radv: Add minimal subgroup support.

Deliberately not implementing workgroup scopes as that is not needed
for core vulkan.

Reviewed-by: Dave Airlie <[email protected]>

2 files changed, 51 insertions, 0 deletions

diff --git a/src/amd/common/ac_nir_to_llvm.c b/src/amd/common/ac_nir_to_llvm.c
index f6ad51a412a..d02238dba7d 100644
--- a/src/amd/common/ac_nir_to_llvm.c
+++ b/src/amd/common/ac_nir_to_llvm.c
@@ -3884,6 +3884,46 @@ visit_load_local_invocation_index(struct ac_nir_context *ctx)
 }
 
 static LLVMValueRef
+visit_load_subgroup_id(struct ac_nir_context *ctx)
+{
+	if (ctx->stage == MESA_SHADER_COMPUTE) {
+		LLVMValueRef result;
+		result = LLVMBuildAnd(ctx->ac.builder, ctx->abi->tg_size,
+				LLVMConstInt(ctx->ac.i32, 0xfc0, false), "");
+		return LLVMBuildLShr(ctx->ac.builder, result,  LLVMConstInt(ctx->ac.i32, 6, false), "");
+	} else {
+		return LLVMConstInt(ctx->ac.i32, 0, false);
+	}
+}
+
+static LLVMValueRef
+visit_load_num_subgroups(struct ac_nir_context *ctx)
+{
+	if (ctx->stage == MESA_SHADER_COMPUTE) {
+		return LLVMBuildAnd(ctx->ac.builder, ctx->abi->tg_size,
+		                    LLVMConstInt(ctx->ac.i32, 0x3f, false), "");
+	} else {
+		return LLVMConstInt(ctx->ac.i32, 1, false);
+	}
+}
+
+static LLVMValueRef
+visit_first_invocation(struct ac_nir_context *ctx)
+{
+	LLVMValueRef active_set = ac_build_ballot(&ctx->ac, ctx->ac.i32_1);
+
+	/* The second argument is whether cttz(0) should be defined, but we do not care. */
+	LLVMValueRef args[] = {active_set, LLVMConstInt(ctx->ac.i1, 0, false)};
+	LLVMValueRef result =  ac_build_intrinsic(&ctx->ac,
+	                                          "llvm.cttz.i64",
+	                                          ctx->ac.i64, args, 2,
+	                                          AC_FUNC_ATTR_NOUNWIND |
+	                                          AC_FUNC_ATTR_READNONE);
+
+	return LLVMBuildTrunc(ctx->ac.builder, result, ctx->ac.i32, "");
+}
+
+static LLVMValueRef
 visit_load_shared(struct ac_nir_context *ctx,
 		   const nir_intrinsic_instr *instr)
 {
@@ -4411,6 +4451,15 @@ static void visit_intrinsic(struct ac_nir_context *ctx,
 	case nir_intrinsic_load_local_invocation_index:
 		result = visit_load_local_invocation_index(ctx);
 		break;
+	case nir_intrinsic_load_subgroup_id:
+		result = visit_load_subgroup_id(ctx);
+		break;
+	case nir_intrinsic_load_num_subgroups:
+		result = visit_load_num_subgroups(ctx);
+		break;
+	case nir_intrinsic_first_invocation:
+		result = visit_first_invocation(ctx);
+		break;
 	case nir_intrinsic_load_push_constant:
 		result = visit_load_push_constant(ctx, instr);
 		break;
diff --git a/src/amd/common/ac_shader_info.c b/src/amd/common/ac_shader_info.c
index 98de963147b..883358faaae 100644
--- a/src/amd/common/ac_shader_info.c
+++ b/src/amd/common/ac_shader_info.c
@@ -61,6 +61,8 @@ gather_intrinsic_info(const nir_shader *nir, const nir_intrinsic_instr *instr,
 		break;
 	}
 	case nir_intrinsic_load_local_invocation_index:
+	case nir_intrinsic_load_subgroup_id:
+	case nir_intrinsic_load_num_subgroups:
 		info->cs.uses_local_invocation_idx = true;
 		break;
 	case nir_intrinsic_load_sample_id: