From 3b0d179de41e4212d94c2920c91004709ab78003 Mon Sep 17 00:00:00 2001
From: Zhang Hao <zhanghao@4paradigm.com>
Date: Tue, 28 Apr 2020 13:54:52 +0800
Subject: [PATCH] [VTA][Runtime] fix hardcode VerifyDep step

---
 docs/vta/dev/config.rst |  2 ++
 vta/runtime/runtime.cc  | 11 ++++++++++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/docs/vta/dev/config.rst b/docs/vta/dev/config.rst
index 2f98d777608e..efbaafc7a619 100644
--- a/docs/vta/dev/config.rst
+++ b/docs/vta/dev/config.rst
@@ -55,6 +55,8 @@ below.
 | ``LOG_WGT_BUFF_SIZE`` | Int (log2) | Weight on-chip buffer in Bytes.                        |
 +-----------------------+------------+--------------------------------------------------------+
 | ``LOG_ACC_BUFF_SIZE`` | Int (log2) | Accumulator on-chip buffer in Bytes.                   |
++-----------------------+------------+--------------------------------------------------------+
+| ``ACC_DEP_DISTANCE``  | Int        | Accumulator dependence distance.                       |
 +-----------------------+------------+--------------------------------------------------------+
 
 
diff --git a/vta/runtime/runtime.cc b/vta/runtime/runtime.cc
index 038d5cfa398c..276872526a14 100644
--- a/vta/runtime/runtime.cc
+++ b/vta/runtime/runtime.cc
@@ -145,6 +145,7 @@ struct DataBuffer {
  */
 class UopKernel {
  public:
+  static const size_t kDefaultAccDepDistance = 3U;
   /*! \brief Loop information. */
   struct LoopEntry {
     uint32_t extent;
@@ -159,6 +160,12 @@ class UopKernel {
    */
   UopKernel(const char* signature, int nbytes)
       : signature_(signature, signature + nbytes) {
+    const char* d_str = std::getenv("VTA_ACC_DEP_DISTANCE");
+    if (d_str) {
+      acc_dep_distance_ = std::atoi(d_str);
+    } else {
+      acc_dep_distance_ = kDefaultAccDepDistance;
+    }
   }
   /*!
    * \brief Verify if the signature is correct.
@@ -288,7 +295,7 @@ class UopKernel {
  private:
   // Verify that we don't write to the same acc_mem index two cycles in a row
   void VerifyDep(uint32_t dst_index) {
-    size_t step = std::min(static_cast<size_t>(2U), seq_.size());
+    size_t step = std::min(acc_dep_distance_ - 1, seq_.size());
     for (size_t i = seq_.size() - step; i < seq_.size(); ++i) {
       CHECK(seq_[i].dst_idx != dst_index);
     }
@@ -308,6 +315,8 @@ class UopKernel {
   std::vector<LoopEntry> loop_;
   // The loop pointer
   size_t loop_ptr_{0};
+  // acc dep distance
+  size_t acc_dep_distance_{0};
 };
 
 /*!