Fix various issues reported by the UB sanitizers

Most of these involved left shifting a negative number, which is
technically undefined (although every modern compiler I'm aware of
will implement this by treating the signed integer as a 2's complement
unsigned integer-- the LEFT_SHIFT() macro just makes this behavior
explicit in order to shut up ubsan.)  This also fixes a couple of
non-issues in the entropy codecs, whereby the sanitizer reported an
out-of-bounds index in the 4th argument of jpeg_make_d_derived_tbl().
In those cases, the index was actually out of bounds (caused by a
malformed JPEG image), but jpeg_make_d_derived_tbl() would have caught
the error and aborted prior to actually using the invalid address.  Here
again, the fix was to make our intentions explicit so as to shut up
ubsan.

9 files changed, 121 insertions, 90 deletions

diff --git a/ChangeLog.txt b/ChangeLog.txt
index fb996c18..3b6b8444 100644
--- a/ChangeLog.txt
+++ b/ChangeLog.txt
@@ -28,6 +28,11 @@ pixels.  The "plain" upsampling routines are normally only used when
 decompressing a non-YCbCr JPEG image, but they are also used when decompressing
 a JPEG image whose scaled output height is 1.
 
+[5] Fixed various negative left shifts and other issues reported by the GCC and
+Clang undefined behavior sanitizers.  None of these 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.
+
 
 1.4.1
 =====
diff --git a/jdarith.c b/jdarith.c
index c6a1a99a..885c8eb3 100644
--- a/jdarith.c
+++ b/jdarith.c
@@ -306,7 +306,7 @@ decode_mcu_DC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
     }
 
     /* Scale and output the DC coefficient (assumes jpeg_natural_order[0]=0) */
-    (*block)[0] = (JCOEF) (entropy->last_dc_val[ci] << cinfo->Al);
+    (*block)[0] = (JCOEF) LEFT_SHIFT(entropy->last_dc_val[ci], cinfo->Al);
   }
 
   return TRUE;
diff --git a/jdhuff.c b/jdhuff.c
index 5c2a9322..aacc0366 100644
--- a/jdhuff.c
+++ b/jdhuff.c
@@ -91,6 +91,7 @@ start_pass_huff_decoder (j_decompress_ptr cinfo)
 {
   huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
   int ci, blkn, dctbl, actbl;
+  d_derived_tbl **pdtbl;
   jpeg_component_info * compptr;
 
   /* Check that the scan parameters Ss, Se, Ah/Al are OK for sequential JPEG.
@@ -107,10 +108,10 @@ start_pass_huff_decoder (j_decompress_ptr cinfo)
     actbl = compptr->ac_tbl_no;
     /* Compute derived values for Huffman tables */
     /* We may do this more than once for a table, but it's not expensive */
-    jpeg_make_d_derived_tbl(cinfo, TRUE, dctbl,
-                            & entropy->dc_derived_tbls[dctbl]);
-    jpeg_make_d_derived_tbl(cinfo, FALSE, actbl,
-                            & entropy->ac_derived_tbls[actbl]);
+    pdtbl = entropy->dc_derived_tbls + dctbl;
+    jpeg_make_d_derived_tbl(cinfo, TRUE, dctbl, pdtbl);
+    pdtbl = entropy->ac_derived_tbls + actbl;
+    jpeg_make_d_derived_tbl(cinfo, FALSE, actbl, pdtbl);
     /* Initialize DC predictions to 0 */
     entropy->saved.last_dc_val[ci] = 0;
   }
@@ -490,7 +491,8 @@ jpeg_huff_decode (bitread_working_state * state,
 #define AVOID_TABLES
 #ifdef AVOID_TABLES
 
-#define HUFF_EXTEND(x,s)  ((x) + ((((x) - (1<<((s)-1))) >> 31) & (((-1)<<(s)) + 1)))
+#define NEG_1 ((unsigned int)-1)
+#define HUFF_EXTEND(x,s)  ((x) + ((((x) - (1<<((s)-1))) >> 31) & (((NEG_1)<<(s)) + 1)))
 
 #else
 
diff --git a/jdphuff.c b/jdphuff.c
index eae15383..7ef8e7b2 100644
--- a/jdphuff.c
+++ b/jdphuff.c
@@ -3,8 +3,8 @@
  *
  * This file was part of the Independent JPEG Group's software:
  * Copyright (C) 1995-1997, Thomas G. Lane.
- * It was modified by The libjpeg-turbo Project to include only code relevant
- * to libjpeg-turbo.
+ * libjpeg-turbo Modifications:
+ * Copyright (C) 2015, D. R. Commander.
  * For conditions of distribution and use, see the accompanying README file.
  *
  * This file contains Huffman entropy decoding routines for progressive JPEG.
@@ -96,6 +96,7 @@ start_pass_phuff_decoder (j_decompress_ptr cinfo)
   phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
   boolean is_DC_band, bad;
   int ci, coefi, tbl;
+  d_derived_tbl **pdtbl;
   int *coef_bit_ptr;
   jpeg_component_info * compptr;
 
