| Age | Commit message (Collapse) | Author |
|---|
|
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161712 91177308-0d34-0410-b5e6-96231b3b80d8
|
|
Trace::getResourceLength() computes the number of cycles required to
execute the trace when ignoring data dependencies. The number can be
compared to the critical path to estimate the trace ILP.
Trace::getPHIDepth() computes the data dependency depth of a PHI in a
trace successor that isn't necessarily part of the trace.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161711 91177308-0d34-0410-b5e6-96231b3b80d8
|
|
When a trace ends with a back-edge, include PHIs in the loop header in
the height computations. This makes the critical path through a loop
more accurate by including the latencies of the last instructions in the
loop.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161688 91177308-0d34-0410-b5e6-96231b3b80d8
|
|
We filter out MachineLoop back-edges during the trace-building PO
traversals, but it is possible to have CFG cycles that aren't natural
loops, and MachineLoopInfo doesn't include such cycles.
Use a standard visited set to detect such CFG cycles, and completely
ignore them when picking traces.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161532 91177308-0d34-0410-b5e6-96231b3b80d8
|
|
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161437 91177308-0d34-0410-b5e6-96231b3b80d8
|
|
Compare the critical paths of the two traces through an if-conversion
candidate. If the difference is larger than the branch brediction
penalty, reject the if-conversion. If would never pay.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161433 91177308-0d34-0410-b5e6-96231b3b80d8
|
|
Whenever both instruction depths and instruction heights are known in a
block, it is possible to compute the length of the critical path as
max(depth+height) over the instructions in the block.
The stored live-in lists make it possible to accurately compute the
length of a critical path that bypasses the current (small) block.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161197 91177308-0d34-0410-b5e6-96231b3b80d8
|
|
The height on an instruction is the minimum number of cycles from the
instruction is issued to the end of the trace. Heights are computed for
all instructions in and below the trace center block.
The method for computing heights is different from the depth
computation. As we visit instructions in the trace bottom-up, heights of
used instructions are pushed upwards. This way, we avoid scanning long
use lists, looking for uses in the current trace.
At each basic block boundary, a list of live-in registers and their
minimum heights is saved in the trace block info. These live-in lists
are used when restarting depth computations on a trace that
converges with an already computed trace. They will also be used to
accurately compute the critical path length.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161138 91177308-0d34-0410-b5e6-96231b3b80d8
|
|
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161115 91177308-0d34-0410-b5e6-96231b3b80d8
|
|
Assuming infinite issue width, compute the earliest each instruction in
the trace can issue, when considering the latency of data dependencies.
The issue cycle is record as a 'depth' from the beginning of the trace.
This is half the computation required to find the length of the critical
path through the trace. Heights are next.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161074 91177308-0d34-0410-b5e6-96231b3b80d8
|
|
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161072 91177308-0d34-0410-b5e6-96231b3b80d8
|
|
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161004 91177308-0d34-0410-b5e6-96231b3b80d8
|
|
This lets traces include the final iteration of a nested loop above the
center block, and the first iteration of a nested loop below the center
block.
We still don't allow traces to contain backedges, and traces are
truncated where they would leave a loop, as seen from the center block.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161003 91177308-0d34-0410-b5e6-96231b3b80d8
|
|
When computing a trace, all the candidates for pred/succ must have been
visited. Filter out back-edges first, though. The PO traversal ignores
them.
Thanks to Andy for spotting this in review.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160995 91177308-0d34-0410-b5e6-96231b3b80d8
|
|
By overriding Pass::verifyAnalysis(), the pass contents will be verified
by the pass manager.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160994 91177308-0d34-0410-b5e6-96231b3b80d8
|
|
This is a cleaned up version of the isFree() function in
MachineTraceMetrics.cpp.
Transient instructions are very unlikely to produce any code in the
final output. Either because they get eliminated by RegisterCoalescing,
or because they are pseudo-instructions like labels and debug values.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160977 91177308-0d34-0410-b5e6-96231b3b80d8
|
|
This function verifies the consistency of cached data in the
MachineTraceMetrics analysis.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160976 91177308-0d34-0410-b5e6-96231b3b80d8
|
|
The MachineTraceMetrics analysis must be invalidated before modifying
the CFG. This will catch some of the violations of that rule.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160969 91177308-0d34-0410-b5e6-96231b3b80d8
|
|
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160905 91177308-0d34-0410-b5e6-96231b3b80d8
|
|
This makes it possible to quickly detect blocks that are outside the
trace.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160904 91177308-0d34-0410-b5e6-96231b3b80d8
|
|
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160798 91177308-0d34-0410-b5e6-96231b3b80d8
|
|
This is still a work in progress.
Out-of-order CPUs usually execute instructions from multiple basic
blocks simultaneously, so it is necessary to look at longer traces when
estimating the performance effects of code transformations.
The MachineTraceMetrics analysis will pick a typical trace through a
given basic block and provide performance metrics for the trace. Metrics
will include:
- Instruction count through the trace.
- Issue count per functional unit.
- Critical path length, and per-instruction 'slack'.
These metrics can be used to determine the performance limiting factor
when executing the trace, and how it will be affected by a code
transformation.
Initially, this will be used by the early if-conversion pass.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160796 91177308-0d34-0410-b5e6-96231b3b80d8
|
