Add CKW flow control writing methods

* Structures: if/else/else if, for, return.
* Add corresponding tests.

Partially resolves: COMPMID-6387
Signed-off-by: Viet-Hoa Do <viet-hoa.do@arm.com>
Change-Id: I2912ccaf46f836907f21bb53fa82bcc1f48dd224
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/10199
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: SiCong Li <sicong.li@arm.com>
Reviewed-by: Gunes Bayir <gunes.bayir@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
Benchmark: Arm Jenkins <bsgcomp@arm.com>

3 files changed, 117 insertions, 2 deletions

diff --git a/compute_kernel_writer/src/cl/CLHelpers.cpp b/compute_kernel_writer/src/cl/CLHelpers.cpp
index e12e5e1b13..ff4408b1a3 100644
--- a/compute_kernel_writer/src/cl/CLHelpers.cpp
+++ b/compute_kernel_writer/src/cl/CLHelpers.cpp
@@ -26,6 +26,7 @@
 
 #include "ckw/Error.h"
 #include "ckw/types/DataType.h"
+#include "ckw/types/Operators.h"
 #include "ckw/types/TensorStorageType.h"
 #include "src/types/DataTypeHelpers.h"
 
@@ -145,6 +146,21 @@ std::string cl_get_variable_storagetype_as_string(TensorStorageType storage)
     return res;
 }
 
+std::string cl_get_assignment_op_as_string(AssignmentOp op)
+{
+    switch(op)
+    {
+        case AssignmentOp::Increment:
+            return "+=";
+
+        case AssignmentOp::Decrement:
+            return "-=";
+
+        default:
+            CKW_THROW_MSG("Unsupported assignment operator!");
+    }
+}
+
 std::tuple<bool, std::string> cl_get_unary_op(UnaryOp op)
 {
     switch(op)
diff --git a/compute_kernel_writer/src/cl/CLKernelWriter.cpp b/compute_kernel_writer/src/cl/CLKernelWriter.cpp
index 79d0f985d0..90707ccbb1 100644
--- a/compute_kernel_writer/src/cl/CLKernelWriter.cpp
+++ b/compute_kernel_writer/src/cl/CLKernelWriter.cpp
@@ -82,8 +82,7 @@ std::unique_ptr<Kernel> CLKernelWriter::emit_kernel(const std::string &name)
             const auto &tile      = component->tile();
             const auto &tile_info = tile.info();
 
-            CKW_ASSERT(tile_info.height() == 1);
-            CKW_ASSERT(tile_info.width() == 1);
+            CKW_ASSERT(tile.is_scalar());
 
             code += cl_get_variable_datatype_as_string(tile_info.data_type(), 1);
             code += " ";
@@ -315,6 +314,77 @@ void CLKernelWriter::op_ternary(const TileOperand &dst, TernaryOp op, const Tile
     }
 }
 