@@ -168,13 +169,13 @@ start_pass_phuff_decoder (j_decompress_ptr cinfo)
     if (is_DC_band) {
       if (cinfo->Ah == 0) {     /* DC refinement needs no table */
         tbl = compptr->dc_tbl_no;
-        jpeg_make_d_derived_tbl(cinfo, TRUE, tbl,
-                                & entropy->derived_tbls[tbl]);
+        pdtbl = entropy->derived_tbls + tbl;
+        jpeg_make_d_derived_tbl(cinfo, TRUE, tbl, pdtbl);
       }
     } else {
       tbl = compptr->ac_tbl_no;
-      jpeg_make_d_derived_tbl(cinfo, FALSE, tbl,
-                              & entropy->derived_tbls[tbl]);
+      pdtbl = entropy->derived_tbls + tbl;
+      jpeg_make_d_derived_tbl(cinfo, FALSE, tbl, pdtbl);
       /* remember the single active table */
       entropy->ac_derived_tbl = entropy->derived_tbls[tbl];
     }
@@ -203,7 +204,8 @@ start_pass_phuff_decoder (j_decompress_ptr cinfo)
 #define AVOID_TABLES
 #ifdef AVOID_TABLES
 
-#define HUFF_EXTEND(x,s)  ((x) < (1<<((s)-1)) ? (x) + (((-1)<<(s)) + 1) : (x))
+#define NEG_1 ((unsigned)-1)
+#define HUFF_EXTEND(x,s)  ((x) < (1<<((s)-1)) ? (x) + (((NEG_1)<<(s)) + 1) : (x))
 
 #else
 
@@ -336,7 +338,7 @@ decode_mcu_DC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
       s += state.last_dc_val[ci];
       state.last_dc_val[ci] = s;
       /* Scale and output the coefficient (assumes jpeg_natural_order[0]=0) */
-      (*block)[0] = (JCOEF) (s << Al);
+      (*block)[0] = (JCOEF) LEFT_SHIFT(s, Al);
     }
 
     /* Completed MCU, so update state */
@@ -404,7 +406,7 @@ decode_mcu_AC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
           r = GET_BITS(s);
           s = HUFF_EXTEND(r, s);
           /* Scale and output coefficient in natural (dezigzagged) order */
-          (*block)[jpeg_natural_order[k]] = (JCOEF) (s << Al);
+          (*block)[jpeg_natural_order[k]] = (JCOEF) LEFT_SHIFT(s, Al);
         } else {
           if (r == 15) {        /* ZRL */
             k += 15;            /* skip 15 zeroes in band */
@@ -495,8 +497,8 @@ decode_mcu_AC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
 {
   phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
   int Se = cinfo->Se;
-  int p1 = 1 << cinfo->Al;      /* 1 in the bit position being coded */
-  int m1 = (-1) << cinfo->Al;   /* -1 in the bit position being coded */
+  int p1 = 1 << cinfo->Al;        /* 1 in the bit position being coded */
+  int m1 = (NEG_1) << cinfo->Al;  /* -1 in the bit position being coded */
   register int s, k, r;
   unsigned int EOBRUN;
   JBLOCKROW block;
diff --git a/jfdctint.c b/jfdctint.c
index 14f486cd..68b08350 100644
--- a/jfdctint.c
+++ b/jfdctint.c
@@ -1,8 +1,10 @@
 /*
  * jfdctint.c
  *
+ * This file was part of the Independent JPEG Group's software.
  * Copyright (C) 1991-1996, Thomas G. Lane.
- * This file is part of the Independent JPEG Group's software.
+ * libjpeg-turbo Modifications:
+ * Copyright (C) 2015, D. R. Commander
  * For conditions of distribution and use, see the accompanying README file.
  *
  * This file contains a slow-but-accurate integer implementation of the
@@ -170,8 +172,8 @@ jpeg_fdct_islow (DCTELEM * data)
     tmp11 = tmp1 + tmp2;
     tmp12 = tmp1 - tmp2;
 
-    dataptr[0] = (DCTELEM) ((tmp10 + tmp11) << PASS1_BITS);
-    dataptr[4] = (DCTELEM) ((tmp10 - tmp11) << PASS1_BITS);
+    dataptr[0] = (DCTELEM) LEFT_SHIFT(tmp10 + tmp11, PASS1_BITS);
+    dataptr[4] = (DCTELEM) LEFT_SHIFT(tmp10 - tmp11, PASS1_BITS);
 
     z1 = MULTIPLY(tmp12 + tmp13, FIX_0_541196100);
     dataptr[2] = (DCTELEM) DESCALE(z1 + MULTIPLY(tmp13, FIX_0_765366865),
diff --git a/jidctint.c b/jidctint.c
index 688fd224..3429795c 100644
--- a/jidctint.c
+++ b/jidctint.c
@@ -1,9 +1,11 @@
 /*
  * jidctint.c
  *
+ * This file was part of the Independent JPEG Group's software.
  * Copyright (C) 1991-1998, Thomas G. Lane.
  * Modification developed 2002-2009 by Guido Vollbeding.
- * This file is part of the Independent JPEG Group's software.
+ * libjpeg-turbo Modifications:
+ * Copyright (C) 2015, D. R. Commander
  * For conditions of distribution and use, see the accompanying README file.
  *
  * This file contains a slow-but-accurate integer implementation of the
@@ -205,7 +207,8 @@ jpeg_idct_islow (j_decompress_ptr cinfo, jpeg_component_info * compptr,
         inptr[DCTSIZE*5] == 0 && inptr[DCTSIZE*6] == 0 &&
         inptr[DCTSIZE*7] == 0) {
       /* AC terms all zero */
-      int dcval = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]) << PASS1_BITS;
+      int dcval = LEFT_SHIFT(DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]),
+                             PASS1_BITS);
 
