Hi, This is a series adding a new NIR pass that will combine redundant SSBO, shared variable and image load instructions. It is based on a previous series that Iago Toral [1] sent a few months ago, which I have updated to account for changes in NIR since then, and also added support for shared variables and image load/store.
Currently, the emitted load instructions for these types of variables are highly redundant. For example, assuming 'value' is an SSBO float, doing: float next = value + 1.0; float prev = value - 1.0; will generate two redundant load_ssbo instructions. The extreme case of this is: mat4 mult = ssbo_mat4 * ssbo_mat4; which will spwan 16 load_ssbo instructions. Compute shader's shared variables and image loads (from ARB_image_load_store) suffer from the same problem. This pass coaleses the redundant loads, and is also able to combine a load with a previous store to the same address. I'm still working on a piglit test series that tied up the different corner cases, but it doesn't hurt to get a few eyes on this already. The WIP piglit branch is at: https://github.com/Igalia/piglit/commits/nir-opt-load-combine-rc1 You can see there a test example for the matrix multiplication cases: https://github.com/Igalia/piglit/commit/b7ea6d2553891c7eec993c39352a10925ebcefbc. This pass is able to reduce the emitted instructions from 210 to 134 (~64%), comparing to Mesa master. No piglit or dEQP-GLES31 regressions observed. cheers, Eduardo [1] https://lists.freedesktop.org/archives/mesa-dev/2015-October/098426.html Eduardo Lima Mitev (3): nir/opt_load_combine: Extend the pass to include shared variables nir/opt_load_combine: Extend the pass to include image load/store Iago Toral (3): nir: add a load-combine pass nir/load_combine: expand the pass to support load-after-store i965: use the load-combine pass src/compiler/Makefile.sources | 1 + src/compiler/nir/nir.h | 2 + src/compiler/nir/nir_opt_load_combine.c | 807 ++++++++++++++++++++++++++++++++ src/mesa/drivers/dri/i965/brw_nir.c | 1 + 4 files changed, 811 insertions(+) create mode 100644 src/compiler/nir/nir_opt_load_combine.c -- 2.7.0 _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
