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
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
Add a Value named "NAME" to each Record. This will be set to the def or defm
name when instantiating multiclasses. This will replace the #NAME# processing
hack once paste functionality is in place.
llvm-svn: 142518
Record names may not be fully resolved at this point so ask for the
record name as a string explicitly. This avoids a potential assert.
llvm-svn: 142502
Allow template arg names to be Inits. This is further work to
implement paste as it allows template names to participate in paste
operations.
llvm-svn: 142500
Add a couple of utility functions to take a variable name and qualify
it with the namespace of the enclosing class and/or multiclass. This
is inpreparation for making template arg names first-class Inits.
llvm-svn: 142498
Make the VarInit name an Init itself. We need this to implement paste
functionality so we can reference variables whose names are not yet
completely resolved.
llvm-svn: 142497
Add accessors to get Record values by Init name. This lets us look up
Record values whose names are not yet fully resolved. More work
toward paste.
llvm-svn: 142496
Add a couple of utility functions to get at the name init and return
the name init as a string. This will be used for paste functionality.
llvm-svn: 142494
layer already had support for printing the results of this analysis, but
the wiring was missing.
Now that printing the analysis works, actually bring some of this
analysis, and the BranchProbabilityInfo analysis that it wraps, under
test! I'm planning on fixing some bugs and doing other work here, so
having a nice place to add regression tests and a way to observe the
results is really useful.
llvm-svn: 142491
Clean up the patterns, fix comments, and avoid confusing both tools
and coders. Note that the special adds/subs SelectionDAG nodes no
longer have the dummy cc_out operand.
llvm-svn: 142397
Some of these can be true at the same time and there are a lot to add,
so this should be turned into a bitfield. Some of the other accessors
should probably be folded into this.
llvm-svn: 142318
.file filenumber "directory" "filename"
This removes one join+split of the directory+filename in MC internals. Because
bitcode files have independent fields for directory and filenames in debug info,
this patch may change the .o files written by existing .bc files.
llvm-svn: 142300
Invalid strings in asm files will result in parse errors. Invalid string literals passed to TargetData constructors will result in an assertion.
llvm-svn: 142288
Some code want to check that *any* call within a function has the 'returns
twice' attribute, not just that the current function has one.
llvm-svn: 142221