       wsptr[DCTSIZE*0] = dcval;
       wsptr[DCTSIZE*1] = dcval;
@@ -235,8 +238,8 @@ jpeg_idct_islow (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     z2 = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]);
     z3 = DEQUANTIZE(inptr[DCTSIZE*4], quantptr[DCTSIZE*4]);
 
-    tmp0 = (z2 + z3) << CONST_BITS;
-    tmp1 = (z2 - z3) << CONST_BITS;
+    tmp0 = LEFT_SHIFT(z2 + z3, CONST_BITS);
+    tmp1 = LEFT_SHIFT(z2 - z3, CONST_BITS);
 
     tmp10 = tmp0 + tmp3;
     tmp13 = tmp0 - tmp3;
@@ -337,8 +340,8 @@ jpeg_idct_islow (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     tmp2 = z1 + MULTIPLY(z3, - FIX_1_847759065);
     tmp3 = z1 + MULTIPLY(z2, FIX_0_765366865);
 
-    tmp0 = ((INT32) wsptr[0] + (INT32) wsptr[4]) << CONST_BITS;
-    tmp1 = ((INT32) wsptr[0] - (INT32) wsptr[4]) << CONST_BITS;
+    tmp0 = LEFT_SHIFT((INT32) wsptr[0] + (INT32) wsptr[4], CONST_BITS);
+    tmp1 = LEFT_SHIFT((INT32) wsptr[0] - (INT32) wsptr[4], CONST_BITS);
 
     tmp10 = tmp0 + tmp3;
     tmp13 = tmp0 - tmp3;
@@ -444,7 +447,7 @@ jpeg_idct_7x7 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     /* Even part */
 
     tmp13 = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]);
-    tmp13 <<= CONST_BITS;
+    tmp13 = LEFT_SHIFT(tmp13, CONST_BITS);
     /* Add fudge factor here for final descale. */
     tmp13 += ONE << (CONST_BITS-PASS1_BITS-1);
 
@@ -499,7 +502,7 @@ jpeg_idct_7x7 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
 
     /* Add fudge factor here for final descale. */
     tmp13 = (INT32) wsptr[0] + (ONE << (PASS1_BITS+2));
-    tmp13 <<= CONST_BITS;
+    tmp13 = LEFT_SHIFT(tmp13, CONST_BITS);
 
     z1 = (INT32) wsptr[2];
     z2 = (INT32) wsptr[4];
@@ -593,7 +596,7 @@ jpeg_idct_6x6 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     /* Even part */
 
     tmp0 = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]);
-    tmp0 <<= CONST_BITS;
+    tmp0 = LEFT_SHIFT(tmp0, CONST_BITS);
     /* Add fudge factor here for final descale. */
     tmp0 += ONE << (CONST_BITS-PASS1_BITS-1);
     tmp2 = DEQUANTIZE(inptr[DCTSIZE*4], quantptr[DCTSIZE*4]);
@@ -611,9 +614,9 @@ jpeg_idct_6x6 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     z2 = DEQUANTIZE(inptr[DCTSIZE*3], quantptr[DCTSIZE*3]);
     z3 = DEQUANTIZE(inptr[DCTSIZE*5], quantptr[DCTSIZE*5]);
     tmp1 = MULTIPLY(z1 + z3, FIX(0.366025404)); /* c5 */
-    tmp0 = tmp1 + ((z1 + z2) << CONST_BITS);
-    tmp2 = tmp1 + ((z3 - z2) << CONST_BITS);
-    tmp1 = (z1 - z2 - z3) << PASS1_BITS;
+    tmp0 = tmp1 + LEFT_SHIFT(z1 + z2, CONST_BITS);
+    tmp2 = tmp1 + LEFT_SHIFT(z3 - z2, CONST_BITS);
+    tmp1 = LEFT_SHIFT(z1 - z2 - z3, PASS1_BITS);
 
     /* Final output stage */
 
@@ -635,7 +638,7 @@ jpeg_idct_6x6 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
 
     /* Add fudge factor here for final descale. */
     tmp0 = (INT32) wsptr[0] + (ONE << (PASS1_BITS+2));
-    tmp0 <<= CONST_BITS;
+    tmp0 = LEFT_SHIFT(tmp0, CONST_BITS);
     tmp2 = (INT32) wsptr[4];
     tmp10 = MULTIPLY(tmp2, FIX(0.707106781));   /* c4 */
     tmp1 = tmp0 + tmp10;
@@ -651,9 +654,9 @@ jpeg_idct_6x6 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     z2 = (INT32) wsptr[3];
     z3 = (INT32) wsptr[5];
     tmp1 = MULTIPLY(z1 + z3, FIX(0.366025404)); /* c5 */
-    tmp0 = tmp1 + ((z1 + z2) << CONST_BITS);
-    tmp2 = tmp1 + ((z3 - z2) << CONST_BITS);
-    tmp1 = (z1 - z2 - z3) << CONST_BITS;
+    tmp0 = tmp1 + LEFT_SHIFT(z1 + z2, CONST_BITS);
+    tmp2 = tmp1 + LEFT_SHIFT(z3 - z2, CONST_BITS);
+    tmp1 = LEFT_SHIFT(z1 - z2 - z3, CONST_BITS);
 
