[mlir] Set implicit operation loc to start of split. (#151499)

Author: jpienaar

mlir/lib/Parser/Parser.cpp

@@ -17,14 +17,32 @@
 
 using namespace mlir;
 
+static std::pair<int64_t, int64_t>
+getLineAndColStart(const llvm::SourceMgr &sourceMgr) {
+  unsigned lastFileID = sourceMgr.getNumBuffers();
+  if (lastFileID == 1)
+    return {0, 0};
+
+  auto bufferID = sourceMgr.getMainFileID();
+  const llvm::MemoryBuffer *main = sourceMgr.getMemoryBuffer(bufferID);
+  const llvm::MemoryBuffer *last = sourceMgr.getMemoryBuffer(lastFileID);
+  // Exclude same start.
+  if (main->getBufferStart() < last->getBufferStart() &&
+      main->getBufferEnd() >= last->getBufferEnd()) {
+    return sourceMgr.getLineAndColumn(
+        llvm::SMLoc::getFromPointer(last->getBufferStart()), bufferID);
+  }
+  return {0, 0};
+}
+
 LogicalResult mlir::parseSourceFile(const llvm::SourceMgr &sourceMgr,
                                     Block *block, const ParserConfig &config,
                                     LocationAttr *sourceFileLoc) {
   const auto *sourceBuf = sourceMgr.getMemoryBuffer(sourceMgr.getMainFileID());
   if (sourceFileLoc) {
-    *sourceFileLoc = FileLineColLoc::get(config.getContext(),
-                                         sourceBuf->getBufferIdentifier(),
-                                         /*line=*/0, /*column=*/0);
+    auto [line, column] = getLineAndColStart(sourceMgr);
+    *sourceFileLoc = FileLineColLoc::get(
+        config.getContext(), sourceBuf->getBufferIdentifier(), line, column);
   }
   if (isBytecode(*sourceBuf))
     return readBytecodeFile(*sourceBuf, block, config);
@@ -37,9 +55,9 @@ mlir::parseSourceFile(const std::shared_ptr<llvm::SourceMgr> &sourceMgr,
   const auto *sourceBuf =
       sourceMgr->getMemoryBuffer(sourceMgr->getMainFileID());
   if (sourceFileLoc) {
-    *sourceFileLoc = FileLineColLoc::get(config.getContext(),
-                                         sourceBuf->getBufferIdentifier(),
-                                         /*line=*/0, /*column=*/0);
+    auto [line, column] = getLineAndColStart(*sourceMgr);
+    *sourceFileLoc = FileLineColLoc::get(
+        config.getContext(), sourceBuf->getBufferIdentifier(), line, column);
   }
   if (isBytecode(*sourceBuf))
     return readBytecodeFile(sourceMgr, block, config);

mlir/test/IR/top-level.mlir

@@ -6,10 +6,10 @@ func.func private @foo()
 
 // -----
 
-// expected-error@-9 {{source must contain a single top-level operation, found: 2}}
+// expected-error@-2 {{source must contain a single top-level operation, found: 2}}
 func.func private @bar()
 func.func private @baz()
 
 // -----
 
-// expected-error@-15 {{source must contain a single top-level operation, found: 0}}
+// expected-error@-2 {{source must contain a single top-level operation, found: 0}}