From b77fd01a8f4423d2ed0868fb53e5588fe6791cd4 Mon Sep 17 00:00:00 2001
From: Peter Klausler <pklausler@nvidia.com>
Date: Wed, 5 Jan 2022 11:42:18 -0800
Subject: [PATCH] [flang] Don't blank-fill remaining lines in internal output

Internal writes to character arrays should not blank-fill
records (elements) past the last one that was written to.

Differential Revision: https://reviews.llvm.org/D117342
---
 flang/runtime/internal-unit.cpp               | 28 +++++++++----------
 flang/runtime/internal-unit.h                 |  2 ++
 .../unittests/Runtime/NumericalFormatTest.cpp |  5 +++-
 3 files changed, 20 insertions(+), 15 deletions(-)

diff --git a/flang/runtime/internal-unit.cpp b/flang/runtime/internal-unit.cpp
index e63b2149793f1..7842cfb2e4494 100644
--- a/flang/runtime/internal-unit.cpp
+++ b/flang/runtime/internal-unit.cpp
@@ -38,15 +38,9 @@ InternalDescriptorUnit<DIR>::InternalDescriptorUnit(
 }
 
 template <Direction DIR> void InternalDescriptorUnit<DIR>::EndIoStatement() {
-  if constexpr (DIR == Direction::Output) { // blank fill
-    while (char *record{CurrentRecord()}) {
-      if (furthestPositionInRecord <
-          recordLength.value_or(furthestPositionInRecord)) {
-        std::fill_n(record + furthestPositionInRecord,
-            *recordLength - furthestPositionInRecord, ' ');
-      }
-      furthestPositionInRecord = 0;
-      ++currentRecordNumber;
+  if constexpr (DIR == Direction::Output) {
+    if (furthestPositionInRecord > 0) {
+      BlankFillOutputRecord();
     }
   }
 }
@@ -127,18 +121,24 @@ bool InternalDescriptorUnit<DIR>::AdvanceRecord(IoErrorHandler &handler) {
     handler.SignalEnd();
     return false;
   }
-  if constexpr (DIR == Direction::Output) { // blank fill
+  if constexpr (DIR == Direction::Output) {
+    BlankFillOutputRecord();
+  }
+  ++currentRecordNumber;
+  BeginRecord();
+  return true;
+}
+
+template <Direction DIR>
+void InternalDescriptorUnit<DIR>::BlankFillOutputRecord() {
+  if constexpr (DIR == Direction::Output) {
     if (furthestPositionInRecord <
         recordLength.value_or(furthestPositionInRecord)) {
       char *record{CurrentRecord()};
-      RUNTIME_CHECK(handler, record != nullptr);
       std::fill_n(record + furthestPositionInRecord,
           *recordLength - furthestPositionInRecord, ' ');
     }
   }
-  ++currentRecordNumber;
-  BeginRecord();
-  return true;
 }
 
 template <Direction DIR>
diff --git a/flang/runtime/internal-unit.h b/flang/runtime/internal-unit.h
index 9fc9c86bd2ccf..ad52cc761de53 100644
--- a/flang/runtime/internal-unit.h
+++ b/flang/runtime/internal-unit.h
@@ -45,6 +45,8 @@ template <Direction DIR> class InternalDescriptorUnit : public ConnectionState {
     return descriptor().template ZeroBasedIndexedElement<char>(
         currentRecordNumber - 1);
   }
+  void BlankFillOutputRecord();
+
   StaticDescriptor<maxRank, true /*addendum*/> staticDescriptor_;
 };
 
diff --git a/flang/unittests/Runtime/NumericalFormatTest.cpp b/flang/unittests/Runtime/NumericalFormatTest.cpp
index a2bd63524cb95..5a99625a1f382 100644
--- a/flang/unittests/Runtime/NumericalFormatTest.cpp
+++ b/flang/unittests/Runtime/NumericalFormatTest.cpp
@@ -118,6 +118,9 @@ TEST(IOApiTests, MultilineOutputTest) {
   auto cookie{IONAME(BeginInternalArrayFormattedOutput)(
       section, format, std::strlen(format))};
 
+  // Fill last line with periods
+  std::memset(buffer[numLines - 1], '.', lineLength);
+
   // Write data to buffer
   IONAME(OutputAscii)(cookie, "WORLD", 5);
   IONAME(OutputAscii)(cookie, "HELLO", 5);
@@ -135,7 +138,7 @@ TEST(IOApiTests, MultilineOutputTest) {
                                   "                                "
                                   "789                 abcd 666 777"
                                   " 888 999                        "
-                                  "                                "};
+                                  "................................"};
   // Ensure formatted string matches expected output
   EXPECT_TRUE(
       CompareFormattedStrings(expect, std::string{buffer[0], sizeof buffer}))