+void CLKernelWriter::op_if_generic(bool is_else, const TileOperand &lhs, BinaryOp op, const TileOperand &rhs, const std::function<void()> &body)
+{
+    const auto &lhs_tile = to_cl_tile(lhs);
+    const auto &rhs_tile = to_cl_tile(rhs);
+
+    const auto op_name = std::get<1>(cl_get_binary_op(op, lhs_tile.info().data_type()));
+    CKW_ASSERT(op == BinaryOp::Less || op == BinaryOp::LessEqual || op == BinaryOp::Equal || op == BinaryOp::GreaterEqual || op == BinaryOp::Greater);
+
+    CKW_ASSERT(lhs_tile.is_scalar());
+    CKW_ASSERT(rhs_tile.is_scalar());
+
+    if(is_else)
+    {
+        append_code("else ");
+    }
+
+    append_code("if (", lhs_tile.scalar(0, 0).str, " ", op_name, " ", rhs_tile.scalar(0, 0).str, ")\n{\n");
+    write_body(body);
+    append_code("}\n");
+}
+
+void CLKernelWriter::op_if(const TileOperand &lhs, BinaryOp op, const TileOperand &rhs, const std::function<void()> &body)
+{
+    op_if_generic(false, lhs, op, rhs, body);
+}
+
+void CLKernelWriter::op_else_if(const TileOperand &lhs, BinaryOp op, const TileOperand &rhs, const std::function<void()> &body)
+{
+    op_if_generic(true, lhs, op, rhs, body);
+}
+
+void CLKernelWriter::op_else(const std::function<void()> &body)
+{
+    append_code("else\n{\n");
+    write_body(body);
+    append_code("}\n");
+}
+
+void CLKernelWriter::op_for_loop(
+    const TileOperand &var, BinaryOp cond_op, const TileOperand &cond_value,
+    const TileOperand &update_var, AssignmentOp update_op, const TileOperand &update_value,
+    const std::function<void()> &body)
+{
+    const auto &var_tile          = to_cl_tile(var);
+    const auto &cond_value_tile   = to_cl_tile(cond_value);
+    const auto &update_var_tile   = to_cl_tile(update_var);
+    const auto &update_value_tile = to_cl_tile(update_value);
+
+    CKW_ASSERT(var_tile.is_scalar());
+    CKW_ASSERT(cond_value_tile.is_scalar());
+    CKW_ASSERT(update_var_tile.is_scalar());
+    CKW_ASSERT(update_value_tile.is_scalar());
+
+    CKW_ASSERT(var_tile.info().data_type() == cond_value_tile.info().data_type());
+    CKW_ASSERT(update_var_tile.info().data_type() == update_value_tile.info().data_type());
+
+    const auto cond_op_name = std::get<1>(cl_get_binary_op(cond_op, var_tile.info().data_type()));
+    CKW_ASSERT(cond_op == BinaryOp::Less || cond_op == BinaryOp::LessEqual || cond_op == BinaryOp::Equal || cond_op == BinaryOp::GreaterEqual || cond_op == BinaryOp::Greater);
+
+    append_code(
+        "for (; ", var_tile.scalar(0, 0).str, " ", cond_op_name, " ", cond_value_tile.scalar(0, 0).str, "; ",
+        update_var_tile.scalar(0, 0).str, " ", cl_get_assignment_op_as_string(update_op), " ", update_value_tile.scalar(0, 0).str, ")\n{\n");
+    write_body(body);
+    append_code("}\n");
+}
+
+void CLKernelWriter::op_return()
+{
+    append_code("return;\n");
+}
+
 void CLKernelWriter::op_comment(const std::string &text)
 {
 #ifdef COMPUTE_KERNEL_WRITER_DEBUG_ENABLED
diff --git a/compute_kernel_writer/src/cl/CLKernelWriter.h b/compute_kernel_writer/src/cl/CLKernelWriter.h
index d2c84f192e..9fc7e550a7 100644
--- a/compute_kernel_writer/src/cl/CLKernelWriter.h
+++ b/compute_kernel_writer/src/cl/CLKernelWriter.h
@@ -75,6 +75,23 @@ public:
     void op_ternary(const TileOperand &dst, TernaryOp op, const TileOperand &first, const TileOperand &second, const TileOperand &third) override;
 
     // =============================================================================================
+    // Flow control
+    // =============================================================================================
+
+    void op_if(const TileOperand &lhs, BinaryOp op, const TileOperand &rhs, const std::function<void()> &body) override;
+
+    void op_else_if(const TileOperand &lhs, BinaryOp op, const TileOperand &rhs, const std::function<void()> &body) override;
+
+    void op_else(const std::function<void()> &body) override;
+
+    void op_for_loop(
+        const TileOperand &var, BinaryOp cond_op, const TileOperand &cond_value,
+        const TileOperand &update_var, AssignmentOp update_op, const TileOperand &update_value,
+        const std::function<void()> &body) override;
+
+    void op_return() override;
+
+    // =============================================================================================
     // Misc
     // =============================================================================================
 
@@ -177,6 +194,18 @@ private:
         const TileOperand &x, const TileOperand &y, const TileOperand &z, const TileOperand &batch,
         const CLTile &dilation_x, const CLTile &dilation_y);
 
+    /** This function is the generic function to write both `if` and `else if` blocks.
+     *
+     * It is used for both @ref CLKernelWriter::op_if and @ref CLKernelWriter::op_else_if.
+     *
+     * @param[in] is_else True if this is an `else if` block, otherwise this is an `if` block.
+     * @param[in] lhs     The LHS tile of the condition.
+     * @param[in] op      The relational binary operator.
+     * @param[in] rhs     The RHS tile of the condition.
+     * @param[in] body    The function that writes the body of the else-if block.
+     */
+    void op_if_generic(bool is_else, const TileOperand &lhs, BinaryOp op, const TileOperand &rhs, const std::function<void()> &body);
+
     // For attributes
 private:
     /** This string contains the kernel body source code, not the full CL source code.