[libc] add sprintf size comparison

To accurately measure the size of sprintf in a finished binary, the
easiest method is to simply build a binary with and without sprintf.
This patch adds an integration test that can be built with and without
sprintf, as well as targets to build it.

Reviewed By: sivachandra

Differential Revision: https://reviews.llvm.org/D131735

libc/cmake/modules/LLVMLibCTestRules.cmake

@@ -387,6 +387,7 @@ endfunction(add_libc_fuzzer)
 #     DEPENDS <list of entrypoint or other object targets>
 #     ARGS <list of command line arguments to be passed to the test>
 #     ENV <list of environment variables to set before running the test>
+#     COMPILE_OPTIONS <list of special compile options for this target>
 #   )
 #
 # The loader target should provide a property named LOADER_OBJECT which is
@@ -404,7 +405,7 @@ function(add_integration_test test_name)
     "INTEGRATION_TEST"
     "" # No optional arguments
     "SUITE;LOADER" # Single value arguments
-    "SRCS;HDRS;DEPENDS;ARGS;ENV" # Multi-value arguments
+    "SRCS;HDRS;DEPENDS;ARGS;ENV;COMPILE_OPTIONS" # Multi-value arguments
     ${ARGN}
   )
 
@@ -522,7 +523,7 @@ function(add_integration_test test_name)
       ${LIBC_BUILD_DIR}
       ${LIBC_BUILD_DIR}/include
   )
-  target_compile_options(${fq_target_name} PRIVATE -ffreestanding)
+  target_compile_options(${fq_target_name} PRIVATE -ffreestanding ${INTEGRATION_TEST_COMPILE_OPTIONS})
   # We set a number of link options to prevent picking up system libc binaries.
   # Also, we restrict the integration tests to fully static executables. The
   # rtlib is set to compiler-rt to make the compiler drivers pick up the compiler

libc/test/integration/src/CMakeLists.txt

@@ -1,4 +1,5 @@
 add_subdirectory(__support)
 add_subdirectory(pthread)
+add_subdirectory(stdio)
 add_subdirectory(stdlib)
 add_subdirectory(threads)

libc/test/integration/src/stdio/CMakeLists.txt

@@ -0,0 +1,39 @@
+add_custom_target(stdio-integration-tests)
+add_dependencies(libc-integration-tests stdio-integration-tests)
+
+# These tests are not for correctness testing, but are instead a convenient way
+# to generate hermetic binaries for comparitive binary size testing.
+add_integration_test(
+  sprintf_size_test
+  SUITE
+    stdio-integration-tests
+  SRCS
+    sprintf_size_test.cpp
+  LOADER
+    libc.loader.linux.crt1
+  DEPENDS
+    libc.src.stdio.sprintf
+  ARGS
+    "%s %c %d"
+    "First arg"
+    "a"
+    "0"
+)
+
+add_integration_test(
+  sprintf_size_test_no_sprintf
+  SUITE
+    stdio-integration-tests
+  SRCS
+    sprintf_size_test.cpp
+  LOADER
+    libc.loader.linux.crt1
+  ARGS
+    "%s %c %d"
+    "First arg"
+    "a"
+    "0"
+  COMPILE_OPTIONS
+    -DINTEGRATION_DISABLE_PRINTF
+)
+

libc/test/integration/src/stdio/sprintf_size_test.cpp

@@ -0,0 +1,60 @@
+//===-- Unittests for getenv ----------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <stddef.h>
+
+#ifndef INTEGRATION_DISABLE_PRINTF
+#include "src/stdio/sprintf.h"
+#endif
+
+#include "utils/IntegrationTest/test.h"
+
+static bool my_streq(const char *lhs, const char *rhs) {
+  if (lhs == rhs)
+    return true;
+  if (((lhs == static_cast<char *>(nullptr)) &&
+       (rhs != static_cast<char *>(nullptr))) ||
+      ((lhs != static_cast<char *>(nullptr)) &&
+       (rhs == static_cast<char *>(nullptr)))) {
+    return false;
+  }
+  const char *l, *r;
+  for (l = lhs, r = rhs; *l != '\0' && *r != '\0'; ++l, ++r)
+    if (*l != *r)
+      return false;
+
+  return *l == '\0' && *r == '\0';
+}
+
+static int my_strlen(const char *str) {
+  const char *other = str;
+  while (*other)
+    ++other;
+  return static_cast<int>(other - str);
+}
+
+TEST_MAIN(int argc, char **argv, char **envp) {
+  ASSERT_EQ(argc, 5);
+  ASSERT_TRUE(my_streq(argv[1], "%s %c %d"));
+  ASSERT_EQ(my_strlen(argv[1]), 8);
+  ASSERT_TRUE(my_streq(argv[2], "First arg"));
+  ASSERT_EQ(my_strlen(argv[2]), 9);
+  ASSERT_TRUE(my_streq(argv[3], "a"));
+  ASSERT_EQ(my_strlen(argv[3]), 1);
+  ASSERT_TRUE(my_streq(argv[4], "0"));
+  ASSERT_EQ(my_strlen(argv[4]), 1);
+
+#ifndef INTEGRATION_DISABLE_PRINTF
+  char buf[100];
+  ASSERT_EQ(__llvm_libc::sprintf(buf, argv[1], argv[2], argv[3][0], argv[4][0]),
+            14);
+  ASSERT_TRUE(my_streq(buf, "First arg a 48"));
+#endif
+
+  return 0;
+}