Subregister definitions are considered uses for the purpose of tracking
liveness of the whole register. At the same time, when calculating live
interval subranges, subregister defs should not be treated as uses.
Differential Revision: https://reviews.llvm.org/D24190
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@280532 91177308-0d34-0410-b5e6-96231b3b80d8
The register allocator can split a live interval of a register into a set
of smaller intervals. After the allocation of registers is complete, the
rewriter will modify the IR to replace virtual registers with the corres-
ponding physical registers. At this stage, if a register corresponding
to a subregister of a virtual register is used, the rewriter will check
if that subregister is undefined, and if so, it will add the <undef> flag
to the machine operand. The function verifying liveness of the subregis-
ter would assume that it is undefined, unless any of the subranges of the
live interval proves otherwise.
The problem is that the live intervals created during splitting do not
have any subranges, even if the original parent interval did. This could
result in the <undef> flag placed on a register that is actually defined.
Differential Revision: http://reviews.llvm.org/D21189
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279625 91177308-0d34-0410-b5e6-96231b3b80d8
We now use LiveRangeCalc::extendToUses() instead of a specially designed
algorithm in constructMainRangeFromSubranges():
- The original motivation for constructMainRangeFromSubranges() were
differences between the main liverange and subranges because of hidden
dead definitions. This case however cannot happen anymore with the
DetectDeadLaneMasks pass in place.
- It simplifies the code.
- This fixes a longstanding bug where we did not properly create new SSA
values on merging control flow (the MachineVerifier missed most of
these cases).
- Move constructMainRangeFromSubranges() to LiveIntervalAnalysis and
LiveRangeCalc to better match the implementation/available helper
functions.
This re-applies r269016. The fixes from r270290 and r270259 should avoid
the machine verifier problems this time.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@270291 91177308-0d34-0410-b5e6-96231b3b80d8
We now use LiveRangeCalc::extendToUses() instead of a specially designed
algorithm in constructMainRangeFromSubranges():
- The original motivation for constructMainRangeFromSubranges() were
differences between the main liverange and subranges because of hidden
dead definitions. This case however cannot happen anymore with the
DetectDeadLaneMasks pass in place.
- It simplifies the code.
- This fixes a longstanding bug where we did not properly create new SSA
values on merging control flow (the MachineVerifier missed most of
these cases).
- Move constructMainRangeFromSubranges() to LiveIntervalAnalysis and
LiveRangeCalc to better match the implementation/available helper
functions.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@269016 91177308-0d34-0410-b5e6-96231b3b80d8
Some subregisters are only to indicate different access sizes, while not
providing any way to actually divide the register up into multiple
disjunct parts. Avoid tracking subregister liveness in these cases as it
is not beneficial.
Differential Revision: http://reviews.llvm.org/D8429
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232695 91177308-0d34-0410-b5e6-96231b3b80d8
This changes subrange calculation to calculate subranges sequentially
instead of in parallel. The code is easier to understand that way and
addresses the code review issues raised about LiveOutData being
hard to understand/needing more comments by removing them :)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224313 91177308-0d34-0410-b5e6-96231b3b80d8
Revert until I find out why non-subreg enabled targets break.
This reverts commit 6097277eefb9c5fb35a7f493c783ee1fd1b9d6a7.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224278 91177308-0d34-0410-b5e6-96231b3b80d8
This changes subrange calculation to calculate subranges sequentially
instead of in parallel. The code is easier to understand that way and
addresses the code review issues raised about LiveOutData being
hard to understand/needing more comments by removing them :)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224272 91177308-0d34-0410-b5e6-96231b3b80d8
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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215558 91177308-0d34-0410-b5e6-96231b3b80d8
It works with clang, but GCC has different rules so we can't make all of those
hidden. This reverts commit r190534.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190536 91177308-0d34-0410-b5e6-96231b3b80d8
When findReachingDefs() finds that only one value can reach the basic
block, just copy the work list of visited blocks directly into the live
interval.
Sort the block list and use a LiveRangeUpdater to make the bulk add
fast.
When multiple reaching defs are found, transfer the work list to the
updateSSA() work list as before. Also use LiveRangeUpdater in
updateLiveIns() following updateSSA().
This makes live interval analysis more than 3x faster on one huge test
case.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@175685 91177308-0d34-0410-b5e6-96231b3b80d8
Catch uses of undefined physregs that haven't been added to basic block
live-in lists. Run the verifier to pinpoint the problem.
Also run the verifier when a virtual register use is not jointly
dominated by defs.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160207 91177308-0d34-0410-b5e6-96231b3b80d8
SplitKit will soon need two copies of these data structures, and the
algorithms will also be useful when LiveIntervalAnalysis becomes
independent of LiveVariables.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@139572 91177308-0d34-0410-b5e6-96231b3b80d8
