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
Summary:
When doing the conversion: MachineInst -> MCInst, we should ignore the
implicit operands, it will expose more opportunity for InstiAlias.
Reviewed By: steven.zhang
Differential Revision: https://reviews.llvm.org/D77118
Summary: b19ec1eb3d has been reverted because of the test failures
with PowerPC targets. This patch addresses the issues from the previous
commit.
Test Plan: ninja check-all. Confirmed that CodeGen/PowerPC/pr36292.ll
and CodeGen/PowerPC/sms-cpy-1.ll pass
Subscribers: llvm-commits
Summary:
This is brought up in
https://reviews.llvm.org/D64662?id=209923#inline-599490
CFI information are non-relevant to quite some testcases,
we should get rid of checking them when its unecessary.
This patch avoid generating cfi info in testcases that are not
testing prolog/epilog or exception handling.
Reviewers: kbarton, hfinkel, nemanjai, #powerpc
Reviewed By: hfinkel
Subscribers: MaskRay, shchenz, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D67016
llvm-svn: 370505
Summary:
This is exposed by adding a new testcase in PowerPC in
https://reviews.llvm.org/rL367732
The testcase got different output on different platform, hence breaking
buildbots.
The problem is that we get differnt FuncUnitOrder when calculateResMII.
The root cause is:
1. Two MachineInstr might get SAME priority(MFUsx) from minFuncUnits.
2. Current comparison operator() will return `MFUs1 > MFUs2`.
3. We use iterators for MachineInstr, so the input to FuncUnitSorter
might be different on differnt platform due to the iterator nature.
So for two MI with same MFU, their order is actually depends on the
iterator order, which is platform (implemtation) dependent.
This is risky, and may cause cross-compiling problems.
The fix is to check make sure we assign a determine order when they are
equal.
Reviewers: bcahoon, hfinkel, jmolloy
Subscribers: nemanjai, hiraditya, MaskRay, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65992
llvm-svn: 368441
Jay Foad