     /* Final output stage */
 
@@ -714,7 +717,7 @@ jpeg_idct_5x5 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     /* Even part */
 
     tmp12 = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]);
-    tmp12 <<= CONST_BITS;
+    tmp12 = LEFT_SHIFT(tmp12, CONST_BITS);
     /* Add fudge factor here for final descale. */
     tmp12 += ONE << (CONST_BITS-PASS1_BITS-1);
     tmp0 = DEQUANTIZE(inptr[DCTSIZE*2], quantptr[DCTSIZE*2]);
@@ -724,7 +727,7 @@ jpeg_idct_5x5 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     z3 = tmp12 + z2;
     tmp10 = z3 + z1;
     tmp11 = z3 - z1;
-    tmp12 -= z2 << 2;
+    tmp12 -= LEFT_SHIFT(z2, 2);
 
     /* Odd part */
 
@@ -754,7 +757,7 @@ jpeg_idct_5x5 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
 
     /* Add fudge factor here for final descale. */
     tmp12 = (INT32) wsptr[0] + (ONE << (PASS1_BITS+2));
-    tmp12 <<= CONST_BITS;
+    tmp12 = LEFT_SHIFT(tmp12, CONST_BITS);
     tmp0 = (INT32) wsptr[2];
     tmp1 = (INT32) wsptr[4];
     z1 = MULTIPLY(tmp0 + tmp1, FIX(0.790569415)); /* (c2+c4)/2 */
@@ -762,7 +765,7 @@ jpeg_idct_5x5 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     z3 = tmp12 + z2;
     tmp10 = z3 + z1;
     tmp11 = z3 - z1;
-    tmp12 -= z2 << 2;
+    tmp12 -= LEFT_SHIFT(z2, 2);
 
     /* Odd part */
 
@@ -828,7 +831,7 @@ jpeg_idct_3x3 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     /* Even part */
 
     tmp0 = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]);
-    tmp0 <<= CONST_BITS;
+    tmp0 = LEFT_SHIFT(tmp0, CONST_BITS);
     /* Add fudge factor here for final descale. */
     tmp0 += ONE << (CONST_BITS-PASS1_BITS-1);
     tmp2 = DEQUANTIZE(inptr[DCTSIZE*2], quantptr[DCTSIZE*2]);
@@ -858,7 +861,7 @@ jpeg_idct_3x3 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
 
     /* Add fudge factor here for final descale. */
     tmp0 = (INT32) wsptr[0] + (ONE << (PASS1_BITS+2));
-    tmp0 <<= CONST_BITS;
+    tmp0 = LEFT_SHIFT(tmp0, CONST_BITS);
     tmp2 = (INT32) wsptr[2];
     tmp12 = MULTIPLY(tmp2, FIX(0.707106781)); /* c2 */
     tmp10 = tmp0 + tmp12;
@@ -919,7 +922,7 @@ jpeg_idct_9x9 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     /* Even part */
 
     tmp0 = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]);
-    tmp0 <<= CONST_BITS;
+    tmp0 = LEFT_SHIFT(tmp0, CONST_BITS);
     /* Add fudge factor here for final descale. */
     tmp0 += ONE << (CONST_BITS-PASS1_BITS-1);
 
@@ -983,7 +986,7 @@ jpeg_idct_9x9 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
 
     /* Add fudge factor here for final descale. */
     tmp0 = (INT32) wsptr[0] + (ONE << (PASS1_BITS+2));
-    tmp0 <<= CONST_BITS;
+    tmp0 = LEFT_SHIFT(tmp0, CONST_BITS);
 
     z1 = (INT32) wsptr[2];
     z2 = (INT32) wsptr[4];
@@ -1091,7 +1094,7 @@ jpeg_idct_10x10 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     /* Even part */
 
     z3 = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]);
-    z3 <<= CONST_BITS;
+    z3 = LEFT_SHIFT(z3, CONST_BITS);
     /* Add fudge factor here for final descale. */
     z3 += ONE << (CONST_BITS-PASS1_BITS-1);
     z4 = DEQUANTIZE(inptr[DCTSIZE*4], quantptr[DCTSIZE*4]);
@@ -1100,8 +1103,8 @@ jpeg_idct_10x10 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     tmp10 = z3 + z1;
     tmp11 = z3 - z2;
 
