Add state index to selector for "select before loop" in merge states …

…mode.

This gives the downstream compiler tools the information needed to
discard false data dependencies in later states.

Also debugging improvements for FSMs
- Better node naming
- Optional, and false positive prone, analysis for these cases with DebugIrTraceFlags_PrevStateIOReferences

PiperOrigin-RevId: 622461336

xls/contrib/xlscc/translate_loops.cc

@@ -427,7 +427,8 @@ absl::Status Translator::GenerateIR_PipelinedLoop(
       }
     }
 
-    lvalue_conditions_tuple = context().fb->Tuple(lvalue_conditions, loc);
+    lvalue_conditions_tuple = context().fb->Tuple(lvalue_conditions, loc,
+                                                  /*name=*/"lvalue_conditions");
     std::vector<std::shared_ptr<CType>> lvalue_conds_tuple_fields;
     lvalue_conds_tuple_fields.resize(lvalue_conditions.size(),
                                      std::make_shared<CBoolType>());
@@ -547,7 +548,8 @@ absl::Status Translator::GenerateIR_PipelinedLoop(
     // Must match if(uses_on_reset) below
     context_tuple_out = CValue(
         context().fb->Tuple({outer_on_reset_value, context_struct_out.rvalue(),
-                             lvalue_conditions_tuple}),
+                             lvalue_conditions_tuple},
+                            loc, /*name=*/"context_out_tuple_inner"),
         context_tuple_type);
   }
 
@@ -649,8 +651,13 @@ absl::Status Translator::GenerateIR_PipelinedLoop(
     context_tuple_out = CValue(
         context().fb->Tuple(
             {on_reset_cval.rvalue(),
-             context().fb->TupleIndex(context_tuple_out.rvalue(), 1, loc),
-             context().fb->TupleIndex(context_tuple_out.rvalue(), 2, loc)}),
+             context().fb->TupleIndex(context_tuple_out.rvalue(), 1, loc,
+                                      /*name=*/"context_out_outer_struct"),
+             context().fb->TupleIndex(
+                 context_tuple_out.rvalue(), 2, loc,
+                 /*name=*/"context_out_outer_lvalue_conditions")},
+            loc,
+            /*name=*/"context_out_tuple_outer"),
         context_tuple_out.type());
   }
 
@@ -661,7 +668,8 @@ absl::Status Translator::GenerateIR_PipelinedLoop(
     op.op = OpType::kSend;
     std::vector<xls::BValue> sp = {context_tuple_out.rvalue(),
                                    context().full_condition_bval(loc)};
-    op.ret_value = context().fb->Tuple(sp, loc);
+    op.ret_value =
+        context().fb->Tuple(sp, loc, /*name=*/"context_out_send_tup");
     XLS_ASSIGN_OR_RETURN(ctx_out_op_ptr,
                          AddOpToChannel(op, context_out_channel, loc));
   }
@@ -1055,9 +1063,14 @@ absl::Status Translator::GenerateIR_PipelinedLoopProc(
 
   xls::BValue receive =
       pb.ReceiveIf(context_out_channel->generated.value(), token,
-                   /*pred=*/placeholder_cond, loc);
-  token = pb.TupleIndex(receive, 0);
-  xls::BValue received_context_tuple = pb.TupleIndex(receive, 1);
+                   /*pred=*/placeholder_cond, loc,
+                   /*name=*/absl::StrFormat("%s_receive_context", name_prefix));
+  token = pb.TupleIndex(
+      receive, 0, loc,
+      /*name=*/absl::StrFormat("%s_receive_context_token", name_prefix));
+  xls::BValue received_context_tuple = pb.TupleIndex(
+      receive, 1, loc,
+      /*name=*/absl::StrFormat("%s_receive_context_tup", name_prefix));
 
   XLS_ASSIGN_OR_RETURN(
       PipelinedLoopContentsReturn contents_ret,
@@ -1183,11 +1196,16 @@ Translator::GenerateIR_PipelinedLoopContents(
 
   xls::BValue token = token_in;
 
