[Mesa-dev] [PATCH 07/25] amd/common: add i1 special case to ac_build_{inclusive, exclusive}_scan

[Nicolai Hähnle]

From: Nicolai Hähnle <nicolai.haeh...@amd.com>

Allow for a unified but efficient treatment of adding a bitmask over a
wave or an entire threadgroup.
---
 src/amd/common/ac_llvm_build.c | 27 +++++++++++++++++++++++++--
 1 file changed, 25 insertions(+), 2 deletions(-)

diff --git a/src/amd/common/ac_llvm_build.c b/src/amd/common/ac_llvm_build.c
index 932f4bbdeef..eb840369d07 100644
--- a/src/amd/common/ac_llvm_build.c
+++ b/src/amd/common/ac_llvm_build.c
@@ -3391,36 +3391,57 @@ ac_build_scan(struct ac_llvm_context *ctx, nir_op op, 
LLVMValueRef src, LLVMValu
        if (maxprefix <= 32)
                return result;
        tmp = ac_build_dpp(ctx, identity, result, dpp_row_bcast31, 0xc, 0xf, 
false);
        result = ac_build_alu_op(ctx, result, tmp, op);
        return result;
 }
 
 LLVMValueRef
 ac_build_inclusive_scan(struct ac_llvm_context *ctx, LLVMValueRef src, nir_op 
op)
 {
-       ac_build_optimization_barrier(ctx, &src);
        LLVMValueRef result;
+
+       if (LLVMTypeOf(src) == ctx->i1 && op == nir_op_iadd) {
+               LLVMBuilderRef builder = ctx->builder;
+               src = LLVMBuildZExt(builder, src, ctx->i32, "");
+               result = ac_build_ballot(ctx, src);
+               result = ac_build_mbcnt(ctx, result);
+               result = LLVMBuildAdd(builder, result, src, "");
+               return result;
+       }
+
+       ac_build_optimization_barrier(ctx, &src);
+
        LLVMValueRef identity =
                get_reduction_identity(ctx, op, 
ac_get_type_size(LLVMTypeOf(src)));
        result = LLVMBuildBitCast(ctx->builder, ac_build_set_inactive(ctx, src, 
identity),
                                  LLVMTypeOf(identity), "");
        result = ac_build_scan(ctx, op, result, identity, 64);
 
        return ac_build_wwm(ctx, result);
 }
 
 LLVMValueRef
 ac_build_exclusive_scan(struct ac_llvm_context *ctx, LLVMValueRef src, nir_op 
op)
 {
-       ac_build_optimization_barrier(ctx, &src);
        LLVMValueRef result;
+
+       if (LLVMTypeOf(src) == ctx->i1 && op == nir_op_iadd) {
+               LLVMBuilderRef builder = ctx->builder;
+               src = LLVMBuildZExt(builder, src, ctx->i32, "");
+               result = ac_build_ballot(ctx, src);
+               result = ac_build_mbcnt(ctx, result);
+               return result;
+       }
+
+       ac_build_optimization_barrier(ctx, &src);
+
        LLVMValueRef identity =
                get_reduction_identity(ctx, op, 
ac_get_type_size(LLVMTypeOf(src)));
        result = LLVMBuildBitCast(ctx->builder, ac_build_set_inactive(ctx, src, 
identity),
                                  LLVMTypeOf(identity), "");
        result = ac_build_dpp(ctx, identity, result, dpp_wf_sr1, 0xf, 0xf, 
false);
        result = ac_build_scan(ctx, op, result, identity, 64);
 
        return ac_build_wwm(ctx, result);
 }
 
@@ -3585,20 +3606,22 @@ ac_build_wg_wavescan(struct ac_llvm_context *ctx, 
struct ac_wg_scan *ws)
  * "Top half" of a scan that reduces per-thread values across an entire
  * workgroup.
  *
  * All lanes must be active when this code runs.
  */
 void
 ac_build_wg_scan_top(struct ac_llvm_context *ctx, struct ac_wg_scan *ws)
 {
        if (ws->enable_exclusive) {
                ws->extra = ac_build_exclusive_scan(ctx, ws->src, ws->op);
+               if (LLVMTypeOf(ws->src) == ctx->i1 && ws->op == nir_op_iadd)
+                       ws->src = LLVMBuildZExt(ctx->builder, ws->src, 
ctx->i32, "");
                ws->src = ac_build_alu_op(ctx, ws->extra, ws->src, ws->op);
        } else {
                ws->src = ac_build_inclusive_scan(ctx, ws->src, ws->op);
        }
 
        bool enable_inclusive = ws->enable_inclusive;
        bool enable_exclusive = ws->enable_exclusive;
        ws->enable_inclusive = false;
        ws->enable_exclusive = ws->enable_exclusive || enable_inclusive;
        ac_build_wg_wavescan_top(ctx, ws);
-- 
2.19.1

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