[Mesa-dev] [PATCH 3/9] radeonsi: use S_BFE/V_BFE for extracting bitfields from parameters

[Marek Olšák]

From: Marek Olšák <marek.olsak at amd.com>

And use AND/OR in special cases.

This universal helper will be used a lot (especially by tessellation).
---
 src/gallium/drivers/radeonsi/si_shader.c | 48 +++++++++++++++++++++-----------
 1 file changed, 32 insertions(+), 16 deletions(-)

diff --git a/src/gallium/drivers/radeonsi/si_shader.c b/src/gallium/drivers/radeonsi/si_shader.c
index f125483..085a350 100644
--- a/src/gallium/drivers/radeonsi/si_shader.c
+++ b/src/gallium/drivers/radeonsi/si_shader.c
@@ -206,6 +206,35 @@ static LLVMValueRef build_bfe(struct gallivm_state *gallivm,
 }
 
 /**
+ * Get the value of a shader input parameter and extract a bitfield.
+ */
+static LLVMValueRef unpack_param(struct si_shader_context *si_shader_ctx,
+				 unsigned param, unsigned rshift,
+				 unsigned bitwidth)
+{
+	struct gallivm_state *gallivm = &si_shader_ctx->radeon_bld.gallivm;
+	LLVMValueRef value = LLVMGetParam(si_shader_ctx->radeon_bld.main_fn,
+					  param);
+
+	if (rshift) {
+		if (rshift + bitwidth < 32)
+			return build_bfe(gallivm, value,
+					 lp_build_const_int32(gallivm, rshift),
+					 lp_build_const_int32(gallivm, bitwidth));
+		else
+			return LLVMBuildLShr(gallivm->builder, value,
+					     lp_build_const_int32(gallivm, rshift), "");
+	} else {
+		if (bitwidth < 32) {
+			unsigned mask = (1 << bitwidth) - 1;
+			return LLVMBuildAnd(gallivm->builder, value,
+					    lp_build_const_int32(gallivm, mask), "");
+		} else
+			return value;
+	}
+}
+
+/**
  * Build an LLVM bytecode indexed load using LLVMBuildGEP + LLVMBuildLoad.
  * It's equivalent to doing a load from &base_ptr[index].
  *
@@ -575,14 +604,8 @@ static void declare_input_fs(
 
 static LLVMValueRef get_sample_id(struct radeon_llvm_context *radeon_bld)
 {
-	struct gallivm_state *gallivm = &radeon_bld->gallivm;
-	LLVMValueRef value = LLVMGetParam(radeon_bld->main_fn,
-					  SI_PARAM_ANCILLARY);
-	value = LLVMBuildLShr(gallivm->builder, value,
-			      lp_build_const_int32(gallivm, 8), "");
-	value = LLVMBuildAnd(gallivm->builder, value,
-			     lp_build_const_int32(gallivm, 0xf), "");
-	return value;
+	return unpack_param(si_shader_context(&radeon_bld->soa.bld_base),
+			    SI_PARAM_ANCILLARY, 8, 4);
 }
 
 /**
@@ -990,16 +1013,9 @@ static void si_llvm_emit_streamout(struct si_shader_context *shader,
 
 	LLVMTypeRef i32 = LLVMInt32TypeInContext(gallivm->context);
 
-	LLVMValueRef so_param =
-		LLVMGetParam(shader->radeon_bld.main_fn,
-			     shader->param_streamout_config);
-
 	/* Get bits [22:16], i.e. (so_param >> 16) & 127; */
 	LLVMValueRef so_vtx_count =
-		LLVMBuildAnd(builder,
-			     LLVMBuildLShr(builder, so_param,
-					   LLVMConstInt(i32, 16, 0), ""),
-			     LLVMConstInt(i32, 127, 0), "");
+		unpack_param(shader, shader->param_streamout_config, 16, 7);
 
 	LLVMValueRef tid = build_intrinsic(builder, "llvm.SI.tid", i32,
 					   NULL, 0, LLVMReadNoneAttribute);
-- 
2.1.0