Expand the resource sharing pass to include additions and subtractions.

docs_src/tools.md

@@ -201,6 +201,13 @@ purposes only.
     re-using the same hardware resources (e.g., multiplier) for multiple
     mutually-exclusive operations. This transformation might increase the
     critical path latency. Defaults to `false`.
+*   `--force_resource_sharing=true|false`: Controls whether to use the heuristic
+    to decide when it is profitable to apply the resource sharing optimization.
+    When set to true, the resource sharing optimization applies the
+    transformation assuming it is always profitable. Finally, this option is
+    only used when the resource sharing pass is enabled. Defaults to `false`.
+*   `--area_model=MODEL`: Specify the area model to use during the IR
+    optimizations. Defaults to `asap7`.
 
 ## [`print_bom`](https://github.com/google/xls/tree/main/xls/tools/print_bom.cc)
 

xls/build_rules/xls_ir_rules.bzl

@@ -225,6 +225,8 @@ def _optimize_ir(ctx, src, original_input_files):
         "use_context_narrowing_analysis",
         "optimize_for_best_case_throughput",
         "enable_resource_sharing",
+        "force_resource_sharing",
+        "area_model",
         "top",
     )
 
@@ -469,6 +471,8 @@ def get_benchmark_ir_cmd(ctx, src, append_cmd_line_args = True):
         "use_context_narrowing_analysis",
         "optimize_for_best_case_throughput",
         "enable_resource_sharing",
+        "force_resource_sharing",
+        "area_model",
         "run_evaluators",
     ] + _CODEGEN_FLAGS + _SCHEDULING_FLAGS
 

xls/build_rules/xls_macros.bzl

@@ -567,6 +567,8 @@ Examples:
         "use_context_narrowing_analysis",
         "optimize_for_best_case_throughput",
         "enable_resource_sharing",
+        "force_resource_sharing",
+        "area_model",
     )
     opt_ir_args = {
         k: v

xls/dev_tools/benchmark_main.cc

@@ -129,6 +129,14 @@ ABSL_FLAG(
     "but at the cost of constraining the schedule and thus increasing area.");
 ABSL_FLAG(bool, enable_resource_sharing, false,
           "Enable the resource sharing optimization to save area.");
+ABSL_FLAG(
+    bool, force_resource_sharing, false,
+    "Force the resource sharing pass to apply the transformation where "
+    "it is legal to do so, overriding therefore the profitability "
+    "heuristic of such pass. This option is only used when the resource "
+    "sharing pass is enabled. This option should be used for testing only.");
+ABSL_FLAG(std::string, area_model, "asap7",
+          "Area model to use for optimizations.");
 ABSL_FLAG(bool, run_evaluators, true,
           "Whether to run the JIT and interpreter.");
 ABSL_FLAG(bool, compare_delay_to_synthesis, false,

xls/passes/BUILD

@@ -982,9 +982,13 @@ cc_library(
         ":pass_base",
         ":post_dominator_analysis",
         ":query_engine",
+        "//xls/common/status:ret_check",
         "//xls/common/status:status_macros",
+        "//xls/estimators/area_model:area_estimator",
+        "//xls/estimators/area_model:area_estimators",
         "//xls/ir",
         "//xls/ir:bits",
+        "//xls/ir:function_builder",
         "//xls/ir:op",
         "@com_google_absl//absl/algorithm:container",
         "@com_google_absl//absl/container:flat_hash_map",
@@ -3946,6 +3950,7 @@ cc_test(
         "@com_google_absl//absl/log:check",
         "@com_google_absl//absl/status:status_matchers",
         "@com_google_absl//absl/status:statusor",
+        "@com_google_absl//absl/types:span",
         "@cppitertools",
         "@googletest//:gtest",
     ],

xls/passes/optimization_pass.h

@@ -182,6 +182,12 @@ struct OptimizationPassOptions : public PassOptionsBase {
 
   // Enable resource sharing to reduce area
   bool enable_resource_sharing = false;
+
+  // Force resource sharing to apply the transformation when is legal
+  bool force_resource_sharing = false;
+
+  // Area model to use
+  std::string area_model = "asap7";
 };
 
 class OptimizationContext {