-  xls::BValue received_on_reset = pb.TupleIndex(received_context_tuple, 0, loc);
-  xls::BValue received_context = pb.TupleIndex(received_context_tuple, 1, loc);
+  xls::BValue received_on_reset = pb.TupleIndex(
+      received_context_tuple, 0, loc,
+      /*name=*/absl::StrFormat("%s_receive_on_reset", name_prefix));
+  xls::BValue received_context = pb.TupleIndex(
+      received_context_tuple, 1, loc,
+      /*name=*/absl::StrFormat("%s_receive_context_data", name_prefix));
 
-  xls::BValue received_lvalue_conds =
-      pb.TupleIndex(received_context_tuple, 2, loc);
+  xls::BValue received_lvalue_conds = pb.TupleIndex(
+      received_context_tuple, 2, loc,
+      /*name=*/absl::StrFormat("%s_receive_context_lvalues", name_prefix));
 
   xls::BValue use_context_in = last_iter_broke_in;
 
@@ -1401,7 +1419,10 @@ Translator::GenerateIR_PipelinedLoopContents(
 
     xls::BValue ret_next =
         pb.TupleIndex(fsm_ret.return_value,
-                      prepared.return_index_for_static.at(namedecl), loc);
+                      prepared.return_index_for_static.at(namedecl), loc,
+                      /*name=*/
+                      absl::StrFormat("%s_fsm_ret_static_%s", name_prefix,
+                                      namedecl->getNameAsString()));
 
     xls::BValue state_elem_bval(
         prepared.state_element_for_variable.at(namedecl), &pb);

xls/contrib/xlscc/translator.cc

@@ -44,6 +44,7 @@
 #include "absl/status/statusor.h"
 #include "absl/strings/match.h"
 #include "absl/strings/str_format.h"
+#include "absl/strings/str_join.h"
 #include "absl/strings/str_replace.h"
 #include "absl/types/span.h"
 #include "clang/include/clang/AST/APValue.h"
@@ -5202,6 +5203,14 @@ std::string Debug_NodeToInfix(const xls::Node* node, int64_t& n_printed) {
     return absl::StrFormat("%s(%i)", Debug_NodeToInfix(tup, n_printed),
                            ti->index());
   }
+  if (node->Is<xls::Tuple>()) {
+    const xls::Tuple* tp = node->As<xls::Tuple>();
+    std::vector<std::string> operand_strings;
+    for (const xls::Node* op : tp->operands()) {
+      operand_strings.push_back(Debug_NodeToInfix(op, n_printed));
+    }
+    return std::string("(") + absl::StrJoin(operand_strings, ", ") + ")";
+  }
   if (node->Is<xls::UnOp>()) {
     const xls::UnOp* op = node->As<xls::UnOp>();
     if (op->op() == xls::Op::kNot) {
@@ -5259,6 +5268,37 @@ std::string Debug_NodeToInfix(const xls::Node* node, int64_t& n_printed) {
                          typeid(*node).name());
 }
 
+std::string Debug_OpName(const IOOp& op) {
+  if (op.op == OpType::kTrace) {
+    return "trace";
+  }
+  if (op.channel != nullptr) {
+    std::string op_type_name;
+    switch (op.op) {
+      case OpType::kSend:
+        op_type_name = "send";
+        break;
+      case OpType::kRecv:
+        op_type_name = "recv";
+        break;
+      case OpType::kRead:
+        op_type_name = "read";
+        break;
+      case OpType::kWrite:
+        op_type_name = "write";
+        break;
+      default:
+        CHECK_EQ("Op type doesn't make sense here", nullptr);
+    }
+    return absl::StrFormat("%s_%s", op.channel->unique_name, op_type_name);
+  }
+  if (!op.final_param_name.empty()) {
+    return op.final_param_name;
+  }
+  CHECK_EQ("Unable to form name for op", nullptr);
+  return "TODO_OpName";
+}
+
 std::string Debug_VariablesChangedBetween(const TranslationContext& before,
                                           const TranslationContext& after) {
   std::ostringstream ostr;
@@ -5284,6 +5324,24 @@ std::string Debug_VariablesChangedBetween(const TranslationContext& before,
   return ostr.str();
 }
 
