Revert r.215058.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_35@215426 91177308-0d34-0410-b5e6-96231b3b80d8
Merging r214670:
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r214670 | spatel | 2014-08-03 15:48:23 -0700 (Sun, 03 Aug 2014) | 8 lines

fix for PR20354 - Miscompile of fabs due to vectorization

This is intended to be the minimal change needed to fix PR20354 ( http://llvm.org/bugs/show_bug.cgi?id=20354 ). The check for a vector operation was wrong; we need to check that the fabs itself is not a vector operation.

This patch will not generate the optimal code. A constant pool load and 'and' op will be generated instead of just returning a value that we can calculate in advance (as we do for the scalar case). I've put a 'TODO' comment for that here and expect to have that patch ready soon.

There is a very similar optimization that we can do in visitFNEG, so I've put another 'TODO' there and expect to have another patch for that too.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_35@215428 91177308-0d34-0410-b5e6-96231b3b80d8
Merging r214674:
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r214674 | spatel | 2014-08-03 16:20:16 -0700 (Sun, 03 Aug 2014) | 2 lines

Account for possible leading '.' in label string.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_35@215429 91177308-0d34-0410-b5e6-96231b3b80d8
Merging r214679:
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r214679 | chandlerc | 2014-08-03 17:54:28 -0700 (Sun, 03 Aug 2014) | 10 lines

[x86] Fix the test case added in r214670 and tweaked in r214674 further.

Fundamentally, there isn't a really portable way to test the constant
pool contents. Instead, pin this test to the bare-metal triple. This
also makes it a 64-bit triple which allows us to only match a single
constant pool rather than two. It can also just hard code the '.' prefix
as the format should be stable now that it has a fixed triple. Finally,
I've switched it to use CHECK-NEXT to be more precise in the instruction
sequence expected and to use variables rather than hard coding decisions
by the register allocator.
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_35@215430 91177308-0d34-0410-b5e6-96231b3b80d8
Merging r215806:
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_35@215874 91177308-0d34-0410-b5e6-96231b3b80d8
Merging r215685:
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r215685 | wschmidt | 2014-08-14 18:25:26 -0700 (Thu, 14 Aug 2014) | 69 lines

[PPC64] Add missing dependency on X2 to LDinto_toc.

The LDinto_toc pattern has been part of 64-bit PowerPC for a long
time, and represents loading from a memory location into the TOC
register (X2).  However, this pattern doesn't explicitly record that
it modifies that register.  This patch adds the missing dependency.

It was very surprising to me that this has never shown up as a problem
in the past, and that we only saw this problem recently in a single
scenario when building a self-hosted clang.  It turns out that in most
cases we have another dependency present that keeps the LDinto_toc
instruction tied in place.  LDinto_toc is used for TOC restore
following a call site, so this is a typical sequence:

   BCTRL8 <regmask>, %CTR8<imp-use>, %RM<imp-use>, %X3<imp-use>, %X12<imp-use>, %X1<imp-def>, ...
   LDinto_toc 24, %X1
   ADJCALLSTACKUP 96, 0, %R1<imp-def>, %R1<imp-use>

Because the LDinto_toc is inserted prior to the ADJCALLSTACKUP, there
is a natural anti-dependency between the two that keeps it in place.

Therefore we don't usually see a problem.  However, in one particular
case, one call is followed immediately by another call, and the second
call requires a parameter that is a TOC-relative address.  This is the
code sequence:

  BCTRL8 <regmask>, %CTR8<imp-use>, %RM<imp-use>, %X3<imp-use>, %X4<imp-use>, %X5<imp-use>, %X12<imp-use>, %X1<imp-def>, ...
  LDinto_toc 24, %X1
  ADJCALLSTACKUP 96, 0, %R1<imp-def>, %R1<imp-use>
  ADJCALLSTACKDOWN 96, %R1<imp-def>, %R1<imp-use>
  %vreg39<def> = ADDIStocHA %X2, <ga:@.str>; G8RC_and_G8RC_NOX0:%vreg39
  %vreg40<def> = ADDItocL %vreg39<kill>, <ga:@.str>; G8RC:%vreg40 G8RC_and_G8RC_NOX0:%vreg39

Note that the back-to-back stack adjustments are the same size!  The
back end is smart enough to recognize this and optimize them away:

  BCTRL8 <regmask>, %CTR8<imp-use>, %RM<imp-use>, %X3<imp-use>, %X4<imp-use>, %X5<imp-use>, %X12<imp-use>, %X1<imp-def>, ...
  LDinto_toc 24, %X1
  %vreg39<def> = ADDIStocHA %X2, <ga:@.str>; G8RC_and_G8RC_NOX0:%vreg39
  %vreg40<def> = ADDItocL %vreg39<kill>, <ga:@.str>; G8RC:%vreg40 G8RC_and_G8RC_NOX0:%vreg39

Now there is nothing to prevent the ADDIStocHA instruction from moving
ahead of the LDinto_toc instruction, and because of the longest-path
heuristic, this is what happens.

With the accompanying patch, %X2 is represented as an implicit def:

  BCTRL8 <regmask>, %CTR8<imp-use>, %RM<imp-use>, %X3<imp-use>, %X4<imp-use>, %X5<imp-use>, %X12<imp-use>, %X1<imp-def>, ...
  LDinto_toc 24, %X1, %X2<imp-def,dead>
  ADJCALLSTACKUP 96, 0, %R1<imp-def,dead>, %R1<imp-use>
  ADJCALLSTACKDOWN 96, %R1<imp-def,dead>, %R1<imp-use>
  %vreg39<def> = ADDIStocHA %X2, <ga:@.str>; G8RC_and_G8RC_NOX0:%vreg39
  %vreg40<def> = ADDItocL %vreg39<kill>, <ga:@.str>; G8RC:%vreg40 G8RC_and_G8RC_NOX0:%vreg39

So now when the two stack adjustments are removed, ADDIStocHA is
prevented from being moved above LDinto_toc.

I have not yet created a test case for this, because the original
failure occurs on a relatively large function that needs reduction.
However, this is a fairly serious bug, despite its infrequency, and I
wanted to get this patch onto the list as soon as possible so that it
can be considered for a 3.5 backport.  I'll work on whittling down a
test case.

Have we missed the boat for 3.5 at this point?

Thanks,
Bill

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_35@215878 91177308-0d34-0410-b5e6-96231b3b80d8
Merging r215711:
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r215711 | wschmidt | 2014-08-15 06:51:57 -0700 (Fri, 15 Aug 2014) | 8 lines

[PPC64] Add test case for r215685.

I had deferred adding this test case until I could get it down to a
reasonable size.  That's done now.

Thanks,
Bill

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_35@215879 91177308-0d34-0410-b5e6-96231b3b80d8