Mesa (master): aco: limit register usage for large work groups

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Module: Mesa
Branch: master
Commit: b5c9688516d00b00184e6fa6868de826916f5fc3
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=b5c9688516d00b00184e6fa6868de826916f5fc3

Author: Rhys Perry <pendingchaos02 at gmail.com>
Date:   Wed Dec 18 16:18:35 2019 +0000

aco: limit register usage for large work groups

Signed-off-by: Rhys Perry <pendingchaos02 at gmail.com>
Reviewed-by: Daniel Schürmann <daniel at schuermann.dev>

---

 .../compiler/aco_instruction_selection_setup.cpp   |  5 ++++
 src/amd/compiler/aco_ir.h                          |  2 ++
 src/amd/compiler/aco_live_var_analysis.cpp         | 32 +++++++++++++++++-----
 src/amd/compiler/aco_scheduler.cpp                 |  1 +
 4 files changed, 33 insertions(+), 7 deletions(-)

diff --git a/src/amd/compiler/aco_instruction_selection_setup.cpp b/src/amd/compiler/aco_instruction_selection_setup.cpp
index d55d4105d39..8a461e7e929 100644
--- a/src/amd/compiler/aco_instruction_selection_setup.cpp
+++ b/src/amd/compiler/aco_instruction_selection_setup.cpp
@@ -819,9 +819,14 @@ setup_isel_context(Program* program,
       program->sgpr_alloc_granule = 7;
       program->sgpr_limit = 104;
    }
+
    /* TODO: we don't have to allocate VCC if we don't need it */
    program->needs_vcc = true;
 
+   calc_min_waves(program);
+   program->vgpr_limit = get_addr_vgpr_from_waves(program, program->min_waves);
+   program->sgpr_limit = get_addr_sgpr_from_waves(program, program->min_waves);
+
    isel_context ctx = {};
    ctx.program = program;
    ctx.args = args;
diff --git a/src/amd/compiler/aco_ir.h b/src/amd/compiler/aco_ir.h
index 82309ba8e38..04647981b68 100644
--- a/src/amd/compiler/aco_ir.h
+++ b/src/amd/compiler/aco_ir.h
@@ -1155,6 +1155,7 @@ public:
    Temp private_segment_buffer;
    Temp scratch_offset;
 
+   uint16_t min_waves = 0;
    uint16_t lds_alloc_granule;
    uint32_t lds_limit; /* in bytes */
    uint16_t vgpr_limit;
@@ -1216,6 +1217,7 @@ void select_program(Program *program,
 void lower_wqm(Program* program, live& live_vars,
                const struct radv_nir_compiler_options *options);
 void lower_bool_phis(Program* program);
+void calc_min_waves(Program* program);
 void update_vgpr_sgpr_demand(Program* program, const RegisterDemand new_demand);
 live live_var_analysis(Program* program, const struct radv_nir_compiler_options *options);
 std::vector<uint16_t> dead_code_analysis(Program *program);
diff --git a/src/amd/compiler/aco_live_var_analysis.cpp b/src/amd/compiler/aco_live_var_analysis.cpp
index 2841ba208f6..44a3ea53430 100644
--- a/src/amd/compiler/aco_live_var_analysis.cpp
+++ b/src/amd/compiler/aco_live_var_analysis.cpp
@@ -228,6 +228,16 @@ void process_live_temps_per_block(Program *program, live& lives, Block* block,
 
    assert(block->index != 0 || new_demand == RegisterDemand());
 }
+
+unsigned calc_waves_per_workgroup(Program *program)
+{
+   unsigned workgroup_size = program->wave_size;
+   if (program->stage == compute_cs) {
+      unsigned* bsize = program->info->cs.block_size;
+      workgroup_size = bsize[0] * bsize[1] * bsize[2];
+   }
+   return align(workgroup_size, program->wave_size) / program->wave_size;
+}
 } /* end namespace */
 
 uint16_t get_extra_sgprs(Program *program)
@@ -284,6 +294,20 @@ uint16_t get_addr_vgpr_from_waves(Program *program, uint16_t max_waves)
     return std::min(vgprs, program->vgpr_limit);
 }
 
+void calc_min_waves(Program* program)
+{
+   unsigned waves_per_workgroup = calc_waves_per_workgroup(program);
+   /* currently min_waves is in wave64 waves */
+   if (program->wave_size == 32)
+      waves_per_workgroup = DIV_ROUND_UP(waves_per_workgroup, 2);
+
+   unsigned simd_per_cu = 4; /* TODO: different on Navi */
+   bool wgp = program->chip_class >= GFX10; /* assume WGP is used on Navi */
+   unsigned simd_per_cu_wgp = wgp ? simd_per_cu * 2 : simd_per_cu;
+
+   program->min_waves = DIV_ROUND_UP(waves_per_workgroup, simd_per_cu_wgp);
+}
+
 void update_vgpr_sgpr_demand(Program* program, const RegisterDemand new_demand)
 {
    /* TODO: max_waves_per_simd, simd_per_cu and the number of physical vgprs for Navi */
@@ -304,13 +328,7 @@ void update_vgpr_sgpr_demand(Program* program, const RegisterDemand new_demand)
       program->max_waves = max_waves_per_simd;
 
       /* adjust max_waves for workgroup and LDS limits */
-      unsigned workgroup_size = program->wave_size;
-      if (program->stage == compute_cs) {
-         unsigned* bsize = program->info->cs.block_size;
-         workgroup_size = bsize[0] * bsize[1] * bsize[2];
-      }
-      unsigned waves_per_workgroup = align(workgroup_size, program->wave_size) / program->wave_size;
-
+      unsigned waves_per_workgroup = calc_waves_per_workgroup(program);
       unsigned workgroups_per_cu_wgp = max_waves_per_simd * simd_per_cu_wgp / waves_per_workgroup;
       if (program->config->lds_size) {
          unsigned lds = program->config->lds_size * program->lds_alloc_granule;
diff --git a/src/amd/compiler/aco_scheduler.cpp b/src/amd/compiler/aco_scheduler.cpp
index 665fcb2db6f..0a8d5af8c78 100644
--- a/src/amd/compiler/aco_scheduler.cpp
+++ b/src/amd/compiler/aco_scheduler.cpp
@@ -932,6 +932,7 @@ void schedule_program(Program *program, live& live_vars)
       ctx.num_waves = 7;
    else
       ctx.num_waves = 8;
+   ctx.num_waves = std::max<uint16_t>(ctx.num_waves, program->min_waves);
 
    assert(ctx.num_waves > 0 && ctx.num_waves <= program->num_waves);
    ctx.max_registers = { int16_t(get_addr_vgpr_from_waves(program, ctx.num_waves) - 2),