alignment attribute such that 0 means unaligned.
This will probably require a rebuild of llvm-gcc because of the change to
Attributes.h. If you see many test failures on "make check", please rebuild
your llvm-gcc.
llvm-svn: 61030
CFG when there is exactly one predecessor where the load is not available.
This is designed to not increase code size but still eliminate partially
redundant loads. This fires 1765 times on 403.gcc even though it doesn't
do critical edge splitting yet (the most common reason for it to fail).
llvm-svn: 61027
cleans up the generated code a bit. This should have the added benefit of
not randomly renaming functions/globals like my previous patch did. :)
llvm-svn: 61023
memdep keeps track of how PHIs affect the pointer in dep queries, which
allows it to eliminate the load in cases like rle-phi-translate.ll, which
basically end up being:
BB1:
X = load P
br BB3
BB2:
Y = load Q
br BB3
BB3:
R = phi [P] [Q]
load R
turning "load R" into a phi of X/Y. In addition to additional exposed
opportunities, this makes memdep safe in many cases that it wasn't before
(which is required for load PRE) and also makes it substantially more
efficient. For example, consider:
bb1: // has many predecessors.
P = some_operator()
load P
In this example, previously memdep would scan all the predecessors of BB1
to see if they had something that would mustalias P. In some cases (e.g.
test/Transforms/GVN/rle-must-alias.ll) it would actually find them and end
up eliminating something. In many other cases though, it would scan and not
find anything useful. MemDep now stops at a block if the pointer is defined
in that block and cannot be phi translated to predecessors. This causes it
to miss the (rare) cases like rle-must-alias.ll, but makes it faster by not
scanning tons of stuff that is unlikely to be useful. For example, this
speeds up GVN as a whole from 3.928s to 2.448s (60%)!. IMO, scalar GVN
should be enhanced to simplify the rle-must-alias pointer base anyway, which
would allow the loads to be eliminated.
In the future, this should be enhanced to phi translate through geps and
bitcasts as well (as indicated by FIXMEs) making memdep even more powerful.
llvm-svn: 61022
callee will not introduce any new aliases of that pointer.
The attributes had all bits allocated already, so I decided to collapse
alignment. Alignment was previously stored as a 16-bit integer from bits 16 to
32 of the attribute, but it was required to be a power of 2. Now it's stored in
log2 encoded form in five bits from 16 to 21. That gives us 11 more bits of
space.
You may have already noticed that you only need four bits to encode a 16-bit
power of two, so why five bits? Because the AsmParser accepted 32-bit
alignments, even though we couldn't store them (they were silently discarded).
Now we can store them in memory, but not in the bitcode.
The bitcode format was already storing these as 64-bit VBR integers. So, the
bitcode format stays the same, keeping the alignment values stored as 16 bit
raw values. There's some hideous code in the reader and writer that deals with
this, waiting to be ripped out the moment we run out of bits again and have to
replace the parameter attributes table encoding.
llvm-svn: 61019
- Overhauled the notion of "types" for TypedRegions. We now distinguish between the "lvalue" of a region (via getLValueRegion()) and the "rvalue" of a region (va getRValueRegion()). Since a region represents a chunk of memory it has both, but we were conflating these concepts in some cases, leading to some insidious bugs.
- Removed AnonPointeeType, partially because it is unused and because it doesn't have a clear notion of lvalue vs rvalue type. We can add it back once there is a need for it and we can resolve its role with these concepts.
StoreManager:
- Overhauled StoreManager::CastRegion. It expects an *lvalue* type for a region. This is actually what motivated the overhaul to the MemRegion type mechanism. It also no longer returns an SVal; we can just return a MemRegion*.
- BasicStoreManager::CastRegion now overlays an "AnonTypedRegion" for pointer-pointer casts. This matches with the MemRegion changes.
- Similar changes to RegionStore, except I've added a bunch of FIXMEs where it wasn't 100% clear where we should use TypedRegion::getRValueRegion() or TypedRegion::getLValueRegion().
AuditCFNumberCreate check:
- Now blasts through AnonTypedRegions that may layer the original memory region, thus checking if the actually memory block is of the appropriate type. This change was needed to work with the changes to StoreManager::CastRegion.
GRExprEngine::VisitCast:
- Conform to the new interface of StoreManager::CastRegion.
Tests:
- None of the analysis tests fail now for using the "basic store".
- Disabled the tests 'array-struct.c' and 'rdar-6442306-1.m' pending further testing and bug fixing.
llvm-svn: 60995
GRExprEngine (VisitCast):
- When using StoreManager::CastRegion, always use the state and value it returns to generate the next node. Failure to do so means that region values returned that don't require the state to be modified will get ignored.
MemRegion:
- Tighten the interface for ElementRegion. Now ElementRegion can only be created with a super region that is a 'TypedRegion' instead of any MemRegion. Code in BasicStoreManager/RegionStoreManager already assumed this, but it would result in a dynamic assertion check (and crash) rather than just having the compiler forbid the construction of such regions.
- Added ElementRegion::getArrayRegion() to return the 'typed version' of an ElementRegion's super region.
- Removed bogus assertion in ElementRegion::getType() that assumed that the super region was an AnonTypedRegion. All that matters is that it is a TypedRegion, which is now true all the time by design.
BasicStore:
- Modified getLValueElement() to check if the 'array' region is a TypedRegion before creating an ElementRegion. This conforms to the updated interface for ElementRegion.
RegionStore:
- In ArrayToPointer() gracefully handle things we don't reason about, and only create an ElementRegion if the array region is indeed a TypedRegion.
llvm-svn: 60990
Chris Lattner