change VP8LPredictorFunc signature to avoid reading 'left'master

... when it's not available. Even if the value was discarded and
never used, some msan config were complaining about reading it
and passing it around.

Change-Id: Iab8d24676c5bb58e607a829121e36c2862da397c

8 files changed, 127 insertions, 80 deletions

diff --git a/src/dsp/lossless.c b/src/dsp/lossless.c
index d8bbb02b..84a54296 100644
--- a/src/dsp/lossless.c
+++ b/src/dsp/lossless.c
@@ -107,63 +107,77 @@ static WEBP_INLINE uint32_t Select(uint32_t a, uint32_t b, uint32_t c) {
 //------------------------------------------------------------------------------
 // Predictors
 
-uint32_t VP8LPredictor0_C(uint32_t left, const uint32_t* const top) {
+uint32_t VP8LPredictor0_C(const uint32_t* const left,
+                          const uint32_t* const top) {
   (void)top;
   (void)left;
   return ARGB_BLACK;
 }
-uint32_t VP8LPredictor1_C(uint32_t left, const uint32_t* const top) {
+uint32_t VP8LPredictor1_C(const uint32_t* const left,
+                          const uint32_t* const top) {
   (void)top;
-  return left;
+  return *left;
 }
-uint32_t VP8LPredictor2_C(uint32_t left, const uint32_t* const top) {
+uint32_t VP8LPredictor2_C(const uint32_t* const left,
+                          const uint32_t* const top) {
   (void)left;
   return top[0];
 }
-uint32_t VP8LPredictor3_C(uint32_t left, const uint32_t* const top) {
+uint32_t VP8LPredictor3_C(const uint32_t* const left,
+                          const uint32_t* const top) {
   (void)left;
   return top[1];
 }
-uint32_t VP8LPredictor4_C(uint32_t left, const uint32_t* const top) {
+uint32_t VP8LPredictor4_C(const uint32_t* const left,
+                          const uint32_t* const top) {
   (void)left;
   return top[-1];
 }
-uint32_t VP8LPredictor5_C(uint32_t left, const uint32_t* const top) {
-  const uint32_t pred = Average3(left, top[0], top[1]);
+uint32_t VP8LPredictor5_C(const uint32_t* const left,
+                          const uint32_t* const top) {
+  const uint32_t pred = Average3(*left, top[0], top[1]);
   return pred;
 }
-uint32_t VP8LPredictor6_C(uint32_t left, const uint32_t* const top) {
-  const uint32_t pred = Average2(left, top[-1]);
+uint32_t VP8LPredictor6_C(const uint32_t* const left,
+                          const uint32_t* const top) {
+  const uint32_t pred = Average2(*left, top[-1]);
   return pred;
 }
-uint32_t VP8LPredictor7_C(uint32_t left, const uint32_t* const top) {
-  const uint32_t pred = Average2(left, top[0]);
+uint32_t VP8LPredictor7_C(const uint32_t* const left,
+                          const uint32_t* const top) {
+  const uint32_t pred = Average2(*left, top[0]);
   return pred;
 }
-uint32_t VP8LPredictor8_C(uint32_t left, const uint32_t* const top) {
+uint32_t VP8LPredictor8_C(const uint32_t* const left,
+                          const uint32_t* const top) {
   const uint32_t pred = Average2(top[-1], top[0]);
   (void)left;
   return pred;
 }
-uint32_t VP8LPredictor9_C(uint32_t left, const uint32_t* const top) {
+uint32_t VP8LPredictor9_C(const uint32_t* const left,
+                          const uint32_t* const top) {
   const uint32_t pred = Average2(top[0], top[1]);
   (void)left;
   return pred;
 }
-uint32_t VP8LPredictor10_C(uint32_t left, const uint32_t* const top) {
-  const uint32_t pred = Average4(left, top[-1], top[0], top[1]);
+uint32_t VP8LPredictor10_C(const uint32_t* const left,
+                           const uint32_t* const top) {
+  const uint32_t pred = Average4(*left, top[-1], top[0], top[1]);
   return pred;
 }
-uint32_t VP8LPredictor11_C(uint32_t left, const uint32_t* const top) {
-  const uint32_t pred = Select(top[0], left, top[-1]);
+uint32_t VP8LPredictor11_C(const uint32_t* const left,
+                           const uint32_t* const top) {
+  const uint32_t pred = Select(top[0], *left, top[-1]);
   return pred;
 }
-uint32_t VP8LPredictor12_C(uint32_t left, const uint32_t* const top) {
-  const uint32_t pred = ClampedAddSubtractFull(left, top[0], top[-1]);
+uint32_t VP8LPredictor12_C(const uint32_t* const left,
+                           const uint32_t* const top) {
+  const uint32_t pred = ClampedAddSubtractFull(*left, top[0], top[-1]);
   return pred;
 }
-uint32_t VP8LPredictor13_C(uint32_t left, const uint32_t* const top) {
-  const uint32_t pred = ClampedAddSubtractHalf(left, top[0], top[-1]);
+uint32_t VP8LPredictor13_C(const uint32_t* const left,
+                           const uint32_t* const top) {
+  const uint32_t pred = ClampedAddSubtractHalf(*left, top[0], top[-1]);
   return pred;
 }
 