-    tmp22 = RIGHT_SHIFT(z3 - ((z1 - z2) << 1),   /* c0 = (c4-c8)*2 */
-                        CONST_BITS-PASS1_BITS);
+    tmp22 = RIGHT_SHIFT(z3 - LEFT_SHIFT(z1 - z2, 1),
+                        CONST_BITS-PASS1_BITS);  /* c0 = (c4-c8)*2 */
 
     z2 = DEQUANTIZE(inptr[DCTSIZE*2], quantptr[DCTSIZE*2]);
     z3 = DEQUANTIZE(inptr[DCTSIZE*6], quantptr[DCTSIZE*6]);
@@ -1126,7 +1129,7 @@ jpeg_idct_10x10 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     tmp13 = z2 - z4;
 
     tmp12 = MULTIPLY(tmp13, FIX(0.309016994));        /* (c3-c7)/2 */
-    z5 = z3 << CONST_BITS;
+    z5 = LEFT_SHIFT(z3, CONST_BITS);
 
     z2 = MULTIPLY(tmp11, FIX(0.951056516));           /* (c3+c7)/2 */
     z4 = z5 + tmp12;
@@ -1135,9 +1138,9 @@ jpeg_idct_10x10 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     tmp14 = MULTIPLY(z1, FIX(0.221231742)) - z2 + z4; /* c9 */
 
     z2 = MULTIPLY(tmp11, FIX(0.587785252));           /* (c1-c9)/2 */
-    z4 = z5 - tmp12 - (tmp13 << (CONST_BITS - 1));
+    z4 = z5 - tmp12 - LEFT_SHIFT(tmp13, CONST_BITS - 1);
 
-    tmp12 = (z1 - tmp13 - z3) << PASS1_BITS;
+    tmp12 = LEFT_SHIFT(z1 - tmp13 - z3, PASS1_BITS);
 
     tmp11 = MULTIPLY(z1, FIX(1.260073511)) - z2 - z4; /* c3 */
     tmp13 = MULTIPLY(z1, FIX(0.642039522)) - z2 + z4; /* c7 */
@@ -1166,14 +1169,14 @@ jpeg_idct_10x10 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
 
     /* Add fudge factor here for final descale. */
     z3 = (INT32) wsptr[0] + (ONE << (PASS1_BITS+2));
-    z3 <<= CONST_BITS;
+    z3 = LEFT_SHIFT(z3, CONST_BITS);
     z4 = (INT32) wsptr[4];
     z1 = MULTIPLY(z4, FIX(1.144122806));         /* c4 */
     z2 = MULTIPLY(z4, FIX(0.437016024));         /* c8 */
     tmp10 = z3 + z1;
     tmp11 = z3 - z2;
 
-    tmp22 = z3 - ((z1 - z2) << 1);               /* c0 = (c4-c8)*2 */
+    tmp22 = z3 - LEFT_SHIFT(z1 - z2, 1);         /* c0 = (c4-c8)*2 */
 
     z2 = (INT32) wsptr[2];
     z3 = (INT32) wsptr[6];
@@ -1192,7 +1195,7 @@ jpeg_idct_10x10 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     z1 = (INT32) wsptr[1];
     z2 = (INT32) wsptr[3];
     z3 = (INT32) wsptr[5];
-    z3 <<= CONST_BITS;
+    z3 = LEFT_SHIFT(z3, CONST_BITS);
     z4 = (INT32) wsptr[7];
 
     tmp11 = z2 + z4;
@@ -1207,9 +1210,9 @@ jpeg_idct_10x10 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     tmp14 = MULTIPLY(z1, FIX(0.221231742)) - z2 + z4; /* c9 */
 
     z2 = MULTIPLY(tmp11, FIX(0.587785252));           /* (c1-c9)/2 */
-    z4 = z3 - tmp12 - (tmp13 << (CONST_BITS - 1));
+    z4 = z3 - tmp12 - LEFT_SHIFT(tmp13, CONST_BITS - 1);
 
-    tmp12 = ((z1 - tmp13) << CONST_BITS) - z3;
+    tmp12 = LEFT_SHIFT(z1 - tmp13, CONST_BITS) - z3;
 
     tmp11 = MULTIPLY(z1, FIX(1.260073511)) - z2 - z4; /* c3 */
     tmp13 = MULTIPLY(z1, FIX(0.642039522)) - z2 + z4; /* c7 */
@@ -1286,7 +1289,7 @@ jpeg_idct_11x11 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     /* Even part */
 
     tmp10 = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]);
-    tmp10 <<= CONST_BITS;
+    tmp10 = LEFT_SHIFT(tmp10, CONST_BITS);
     /* Add fudge factor here for final descale. */
     tmp10 += ONE << (CONST_BITS-PASS1_BITS-1);
 
@@ -1359,7 +1362,7 @@ jpeg_idct_11x11 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
 
     /* Add fudge factor here for final descale. */
     tmp10 = (INT32) wsptr[0] + (ONE << (PASS1_BITS+2));
-    tmp10 <<= CONST_BITS;
+    tmp10 = LEFT_SHIFT(tmp10, CONST_BITS);
 
     z1 = (INT32) wsptr[2];
     z2 = (INT32) wsptr[4];
@@ -1480,7 +1483,7 @@ jpeg_idct_12x12 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     /* Even part */
 
     z3 = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]);
-    z3 <<= CONST_BITS;
+    z3 = LEFT_SHIFT(z3, CONST_BITS);
     /* Add fudge factor here for final descale. */
     z3 += ONE << (CONST_BITS-PASS1_BITS-1);
 
