+/**
+ * Perform the occlusion test and increase the counter.
+ * Test the depth mask. Add the number of channel which has none zero mask
+ * into the occlusion counter. e.g. maskvalue is {-1, -1, -1, -1}.
+ * The counter will add 4.
+ *
+ * \param type holds element type of the mask vector.
+ * \param maskvalue is the depth test mask.
+ * \param counter is a pointer of the uint32 counter.
+ */
+void
+lp_build_occlusion_count(struct gallivm_state *gallivm,
+ struct lp_type type,
+ LLVMValueRef maskvalue,
+ LLVMValueRef counter)
+{
+ LLVMBuilderRef builder = gallivm->builder;
+ LLVMContextRef context = gallivm->context;
+ LLVMValueRef countmask = lp_build_const_int_vec(gallivm, type, 1);
+ LLVMValueRef countv = LLVMBuildAnd(builder, maskvalue, countmask, "countv");
+ LLVMTypeRef i8v16 = LLVMVectorType(LLVMInt8TypeInContext(context), 16);
+ LLVMValueRef counti = LLVMBuildBitCast(builder, countv, i8v16, "counti");
+ LLVMValueRef maskarray[4] = {
+ lp_build_const_int32(gallivm, 0),
+ lp_build_const_int32(gallivm, 4),
+ lp_build_const_int32(gallivm, 8),
+ lp_build_const_int32(gallivm, 12)
+ };
+ LLVMValueRef shufflemask = LLVMConstVector(maskarray, 4);
+ LLVMValueRef shufflev = LLVMBuildShuffleVector(builder, counti, LLVMGetUndef(i8v16), shufflemask, "shufflev");
+ LLVMValueRef shuffle = LLVMBuildBitCast(builder, shufflev, LLVMInt32TypeInContext(context), "shuffle");
+ LLVMValueRef count = lp_build_intrinsic_unary(builder, "llvm.ctpop.i32", LLVMInt32TypeInContext(context), shuffle);
+ LLVMValueRef orig = LLVMBuildLoad(builder, counter, "orig");
+ LLVMValueRef incr = LLVMBuildAdd(builder, orig, count, "incr");
+ LLVMBuildStore(builder, incr, counter);
+}
+
+