+std::optional<std::list<const xls::Node*>> Debug_DeeplyCheckOperandsFromPrev(
+    const xls::Node* node,
+    const absl::flat_hash_set<const xls::Node*>& prev_state_io_nodes) {
+  for (const xls::Node* op : node->operands()) {
+    if (prev_state_io_nodes.contains(op)) {
+      return std::list<const xls::Node*>({op});
+    }
+    std::optional<std::list<const xls::Node*>> opt_path =
+        Debug_DeeplyCheckOperandsFromPrev(op, prev_state_io_nodes);
+    if (opt_path.has_value()) {
+      std::list<const xls::Node*> path = opt_path.value();
+      path.push_front(op);
+      return path;
+    }
+  }
+  return std::nullopt;
+}
+
 absl::StatusOr<Z3_lbool> Translator::CheckAssumptions(
     absl::Span<xls::Node*> positive_nodes,
     absl::Span<xls::Node*> negative_nodes, Z3_solver& solver,

xls/contrib/xlscc/translator.h

@@ -111,8 +111,7 @@ class CVoidType : public CType {
   absl::Status GetMetadata(Translator& translator, xlscc_metadata::Type* output,
                            absl::flat_hash_set<const clang::NamedDecl*>&
                                aliases_used) const override;
-  absl::Status GetMetadataValue(Translator& translator,
-                                ConstValue const_value,
+  absl::Status GetMetadataValue(Translator& translator, ConstValue const_value,
                                 xlscc_metadata::Value* output) const override;
 
   bool operator==(const CType& o) const override;
@@ -129,8 +128,7 @@ class CBitsType : public CType {
   absl::Status GetMetadata(Translator& translator, xlscc_metadata::Type* output,
                            absl::flat_hash_set<const clang::NamedDecl*>&
                                aliases_used) const override;
-  absl::Status GetMetadataValue(Translator& translator,
-                                ConstValue const_value,
+  absl::Status GetMetadataValue(Translator& translator, ConstValue const_value,
                                 xlscc_metadata::Value* output) const override;
 
   bool operator==(const CType& o) const override;
@@ -151,8 +149,7 @@ class CIntType : public CType {
   absl::Status GetMetadata(Translator& translator, xlscc_metadata::Type* output,
                            absl::flat_hash_set<const clang::NamedDecl*>&
                                aliases_used) const override;
-  absl::Status GetMetadataValue(Translator& translator,
-                                ConstValue const_value,
+  absl::Status GetMetadataValue(Translator& translator, ConstValue const_value,
                                 xlscc_metadata::Value* output) const override;
 
   bool operator==(const CType& o) const override;
@@ -213,8 +210,7 @@ class CEnumType : public CIntType {
   absl::Status GetMetadata(Translator& translator, xlscc_metadata::Type* output,
                            absl::flat_hash_set<const clang::NamedDecl*>&
                                aliases_used) const override;
-  absl::Status GetMetadataValue(Translator& translator,
-                                ConstValue const_value,
+  absl::Status GetMetadataValue(Translator& translator, ConstValue const_value,
                                 xlscc_metadata::Value* output) const override;
 
   bool operator==(const CType& o) const override;
@@ -241,8 +237,7 @@ class CBoolType : public CType {
   absl::Status GetMetadata(Translator& translator, xlscc_metadata::Type* output,
                            absl::flat_hash_set<const clang::NamedDecl*>&
                                aliases_used) const override;
-  absl::Status GetMetadataValue(Translator& translator,
-                                ConstValue const_value,
+  absl::Status GetMetadataValue(Translator& translator, ConstValue const_value,
                                 xlscc_metadata::Value* output) const override;
   bool operator==(const CType& o) const override;
   bool StoredAsXLSBits() const override;
@@ -279,8 +274,7 @@ class CStructType : public CType {
   absl::Status GetMetadata(Translator& translator, xlscc_metadata::Type* output,
                            absl::flat_hash_set<const clang::NamedDecl*>&
                                aliases_used) const override;
-  absl::Status GetMetadataValue(Translator& translator,
-                                ConstValue const_value,
+  absl::Status GetMetadataValue(Translator& translator, ConstValue const_value,
                                 xlscc_metadata::Value* output) const override;
   bool operator==(const CType& o) const override;
   absl::StatusOr<bool> ContainsLValues(Translator& translator) const override;
@@ -314,8 +308,7 @@ class CInternalTuple : public CType {
   absl::Status GetMetadata(Translator& translator, xlscc_metadata::Type* output,
                            absl::flat_hash_set<const clang::NamedDecl*>&
                                aliases_used) const override;
-  absl::Status GetMetadataValue(Translator& translator,
-                                ConstValue const_value,
+  absl::Status GetMetadataValue(Translator& translator, ConstValue const_value,
                                 xlscc_metadata::Value* output) const override;
   bool operator==(const CType& o) const override;
 
