[MLIR] Add support for sync_read_mem (#1203)

Co-authored-by: rsetaluri <[email protected]>

magma/backend/mlir/hardware_module.py

@@ -26,6 +26,12 @@
     visit_value_or_value_wrapper_by_direction as
     visit_magma_value_or_value_wrapper_by_direction,
 )
+from magma.backend.mlir.mem_utils import (
+    make_mem_reg,
+    make_mem_read,
+    emit_conditional_assign,
+    make_index_op,
+)
 from magma.backend.mlir.mlir import (
     MlirType, MlirValue, MlirSymbol, MlirAttribute, MlirBlock, push_block,
     push_location
@@ -366,29 +372,35 @@ def make_concat(self, operands, result):
     def visit_coreir_mem(self, module: ModuleWrapper) -> bool:
         inst = module.module
         defn = type(inst)
-        assert defn.coreir_name == "mem"
+        assert (
+            defn.coreir_name == "mem"
+            or defn.coreir_name == "sync_read_mem"
+        )
         # TODO(rsetaluri): Add support for initialization.
         if defn.coreir_genargs["has_init"]:
             raise NotImplementedError("coreir.mem init not supported")
         width = defn.coreir_genargs["width"]
         depth = defn.coreir_genargs["depth"]
-        raddr, waddr, wdata, clk, wen = module.operands
+        is_sync_read_mem = (defn.coreir_name == "sync_read_mem")
+        raddr, waddr, wdata, clk, wen = module.operands[:5]
         rdata = module.results[0]
-        elt_type = hw.InOutType(builtin.IntegerType(width))
-        reg_type = hw.InOutType(hw.ArrayType((depth,), elt_type.T))
-        reg = self.ctx.new_value(reg_type)
-        sv.RegOp(name=inst.name, results=[reg])
+        mem = make_mem_reg(
+            self._ctx, inst.name, depth, builtin.IntegerType(width)
+        )
         # Register read logic.
-        read = self.ctx.new_value(elt_type)
-        sv.ArrayIndexInOutOp(operands=[reg, raddr], results=[read])
-        sv.ReadInOutOp(operands=[read], results=[rdata])
+        read = make_index_op(self._ctx, mem, raddr)
+        read_reg, read_temp = make_mem_read(
+            self._ctx, read, rdata, is_sync_read_mem
+        )
         # Register write logic.
-        write = self.ctx.new_value(elt_type)
-        sv.ArrayIndexInOutOp(operands=[reg, waddr], results=[write])
+        write = make_index_op(self._ctx, mem, waddr)
+        # Always logic.
         always = sv.AlwaysFFOp(operands=[clk], clock_edge="posedge").body_block
         with push_block(always):
-            with push_block(sv.IfOp(operands=[wen]).then_block):
-                sv.PAssignOp(operands=[write, wdata])
+            emit_conditional_assign(write, wdata, wen)
+            if is_sync_read_mem:
+                ren = module.operands[-1]
+                emit_conditional_assign(read_reg, read_temp, ren)
         return True
 
     @wrap_with_not_implemented_error
@@ -498,8 +510,15 @@ def _visit(value, counter):
     def visit_coreir_primitive(self, module: ModuleWrapper) -> bool:
         inst = module.module
         defn = type(inst)
-        assert (defn.coreir_lib == "coreir" or defn.coreir_lib == "corebit")
-        if defn.coreir_name == "mem":
+        assert (
+            defn.coreir_lib == "coreir"
+            or defn.coreir_lib == "corebit"
+            or defn.coreir_lib == "memory"
+        )
+        if (
+            defn.coreir_name == "mem"
+            or defn.coreir_name == "sync_read_mem"
+        ):
             return self.visit_coreir_mem(module)
         if defn.coreir_name == "not":
             return self.visit_coreir_not(module)
@@ -660,7 +679,11 @@ def visit_primitive(self, module: ModuleWrapper) -> bool:
         inst = module.module
         defn = type(inst)
         assert isprimitive(defn)
-        if defn.coreir_lib == "coreir" or defn.coreir_lib == "corebit":
+        if (
+            defn.coreir_lib == "coreir"
+            or defn.coreir_lib == "corebit"
+            or defn.coreir_lib == "memory"
+        ):
             return self.visit_coreir_primitive(module)
         if defn.coreir_lib == "commonlib":
             return self.visit_commonlib_primitive(module)

magma/backend/mlir/mem_utils.py

@@ -0,0 +1,33 @@
+from magma.backend.mlir.hw import hw
+from magma.backend.mlir.mlir import push_block
+from magma.backend.mlir.sv import sv
+
+
+def make_mem_reg(ctx, name, N, T):
+    mem_type = hw.InOutType(hw.ArrayType((N,), T))
+    mem = ctx.new_value(mem_type)
+    sv.RegOp(name=name, results=[mem])
+    return mem
+
+
+def make_mem_read(ctx, target, value, has_enable, name="read_reg"):
+    if not has_enable:
+        sv.ReadInOutOp(operands=[target], results=[value])
+        return None, None
+    reg_out = ctx.new_value(target.type.T)
+    sv.ReadInOutOp(operands=[target], results=[reg_out])
+    reg = ctx.new_value(target.type)
+    sv.RegOp(name=name, results=[reg])
+    sv.ReadInOutOp(operands=[reg], results=[value])
+    return reg, reg_out
+
+
+def emit_conditional_assign(target, value, en):
+    with push_block(sv.IfOp(operands=[en]).then_block):
+        sv.PAssignOp(operands=[target, value])
+
+
+def make_index_op(ctx, value, idx):
+    result = ctx.new_value(hw.InOutType(value.type.T.T))
+    sv.ArrayIndexInOutOp(operands=[value, idx], results=[result])
+    return result