@@ -1492,9 +1495,9 @@ jpeg_idct_12x12 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
 
     z1 = DEQUANTIZE(inptr[DCTSIZE*2], quantptr[DCTSIZE*2]);
     z4 = MULTIPLY(z1, FIX(1.366025404)); /* c2 */
-    z1 <<= CONST_BITS;
+    z1 = LEFT_SHIFT(z1, CONST_BITS);
     z2 = DEQUANTIZE(inptr[DCTSIZE*6], quantptr[DCTSIZE*6]);
-    z2 <<= CONST_BITS;
+    z2 = LEFT_SHIFT(z2, CONST_BITS);
 
     tmp12 = z1 - z2;
 
@@ -1563,7 +1566,7 @@ jpeg_idct_12x12 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
 
     /* Add fudge factor here for final descale. */
     z3 = (INT32) wsptr[0] + (ONE << (PASS1_BITS+2));
-    z3 <<= CONST_BITS;
+    z3 = LEFT_SHIFT(z3, CONST_BITS);
 
     z4 = (INT32) wsptr[4];
     z4 = MULTIPLY(z4, FIX(1.224744871)); /* c4 */
@@ -1573,9 +1576,9 @@ jpeg_idct_12x12 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
 
     z1 = (INT32) wsptr[2];
     z4 = MULTIPLY(z1, FIX(1.366025404)); /* c2 */
-    z1 <<= CONST_BITS;
+    z1 = LEFT_SHIFT(z1, CONST_BITS);
     z2 = (INT32) wsptr[6];
-    z2 <<= CONST_BITS;
+    z2 = LEFT_SHIFT(z2, CONST_BITS);
 
     tmp12 = z1 - z2;
 
@@ -1696,7 +1699,7 @@ jpeg_idct_13x13 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     /* Even part */
 
     z1 = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]);
-    z1 <<= CONST_BITS;
+    z1 = LEFT_SHIFT(z1, CONST_BITS);
     /* Add fudge factor here for final descale. */
     z1 += ONE << (CONST_BITS-PASS1_BITS-1);
 
@@ -1784,7 +1787,7 @@ jpeg_idct_13x13 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
 
     /* Add fudge factor here for final descale. */
     z1 = (INT32) wsptr[0] + (ONE << (PASS1_BITS+2));
-    z1 <<= CONST_BITS;
+    z1 = LEFT_SHIFT(z1, CONST_BITS);
 
     z2 = (INT32) wsptr[2];
     z3 = (INT32) wsptr[4];
@@ -1924,7 +1927,7 @@ jpeg_idct_14x14 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     /* Even part */
 
     z1 = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]);
-    z1 <<= CONST_BITS;
+    z1 = LEFT_SHIFT(z1, CONST_BITS);
     /* Add fudge factor here for final descale. */
     z1 += ONE << (CONST_BITS-PASS1_BITS-1);
     z4 = DEQUANTIZE(inptr[DCTSIZE*4], quantptr[DCTSIZE*4]);
@@ -1936,8 +1939,8 @@ jpeg_idct_14x14 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     tmp11 = z1 + z3;
     tmp12 = z1 - z4;
 
-    tmp23 = RIGHT_SHIFT(z1 - ((z2 + z3 - z4) << 1), /* c0 = (c4+c12-c8)*2 */
-                        CONST_BITS-PASS1_BITS);
+    tmp23 = RIGHT_SHIFT(z1 - LEFT_SHIFT(z2 + z3 - z4, 1),
+                        CONST_BITS-PASS1_BITS);  /* c0 = (c4+c12-c8)*2 */
 
     z1 = DEQUANTIZE(inptr[DCTSIZE*2], quantptr[DCTSIZE*2]);
     z2 = DEQUANTIZE(inptr[DCTSIZE*6], quantptr[DCTSIZE*6]);
@@ -1962,7 +1965,7 @@ jpeg_idct_14x14 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     z2 = DEQUANTIZE(inptr[DCTSIZE*3], quantptr[DCTSIZE*3]);
     z3 = DEQUANTIZE(inptr[DCTSIZE*5], quantptr[DCTSIZE*5]);
     z4 = DEQUANTIZE(inptr[DCTSIZE*7], quantptr[DCTSIZE*7]);
-    tmp13 = z4 << CONST_BITS;
+    tmp13 = LEFT_SHIFT(z4, CONST_BITS);
 
     tmp14 = z1 + z3;
     tmp11 = MULTIPLY(z1 + z2, FIX(1.334852607));           /* c3 */
@@ -1981,7 +1984,7 @@ jpeg_idct_14x14 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     tmp14 += z4 + tmp13 - MULTIPLY(z3, FIX(1.6906431334)); /* c1+c9-c11 */
     tmp15 += z4 + MULTIPLY(z2, FIX(0.674957567));          /* c1+c11-c5 */
 
-    tmp13 = (z1 - z3) << PASS1_BITS;
+    tmp13 = LEFT_SHIFT(z1 - z3, PASS1_BITS);
 
     /* Final output stage */
 
@@ -2011,7 +2014,7 @@ jpeg_idct_14x14 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
 