diff --git a/src/dsp/lossless.h b/src/dsp/lossless.h
index ebd316d1..c26c6bca 100644
--- a/src/dsp/lossless.h
+++ b/src/dsp/lossless.h
@@ -28,23 +28,38 @@ extern "C" {
 //------------------------------------------------------------------------------
 // Decoding
 
-typedef uint32_t (*VP8LPredictorFunc)(uint32_t left, const uint32_t* const top);
+typedef uint32_t (*VP8LPredictorFunc)(const uint32_t* const left,
+                                      const uint32_t* const top);
 extern VP8LPredictorFunc VP8LPredictors[16];
 
-uint32_t VP8LPredictor0_C(uint32_t left, const uint32_t* const top);
-uint32_t VP8LPredictor1_C(uint32_t left, const uint32_t* const top);
-uint32_t VP8LPredictor2_C(uint32_t left, const uint32_t* const top);
-uint32_t VP8LPredictor3_C(uint32_t left, const uint32_t* const top);
-uint32_t VP8LPredictor4_C(uint32_t left, const uint32_t* const top);
-uint32_t VP8LPredictor5_C(uint32_t left, const uint32_t* const top);
-uint32_t VP8LPredictor6_C(uint32_t left, const uint32_t* const top);
-uint32_t VP8LPredictor7_C(uint32_t left, const uint32_t* const top);
-uint32_t VP8LPredictor8_C(uint32_t left, const uint32_t* const top);
-uint32_t VP8LPredictor9_C(uint32_t left, const uint32_t* const top);
-uint32_t VP8LPredictor10_C(uint32_t left, const uint32_t* const top);
-uint32_t VP8LPredictor11_C(uint32_t left, const uint32_t* const top);
-uint32_t VP8LPredictor12_C(uint32_t left, const uint32_t* const top);
-uint32_t VP8LPredictor13_C(uint32_t left, const uint32_t* const top);
+uint32_t VP8LPredictor0_C(const uint32_t* const left,
+                          const uint32_t* const top);
+uint32_t VP8LPredictor1_C(const uint32_t* const left,
+                          const uint32_t* const top);
+uint32_t VP8LPredictor2_C(const uint32_t* const left,
+                          const uint32_t* const top);
+uint32_t VP8LPredictor3_C(const uint32_t* const left,
+                          const uint32_t* const top);
+uint32_t VP8LPredictor4_C(const uint32_t* const left,
+                          const uint32_t* const top);
+uint32_t VP8LPredictor5_C(const uint32_t* const left,
+                          const uint32_t* const top);
+uint32_t VP8LPredictor6_C(const uint32_t* const left,
+                          const uint32_t* const top);
+uint32_t VP8LPredictor7_C(const uint32_t* const left,
+                          const uint32_t* const top);
+uint32_t VP8LPredictor8_C(const uint32_t* const left,
+                          const uint32_t* const top);
+uint32_t VP8LPredictor9_C(const uint32_t* const left,
+                          const uint32_t* const top);
+uint32_t VP8LPredictor10_C(const uint32_t* const left,
+                           const uint32_t* const top);
+uint32_t VP8LPredictor11_C(const uint32_t* const left,
+                           const uint32_t* const top);
+uint32_t VP8LPredictor12_C(const uint32_t* const left,
+                           const uint32_t* const top);
+uint32_t VP8LPredictor13_C(const uint32_t* const left,
+                           const uint32_t* const top);
 
