Before register allocation, instructions can be moved across calls in
order to reduce register pressure. After register allocation, we don't
gain a lot by moving callee-saved defs across calls. In fact, since the
scheduler doesn't have a good idea how registers are used in the callee,
it can't really make good scheduling decisions.
This changes the schedule in two ways: 1. Latencies to call uses and
defs are no longer accounted for, causing some random shuffling around
calls. This isn't really a problem since those uses and defs are
inaccurate proxies for what happens inside the callee. They don't
represent registers used by the call instruction itself.
2. Instructions are no longer moved across calls. This didn't happen
very often, and the scheduling decision was made on dubious information
anyway.
As with any scheduling change, benchmark numbers shift around a bit,
but there is no positive or negative trend from this change.
This makes the post-ra scheduler 5% faster for ARM targets.
The secret motivation for this patch is the introduction of register
mask operands representing call clobbers. The most efficient way of
handling regmasks in ScheduleDAGInstrs is to model them as barriers for
physreg live ranges, but not for virtreg live ranges. That's fine
pre-ra, but post-ra it would have the same effect as this patch.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151265 91177308-0d34-0410-b5e6-96231b3b80d8
Added array subscript to SparseSet for convenience.
Slight reorg to make it easier to manage the def/use sets.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151228 91177308-0d34-0410-b5e6-96231b3b80d8
The standard function epilog includes a .size directive, but ppc64 uses
an alternate local symbol to tag the actual start of each function.
Until recently, binutils accepted the .size directive as:
.size test1, .Ltmp0-test1
however, using this directive with recent binutils will result in the error:
.size expression for XXX does not evaluate to a constant
so we must use the label which actually tags the start of the function.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151200 91177308-0d34-0410-b5e6-96231b3b80d8
The vast majority of virtual register definitions don't need an entry
in the DAG builder's VRegDefs set.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151136 91177308-0d34-0410-b5e6-96231b3b80d8
Affect on SD scheduling and postRA scheduling:
Printing the DAG will display the nodes in top-down topological order.
This matches the order within the MBB and makes my life much easier in general.
Affect on misched:
We don't need to track virtual register uses at all. This is awesome.
I also intend to rely on the SUnit ID as a topo-sort index. So if A < B then we cannot have an edge B -> A.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151135 91177308-0d34-0410-b5e6-96231b3b80d8
This makes RAFast 4% faster, and it gets rid of the dodgy DenseMap
iteration.
This also revealed that RAFast would sometimes dereference DenseMap
iterators after erasing other elements from the map. That does seem to
work in the current DenseMap implementation, but SparseSet doesn't allow
it.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151111 91177308-0d34-0410-b5e6-96231b3b80d8
bundles. This method takes a bundle start and an MI being bundled, and makes
the intervals for the MI's operands appear to start/end on the bundle start.
Also fixes some minor cosmetic issues (whitespace, naming convention) in the
HMEditor code.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151099 91177308-0d34-0410-b5e6-96231b3b80d8
Passes after RegAlloc should be able to rely on MRI->getNumVirtRegs() == 0.
This makes sharing code for pre/postRA passes more robust.
Now, to check if a pass is running before the RA pipeline begins, use MRI->isSSA().
To check if a pass is running after the RA pipeline ends, use !MRI->getNumVirtRegs().
PEI resets virtual regs when it's done scavenging.
PTX will either have to provide its own PEI pass or assign physregs.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151032 91177308-0d34-0410-b5e6-96231b3b80d8
ecx = mov eax
al = mov ch
The second copy is not a nop because the sub-indices of ecx,ch is not the
same of that of eax/al.
Re-enabled machine-cp.
PR11940
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151002 91177308-0d34-0410-b5e6-96231b3b80d8
MRI keeps track of which physregs have been used. Make sure it gets
updated with all the regmask-clobbered registers.
Delete the closePhysRegsUsed() function which isn't necessary.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150830 91177308-0d34-0410-b5e6-96231b3b80d8
any changes.
Internally this adds a private inner class HMEditor, to LiveIntervals. HMEditor provides
an API for updating live intervals when code is moved or bundled.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150826 91177308-0d34-0410-b5e6-96231b3b80d8
This caused miscompilations on out-of-tree targets, and possibly i386 as
well.
I'll find some other way of hoisting %rip-relative loads from loops
containing calls.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150816 91177308-0d34-0410-b5e6-96231b3b80d8