From 4fef9689abb81286af4d9c6bc420b78f61d89550 Mon Sep 17 00:00:00 2001
From: Graham Edgecombe <gpe@grahamedgecombe.com>
Date: Sat, 8 Dec 2018 09:59:56 +0000
Subject: [PATCH] memory_bram: Fix initdata bit order after shuffling
In some cases the memory_bram pass shuffles the order of the bits in a
memory's RD_DATA port. Although the order of the bits in the WR_DATA and
WR_EN ports is changed to match the RD_DATA port, the order of the bits
in the initialization data is not.
This causes reads of initialized memories to return invalid data (until
the initialization data is overwritten).
This commit fixes the bug by shuffling the initdata bits in exactly the
same order as the RD_DATA/WR_DATA/WR_EN bits.
---
passes/memory/memory_bram.cc | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/passes/memory/memory_bram.cc b/passes/memory/memory_bram.cc
index 8740042c4..cf4095d06 100644
--- a/passes/memory/memory_bram.cc
+++ b/passes/memory/memory_bram.cc
@@ -472,8 +472,12 @@ bool replace_cell(Cell *cell, const rules_t &rules, const rules_t::bram_t &bram,
std::vector<SigSpec> new_wr_en(GetSize(old_wr_en));
std::vector<SigSpec> new_wr_data(GetSize(old_wr_data));
std::vector<SigSpec> new_rd_data(GetSize(old_rd_data));
+ std::vector<std::vector<State>> new_initdata;
std::vector<int> shuffle_map;
+ if (cell_init)
+ new_initdata.resize(mem_size);
+
for (auto &it : en_order)
{
auto &bits = bits_wr_en.at(it);
@@ -489,6 +493,10 @@ bool replace_cell(Cell *cell, const rules_t &rules, const rules_t::bram_t &bram,
}
for (int j = 0; j < rd_ports; j++)
new_rd_data[j].append(old_rd_data[j][bits[i]]);
+ if (cell_init) {
+ for (int j = 0; j < mem_size; j++)
+ new_initdata[j].push_back(initdata[j][bits[i]]);
+ }
shuffle_map.push_back(bits[i]);
}
@@ -499,6 +507,10 @@ bool replace_cell(Cell *cell, const rules_t &rules, const rules_t::bram_t &bram,
}
for (int j = 0; j < rd_ports; j++)
new_rd_data[j].append(State::Sx);
+ if (cell_init) {
+ for (int j = 0; j < mem_size; j++)
+ new_initdata[j].push_back(State::Sx);
+ }
shuffle_map.push_back(-1);
}
}
@@ -522,6 +534,11 @@ bool replace_cell(Cell *cell, const rules_t &rules, const rules_t::bram_t &bram,
for (int i = 0; i < rd_ports; i++)
rd_data.replace(i*mem_width, new_rd_data[i]);
+
+ if (cell_init) {
+ for (int i = 0; i < mem_size; i++)
+ initdata[i] = Const(new_initdata[i]);
+ }
}
// assign write ports