Commit Graph

17 Commits

Author SHA1 Message Date
Andrew Trick
6a7770b7ae Enable MI Sched for x86.
This changes the SelectionDAG scheduling preference to source
order. Soon, the SelectionDAG scheduler can be bypassed saving
a nice chunk of compile time.

Performance differences that result from this change are often a
consequence of register coalescing. The register coalescer is far from
perfect. Bugs can be filed for deficiencies.

On x86 SandyBridge/Haswell, the source order schedule is often
preserved, particularly for small blocks.

Register pressure is generally improved over the SD scheduler's ILP
mode. However, we are still able to handle large blocks that require
latency hiding, unlike the SD scheduler's BURR mode. MI scheduler also
attempts to discover the critical path in single-block loops and
adjust heuristics accordingly.

The MI scheduler relies on the new machine model. This is currently
unimplemented for AVX, so we may not be generating the best code yet.

Unit tests are updated so they don't depend on SD scheduling heuristics.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192750 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-15 23:33:07 +00:00
Will Dietz
e4b44c1617 MachineSink: Fix and tweak critical-edge breaking heuristic.
Per original comment, the intention of this loop
is to go ahead and break the critical edge
(in order to sink this instruction) if there's
reason to believe doing so might "unblock" the
sinking of additional instructions that define
registers used by this one.  The idea is that if
we have a few instructions to sink "together"
breaking the edge might be worthwhile.

This commit makes a few small changes
to help better realize this goal:

First, modify the loop to ignore registers
defined by this instruction.  We don't
sink definitions of physical registers,
and sinking an SSA definition isn't
going to unblock an upstream instruction.

Second, ignore uses of physical registers.
Instructions that define physical registers are
rejected for sinking, and so moving this one
won't enable moving any defining instructions.
As an added bonus, while virtual register
use-def chains are generally small due
to SSA goodness, iteration over the uses
and definitions (used by hasOneNonDBGUse)
for physical registers like EFLAGS
can be rather expensive in practice.
(This is the original reason for looking at this)

Finally, to keep things simple continue
to only consider this trick for registers that
have a single use (via hasOneNonDBGUse),
but to avoid spuriously breaking critical edges
only do so if the definition resides
in the same MBB and therefore this one directly
blocks it from being sunk as well.
If sinking them together is meant to be,
let the iterative nature of this pass
sink the definition into this block first.

Update tests to accomodate this change,
add new testcase where sinking avoids pipeline stalls.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192608 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-14 16:57:17 +00:00
Stephen Lin
b4dc0233c9 Convert CodeGen/*/*.ll tests to use the new CHECK-LABEL for easier debugging. No functionality change and all tests pass after conversion.
This was done with the following sed invocation to catch label lines demarking function boundaries:
    sed -i '' "s/^;\( *\)\([A-Z0-9_]*\):\( *\)test\([A-Za-z0-9_-]*\):\( *\)$/;\1\2-LABEL:\3test\4:\5/g" test/CodeGen/*/*.ll
which was written conservatively to avoid false positives rather than false negatives. I scanned through all the changes and everything looks correct.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186258 91177308-0d34-0410-b5e6-96231b3b80d8
2013-07-13 20:38:47 +00:00
Andrew Trick
b2b5dc642c Revert "Temporarily enable MI-Sched on X86."
This reverts commit 98a9b72e8c.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184823 91177308-0d34-0410-b5e6-96231b3b80d8
2013-06-25 02:48:58 +00:00
Andrew Trick
98a9b72e8c Temporarily enable MI-Sched on X86.
Sorry for the unit test churn. I'll try to make the change permanently
next time.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184705 91177308-0d34-0410-b5e6-96231b3b80d8
2013-06-24 09:13:20 +00:00
Nadav Rotem
b9d6b8449d Reapply r162160 with a fix: Optimize Arith->Trunc->SETCC sequence to allow better compare/branch code.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@162172 91177308-0d34-0410-b5e6-96231b3b80d8
2012-08-18 17:53:03 +00:00
Nadav Rotem
d5c66a0b1f Revert r162160 because it made a few buildbots fail.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@162164 91177308-0d34-0410-b5e6-96231b3b80d8
2012-08-18 05:02:36 +00:00
Nadav Rotem
b5838689c6 The X86 backend has a number of optimizations for SETCC nodes which use
arithmetic instructions. However, when small data types are used, a truncate
node appears between the SETCC node and the arithmetic operation. This patch
adds support for this pattern.