@@ -349,8 +342,7 @@ class CInstantiableTypeAlias : public CType {
   absl::Status GetMetadata(Translator& translator, xlscc_metadata::Type* output,
                            absl::flat_hash_set<const clang::NamedDecl*>&
                                aliases_used) const override;
-  absl::Status GetMetadataValue(Translator& translator,
-                                ConstValue const_value,
+  absl::Status GetMetadataValue(Translator& translator, ConstValue const_value,
                                 xlscc_metadata::Value* output) const override;
   explicit operator std::string() const override;
   int GetBitWidth() const override;
@@ -370,8 +362,7 @@ class CArrayType : public CType {
   absl::Status GetMetadata(Translator& translator, xlscc_metadata::Type* output,
                            absl::flat_hash_set<const clang::NamedDecl*>&
                                aliases_used) const override;
-  absl::Status GetMetadataValue(Translator& translator,
-                                ConstValue const_value,
+  absl::Status GetMetadataValue(Translator& translator, ConstValue const_value,
                                 xlscc_metadata::Value* output) const override;
   absl::StatusOr<bool> ContainsLValues(Translator& translator) const override;
 
@@ -393,8 +384,7 @@ class CPointerType : public CType {
   absl::Status GetMetadata(Translator& translator, xlscc_metadata::Type* output,
                            absl::flat_hash_set<const clang::NamedDecl*>&
                                aliases_used) const override;
-  absl::Status GetMetadataValue(Translator& translator,
-                                ConstValue const_value,
+  absl::Status GetMetadataValue(Translator& translator, ConstValue const_value,
                                 xlscc_metadata::Value* output) const override;
   absl::StatusOr<bool> ContainsLValues(Translator& translator) const override;
 
@@ -414,8 +404,7 @@ class CReferenceType : public CType {
   absl::Status GetMetadata(Translator& translator, xlscc_metadata::Type* output,
                            absl::flat_hash_set<const clang::NamedDecl*>&
                                aliases_used) const override;
-  absl::Status GetMetadataValue(Translator& translator,
-                                ConstValue const_value,
+  absl::Status GetMetadataValue(Translator& translator, ConstValue const_value,
                                 xlscc_metadata::Value* output) const override;
   absl::StatusOr<bool> ContainsLValues(Translator& translator) const override;
 
@@ -442,8 +431,7 @@ class CChannelType : public CType {
   absl::Status GetMetadata(Translator& translator, xlscc_metadata::Type* output,
                            absl::flat_hash_set<const clang::NamedDecl*>&
                                aliases_used) const override;
-  absl::Status GetMetadataValue(Translator& translator,
-                                ConstValue const_value,
+  absl::Status GetMetadataValue(Translator& translator, ConstValue const_value,
                                 xlscc_metadata::Value* output) const override;
 
   std::shared_ptr<CType> GetItemType() const;
@@ -923,6 +911,7 @@ int Debug_CountNodes(const xls::Node* node,
                      std::set<const xls::Node*>& visited);
 std::string Debug_NodeToInfix(xls::BValue bval);
 std::string Debug_NodeToInfix(const xls::Node* node, int64_t& n_printed);
+std::string Debug_OpName(const IOOp& op);
 
 // Encapsulates a context for translating Clang AST to XLS IR.
 // This is roughly equivalent to a "scope" in C++. There will typically
@@ -1086,6 +1075,10 @@ struct TranslationContext {
 std::string Debug_VariablesChangedBetween(const TranslationContext& before,
                                           const TranslationContext& after);
 
+std::optional<std::list<const xls::Node*>> Debug_DeeplyCheckOperandsFromPrev(
+    const xls::Node* node,
+    const absl::flat_hash_set<const xls::Node*>& prev_state_io_nodes);
+
 enum IOOpOrdering {
   kNone = 0,
   kChannelWise = 1,
@@ -1102,7 +1095,8 @@ enum DebugIrTraceFlags {
   DebugIrTraceFlags_None = 0,
   DebugIrTraceFlags_LoopContext = 1,
   DebugIrTraceFlags_LoopControl = 2,
-  DebugIrTraceFlags_FSMStates = 4
+  DebugIrTraceFlags_FSMStates = 4,
+  DebugIrTraceFlags_PrevStateIOReferences = 8
 };
 
 class Translator {
@@ -1706,6 +1700,16 @@ class Translator {
       PreparedBlock& prepared, xls::ProcBuilder& pb, int nesting_level,
       const xls::SourceInfo& body_loc);
 