     /* Add fudge factor here for final descale. */
     z1 = (INT32) wsptr[0] + (ONE << (PASS1_BITS+2));
-    z1 <<= CONST_BITS;
+    z1 = LEFT_SHIFT(z1, CONST_BITS);
     z4 = (INT32) wsptr[4];
     z2 = MULTIPLY(z4, FIX(1.274162392));         /* c4 */
     z3 = MULTIPLY(z4, FIX(0.314692123));         /* c12 */
@@ -2021,7 +2024,7 @@ jpeg_idct_14x14 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     tmp11 = z1 + z3;
     tmp12 = z1 - z4;
 
-    tmp23 = z1 - ((z2 + z3 - z4) << 1);          /* c0 = (c4+c12-c8)*2 */
+    tmp23 = z1 - LEFT_SHIFT(z2 + z3 - z4, 1);    /* c0 = (c4+c12-c8)*2 */
 
     z1 = (INT32) wsptr[2];
     z2 = (INT32) wsptr[6];
@@ -2046,7 +2049,7 @@ jpeg_idct_14x14 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     z2 = (INT32) wsptr[3];
     z3 = (INT32) wsptr[5];
     z4 = (INT32) wsptr[7];
-    z4 <<= CONST_BITS;
+    z4 = LEFT_SHIFT(z4, CONST_BITS);
 
     tmp14 = z1 + z3;
     tmp11 = MULTIPLY(z1 + z2, FIX(1.334852607));           /* c3 */
@@ -2064,7 +2067,7 @@ jpeg_idct_14x14 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     tmp14 += tmp13 + z4 - MULTIPLY(z3, FIX(1.6906431334)); /* c1+c9-c11 */
     tmp15 += tmp13 + MULTIPLY(z2, FIX(0.674957567));       /* c1+c11-c5 */
 
-    tmp13 = ((z1 - z3) << CONST_BITS) + z4;
+    tmp13 = LEFT_SHIFT(z1 - z3, CONST_BITS) + z4;
 
     /* Final output stage */
 
@@ -2150,7 +2153,7 @@ jpeg_idct_15x15 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     /* Even part */
 
     z1 = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]);
-    z1 <<= CONST_BITS;
+    z1 = LEFT_SHIFT(z1, CONST_BITS);
     /* Add fudge factor here for final descale. */
     z1 += ONE << (CONST_BITS-PASS1_BITS-1);
 
@@ -2163,7 +2166,7 @@ jpeg_idct_15x15 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
 
     tmp12 = z1 - tmp10;
     tmp13 = z1 + tmp11;
-    z1 -= (tmp11 - tmp10) << 1;             /* c0 = (c6-c12)*2 */
+    z1 -= LEFT_SHIFT(tmp11 - tmp10, 1);     /* c0 = (c6-c12)*2 */
 
     z4 = z2 - z3;
     z3 += z2;
@@ -2243,7 +2246,7 @@ jpeg_idct_15x15 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
 
     /* Add fudge factor here for final descale. */
     z1 = (INT32) wsptr[0] + (ONE << (PASS1_BITS+2));
-    z1 <<= CONST_BITS;
+    z1 = LEFT_SHIFT(z1, CONST_BITS);
 
     z2 = (INT32) wsptr[2];
     z3 = (INT32) wsptr[4];
@@ -2254,7 +2257,7 @@ jpeg_idct_15x15 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
 
     tmp12 = z1 - tmp10;
     tmp13 = z1 + tmp11;
-    z1 -= (tmp11 - tmp10) << 1;             /* c0 = (c6-c12)*2 */
+    z1 -= LEFT_SHIFT(tmp11 - tmp10, 1);     /* c0 = (c6-c12)*2 */
 
     z4 = z2 - z3;
     z3 += z2;
@@ -2392,7 +2395,7 @@ jpeg_idct_16x16 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     /* Even part */
 
     tmp0 = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]);
-    tmp0 <<= CONST_BITS;
+    tmp0 = LEFT_SHIFT(tmp0, CONST_BITS);
     /* Add fudge factor here for final descale. */
     tmp0 += 1 << (CONST_BITS-PASS1_BITS-1);
 
@@ -2494,7 +2497,7 @@ jpeg_idct_16x16 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
 
     /* Add fudge factor here for final descale. */
     tmp0 = (INT32) wsptr[0] + (ONE << (PASS1_BITS+2));
-    tmp0 <<= CONST_BITS;
+    tmp0 = LEFT_SHIFT(tmp0, CONST_BITS);
 
     z1 = (INT32) wsptr[4];
     tmp1 = MULTIPLY(z1, FIX(1.306562965));      /* c4[16] = c2[8] */
diff --git a/jidctred.c b/jidctred.c
index 2b385f86..4598698f 100644
--- a/jidctred.c
+++ b/jidctred.c
@@ -1,8 +1,10 @@
 /*
  * jidctred.c
  *
+ * This file was part of the Independent JPEG Group's software.
  * Copyright (C) 1994-1998, Thomas G. Lane.
- * This file is part of the Independent JPEG Group's software.
+ * libjpeg-turbo Modifications:
+ * Copyright (C) 2015, D. R. Commander
  * For conditions of distribution and use, see the accompanying README file.
  *
  * This file contains inverse-DCT routines that produce reduced-size output:
@@ -143,7 +145,8 @@ jpeg_idct_4x4 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
         inptr[DCTSIZE*3] == 0 && inptr[DCTSIZE*5] == 0 &&
         inptr[DCTSIZE*6] == 0 && inptr[DCTSIZE*7] == 0) {
       /* AC terms all zero; we need not examine term 4 for 4x4 output */
-      int dcval = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]) << PASS1_BITS;
+      int dcval = LEFT_SHIFT(DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]),
+                             PASS1_BITS);
 