Before:
  xorl  %esi, %edi
  testb %dil, %dil
  setne %al
  ret

After:
  xorb  %dil, %sil
  setne %al
  ret

rdar://12081007



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@162160 91177308-0d34-0410-b5e6-96231b3b80d8
2012-08-18 02:43:28 +00:00
Manman Ren
d7d003c2b7 X86 Peephole: fold loads to the source register operand if possible.
Machine CSE and other optimizations can remove instructions so folding
is possible at peephole while not possible at ISel.

This patch is a rework of r160919 and was tested on clang self-host on my local
machine.

rdar://10554090 and rdar://11873276


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161152 91177308-0d34-0410-b5e6-96231b3b80d8
2012-08-02 00:56:42 +00:00
Manman Ren
e8b4a4a9d1 Revert r160920 and r160919 due to dragonegg and clang selfhost failure
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160927 91177308-0d34-0410-b5e6-96231b3b80d8
2012-07-29 02:44:09 +00:00
Manman Ren
0eb3edea9c X86 Peephole: fold loads to the source register operand if possible.
Machine CSE and other optimizations can remove instructions so folding
is possible at peephole while not possible at ISel.

rdar://10554090 and rdar://11873276


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160919 91177308-0d34-0410-b5e6-96231b3b80d8
2012-07-28 16:48:01 +00:00
Andrew Trick
922d314e8f Instruction scheduling itinerary for Intel Atom.
Adds an instruction itinerary to all x86 instructions, giving each a default latency of 1, using the InstrItinClass IIC_DEFAULT.

Sets specific latencies for Atom for the instructions in files X86InstrCMovSetCC.td, X86InstrArithmetic.td, X86InstrControl.td, and X86InstrShiftRotate.td. The Atom latencies for the remainder of the x86 instructions will be set in subsequent patches.

Adds a test to verify that the scheduler is working.

Also changes the scheduling preference to "Hybrid" for i386 Atom, while leaving x86_64 as ILP.

Patch by Preston Gurd!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@149558 91177308-0d34-0410-b5e6-96231b3b80d8
2012-02-01 23:20:51 +00:00
Chris Lattner
bd1fccfad5 Fix rdar://7517201, a regression introduced by r92849.
When folding a and(any_ext(load)) both the any_ext and the
load have to have only a single use.

This removes the anyext-uses.ll testcase which started failing
because it is unreduced and unclear what it is testing.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@92950 91177308-0d34-0410-b5e6-96231b3b80d8
2010-01-07 21:59:23 +00:00
Dan Gohman
36a0947820 Eliminate more uses of llvm-as and llvm-dis.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@81290 91177308-0d34-0410-b5e6-96231b3b80d8
2009-09-08 23:54:48 +00:00
Evan Cheng
bc7e0f5dd6 Add -march=x86.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60135 91177308-0d34-0410-b5e6-96231b3b80d8
2008-11-27 00:37:06 +00:00
Tanya Lattner
33eefffb2b Remove llvm-upgrade and update tests.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@47432 91177308-0d34-0410-b5e6-96231b3b80d8
2008-02-21 07:42:26 +00:00
Chris Lattner
22c31769fb rename tests to avoid a test- prefix when they aren't related to the test instruction.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@47329 91177308-0d34-0410-b5e6-96231b3b80d8
2008-02-19 17:33:52 +00:00