PowerPC has its custom scheduler heuristic. It calls parent classes'
tryCandidate in override version, but the function returns void, so this
way doesn't actually help. This patch duplicates code from base scheduler
into PPC machine scheduler class, which does what we wanted.
Reviewed By: steven.zhang
Differential Revision: https://reviews.llvm.org/D94464
tryLatency compares two sched candidates. For the top zone it prefers
the one with lesser depth, but only if that depth is greater than the
total latency of the instructions we've already scheduled -- otherwise
its latency would be hidden and there would be no stall.
Unfortunately it only tests the depth of one of the candidates. This can
lead to situations where the TopDepthReduce heuristic does not kick in,
but a lower priority heuristic chooses the other candidate, whose depth
*is* greater than the already scheduled latency, which causes a stall.
The fix is to apply the heuristic if the depth of *either* candidate is
greater than the already scheduled latency.
All this also applies to the BotHeightReduce heuristic in the bottom
zone.
Differential Revision: https://reviews.llvm.org/D72392
The instruction addi is usually used to post increase the loop indvar, which looks like this:
label_X:
load x, base(i)
...
y = op x
...
i = addi i, 1
goto label_X
However, for PowerPC, if there are too many vsx instructions that between y = op x and i = addi i, 1,
it will use all the hw resource that block the execution of i = addi, i, 1, which result in the stall
of the load instruction in next iteration. So, a heuristic is added to move the addi as early as possible
to have the load hide the latency of vsx instructions, if other heuristic didn't apply to avoid the starve.
Reviewed By: jji
Differential Revision: https://reviews.llvm.org/D80269
This was exposed by PowerPC target enablement.
In ScheduleDAG, if we haven't seen any uses in this scheduling region,
we will create a dependence edge to ExitSU to model the live-out latency.
This is required for vreg defs with no in-region use, and prefetches with
no vreg def.
When we build NodeOrder in Scheduler, we ignore these boundary nodes.
However, when we check Succs in checkValidNodeOrder, we did not skip
them, so we still assume all the nodes have been sorted and in order in
Indices array. So when we call lower_bound() for ExitSU, it will return
Indices.end(), causing memory issues in following Node access.
Differential Revision: https://reviews.llvm.org/D63282
llvm-svn: 363329
Looks like a MachinePipeliner algorithm problem found by
sanitizer-x86_64-linux-fast.
I will backout this test first while investigating the problem to
unblock buildbot.
==49637==ERROR: AddressSanitizer: heap-buffer-overflow on address
0x614000002e08 at pc 0x000004364350 bp 0x7ffe228a3bd0 sp 0x7ffe228a3bc8
READ of size 4 at 0x614000002e08 thread T0
#0 0x436434f in
llvm::SwingSchedulerDAG::checkValidNodeOrder(llvm::SmallVector<llvm::NodeSet,
8u> const&) const
/b/sanitizer-x86_64-linux-fast/build/llvm/lib/CodeGen/MachinePipeliner.cpp:3736:11
#1 0x4342cd0 in llvm::SwingSchedulerDAG::schedule()
/b/sanitizer-x86_64-linux-fast/build/llvm/lib/CodeGen/MachinePipeliner.cpp:486:3
#2 0x434042d in
llvm::MachinePipeliner::swingModuloScheduler(llvm::MachineLoop&)
/b/sanitizer-x86_64-linux-fast/build/llvm/lib/CodeGen/MachinePipeliner.cpp:385:7
#3 0x433eb90 in
llvm::MachinePipeliner::runOnMachineFunction(llvm::MachineFunction&)
/b/sanitizer-x86_64-linux-fast/build/llvm/lib/CodeGen/MachinePipeliner.cpp:207:5
#4 0x428b7ea in
llvm::MachineFunctionPass::runOnFunction(llvm::Function&)
/b/sanitizer-x86_64-linux-fast/build/llvm/lib/CodeGen/MachineFunctionPass.cpp:73:13
#5 0x4d1a913 in llvm::FPPassManager::runOnFunction(llvm::Function&)
/b/sanitizer-x86_64-linux-fast/build/llvm/lib/IR/LegacyPassManager.cpp:1648:27
#6 0x4d1b192 in llvm::FPPassManager::runOnModule(llvm::Module&)
/b/sanitizer-x86_64-linux-fast/build/llvm/lib/IR/LegacyPassManager.cpp:1685:16
#7 0x4d1c06d in runOnModule
/b/sanitizer-x86_64-linux-fast/build/llvm/lib/IR/LegacyPassManager.cpp:1752:27
#8 0x4d1c06d in llvm::legacy::PassManagerImpl::run(llvm::Module&)
/b/sanitizer-x86_64-linux-fast/build/llvm/lib/IR/LegacyPassManager.cpp:1865
#9 0xa48ca3 in compileModule(char**, llvm::LLVMContext&)
/b/sanitizer-x86_64-linux-fast/build/llvm/tools/llc/llc.cpp:611:8
#10 0xa4270f in main
/b/sanitizer-x86_64-linux-fast/build/llvm/tools/llc/llc.cpp:365:22
#11 0x7fec902572e0 in __libc_start_main
(/lib/x86_64-linux-gnu/libc.so.6+0x202e0)
#12 0x971b69 in _start
(/b/sanitizer-x86_64-linux-fast/build/llvm_build_asan/bin/llc+0x971b69)
llvm-svn: 363105
Implement necessary target hooks to enable MachinePipeliner for P9 only.
The pass is off by default, can be enabled with -ppc-enable-pipeliner for P9.
Differential Revision: https://reviews.llvm.org/D62164
llvm-svn: 363085
Qiu Chaofan