On 02/15/2013 10:26 PM, Eric Anholt wrote:
This should fix the register allocation explosion on the GLES 3.0
test on gen6.
Except that it doesn't. You can check by running it with
INTEL_DEVID_OVERRIDE=0x116.
A tiny change below makes it work though...
---
src/mesa/drivers/dri/i965/brw_fs.cpp | 63 +++++++++++++++++++++++++-
src/mesa/drivers/dri/i965/brw_fs.h | 1 +
src/mesa/drivers/dri/i965/brw_fs_visitor.cpp | 28 ++----------
3 files changed, 65 insertions(+), 27 deletions(-)
diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp
b/src/mesa/drivers/dri/i965/brw_fs.cpp
index 35cdc6a..1f98b27 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -1710,8 +1710,6 @@ fs_visitor::setup_pull_constants()
dst, index, offset);
pull->ir = inst->ir;
pull->annotation = inst->annotation;
- pull->base_mrf = 14;
- pull->mlen = 1;
inst->insert_before(pull);
@@ -2447,6 +2445,66 @@ fs_visitor::insert_gen4_send_dependency_workarounds()
}
}
+/**
+ * Turns the generic expression-style uniform pull constant load instruction
+ * into a hardware-specific series of instructions for loading a pull
+ * constant.
+ *
+ * The expression style allows the CSE pass before this to optimize out
+ * repeated loads from the same offset, and gives the pre-register-allocation
+ * scheduling full flexibility, while the conversion to native instructions
+ * allows the post-register-allocation scheduler the best information
+ * possible.
+ */
+void
+fs_visitor::lower_uniform_pull_constant_loads()
+{
+ foreach_list(node, &this->instructions) {
+ fs_inst *inst = (fs_inst *)node;
+
+ if (inst->opcode != FS_OPCODE_UNIFORM_PULL_CONSTANT_LOAD)
+ continue;
+
+ if (intel->gen >= 7) {
+ fs_reg const_offset_reg = inst->src[1];
+ assert(const_offset_reg.file == IMM &&
+ const_offset_reg.type == BRW_REGISTER_TYPE_UD);
+ const_offset_reg.imm.u /= 16;
+ fs_reg payload = fs_reg(this, glsl_type::uint_type);
+ struct brw_reg g0 = retype(brw_vec8_grf(0, 0),
+ BRW_REGISTER_TYPE_UD);
+
+ fs_inst *setup1 = MOV(payload, fs_reg(g0));
+ setup1->force_writemask_all = true;
+ /* We don't need the second half of this vgrf to be filled with g1
+ * in the 16-wide case, but if we use force_uncompressed then live
+ * variable analysis won't consider this a def!
+ */
+
+ fs_inst *setup2 = new(mem_ctx) fs_inst(FS_OPCODE_SET_GLOBAL_OFFSET,
+ payload, payload,
+ const_offset_reg);
+
+ setup1->ir = inst->ir;
+ setup1->annotation = inst->annotation;
+ inst->insert_before(setup1);
+ setup2->ir = inst->ir;
+ setup2->annotation = inst->annotation;
+ inst->insert_before(setup2);
+ inst->opcode = FS_OPCODE_UNIFORM_PULL_CONSTANT_LOAD_GEN7;
+ inst->src[1] = payload;
+ } else {
+ /* Before register allocation, we didn't tell the scheduler about the
+ * MRF we use. We know it's safe to use this MRF because nothing
+ * else does except for register spill/unspill, which generates and
+ * uses its MRF within a single IR instruction.
+ */
+ inst->base_mrf = 14;
+ inst->mlen = 1;
+ }
+ }
+}
+
void
fs_visitor::dump_instruction(fs_inst *inst)
{
@@ -2746,6 +2804,7 @@ fs_visitor::run()
remove_dead_constants();
+ lower_uniform_pull_constant_loads();
schedule_instructions(false);
You need to do lower_uniform_pull_constant_loads() *after* the first
scheduling pass, or else you hit the same strongly-ordered scheduling
dependency problem we had before.
With tha change, the reg. alloc explosion is fixed. (I haven't actually
tested on a real SNB though.)
Assuming you fix that (and it passes piglit), this series gets a:
NOTE: This is a candidate for the 9.1 branch.
Reviewed-by: Kenneth Graunke <kenn...@whitecape.org>
Also, nice work! I'm really glad to see CSE of UBO loads.
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