Fix an UBSan error (signed overflow) in saturating addition and subtraction

webrtc/common_audio/signal_processing/signal_processing_unittest.cc

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
+#include <algorithm>
+#include <sstream>
+
 #include "testing/gtest/include/gtest/gtest.h"
 #include "webrtc/common_audio/signal_processing/include/signal_processing_library.h"
 
 static const size_t kVector16Size = 9;
 static const int16_t vector16[kVector16Size] = {1, -15511, 4323, 1963,
   WEBRTC_SPL_WORD16_MAX, 0, WEBRTC_SPL_WORD16_MIN + 5, -3333, 345};
 
 class SplTest : public testing::Test {
  protected:
    SplTest() {
@@ skipping 90 matching lines @@
       EXPECT_EQ(14 - ii, WebRtcSpl_NormW16(value));
       EXPECT_EQ(15 - ii, WebRtcSpl_NormW16(-value));
     }
 
     EXPECT_EQ(0, WebRtcSpl_NormU32(0u));
     EXPECT_EQ(0, WebRtcSpl_NormU32(0xffffffff));
     EXPECT_EQ(15, WebRtcSpl_NormU32(static_cast<uint32_t>(a32)));
 
     EXPECT_EQ(104, WebRtcSpl_AddSatW16(a16, b16));
     EXPECT_EQ(138, WebRtcSpl_SubSatW16(a16, b16));
+}
 
-    EXPECT_EQ(109410, WebRtcSpl_AddSatW32(a32, b32));
-    EXPECT_EQ(112832, WebRtcSpl_SubSatW32(a32, b32));
-
-    a32 = 0x80000000;
-    b32 = 0x80000000;
-    // Cast to signed int to avoid compiler complaint on gtest.h.
-    EXPECT_EQ(static_cast<int>(0x80000000), WebRtcSpl_AddSatW32(a32, b32));
-    a32 = 0x7fffffff;
-    b32 = 0x7fffffff;
-    EXPECT_EQ(0x7fffffff, WebRtcSpl_AddSatW32(a32, b32));
-    a32 = 0;
-    b32 = 0x80000000;
-    EXPECT_EQ(0x7fffffff, WebRtcSpl_SubSatW32(a32, b32));
-    a32 = 0x7fffffff;
-    b32 = 0x80000000;
-    EXPECT_EQ(0x7fffffff, WebRtcSpl_SubSatW32(a32, b32));
-    a32 = 0x80000000;
-    b32 = 0x7fffffff;
-    EXPECT_EQ(static_cast<int>(0x80000000), WebRtcSpl_SubSatW32(a32, b32));
+TEST_F(SplTest, AddSubSatW32) {
+  static constexpr int32_t kAddSubArgs[] = {
+      INT32_MIN, INT32_MIN + 1, -3,       -2, -1, 0, 1, -1, 2,
+      3,         INT32_MAX - 1, INT32_MAX};
+  for (int32_t a : kAddSubArgs) {
+    for (int32_t b : kAddSubArgs) {
+      const int64_t sum = std::max<int64_t>(
+          INT32_MIN, std::min<int64_t>(INT32_MAX, static_cast<int64_t>(a) + b));
+      const int64_t diff = std::max<int64_t>(
+          INT32_MIN, std::min<int64_t>(INT32_MAX, static_cast<int64_t>(a) - b));
+      std::ostringstream ss;
+      ss << a << " +/- " << b << ": sum " << sum << ", diff " << diff;
+      SCOPED_TRACE(ss.str());
+      EXPECT_EQ(sum, WebRtcSpl_AddSatW32(a, b));
+      EXPECT_EQ(diff, WebRtcSpl_SubSatW32(a, b));
+    }
+  }
 }
 
 TEST_F(SplTest, MathOperationsTest) {
     int A = 1134567892;
     int32_t num = 117;
     int32_t den = -5;
     uint16_t denU = 5;
     EXPECT_EQ(33700, WebRtcSpl_Sqrt(A));
     EXPECT_EQ(33683, WebRtcSpl_SqrtFloor(A));
 
@@ skipping 419 matching lines @@
   // 12-15 are skipped to account for the filter lag.
   for (size_t i = 0; i < 12; ++i) {
     EXPECT_EQ(kRefValue32kHz1, out_vector[i]);
     EXPECT_EQ(kRefValue16kHz1, out_vector_w16[i]);
   }
   for (size_t i = 16; i < 2 * kBlockSize; ++i) {
     EXPECT_EQ(kRefValue32kHz2, out_vector[i]);
     EXPECT_EQ(kRefValue16kHz2, out_vector_w16[i]);
   }
 }