From 12822ad0d01ff58b3ce9aa23ff73a106ee869c02 Mon Sep 17 00:00:00 2001
From: Hideto Ueno <uenoku.tokotoko@gmail.com>
Date: Thu, 8 Aug 2024 15:40:35 +0900
Subject: [PATCH] [SimToSV] Add include guards to DPI import (#7459)

This adds include guards `__CIRCT_DPI_IMPORT_*` to DPI import statements generated in SimToSV.

Fix https://github.com/llvm/circt/issues/7458.
---
 lib/Conversion/SimToSV/SimToSV.cpp | 11 ++++++++++-
 test/Conversion/SimToSV/dpi.mlir   |  7 ++++++-
 test/firtool/dpi.fir               | 16 +++++++++++++---
 3 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/lib/Conversion/SimToSV/SimToSV.cpp b/lib/Conversion/SimToSV/SimToSV.cpp
index a1d0af51ab42..bcdef4e024ec 100644
--- a/lib/Conversion/SimToSV/SimToSV.cpp
+++ b/lib/Conversion/SimToSV/SimToSV.cpp
@@ -268,8 +268,17 @@ void LowerDPIFunc::lower(sim::DPIFuncOp func) {
   auto name = builder.getStringAttr(nameSpace.newName(
       func.getSymNameAttr().getValue(), "dpi_import_fragument"));
 
+  // Add include guards to avoid duplicate declarations. See Issue 7458.
+  auto macroDecl = builder.create<sv::MacroDeclOp>(nameSpace.newName(
+      "__CIRCT_DPI_IMPORT", func.getSymNameAttr().getValue().upper()));
   builder.create<emit::FragmentOp>(name, [&]() {
-    builder.create<sv::FuncDPIImportOp>(func.getSymNameAttr(), StringAttr());
+    builder.create<sv::IfDefOp>(
+        macroDecl.getSymNameAttr(), []() {},
+        [&]() {
+          builder.create<sv::FuncDPIImportOp>(func.getSymNameAttr(),
+                                              StringAttr());
+          builder.create<sv::MacroDefOp>(macroDecl.getSymNameAttr(), "");
+        });
   });
 
   symbolToFragment.insert({func.getSymNameAttr(), name});
diff --git a/test/Conversion/SimToSV/dpi.mlir b/test/Conversion/SimToSV/dpi.mlir
index c352d5907ade..959e5152e2ef 100644
--- a/test/Conversion/SimToSV/dpi.mlir
+++ b/test/Conversion/SimToSV/dpi.mlir
@@ -3,8 +3,13 @@
 
 sim.func.dpi @dpi(out arg0: i1, in %arg1: i1, out arg2: i1)
 // CHECK:       sv.func private @dpi(out arg0 : i1, in %arg1 : i1, out arg2 : i1)
+// CHECK-NEXT:  sv.macro.decl @__CIRCT_DPI_IMPORT_DPI
 // CHECK-NEXT:  emit.fragment @dpi_dpi_import_fragument {
-// CHECK-NEXT:    sv.func.dpi.import @dpi
+// CHECK-NEXT:    sv.ifdef @__CIRCT_DPI_IMPORT_DPI {
+// CHECK-NEXT:    } else {
+// CHECK-NEXT:      sv.func.dpi.import @dpi
+// CHECK-NEXT:      sv.macro.def @__CIRCT_DPI_IMPORT_DPI ""
+// CHECK-NEXT:    }
 // CHECK-NEXT:  }
 
 // VERILOG:      import "DPI-C" context function void dpi(
diff --git a/test/firtool/dpi.fir b/test/firtool/dpi.fir
index b7a353b2c77c..ce47feb2529e 100644
--- a/test/firtool/dpi.fir
+++ b/test/firtool/dpi.fir
@@ -2,23 +2,33 @@
 
 FIRRTL version 4.0.0
 circuit DPI:
-; CHECK-LABEL: import "DPI-C" context function void clocked_result(
+; CHECK-LABEL: `ifndef __CIRCT_DPI_IMPORT_CLOCKED_RESULT
+; CHECK-NEXT: import "DPI-C" context function void clocked_result(
 ; CHECK-NEXT:   input  byte foo,
 ; CHECK-NEXT:               bar,
 ; CHECK-NEXT:   output byte baz
 ; CHECK-NEXT: );
+; CHECK:      `define __CIRCT_DPI_IMPORT_CLOCKED_RESULT
+; CHECK-NEXT: `endif
 
-; CHECK-LABEL: import "DPI-C" context function void clocked_void(
+; CHECK-LABEL: `ifndef __CIRCT_DPI_IMPORT_CLOCKED_VOID
+; CHECK-NEXT: import "DPI-C" context function void clocked_void(
 ; CHECK-NEXT:   input byte in_0,
 ; CHECK-NEXT:              in_1,
 ; CHECK-NEXT:              in_2[]
 ; CHECK-NEXT: );
+; CHECK:      `define __CIRCT_DPI_IMPORT_CLOCKED_VOID
+; CHECK-NEXT: `endif
 
-; CHECK-LABEL: import "DPI-C" context function void unclocked_result(
+
+; CHECK-LABEL: `ifndef __CIRCT_DPI_IMPORT_UNCLOCKED_RESULT
+; CHECK-NEXT: import "DPI-C" context function void unclocked_result(
 ; CHECK-NEXT:   input  byte in_0,
 ; CHECK-NEXT:                    in_1,
 ; CHECK-NEXT:   output byte out_0
 ; CHECK-NEXT: );
+; CHECK:      `define __CIRCT_DPI_IMPORT_UNCLOCKED_RESULT
+; CHECK-NEXT: `endif
 
 ; CHECK-LABEL: module DPI(
 ; CHECK:        logic [7:0] [[TMP:_.+]];