesting code and use an obscure iterator
abstraction that dates back many many years.
Move EraseDeadInstructions to Transforms/Utils and name it
RecursivelyDeleteTriviallyDeadInstructions.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60191 91177308-0d34-0410-b5e6-96231b3b80d8
1. Make it fold blocks separated by an unconditional branch. This enables
jump threading to see a broader scope.
2. Make jump threading able to eliminate locally redundant loads when they
feed the branch condition of a block. This frequently occurs due to
reg2mem running.
3. Make jump threading able to eliminate *partially redundant* loads when
they feed the branch condition of a block. This is common in code with
lots of loads and stores like C++ code and 255.vortex.
This implements thread-loads.ll and rdar://6402033.
Per the fixme's, several pieces of this should be moved into Transforms/Utils.
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performance in most cases on the Grawp tester, but does speed some
things up (like shootout/hash by 15%). This also doesn't impact
compile time in a noticable way on the Grawp tester.
It also, of course, gets the testcase it was designed for right :)
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heuristic: the value is already live at the new memory operation if
it is used by some other instruction in the memop's block. This is
cheap and simple to compute (moreso than full liveness).
This improves the new heuristic even more. For example, it cuts two
out of three new instructions out of 255.vortex:DbmFileInGrpHdr,
which is one of the functions that the heuristic regressed. This
overall eliminates another 40 instructions from 403.gcc and visibly
reduces register pressure in 255.vortex (though this only actually
ends up saving the 2 instructions from the whole program).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60084 91177308-0d34-0410-b5e6-96231b3b80d8
