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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61022 91177308-0d34-0410-b5e6-96231b3b80d8
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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61019 91177308-0d34-0410-b5e6-96231b3b80d8
* Lowercased all HTML element names
* Standardized spacing around { and }
* removed class "doc_table_nw": grep finds no uses
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61004 91177308-0d34-0410-b5e6-96231b3b80d8
llvm[2]: Linking Release executable opt (without symbols)
...
Undefined symbols:
"llvm::APFloat::IEEEsingle", referenced from:
__ZN4llvm7APFloat10IEEEsingleE$non_lazy_ptr in libLLVMCore.a(Constants.o)
__ZN4llvm7APFloat10IEEEsingleE$non_lazy_ptr in libLLVMCore.a(AsmWriter.o)
__ZN4llvm7APFloat10IEEEsingleE$non_lazy_ptr in libLLVMCore.a(ConstantFold.o)
"llvm::APFloat::IEEEdouble", referenced from:
__ZN4llvm7APFloat10IEEEdoubleE$non_lazy_ptr in libLLVMCore.a(Constants.o)
__ZN4llvm7APFloat10IEEEdoubleE$non_lazy_ptr in libLLVMCore.a(AsmWriter.o)
__ZN4llvm7APFloat10IEEEdoubleE$non_lazy_ptr in libLLVMCore.a(ConstantFold.o)
ld: symbol(s) not found
This is in release mode. To replicate, compile llvm and llvm-gcc in optimized
mode. Then build llvm, in optimized mode, with the newly created compiler.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60977 91177308-0d34-0410-b5e6-96231b3b80d8
width register load followed by a truncating
store for the copy, since the load will not place
the value in the lower bits. Probably partial
loads/stores can never happen here, but fix it
anyway.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60972 91177308-0d34-0410-b5e6-96231b3b80d8
use of illegal integer types: instead, use a stack slot
and copying via integer registers. The existing code
is still used if the bitconvert is to a legal integer
type.
This fires on the PPC testcases 2007-09-08-unaligned.ll
and vec_misaligned.ll. It looks like equivalent code
is generated with these changes, just permuted, but
it's hard to tell.
With these changes, nothing in LegalizeDAG produces
illegal integer types anymore. This is a prerequisite
for removing the LegalizeDAG type legalization code.
While there I noticed that the existing code doesn't
handle trunc store of f64 to f32: it turns this into
an i64 store, which represents a 4 byte stack smash.
I added a FIXME about this. Hopefully someone more
motivated than I am will take care of it.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60964 91177308-0d34-0410-b5e6-96231b3b80d8
which are identical to the original patterns.
- Change the multiply with overflow so that we distinguish between signed and
unsigned multiplication. Currently, unsigned multiplication with overflow
isn't working!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60963 91177308-0d34-0410-b5e6-96231b3b80d8
do an extending load of the 4 bytes rather than a
potentially illegal (type) i32 load followed by a
sign extend.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60945 91177308-0d34-0410-b5e6-96231b3b80d8
ISD::ADD to emit an implicit EFLAGS. This was horribly broken. Instead, replace
the intrinsic with an ISD::SADDO node. Then custom lower that into an
X86ISD::ADD node with a associated SETCC that checks the correct condition code
(overflow or carry). Then that gets lowered into the correct X86::ADDOvf
instruction.
Similar for SUB and MUL instructions.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60915 91177308-0d34-0410-b5e6-96231b3b80d8