       wsptr[DCTSIZE*0] = dcval;
       wsptr[DCTSIZE*1] = dcval;
@@ -156,7 +159,7 @@ jpeg_idct_4x4 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     /* Even part */
 
     tmp0 = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]);
-    tmp0 <<= (CONST_BITS+1);
+    tmp0 = LEFT_SHIFT(tmp0, CONST_BITS+1);
 
     z2 = DEQUANTIZE(inptr[DCTSIZE*2], quantptr[DCTSIZE*2]);
     z3 = DEQUANTIZE(inptr[DCTSIZE*6], quantptr[DCTSIZE*6]);
@@ -217,7 +220,7 @@ jpeg_idct_4x4 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
 
     /* Even part */
 
-    tmp0 = ((INT32) wsptr[0]) << (CONST_BITS+1);
+    tmp0 = LEFT_SHIFT((INT32) wsptr[0], CONST_BITS+1);
 
     tmp2 = MULTIPLY((INT32) wsptr[2], FIX_1_847759065)
          + MULTIPLY((INT32) wsptr[6], - FIX_0_765366865);
@@ -294,7 +297,8 @@ jpeg_idct_2x2 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     if (inptr[DCTSIZE*1] == 0 && inptr[DCTSIZE*3] == 0 &&
         inptr[DCTSIZE*5] == 0 && inptr[DCTSIZE*7] == 0) {
       /* AC terms all zero; we need not examine terms 2,4,6 for 2x2 output */
-      int dcval = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]) << PASS1_BITS;
+      int dcval = LEFT_SHIFT(DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]),
+                             PASS1_BITS);
 
       wsptr[DCTSIZE*0] = dcval;
       wsptr[DCTSIZE*1] = dcval;
@@ -305,7 +309,7 @@ jpeg_idct_2x2 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
     /* Even part */
 
     z1 = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]);
-    tmp10 = z1 << (CONST_BITS+2);
+    tmp10 = LEFT_SHIFT(z1, CONST_BITS+2);
 
     /* Odd part */
 
@@ -347,7 +351,7 @@ jpeg_idct_2x2 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
 
     /* Even part */
 
-    tmp10 = ((INT32) wsptr[0]) << (CONST_BITS+2);
+    tmp10 = LEFT_SHIFT((INT32) wsptr[0], CONST_BITS+2);
 
     /* Odd part */
 
diff --git a/jmorecfg.h b/jmorecfg.h
index 8e3007c4..be891896 100644
--- a/jmorecfg.h
+++ b/jmorecfg.h
@@ -5,7 +5,7 @@
  * Copyright (C) 1991-1997, Thomas G. Lane.
  * Modified 1997-2009 by Guido Vollbeding.
  * libjpeg-turbo Modifications:
- * Copyright (C) 2009, 2011, 2014, D. R. Commander.
+ * Copyright (C) 2009, 2011, 2014-2015, D. R. Commander.
  * For conditions of distribution and use, see the accompanying README file.
  *
  * This file contains additional configuration options that customize the
@@ -152,6 +152,7 @@ typedef short INT16;
 #ifndef _BASETSD_H_		/* Microsoft defines it in basetsd.h */
 #ifndef _BASETSD_H		/* MinGW is slightly different */
 #ifndef QGLOBAL_H		/* Qt defines it in qglobal.h */
+#define __INT32_IS_ACTUALLY_LONG
 typedef long INT32;
 #endif
 #endif
diff --git a/jpegint.h b/jpegint.h
index 025accd9..5f56b110 100644
--- a/jpegint.h
+++ b/jpegint.h
@@ -4,8 +4,8 @@
  * This file was part of the Independent JPEG Group's software:
  * Copyright (C) 1991-1997, Thomas G. Lane.
  * Modified 1997-2009 by Guido Vollbeding.
- * It was modified by The libjpeg-turbo Project to include only code relevant
- * to libjpeg-turbo.
+ * libjpeg-turbo Modifications:
+ * Copyright (C) 2015, D. R. Commander
  * For conditions of distribution and use, see the accompanying README file.
  *
  * This file provides common declarations for the various JPEG modules.
@@ -42,6 +42,18 @@ typedef enum {            /* Operating modes for buffer controllers */
 #define DSTATE_STOPPING 210     /* looking for EOI in jpeg_finish_decompress */
 
 
+/*
+ * Left shift macro that handles a negative operand without causing any
+ * sanitizer warnings
+ */
+
+#ifdef __INT32_IS_ACTUALLY_LONG
+#define LEFT_SHIFT(a, b) ((INT32)((unsigned long)(a) << (b)))
+#else
+#define LEFT_SHIFT(a, b) ((INT32)((unsigned int)(a) << (b)))
+#endif
+
+
 /* Declarations for compression modules */
 
 /* Master control module */