 // These Add/Sub function expects upper[-1] and out[-1] to be readable.
 typedef void (*VP8LPredictorAddSubFunc)(const uint32_t* in,
diff --git a/src/dsp/lossless_common.h b/src/dsp/lossless_common.h
index 96a106f9..6a2f736b 100644
--- a/src/dsp/lossless_common.h
+++ b/src/dsp/lossless_common.h
@@ -179,7 +179,7 @@ static void PREDICTOR_ADD(const uint32_t* in, const uint32_t* upper, \
   int x;                                                             \
   assert(upper != NULL);                                             \
   for (x = 0; x < num_pixels; ++x) {                                 \
-    const uint32_t pred = (PREDICTOR)(out[x - 1], upper + x);        \
+    const uint32_t pred = (PREDICTOR)(&out[x - 1], upper + x);       \
     out[x] = VP8LAddPixels(in[x], pred);                             \
   }                                                                  \
 }
diff --git a/src/dsp/lossless_enc.c b/src/dsp/lossless_enc.c
index c3e8537a..1580631e 100644
--- a/src/dsp/lossless_enc.c
+++ b/src/dsp/lossless_enc.c
@@ -745,7 +745,7 @@ static void PredictorSub##PREDICTOR_I##_C(const uint32_t* in,              \
   assert(upper != NULL);                                                   \
   for (x = 0; x < num_pixels; ++x) {                                       \
     const uint32_t pred =                                                  \
-        VP8LPredictor##PREDICTOR_I##_C(in[x - 1], upper + x);              \
+        VP8LPredictor##PREDICTOR_I##_C(&in[x - 1], upper + x);             \
     out[x] = VP8LSubPixels(in[x], pred);                                   \
   }                                                                        \
 }
diff --git a/src/dsp/lossless_mips_dsp_r2.c b/src/dsp/lossless_mips_dsp_r2.c
index 9888854d..bfe5ea6b 100644
--- a/src/dsp/lossless_mips_dsp_r2.c
+++ b/src/dsp/lossless_mips_dsp_r2.c
@@ -188,46 +188,51 @@ static WEBP_INLINE uint32_t Average4(uint32_t a0, uint32_t a1,
   return Average2(Average2(a0, a1), Average2(a2, a3));
 }
 
-static uint32_t Predictor5_MIPSdspR2(uint32_t left, const uint32_t* const top) {
-  return Average3(left, top[0], top[1]);
+static uint32_t Predictor5_MIPSdspR2(const uint32_t* const left,
+                                     const uint32_t* const top) {
+  return Average3(*left, top[0], top[1]);
 }
 
-static uint32_t Predictor6_MIPSdspR2(uint32_t left, const uint32_t* const top) {
-  return Average2(left, top[-1]);
+static uint32_t Predictor6_MIPSdspR2(const uint32_t* const left,
+                                     const uint32_t* const top) {
+  return Average2(*left, top[-1]);
 }
 
-static uint32_t Predictor7_MIPSdspR2(uint32_t left, const uint32_t* const top) {
-  return Average2(left, top[0]);
+static uint32_t Predictor7_MIPSdspR2(const uint32_t* const left,
+                                     const uint32_t* const top) {
+  return Average2(*left, top[0]);
 }
 
-static uint32_t Predictor8_MIPSdspR2(uint32_t left, const uint32_t* const top) {
+static uint32_t Predictor8_MIPSdspR2(const uint32_t* const left,
+                                     const uint32_t* const top) {
   (void)left;
   return Average2(top[-1], top[0]);
 }
 
-static uint32_t Predictor9_MIPSdspR2(uint32_t left, const uint32_t* const top) {
+static uint32_t Predictor9_MIPSdspR2(const uint32_t* const left,
+                                     const uint32_t* const top) {
   (void)left;
   return Average2(top[0], top[1]);
 }
 
-static uint32_t Predictor10_MIPSdspR2(uint32_t left,
+static uint32_t Predictor10_MIPSdspR2(const uint32_t* const left,
                                       const uint32_t* const top) {
-  return Average4(left, top[-1], top[0], top[1]);
+  return Average4(*left, top[-1], top[0], top[1]);
 }
 
