Re: [Mesa-dev] [PATCH] ac/nir/radeonsi: add ARB_shader_ballot support

[Nicolai Hähnle]

On 22.01.2018 02:54, Timothy Arceri wrote:

---
  src/amd/common/ac_nir_to_llvm.c              | 38 ++++++++++++++++++++++++++++
  src/gallium/drivers/radeonsi/si_shader_nir.c |  9 +++++++
  2 files changed, 47 insertions(+)

diff --git a/src/amd/common/ac_nir_to_llvm.c b/src/amd/common/ac_nir_to_llvm.c
index eabdc83f16..2c9b85bf82 100644
--- a/src/amd/common/ac_nir_to_llvm.c
+++ b/src/amd/common/ac_nir_to_llvm.c
@@ -4260,6 +4260,44 @@ static void visit_intrinsic(struct ac_nir_context *ctx,
        LLVMValueRef result = NULL;

switch (instr->intrinsic) {

+       case nir_intrinsic_ballot:
+               result = ac_build_ballot(&ctx->ac, get_src(ctx, instr->src[0]));
+               break;
+       case nir_intrinsic_read_invocation:
+       case nir_intrinsic_read_first_invocation: {
+               const char *intr_names[2] = {"llvm.amdgcn.readlane", 
"llvm.amdgcn.readfirstlane"};
+               LLVMValueRef args[2];
+
+               /* Value */
+               args[0] = get_src(ctx, instr->src[0]);
+
+               unsigned num_args;
+               const char *intr_name;
+               if (instr->intrinsic == nir_intrinsic_read_invocation) {
+                       num_args = 2;
+                       intr_name = intr_names[0];

Please just inline the intrinsic names here.

With that fixed:

Reviewed-by: Nicolai Hähnle <nicolai.haeh...@amd.com>

+
+                       /* Invocation */
+                       args[1] = get_src(ctx, instr->src[1]);
+               } else {
+                       num_args = 1;
+                       intr_name = intr_names[1];
+               }
+
+               /* We currently have no other way to prevent LLVM from lifting 
the icmp
+                * calls to a dominating basic block.
+                */
+               ac_build_optimization_barrier(&ctx->ac, &args[0]);
+
+               result = ac_build_intrinsic(&ctx->ac, intr_name,
+                                           ctx->ac.i32, args, num_args,
+                                           AC_FUNC_ATTR_READNONE |
+                                           AC_FUNC_ATTR_CONVERGENT);
+               break;
+       }
+       case nir_intrinsic_load_subgroup_invocation:
+               result = ac_get_thread_id(&ctx->ac);
+               break;
        case nir_intrinsic_load_work_group_id: {
                LLVMValueRef values[3];

diff --git a/src/gallium/drivers/radeonsi/si_shader_nir.c b/src/gallium/drivers/radeonsi/si_shader_nir.c

index 2f19bae813..5b941da949 100644
--- a/src/gallium/drivers/radeonsi/si_shader_nir.c
+++ b/src/gallium/drivers/radeonsi/si_shader_nir.c
@@ -566,6 +566,15 @@ si_lower_nir(struct si_shader_selector* sel)
        };
        NIR_PASS_V(sel->nir, nir_lower_tex, &lower_tex_options);

+ const nir_lower_subgroups_options subgroups_options = {

+               .subgroup_size = 64,
+               .ballot_bit_size = 32,
+               .lower_to_scalar = true,
+               .lower_subgroup_masks = true,
+               .lower_vote_trivial = false,
+       };
+       NIR_PASS_V(sel->nir, nir_lower_subgroups, &subgroups_options);
+
        bool progress;
        do {
                progress = false;

--
Lerne, wie die Welt wirklich ist,
Aber vergiss niemals, wie sie sein sollte.
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