Fix -Wshift-negative-value errors.

BUG=706832
TEST=Remove -Wno-shift-negative-values from Chrome OS build.
TEST=Build Chrome for Chrome OS, no warnings/errors.

Change-Id: Icb4f50452d87a8b2dc680752a2bb965f31c33639
Reviewed-on: https://chromium-review.googlesource.com/544198Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Jorge Lucangeli Obes <jorgelo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#481657}

third_party/libjpeg/README.chromium

@@ -8,7 +8,7 @@ License Android Compatible: yes
 Description:
 This contains a copy of libjpeg-6b.
 
-The project files does not incldue from the distribution:
+The project files does not include from the distribution:
   jidctred.c : downsampling
   jdtrans.c : decoder transcoder
 
@@ -23,3 +23,6 @@ avoid conflicts that arise when system libraries attempt to use our libjpeg.
 
 Also patch in google.jdmarker.patch to better handle multiple SOS CSi values and
 their ordering.
+
+Also patch in google.shift-negative-values.patch to fix -Wshift-negative-value
+errors.

third_party/libjpeg/google.shift-negative-values.patch

+diff --git a/third_party/libjpeg/jdphuff.c b/third_party/libjpeg/jdphuff.c
+index 22678099451a..32df3af76707 100644
+--- a/third_party/libjpeg/jdphuff.c
++++ b/third_party/libjpeg/jdphuff.c
+@@ -195,26 +195,22 @@ start_pass_phuff_decoder (j_decompress_ptr cinfo)
+ 
+ /*
+  * Figure F.12: extend sign bit.
+- * On some machines, a shift and add will be faster than a table lookup.
++ * On some machines, a shift and sub will be faster than a table lookup.
+  */
+ 
+ #ifdef AVOID_TABLES
+ 
+-#define HUFF_EXTEND(x,s)  ((x) < (1<<((s)-1)) ? (x) + (((-1)<<(s)) + 1) : (x))
++#define BIT_MASK(nbits)   ((1<<(nbits))-1)
++#define HUFF_EXTEND(x,s)  ((x) < (1<<((s)-1)) ? (x) - ((1<<(s))-1) : (x))
+ 
+ #else
+ 
+-#define HUFF_EXTEND(x,s)  ((x) < extend_test[s] ? (x) + extend_offset[s] : (x))
++#define BIT_MASK(nbits)   bmask[nbits]
++#define HUFF_EXTEND(x,s)  ((x) <= bmask[(s) - 1] ? (x) - bmask[s] : (x))
+ 
+-static const int extend_test[16] =   /* entry n is 2**(n-1) */
+-  { 0, 0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080,
+-    0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000 };
+-
+-static const int extend_offset[16] = /* entry n is (-1 << n) + 1 */
+-  { 0, ((-1)<<1) + 1, ((-1)<<2) + 1, ((-1)<<3) + 1, ((-1)<<4) + 1,
+-    ((-1)<<5) + 1, ((-1)<<6) + 1, ((-1)<<7) + 1, ((-1)<<8) + 1,
+-    ((-1)<<9) + 1, ((-1)<<10) + 1, ((-1)<<11) + 1, ((-1)<<12) + 1,
+-    ((-1)<<13) + 1, ((-1)<<14) + 1, ((-1)<<15) + 1 };
++static const int bmask[16] =  /* bmask[n] is mask for n rightmost bits */
++  { 0, 0x0001, 0x0003, 0x0007, 0x000F, 0x001F, 0x003F, 0x007F, 0x00FF,
++    0x01FF, 0x03FF, 0x07FF, 0x0FFF, 0x1FFF, 0x3FFF, 0x7FFF };
+ 
+ #endif /* AVOID_TABLES */
+ 

third_party/libjpeg/jdphuff.c

@@ -195,26 +195,22 @@ start_pass_phuff_decoder (j_decompress_ptr cinfo)
 
 /*
  * Figure F.12: extend sign bit.
- * On some machines, a shift and add will be faster than a table lookup.
+ * On some machines, a shift and sub will be faster than a table lookup.
  */
 
 #ifdef AVOID_TABLES
 
-#define HUFF_EXTEND(x,s)  ((x) < (1<<((s)-1)) ? (x) + (((-1)<<(s)) + 1) : (x))
+#define BIT_MASK(nbits)   ((1<<(nbits))-1)
+#define HUFF_EXTEND(x,s)  ((x) < (1<<((s)-1)) ? (x) - ((1<<(s))-1) : (x))
 
 #else
 
-#define HUFF_EXTEND(x,s)  ((x) < extend_test[s] ? (x) + extend_offset[s] : (x))
+#define BIT_MASK(nbits)   bmask[nbits]
+#define HUFF_EXTEND(x,s)  ((x) <= bmask[(s) - 1] ? (x) - bmask[s] : (x))
 
-static const int extend_test[16] =   /* entry n is 2**(n-1) */
-  { 0, 0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080,
-    0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000 };
-
-static const int extend_offset[16] = /* entry n is (-1 << n) + 1 */
-  { 0, ((-1)<<1) + 1, ((-1)<<2) + 1, ((-1)<<3) + 1, ((-1)<<4) + 1,
-    ((-1)<<5) + 1, ((-1)<<6) + 1, ((-1)<<7) + 1, ((-1)<<8) + 1,
-    ((-1)<<9) + 1, ((-1)<<10) + 1, ((-1)<<11) + 1, ((-1)<<12) + 1,
-    ((-1)<<13) + 1, ((-1)<<14) + 1, ((-1)<<15) + 1 };
+static const int bmask[16] =  /* bmask[n] is mask for n rightmost bits */
+  { 0, 0x0001, 0x0003, 0x0007, 0x000F, 0x001F, 0x003F, 0x007F, 0x00FF,
+    0x01FF, 0x03FF, 0x07FF, 0x0FFF, 0x1FFF, 0x3FFF, 0x7FFF };
 
 #endif /* AVOID_TABLES */