"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
nearby FIXME.
I'm not sure what the right way to fix the Cell test was; if the
approach I used isn't okay, please let me know.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60277 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
ReverseLocalDeps when we update it. This fixes a regression test
failure from my last commit.
Second, for each non-local cached information structure, keep a bit that
indicates whether it is dirty or not. This saves us a scan over the whole
thing in the common case when it isn't dirty.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60274 91177308-0d34-0410-b5e6-96231b3b80d8
Hopefully this doesn't break anyone else's build... it shouldn't unless
the MinGW variable means something other than compiling with MinGW.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60273 91177308-0d34-0410-b5e6-96231b3b80d8
instead of containing them by value. This increases the density
(!) of NonLocalDeps as well as making the reallocation case
faster. This speeds up gvn on 403.gcc by 2% and makes room for
future improvements.
I'm not super thrilled with having to explicitly manage the new/delete
of the map, but it is necesary for the next change.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60271 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
method that returns its result as a DepResultTy instead of as a
MemDepResult. This reduces conversion back and forth.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60266 91177308-0d34-0410-b5e6-96231b3b80d8
dependencies. The basic situation was this: consider if we had:
store1
...
store2
...
store3
Where memdep thinks that store3 depends on store2 and store2 depends
on store1. The problem happens when we delete store2: The code in
question was updating dep info for store3 to be store1. This is a
spiffy optimization, but is not safe at all, because aliasing isn't
transitive. This bug isn't exposed today with DSE because DSE will only
zap store2 if it is identifical to store 3, and in this case, it is
safe to update it to depend on store1. However, memcpyopt is not so
fortunate, which is presumably why the "dropInstruction" code used to
exist.
Since this doesn't actually provide a speedup in practice, just rip the
code out.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60263 91177308-0d34-0410-b5e6-96231b3b80d8
an entry in the nonlocal deps map, don't reset entries
referencing that instruction to [dirty, null], instead, set
them to [dirty,next] where next is the instruction after the
deleted one. Use this information in the non-local deps
code to avoid rescanning entire blocks.
This speeds up GVN slightly by avoiding pointless work. On
403.gcc this makes GVN 1.5% faster.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60256 91177308-0d34-0410-b5e6-96231b3b80d8
Put a some code back to handle buggy behavior that GVN expects: it wants
loads to depend on each other, and accesses to depend on their allocations.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60240 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
Document the Dirty value more precisely, use it for the uninitialized
DepResultTy value. Change reverse mappings to be from an instruction*
instead of DepResultTy, and stop tracking other forms. This makes it more
clear that we only care about the instruction cases.
Eliminate a DepResultTy,bool pair by using Dirty in the local case as well,
shrinking the map and simplifying the code.
This speeds up GVN by ~3% on 403.gcc.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60232 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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60230 91177308-0d34-0410-b5e6-96231b3b80d8
properly updates the reverse dependency map when it installs updated
dependencies for instructions that depend on the removed instruction.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60222 91177308-0d34-0410-b5e6-96231b3b80d8
