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fix memory handling in functional backend, add more error messages and comments for memory edgecases

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This commit is contained in:
Emily Schmidt 2024-07-18 14:10:15 +01:00
parent 4722f13a5d
commit 145af6f10d
3 changed files with 86 additions and 17 deletions
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52
kernel/functionalir.cc
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@ -461,11 +461,19 @@ public:
memories[mem.cell] = &mem;
}
}
Node concatenate_read_results(Mem *, vector<Node> results)
Node concatenate_read_results(Mem *mem, vector<Node> results)
{
/* TODO: write code to check that this is ok to do */
if(results.size() == 0)
return factory.undriven(0);
// sanity check: all read ports concatenated should equal to the RD_DATA port
const SigSpec &rd_data = mem->cell->connections().at(ID(RD_DATA));
int current = 0;
for(size_t i = 0; i < mem->rd_ports.size(); i++) {
int width = mem->width << mem->rd_ports[i].wide_log2;
log_assert (results[i].width() == width);
log_assert (mem->rd_ports[i].data == rd_data.extract(current, width));
current += width;
}
log_assert (current == rd_data.size());
log_assert (!results.empty());
Node node = results[0];
for(size_t i = 1; i < results.size(); i++)
node = factory.concat(node, results[i]);
@ -473,16 +481,23 @@ public:
}
Node handle_memory(Mem *mem)
{
// To simplify memory handling, the functional backend makes the following assumptions:
// - Since async2sync or clk2fflogic must be run to use the functional backend,
// we can assume that all ports are asynchronous.
// - Async rd/wr are always transparent and so we must do reads after writes,
// but we can ignore transparency_mask.
// - We ignore collision_x_mask because x is a dont care value for us anyway.
// - Since wr port j can only have priority over wr port i if j > i, if we do writes in
// ascending index order the result will obey the priorty relation.
vector<Node> read_results;
int addr_width = ceil_log2(mem->size);
int data_width = mem->width;
Node node = factory.state_memory(mem->cell->name, addr_width, data_width);
for (auto &rd : mem->rd_ports) {
log_assert(!rd.clk_enable);
Node addr = enqueue(driver_map(DriveSpec(rd.addr)));
read_results.push_back(factory.memory_read(node, addr));
}
for (auto &wr : mem->wr_ports) {
for (size_t i = 0; i < mem->wr_ports.size(); i++) {
const auto &wr = mem->wr_ports[i];
if (wr.clk_enable)
log_error("Write port %zd of memory %s.%s is clocked. This is not supported by the functional backend. "
"Call async2sync or clk2fflogic to avoid this error.\n", i, log_id(mem->module), log_id(mem->memid));
Node en = enqueue(driver_map(DriveSpec(wr.en)));
Node addr = enqueue(driver_map(DriveSpec(wr.addr)));
Node new_data = enqueue(driver_map(DriveSpec(wr.data)));
@ -490,6 +505,17 @@ public:
Node wr_data = simplifier.bitwise_mux(old_data, new_data, en);
node = factory.memory_write(node, addr, wr_data);
}
if (mem->rd_ports.empty())
log_error("Memory %s.%s has no read ports. This is not supported by the functional backend. "
"Call opt_clean to remove it.", log_id(mem->module), log_id(mem->memid));
for (size_t i = 0; i < mem->rd_ports.size(); i++) {
const auto &rd = mem->rd_ports[i];
if (rd.clk_enable)
log_error("Read port %zd of memory %s.%s is clocked. This is not supported by the functional backend. "
"Call memory_nordff to avoid this error.\n", i, log_id(mem->module), log_id(mem->memid));
Node addr = enqueue(driver_map(DriveSpec(rd.addr)));
read_results.push_back(factory.memory_read(node, addr));
}
factory.declare_state_memory(node, mem->cell->name, addr_width, data_width);
return concatenate_read_results(mem, read_results);
}
@ -497,7 +523,11 @@ public:
{
if (cell->is_mem_cell()) {
Mem *mem = memories.at(cell, nullptr);
log_assert(mem != nullptr);
if (mem == nullptr) {
log_assert(cell->has_memid());
log_error("The design contains an unpacked memory at %s. This is not supported by the functional backend. "
"Call memory_collect to avoid this error.\n", log_const(cell->parameters.at(ID(MEMID))));
}
Node node = handle_memory(mem);
factory.update_pending(cell_outputs.at({cell, ID(RD_DATA)}), node);
} else {