[Mesa-dev] [PATCH 00/31] i965: Scalar back-end support for SIMD32, part 1.

Jason Ekstrand jason at jlekstrand.net
Mon May 23 23:17:17 UTC 2016

On Fri, May 20, 2016 at 10:47 PM, Francisco Jerez <currojerez at riseup.net>

> The purpose of this series is to improve the back-end infrastructure
> so that lowering of most IR instructions that are too wide to execute
> natively (which is far more common than usual in SIMD32 dispatch mode)
> happens semi-automatically at the IR level.
> Patches 1-6 address some issues in a few optimization and lowering
> passes that would otherwise lead to regressions in the following
> changes of the series.  Patches 7-12 move the construction of several
> messages into lower_logical_sends() so the SIMD lowering pass can deal
> with them.  Patches 13-22 teach the SIMD lowering pass about a number
> of additional ISA restrictions that can be enforced easily by
> splitting SIMD instructions into smaller chunks.  Patches 23-31 are
> mainly about removing generator code that wouldn't have worked on
> SIMD32 but is no longer necessary given the infrastructure introduced
> in the first part of the series.
> Some of the changes from this series that remove SIMD workarounds
> currently implemented in the generator could potentially be left out
> at least in the initial merge at the cost of losing ARB_compute_shader
> support on VLV and low-end IVB which like Gen8+ don't have enough
> threads per subslice to reach the workgroup size requirement specified
> by the extension in SIMD16 mode.  Some other changes like the removal
> of DDY unrolling from the generator are completely optional right now
> although they will eventually be required for SIMD32 fragment shader
> support and they seemed like a nice clean-up.
> Expect two more series of roughly the same size coming up soon-ish,
> the second one will get the generator code in good shape for SIMD32,
> and the third one will address some of the remaining issues of the
> compiler back-end so we can start plumbing 32-wide compute shaders
> through it and turn the GL 4.3 switch.
> [PATCH 01/31] i965/fs: Fix byte_offset() for MRF/ARF/FIXED_GRF regs.
> [PATCH 02/31] i965/fs: Generalize is_uniform() to is_periodic().
> [PATCH 03/31] i965/fs: No need to unzip SIMD-periodic sources during SIMD
> lowering.
> [PATCH 04/31] i965/fs: Handle instruction predication in SIMD lowering
> pass.
> [PATCH 05/31] i965/fs: Fix CSE temporary copy for some LOAD_PAYLOAD corner
> cases.
> [PATCH 06/31] i965/fs: Avoid constant propagation when the type sizes
> don't match.

5 and 6 are Reviewed-by: Jason Ekstrand <jason at jlekstrand.net>

> [PATCH 07/31] i965/fs: Hide varying pull constant load message setup
> behind logical opcode.
> [PATCH 08/31] i965/fs: Implement promotion of varying pull loads on Gen4
> during SIMD lowering.
> [PATCH 09/31] i965/fs: Rename Gen4 physical varying pull constant load
> opcode.
> [PATCH 10/31] i965/fs: Add missing get_latency_gen7() cases for the Gen7
> pull constant opcodes.
> [PATCH 11/31] i965/fs: Lower math into Gen4-5 send-like instructions in
> lower_logical_sends.
> [PATCH 12/31] i965/fs: Handle SAMPLEINFO consistently like other texturing
> instructions.

> [PATCH 13/31] i965/fs: Enforce extended math exec size limits during SIMD
> lowering.
> [PATCH 14/31] i965/fs: Enforce common regioning restrictions by SIMD
> splitting.
> [PATCH 15/31] i965/fs: Implement workaround for IVB CMP dependency race in
> the SIMD lowering pass.
> [PATCH 16/31] i965/fs: Implement HSW BFI exec size workarounds in the SIMD
> lowering pass.
> [PATCH 17/31] i965/fs: Assert that IF instruction with embedded compare
> has legal exec_size.
> [PATCH 18/31] i965/fs: Calculate maximum execution size of MOV_INDIRECT
> correctly.
> [PATCH 19/31] i965/fs: Apply usual FPU-like execution size restrictions to
> [PATCH 20/31] i965/fs: Lower DDY instructions to SIMD8 during SIMD
> lowering time

13-20 Reviewed-by: Jason Ekstrand <jason at jlekstrand.net>

> [PATCH 21/31] i965/fs: Lower LOAD_PAYLOAD instructions of unsupported
> width.

This one is Reviewed-by: Jason Ekstrand <jason at jlekstrand.net> with
substantial reservations.  If we ever hit the asserts, we can fix the bugs

[PATCH 22/31] i965/fs: Limit SIMD width of various virtual opcodes to the
> maximum supported value.
> [PATCH 23/31] i965/fs: Remove handcrafted math SIMD lowering from the
> generator.
> [PATCH 24/31] i965/fs: Set default access mode to Align1 for all
> instructions in the generator.
> [PATCH 25/31] i965/fs: Drop lowering code for a few three-source
> instructions from the generator.
> [PATCH 26/31] i965/fs: Drop Gen7 CMP SIMD unrolling workaround from the
> generator.
> [PATCH 27/31] i965/fs: Remove manual unrolling of BFI instructions from
> the generator.
> [PATCH 28/31] i965/fs: Remove manual splitting of DDY ops in the generator.
> [PATCH 29/31] i965: Define brw_int_type() helper.
> [PATCH 30/31] i965/fs: Remove extract virtual opcodes.
> [PATCH 31/31] i965/fs: Remove FS_OPCODE_PACK_STENCIL_REF virtual
> instruction.

22-31 are Reviewed-by: Jason Ekstrand <jason at jlekstrand.net>

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