From cdf69f6163f4a52e9f860ab47669048e20221984 Mon Sep 17 00:00:00 2001
From: Andreas Kloeckner <inform@tiker.net>
Date: Wed, 4 May 2016 18:18:53 -0500
Subject: [PATCH] Make radix sort work with debug scan kernel

---
 pyopencl/scan.py       | 33 ++++++++++++++++++++++++++-------
 test/test_algorithm.py | 14 +++++++++-----
 2 files changed, 35 insertions(+), 12 deletions(-)

diff --git a/pyopencl/scan.py b/pyopencl/scan.py
index 0ca0aa6a..272e6996 100644
--- a/pyopencl/scan.py
+++ b/pyopencl/scan.py
@@ -764,7 +764,7 @@ _PREFIX_WORDS = set("""
         group_base seg_end my_val DEBUG ARGS
         ints_to_store ints_per_wg scan_types_per_int linear_index
         linear_scan_data_idx dest src store_base wrapped_scan_type
-        dummy
+        dummy scan_tmp
 
         LID_2 LID_1 LID_0
         LDIM_0 LDIM_1 LDIM_2
@@ -1419,11 +1419,12 @@ DEBUG_SCAN_TEMPLATE = SHARED_PREAMBLE + r"""//CL//
 KERNEL
 REQD_WG_SIZE(1, 1, 1)
 void ${name_prefix}_debug_scan(
+    __global scan_type *scan_tmp,
     ${argument_signature},
     const index_type N)
 {
-    scan_type item = ${neutral};
-    scan_type last_item;
+    scan_type current = ${neutral};
+    scan_type prev;
 
     for (index_type i = 0; i < N; ++i)
     {
@@ -1439,18 +1440,31 @@ void ${name_prefix}_debug_scan(
 
         scan_type my_val = INPUT_EXPR(i);
 
-        last_item = item;
+        prev = current;
         %if is_segmented:
             bool is_seg_start = IS_SEG_START(i, my_val);
         %endif
 
-        item = SCAN_EXPR(last_item, my_val,
+        current = SCAN_EXPR(prev, my_val,
             %if is_segmented:
                 is_seg_start
             %else:
                 false
             %endif
             );
+        scan_tmp[i] = current;
+    }
+
+    scan_type last_item = scan_tmp[N-1];
+
+    for (index_type i = 0; i < N; ++i)
+    {
+        scan_type item = scan_tmp[i];
+        scan_type prev_item;
+        if (i)
+            prev_item = scan_tmp[i-1];
+        else
+            prev_item = ${neutral};
 
         {
             ${output_statement};
@@ -1477,7 +1491,8 @@ class GenericDebugScanKernel(_GenericScanKernelBase):
         self.kernel = getattr(
                 scan_prg, self.name_prefix+"_debug_scan")
         scalar_arg_dtypes = (
-                get_arg_list_scalar_arg_dtypes(self.parsed_args)
+                [None]
+                + get_arg_list_scalar_arg_dtypes(self.parsed_args)
                 + [self.index_dtype])
         self.kernel.set_scalar_arg_dtypes(scalar_arg_dtypes)
 
@@ -1500,7 +1515,11 @@ class GenericDebugScanKernel(_GenericScanKernelBase):
         if n is None:
             n, = first_array.shape
 
-        data_args = []
+        scan_tmp = cl.array.empty(queue,
+                n, dtype=self.dtype,
+                allocator=allocator)
+
+        data_args = [scan_tmp.data]
         from pyopencl.tools import VectorArg
         for arg_descr, arg_val in zip(self.parsed_args, args):
             if isinstance(arg_descr, VectorArg):
diff --git a/test/test_algorithm.py b/test/test_algorithm.py
index 02e6adcd..952a38dd 100644
--- a/test/test_algorithm.py
+++ b/test/test_algorithm.py
@@ -38,7 +38,8 @@ import pyopencl.array as cl_array  # noqa
 from pyopencl.tools import (  # noqa
         pytest_generate_tests_for_pyopencl as pytest_generate_tests)
 from pyopencl.characterize import has_double_support, has_struct_arg_count_bug
-from pyopencl.scan import InclusiveScanKernel, ExclusiveScanKernel
+from pyopencl.scan import (InclusiveScanKernel, ExclusiveScanKernel,
+        GenericScanKernel, GenericDebugScanKernel)
 
 
 # {{{ elementwise
@@ -668,7 +669,6 @@ def test_segmented_scan(ctx_factory):
         else:
             output_statement = "out[i] = item"
 
-        from pyopencl.scan import GenericScanKernel
         knl = GenericScanKernel(context, dtype,
                 arguments="__global %s *ary, __global char *segflags, "
                     "__global %s *out" % (ctype, ctype),
@@ -748,7 +748,8 @@ def test_segmented_scan(ctx_factory):
             print("%d excl:%s done" % (n, is_exclusive))
 
 
-def test_sort(ctx_factory):
+@pytest.mark.parametrize("scan_kernel", [GenericScanKernel, GenericDebugScanKernel])
+def test_sort(ctx_factory, scan_kernel):
     from pytest import importorskip
     importorskip("mako")
 
@@ -759,7 +760,7 @@ def test_sort(ctx_factory):
 
     from pyopencl.algorithm import RadixSort
     sort = RadixSort(context, "int *ary", key_expr="ary[i]",
-            sort_arg_names=["ary"])
+            sort_arg_names=["ary"], scan_kernel=scan_kernel)
 
     from pyopencl.clrandom import RanluxGenerator
     rng = RanluxGenerator(queue, seed=15)
@@ -768,6 +769,9 @@ def test_sort(ctx_factory):
 
     # intermediate arrays for largest size cause out-of-memory on low-end GPUs
     for n in scan_test_counts[:-1]:
+        if n >= 2000 and isinstance(scan_kernel, GenericDebugScanKernel):
+            continue
+
         print(n)
 
         print("  rng")
@@ -785,7 +789,7 @@ def test_sort(ctx_factory):
 
         numpy_elapsed = numpy_end-dev_end
         dev_elapsed = dev_end-dev_start
-        print ("  dev: %.2f MKeys/s numpy: %.2f MKeys/s ratio: %.2fx" % (
+        print("  dev: %.2f MKeys/s numpy: %.2f MKeys/s ratio: %.2fx" % (
                 1e-6*n/dev_elapsed, 1e-6*n/numpy_elapsed, numpy_elapsed/dev_elapsed))
         assert (a_dev_sorted.get() == a_sorted).all()
 
-- 
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