block frequency analyses. This differs substantially from the existing
block-placement pass in LLVM:
1) It operates on the Machine-IR in the CodeGen layer. This exposes much
more (and more precise) information and opportunities. Also, the
results are more stable due to fewer transforms ocurring after the
pass runs.
2) It uses the generalized probability and frequency analyses. These can
model static heuristics, code annotation derived heuristics as well
as eventual profile loading. By basing the optimization on the
analysis interface it can work from any (or a combination) of these
inputs.
3) It uses a more aggressive algorithm, both building chains from tho
bottom up to maximize benefit, and using an SCC-based walk to layout
chains of blocks in a profitable ordering without O(N^2) iterations
which the old pass involves.
The pass is currently gated behind a flag, and not enabled by default
because it still needs to grow some important features. Most notably, it
needs to support loop aligning and careful layout of loop structures
much as done by hand currently in CodePlacementOpt. Once it supports
these, and has sufficient testing and quality tuning, it should replace
both of these passes.
Thanks to Nick Lewycky and Richard Smith for help authoring & debugging
this, and to Jakob, Andy, Eric, Jim, and probably a few others I'm
forgetting for reviewing and answering all my questions. Writing
a backend pass is *sooo* much better now than it used to be. =D
llvm-svn: 142641
the last compiler built for the previous flavour is used for the next,
for example the Debug clang compiler was being used for the initial build
of the Release LLVM. Flavors should be independent of each other. This
especially matters if the compiler built for the previous flavour doesn't
actually work!
llvm-svn: 142607
AsmParser. This patch adds validation for target data layout strings upon
construction of TargetData objects. An attempt to construct a TargetData object
from a malformed string will trigger an assertion.
llvm-svn: 142605
When checking the availability of instructions using the TLI, a 'promoted'
instruction IS available. It means that the value is bitcasted to another type
for which there is an operation. The correct check for the availablity of an
instruction is to check if it should be expanded.
llvm-svn: 142542
On spec/gcc, this caused a codesize improvement of ~1.9% for ARM mode and ~4.9% for Thumb(2) mode. This is
codesize including literal pools.
The pools themselves doubled in size for ARM mode and quintupled for Thumb mode, leaving suggestion that there
is still perhaps redundancy in LLVM's use of constant pools that could be decreased by sharing entries.
Fixes PR11087.
llvm-svn: 142530
Add a paste operator '#' to take two identifier-like strings and joint
them. Internally paste gets represented as a !strconcat() with any
necessary casts to string added.
This will be used to implement basic for loop functionality as in:
for i = [0, 1, 2, 3, 4, 5, 6, 7] {
def R#i : Register<...>
}
llvm-svn: 142525
Stop parsing a value if we are in name parsing mode and we see a left
brace. A left brace indicates the start of an object body when we are
parsing a name.
llvm-svn: 142521
Add a mode control to value and ID parsers. The two modes are:
- Parse a value. Expect the parsed ID to map to an existing object.
- Parse a name. Expect the parsed ID to not map to any existing object.
The first is used when parsing an identifier to be looked up, for
example a record field or template argument. The second is used for
parsing declarations. Paste functionality implies that declarations
can contain arbitrary expressions so we need to be able to call into
the general value parser to parse declarations with paste operators.
So we need a way to parse a value-like thing without expecting that
the result will map to some existing object. This parse mode provides
that.
llvm-svn: 142519
