To do this, change the representation of lazy loaded functions.
The previous representation cannot differentiate between a function whose body
has been removed and one whose body hasn't been read from the .bc file. That
means that in order to drop a function, the entire body had to be read.
llvm-svn: 220580
The attached patch simplifies a few interfaces that don't need to take
ownership of a buffer.
For example, both parseAssembly and parseBitcodeFile will parse the
entire buffer before returning. There is no need to take ownership.
Using a MemoryBufferRef makes it obvious in the type signature that
there is no ownership transfer.
llvm-svn: 216488
Block address forward-references are implemented by creating a
`BasicBlock` ahead of time that gets inserted in the `Function` when
it's eventually encountered.
However, if the same blockaddress was used in two separate functions
that were parsed *before* the referenced function (and the blockaddress
was never used at global scope), two separate basic blocks would get
created, one of which would be forgotten creating invalid IR.
This commit changes the forward-reference logic to create only one basic
block (and always return the same blockaddress).
llvm-svn: 215805
Add header guards to files that were missing guards. Remove #endif comments
as they don't seem common in LLVM (we can easily add them back if we decide
they're useful)
Changes made by clang-tidy with minor tweaks.
llvm-svn: 215558
`BasicBlockFwdRefs` (and `BlockAddrFwdRefs` before it) was being emptied
in a non-deterministic order. When predicting use-list order I've
worked around this another way, but even when parsing lazily (and we
can't recreate use-list order) use-lists should be deterministic.
Make them so by using a side-queue of functions with forward-referenced
blocks that gets visited in order.
llvm-svn: 214899
Now that we can reliably handle forward references to `BlockAddress`
(r214563), change the mechanics to simplify predicting use-list order.
Previously, we created dummy `GlobalVariable`s to represent block
addresses. After every function was materialized, we'd go through any
forward references to its blocks and RAUW them with a proper
`BlockAddress` constant. This causes some (potentially a lot of)
unnecessary use-list churn, since any constant expression that it's a
part of will need to be rematerialized as well.
Instead, pre-construct a `BasicBlock` immediately -- without attaching
it to its (empty) `Function` -- and use that to construct a
`BlockAddress`. This constant will not have to be regenerated. When
the function body is parsed, hook this pre-constructed basic block up
in the right place using `BasicBlock::insertInto()`.
Both before and after this change, the IR is temporarily in an invalid
state that gets resolved when `materializeForwardReferencedFunctions()`
gets called.
This is a prep commit that's part of PR5680, but the only functionality
change is the reduction of churn in the constant pool.
llvm-svn: 214570
`BlockAddress`es are interesting in that they can reference basic blocks
from *outside* the block's function. Since basic blocks are not global
values, this presents particular challenges for lazy parsing.
One corner case was found in PR11677 and fixed in r147425. In that
case, a global variable references a block address. It's necessary to
load the relevant function to resolve the forward reference before doing
anything with the module.
By inspection, I found (and have fixed here) two other cases:
- An instruction from one function references a block address from
another function, and only the first function is lazily loaded.
I fixed this the same way as PR11677: by eagerly loading the
referenced function.
- A function whose block address is taken is dematerialized, leaving
invalid references to it.
I fixed this by refusing to dematerialize functions whose block
addresses are taken (if you have to load it, you can't unload it).
llvm-svn: 214559
This will let users in other libraries know which error occurred. In particular,
it will be possible to check if the parsing failed or if the file is not
bitcode.
llvm-svn: 214209
Predict and serialize use-list order in bitcode. This makes the option
`-preserve-bc-use-list-order` work *most* of the time, but this is still
experimental.
- Builds a full value-table up front in the writer, sets up a list of
use-list orders to write out, and discards the table. This is a
simpler first step than determining the order from the various
overlapping IDs of values on-the-fly.
- The shuffles stored in the use-list order list have an unnecessarily
large memory footprint.
- `blockaddress` expressions cause functions to be materialized
out-of-order. For now I've ignored this problem, so use-list orders
will be wrong for constants used by functions that have block
addresses taken. There are a couple of ways to fix this, but I
don't have a concrete plan yet.
- When materializing functions lazily, the use-lists for constants
will not be correct. This use case is out of scope: what should the
use-list order be, if it's incomplete?
This is part of PR5680.
llvm-svn: 214125
This reverts commit r212342.
We can get a StringRef into the current Record, but not one in the bitcode
itself since the string is compressed in it.
llvm-svn: 212356
This new IR facility allows us to represent the object-file semantic of
a COMDAT group.
COMDATs allow us to tie together sections and make the inclusion of one
dependent on another. This is required to implement features like MS
ABI VFTables and optimizing away certain kinds of initialization in C++.
This functionality is only representable in COFF and ELF, Mach-O has no
similar mechanism.
Differential Revision: http://reviews.llvm.org/D4178
llvm-svn: 211920
This allows us to just use a std::unique_ptr to store the pointer to the buffer.
The flip side is that they have to support releasing the buffer back to the
caller.
Overall this looks like a more efficient and less brittle api.
llvm-svn: 211542
LLVMGetBitcodeModuleInContext should not take ownership on error. I will
try to localize this odd api requirement, but this should get the bots green.
llvm-svn: 211213
We do have use cases for the bitcode reader owning the buffer or not, but we
always know which one we have when we construct it.
It might be possible to simplify this further, but this is a step in the
right direction.
llvm-svn: 211205
This compiles with no changes to clang/lld/lldb with MSVC and includes
overloads to various functions which are used by those projects and llvm
which have OwningPtr's as parameters. This should allow out of tree
projects some time to move. There are also no changes to libs/Target,
which should help out of tree targets have time to move, if necessary.
llvm-svn: 203083
implementation already lived.
After this commit, the only IR-library headers in include/llvm/* are
ones related to the legacy pass infrastructure that I'm planning to
leave there until the new one is farther along.
The only other headers at the top level are linking and initialization
aids that aren't really libraries but just headers.
llvm-svn: 203069
Rafael Espindola
Duncan P. N. Exon Smith
Benjamin Kramer
David Majnemer
Craig Topper
Ahmed Charles
Chandler Carruth