Fix additional issues reported by UB sanitizers

Most of these involved overrunning the signed 32-bit JLONG type whenever
building libjpeg-turbo with a 32-bit compiler.  These issues are not
believed to represent actual security threats, but eliminating them
makes it easier to detect such threats should they arise in the future.

ChangeLog.txt

@@ -29,6 +29,12 @@ backward API or ABI incompatibilities with prior libjpeg-turbo releases.
 [6] The MIPS DSPr2 SIMD code can now be compiled to support either FR=0 or FR=1
 FPUs.
 
+[7] Fixed additional negative left shifts and other issues reported by the GCC
+and Clang undefined behavior sanitizers.  Most of these issues affected only
+32-bit code, and none of them was known to pose a security threat, but removing
+the warnings makes it easier to detect actual security issues, should they
+arise in the future.
+
 
 1.4.2
 =====

jcdctmgr.c

@@ -6,7 +6,7 @@
  * libjpeg-turbo Modifications:
  * Copyright (C) 1999-2006, MIYASAKA Masaru.
  * Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
- * Copyright (C) 2011, 2014-2015 D. R. Commander
+ * Copyright (C) 2011, 2014-2015, D. R. Commander.
  * For conditions of distribution and use, see the accompanying README.ijg
  * file.
  *
@@ -209,7 +209,11 @@ compute_reciprocal (UINT16 divisor, DCTELEM * dtbl)
 
   dtbl[DCTSIZE2 * 0] = (DCTELEM) fq;      /* reciprocal */
   dtbl[DCTSIZE2 * 1] = (DCTELEM) c;       /* correction + roundfactor */
+#ifdef WITH_SIMD
   dtbl[DCTSIZE2 * 2] = (DCTELEM) (1 << (sizeof(DCTELEM)*8*2 - r));  /* scale */
+#else
+  dtbl[DCTSIZE2 * 2] = 1;
+#endif
   dtbl[DCTSIZE2 * 3] = (DCTELEM) r - sizeof(DCTELEM)*8; /* shift */
 
   if(r <= 16) return 0;

jcphuff.c

@@ -231,7 +231,7 @@ emit_bits (phuff_entropy_ptr entropy, unsigned int code, int size)
 /* Emit some bits, unless we are in gather mode */
 {
   /* This routine is heavily used, so it's worth coding tightly. */
-  register JLONG put_buffer = (JLONG) code;
+  register size_t put_buffer = (size_t) code;
   register int put_bits = entropy->put_bits;
 
   /* if size is 0, caller used an invalid Huffman table entry */

jdcolor.c

@@ -604,7 +604,7 @@ ycck_cmyk_convert (j_decompress_ptr cinfo,
  */
 
 #define DITHER_MASK       0x3
-#define DITHER_ROTATE(x)  (((x) << 24) | (((x) >> 8) & 0x00FFFFFF))
+#define DITHER_ROTATE(x)  ((((x) & 0xFF) << 24) | (((x) >> 8) & 0x00FFFFFF))
 static const JLONG dither_matrix[4] = {
   0x0008020A,
   0x0C040E06,

jdhuff.h

@@ -74,12 +74,12 @@ EXTERN(void) jpeg_make_d_derived_tbl
 
 #if SIZEOF_SIZE_T==8 || defined(_WIN64)
 
-typedef size_t bit_buf_type;    /* type of bit-extraction buffer */
+typedef size_t bit_buf_type;            /* type of bit-extraction buffer */
 #define BIT_BUF_SIZE  64                /* size of buffer in bits */
 
 #else
 
-typedef JLONG bit_buf_type;     /* type of bit-extraction buffer */
+typedef unsigned long bit_buf_type;     /* type of bit-extraction buffer */
 #define BIT_BUF_SIZE  32                /* size of buffer in bits */
 
 #endif

jdmerge.c

@@ -456,7 +456,7 @@ h2v2_merged_upsample (j_decompress_ptr cinfo,
  */
 
 #define DITHER_MASK       0x3
-#define DITHER_ROTATE(x)  (((x) << 24) | (((x) >> 8) & 0x00FFFFFF))
+#define DITHER_ROTATE(x)  ((((x) & 0xFF) << 24) | (((x) >> 8) & 0x00FFFFFF))
 static const JLONG dither_matrix[4] = {
   0x0008020A,
   0x0C040E06,