Revert "ac/nir: Lower large indirect variables to scratch"

This reverts commit 74470baebbdacc8fd31c9912eb8c00c0cd102903.

This change introduces some significant performance regressions. We
are fixing those on master, but the follow up work is large enough
not to backport to 19.2 .

Fixes: 74470baebbd "ac/nir: Lower large indirect variables to scratch"
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111576
Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

1 files changed, 0 insertions, 68 deletions

diff --git a/src/amd/common/ac_nir_to_llvm.c b/src/amd/common/ac_nir_to_llvm.c
index d97387ef13d..a462f1e83c6 100644
--- a/src/amd/common/ac_nir_to_llvm.c
+++ b/src/amd/common/ac_nir_to_llvm.c
@@ -42,8 +42,6 @@ struct ac_nir_context {
 
 	LLVMValueRef *ssa_defs;
 
-	LLVMValueRef scratch;
-
 	struct hash_table *defs;
 	struct hash_table *phis;
 	struct hash_table *vars;
@@ -3618,50 +3616,6 @@ static void visit_intrinsic(struct ac_nir_context *ctx,
 	case nir_intrinsic_mbcnt_amd:
 		result = ac_build_mbcnt(&ctx->ac, get_src(ctx, instr->src[0]));
 		break;
-	case nir_intrinsic_load_scratch: {
-		LLVMValueRef offset = get_src(ctx, instr->src[0]);
-		LLVMValueRef ptr = ac_build_gep0(&ctx->ac, ctx->scratch,
-						 offset);
-		LLVMTypeRef comp_type =
-			LLVMIntTypeInContext(ctx->ac.context, instr->dest.ssa.bit_size);
-		LLVMTypeRef vec_type =
-			instr->dest.ssa.num_components == 1 ? comp_type :
-			LLVMVectorType(comp_type, instr->dest.ssa.num_components);
-		unsigned addr_space = LLVMGetPointerAddressSpace(LLVMTypeOf(ptr));
-		ptr = LLVMBuildBitCast(ctx->ac.builder, ptr,
-				       LLVMPointerType(vec_type, addr_space), "");
-		result = LLVMBuildLoad(ctx->ac.builder, ptr, "");
-		break;
-	}
-	case nir_intrinsic_store_scratch: {
-		LLVMValueRef offset = get_src(ctx, instr->src[1]);
-		LLVMValueRef ptr = ac_build_gep0(&ctx->ac, ctx->scratch,
-						 offset);
-		LLVMTypeRef comp_type =
-			LLVMIntTypeInContext(ctx->ac.context, instr->src[0].ssa->bit_size);
-		unsigned addr_space = LLVMGetPointerAddressSpace(LLVMTypeOf(ptr));
-		ptr = LLVMBuildBitCast(ctx->ac.builder, ptr,
-				       LLVMPointerType(comp_type, addr_space), "");
-		LLVMValueRef src = get_src(ctx, instr->src[0]);
-		unsigned wrmask = nir_intrinsic_write_mask(instr);
-		while (wrmask) {
-			int start, count;
-			u_bit_scan_consecutive_range(&wrmask, &start, &count);
-			
-			LLVMValueRef offset = LLVMConstInt(ctx->ac.i32, start, false);
-			LLVMValueRef offset_ptr = LLVMBuildGEP(ctx->ac.builder, ptr, &offset, 1, "");
-			LLVMTypeRef vec_type =
-				count == 1 ? comp_type : LLVMVectorType(comp_type, count);
-			offset_ptr = LLVMBuildBitCast(ctx->ac.builder,
-						      offset_ptr,
-						      LLVMPointerType(vec_type, addr_space),
-						      "");
-			LLVMValueRef offset_src =
-				ac_extract_components(&ctx->ac, src, start, count);
-			LLVMBuildStore(ctx->ac.builder, offset_src, offset_ptr);
-		}
-		break;
-	}
 	default:
 		fprintf(stderr, "Unknown intrinsic: ");
 		nir_print_instr(&instr->instr, stderr);
@@ -4563,18 +4517,6 @@ setup_locals(struct ac_nir_context *ctx,
 }
 
 static void
-setup_scratch(struct ac_nir_context *ctx,
-	      struct nir_shader *shader)
-{
-	if (shader->scratch_size == 0)
-		return;
-
-	ctx->scratch = ac_build_alloca_undef(&ctx->ac,
-					     LLVMArrayType(ctx->ac.i8, shader->scratch_size),
-					     "scratch");
-}
-
-static void
 setup_shared(struct ac_nir_context *ctx,
 	     struct nir_shader *nir)
 {
@@ -4619,7 +4561,6 @@ void ac_nir_translate(struct ac_llvm_context *ac, struct ac_shader_abi *abi,
 	ctx.ssa_defs = calloc(func->impl->ssa_alloc, sizeof(LLVMValueRef));
 
 	setup_locals(&ctx, func);
-	setup_scratch(&ctx, nir);
 
 	if (gl_shader_stage_is_compute(nir->info.stage))
 		setup_shared(&ctx, nir);
@@ -4641,15 +4582,6 @@ void ac_nir_translate(struct ac_llvm_context *ac, struct ac_shader_abi *abi,
 void
 ac_lower_indirect_derefs(struct nir_shader *nir, enum chip_class chip_class)
 {
-	/* Lower large variables to scratch first so that we won't bloat the
-	 * shader by generating large if ladders for them. We later lower
-	 * scratch to alloca's, assuming LLVM won't generate VGPR indexing.
-	 */
-	NIR_PASS_V(nir, nir_lower_vars_to_scratch,
-		   nir_var_function_temp,
-		   256,
-		   glsl_get_natural_size_align_bytes);
-
 	/* While it would be nice not to have this flag, we are constrained
 	 * by the reality that LLVM 9.0 has buggy VGPR indexing on GFX9.
 	 */