tests/test_backend/test_mlir/examples.py

@@ -511,6 +511,28 @@ class simple_memory_wrapper(m.Circuit):
     )
 
 
+class sync_memory_wrapper(m.Circuit):
+    T = m.Bits[12]
+    height = 128
+    addr_type = m.Bits[m.bitutils.clog2(height)]
+    io = m.IO(
+        RADDR=m.In(addr_type),
+        RDATA=m.Out(T),
+        CLK=m.In(m.Clock),
+        WADDR=m.In(addr_type),
+        WDATA=m.In(T),
+        WE=m.In(m.Enable),
+    )
+    mem = m.Memory(height=height, T=T, read_latency=1)()
+    io.RDATA @= mem(
+        RADDR=io.RADDR,
+        RDATA=io.RDATA,
+        WADDR=io.WADDR,
+        WDATA=io.WDATA,
+        WE=io.WE,
+    )
+
+
 m.passes.clock.WireClockPass(simple_memory_wrapper).run()
 
 

tests/test_backend/test_mlir/golds/sync_memory_wrapper.mlir

@@ -0,0 +1,24 @@
+module attributes {circt.loweringOptions = "locationInfoStyle=none"} {
+    hw.module @Memory(%RADDR: i7, %CLK: i1, %WADDR: i7, %WDATA: i12, %WE: i1) -> (RDATA: i12) {
+        %0 = hw.constant 1 : i1
+        %2 = sv.reg name "coreir_mem128x12_inst0" : !hw.inout<!hw.array<128xi12>>
+        %3 = sv.array_index_inout %2[%RADDR] : !hw.inout<!hw.array<128xi12>>, i7
+        %4 = sv.read_inout %3 : !hw.inout<i12>
+        %5 = sv.reg name "read_reg" : !hw.inout<i12>
+        %1 = sv.read_inout %5 : !hw.inout<i12>
+        %6 = sv.array_index_inout %2[%WADDR] : !hw.inout<!hw.array<128xi12>>, i7
+        sv.alwaysff(posedge %CLK) {
+            sv.if %WE {
+                sv.passign %6, %WDATA : i12
+            }
+            sv.if %0 {
+                sv.passign %5, %4 : i12
+            }
+        }
+        hw.output %1 : i12
+    }
+    hw.module @sync_memory_wrapper(%RADDR: i7, %CLK: i1, %WADDR: i7, %WDATA: i12, %WE: i1) -> (RDATA: i12) {
+        %0 = hw.instance "Memory_inst0" @Memory(RADDR: %RADDR: i7, CLK: %CLK: i1, WADDR: %WADDR: i7, WDATA: %WDATA: i12, WE: %WE: i1) -> (RDATA: i12)
+        hw.output %0 : i12
+    }
+}

tests/test_backend/test_mlir/golds/sync_memory_wrapper.v

@@ -0,0 +1,39 @@
+// Generated by CIRCT circtorg-0.0.0-1773-g7abbc4313
+module Memory(
+  input  [6:0]  RADDR,
+  input         CLK,
+  input  [6:0]  WADDR,
+  input  [11:0] WDATA,
+  input         WE,
+  output [11:0] RDATA
+);
+
+  reg [127:0][11:0] coreir_mem128x12_inst0;
+  reg [11:0]        read_reg;
+  always_ff @(posedge CLK) begin
+    if (WE)
+      coreir_mem128x12_inst0[WADDR] <= WDATA;
+    read_reg <= coreir_mem128x12_inst0[RADDR];
+  end // always_ff @(posedge)
+  assign RDATA = read_reg;
+endmodule
+
+module sync_memory_wrapper(
+  input  [6:0]  RADDR,
+  input         CLK,
+  input  [6:0]  WADDR,
+  input  [11:0] WDATA,
+  input         WE,
+  output [11:0] RDATA
+);
+
+  Memory Memory_inst0 (
+    .RADDR (RADDR),
+    .CLK   (CLK),
+    .WADDR (WADDR),
+    .WDATA (WDATA),
+    .WE    (WE),
+    .RDATA (RDATA)
+  );
+endmodule
+

tests/test_backend/test_mlir/test_utils.py

@@ -189,6 +189,7 @@ def get_local_examples() -> List[DefineCircuitKind]:
         examples.simple_undriven,
         examples.complex_undriven,
         examples.simple_memory_wrapper,
+        examples.sync_memory_wrapper,
         examples.simple_undriven_instances,
         examples.simple_neg,
         examples.simple_array_slice,