+  struct LayoutFSMStatesReturn {
+    absl::flat_hash_map<const IOOp*, const State*> state_by_io_op;
+    std::vector<std::unique_ptr<State>> states;
+    bool has_pipelined_loop = false;
+  };
+
+  absl::StatusOr<LayoutFSMStatesReturn> LayoutFSMStates(
+      PreparedBlock& prepared, xls::ProcBuilder& pb,
+      const xls::SourceInfo& body_loc);
+
   std::set<ChannelBundle> GetChannelsUsedByOp(
       const IOOp& op, const PipelinedLoopSubProc* sub_procp,
       const xls::SourceInfo& loc);
@@ -1760,9 +1764,9 @@ class Translator {
   };
   // Checks if an expression is an IO op, and if so, generates the value
   //  to replace it in IR generation.
-  absl::StatusOr<IOOpReturn> InterceptIOOp(
-      const clang::Expr* expr, const xls::SourceInfo& loc,
-      CValue assignment_value = CValue());
+  absl::StatusOr<IOOpReturn> InterceptIOOp(const clang::Expr* expr,
+                                           const xls::SourceInfo& loc,
+                                           CValue assignment_value = CValue());
 
   // IOOp must have io_call, and op members filled in
   // This will add a parameter for IO input if needed,

xls/contrib/xlscc/unit_tests/testdata/translator_verilog_test_IOProcComboGenNToOneMux.svtxt

@@ -15,12 +15,14 @@ module foo_proc(
   wire [31:0] in2_select;
   wire [31:0] in1_select;
   wire p0_all_active_inputs_valid;
+  wire [31:0] out_send_value;
   assign in1_op0_ret_io_value = dir == 32'h0000_0000;
   assign in2_op0_ret_io_value = ~in1_op0_ret_io_value;
   assign in2_select = in2_op0_ret_io_value ? in2 : 32'h0000_0000;
   assign in1_select = in1_op0_ret_io_value ? in1 : 32'h0000_0000;
   assign p0_all_active_inputs_valid = (~in1_op0_ret_io_value | in1_vld) & (~in2_op0_ret_io_value | in2_vld);
-  assign out = in1_op0_ret_io_value ? in1_select : in2_select;
+  assign out_send_value = in1_op0_ret_io_value ? in1_select : in2_select;
+  assign out = out_send_value;
   assign out_vld = p0_all_active_inputs_valid & 1'h1 & 1'h1;
   assign in1_rdy = in1_op0_ret_io_value & out_rdy;
   assign in2_rdy = in2_op0_ret_io_value & out_rdy;

xls/contrib/xlscc/unit_tests/testdata/translator_verilog_test_IOProcComboGenNToOneMux.vtxt

@@ -15,12 +15,14 @@ module foo_proc(
   wire [31:0] in2_select;
   wire [31:0] in1_select;
   wire p0_all_active_inputs_valid;
+  wire [31:0] out_send_value;
   assign in1_op0_ret_io_value = dir == 32'h0000_0000;
   assign in2_op0_ret_io_value = ~in1_op0_ret_io_value;
   assign in2_select = in2_op0_ret_io_value ? in2 : 32'h0000_0000;
   assign in1_select = in1_op0_ret_io_value ? in1 : 32'h0000_0000;
   assign p0_all_active_inputs_valid = (~in1_op0_ret_io_value | in1_vld) & (~in2_op0_ret_io_value | in2_vld);
-  assign out = in1_op0_ret_io_value ? in1_select : in2_select;
+  assign out_send_value = in1_op0_ret_io_value ? in1_select : in2_select;
+  assign out = out_send_value;
   assign out_vld = p0_all_active_inputs_valid & 1'h1 & 1'h1;
   assign in1_rdy = in1_op0_ret_io_value & out_rdy;
   assign in2_rdy = in2_op0_ret_io_value & out_rdy;