[Bug 87389] New: [ILK] HL2 & CS:Source water shader broken

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=87389

            Bug ID: 87389
           Summary: [ILK] HL2 & CS:Source water shader broken
           Product: Mesa
           Version: 10.4
          Hardware: Other
                OS: All
            Status: NEW
          Severity: normal
          Priority: medium
         Component: Drivers/DRI/i965
          Assignee: idr at freedesktop.org
          Reporter: chrisf at ijw.co.nz
        QA Contact: intel-3d-bugs at lists.freedesktop.org

SIMD16 water fragment shader produces garbage for some pixels on Ironlake.

Bisected to:

commit 2ec161b2396b08341264965a5825152784b54549
Refs: 10.2-branchpoint-3378-g2ec161b
Author:     Jason Ekstrand <jason.ekstrand at intel.com>
AuthorDate: Mon Oct 6 21:27:06 2014 -0700
Commit:     Jason Ekstrand <jason.ekstrand at intel.com>
CommitDate: Fri Oct 24 16:24:05 2014 -0700

    i965/fs: Don't interfere with too many base registers

    On older GENs in SIMD16 mode, we were accidentally building too much
    interference into our register classes.  Since everything is divided by 2,
    the reigster allocator thinks we have 64 base registers instead of 128.
    The actual GRF mapping still needs to be doubled, but as far as the ra_set
    is concerned, we only have 64.  We were accidentally adding way too much
    interference.

This commit isn't actually broken -- but before this we failed to compile this
shader as SIMD16.

The SIMD8 version of the shader works correctly (we get correct rendering with
INTEL_DEBUG=no16)

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