-static uint32_t Predictor11_MIPSdspR2(uint32_t left,
+static uint32_t Predictor11_MIPSdspR2(const uint32_t* const left,
                                       const uint32_t* const top) {
-  return Select(top[0], left, top[-1]);
+  return Select(top[0], *left, top[-1]);
 }
 
-static uint32_t Predictor12_MIPSdspR2(uint32_t left,
+static uint32_t Predictor12_MIPSdspR2(const uint32_t* const left,
                                       const uint32_t* const top) {
-  return ClampedAddSubtractFull(left, top[0], top[-1]);
+  return ClampedAddSubtractFull(*left, top[0], top[-1]);
 }
 
-static uint32_t Predictor13_MIPSdspR2(uint32_t left,
+static uint32_t Predictor13_MIPSdspR2(const uint32_t* const left,
                                       const uint32_t* const top) {
-  return ClampedAddSubtractHalf(left, top[0], top[-1]);
+  return ClampedAddSubtractHalf(*left, top[0], top[-1]);
 }
 
 // Add green to blue and red channels (i.e. perform the inverse transform of
diff --git a/src/dsp/lossless_neon.c b/src/dsp/lossless_neon.c
index 76a1b6f8..89e3e013 100644
--- a/src/dsp/lossless_neon.c
+++ b/src/dsp/lossless_neon.c
@@ -188,17 +188,21 @@ static WEBP_INLINE uint32_t Average3_NEON(uint32_t a0, uint32_t a1,
   return avg;
 }
 
-static uint32_t Predictor5_NEON(uint32_t left, const uint32_t* const top) {
-  return Average3_NEON(left, top[0], top[1]);
+static uint32_t Predictor5_NEON(const uint32_t* const left,
+                                const uint32_t* const top) {
+  return Average3_NEON(*left, top[0], top[1]);
 }
-static uint32_t Predictor6_NEON(uint32_t left, const uint32_t* const top) {
-  return Average2_NEON(left, top[-1]);
+static uint32_t Predictor6_NEON(const uint32_t* const left,
+                                const uint32_t* const top) {
+  return Average2_NEON(*left, top[-1]);
 }
-static uint32_t Predictor7_NEON(uint32_t left, const uint32_t* const top) {
-  return Average2_NEON(left, top[0]);
+static uint32_t Predictor7_NEON(const uint32_t* const left,
+                                const uint32_t* const top) {
+  return Average2_NEON(*left, top[0]);
 }
-static uint32_t Predictor13_NEON(uint32_t left, const uint32_t* const top) {
-  return ClampedAddSubtractHalf_NEON(left, top[0], top[-1]);
+static uint32_t Predictor13_NEON(const uint32_t* const left,
+                                 const uint32_t* const top) {
+  return ClampedAddSubtractHalf_NEON(*left, top[0], top[-1]);
 }
 
 // Batch versions of those functions.
diff --git a/src/dsp/lossless_sse2.c b/src/dsp/lossless_sse2.c
index 3a0eb440..396cb0bd 100644
--- a/src/dsp/lossless_sse2.c
+++ b/src/dsp/lossless_sse2.c
@@ -138,42 +138,51 @@ static WEBP_INLINE uint32_t Average4_SSE2(uint32_t a0, uint32_t a1,
   return output;
 }
 
-static uint32_t Predictor5_SSE2(uint32_t left, const uint32_t* const top) {
-  const uint32_t pred = Average3_SSE2(left, top[0], top[1]);
+static uint32_t Predictor5_SSE2(const uint32_t* const left,
+                                const uint32_t* const top) {
+  const uint32_t pred = Average3_SSE2(*left, top[0], top[1]);
   return pred;
 }
-static uint32_t Predictor6_SSE2(uint32_t left, const uint32_t* const top) {
-  const uint32_t pred = Average2_SSE2(left, top[-1]);
+static uint32_t Predictor6_SSE2(const uint32_t* const left,
+                                const uint32_t* const top) {
+  const uint32_t pred = Average2_SSE2(*left, top[-1]);
   return pred;
 }
-static uint32_t Predictor7_SSE2(uint32_t left, const uint32_t* const top) {
-  const uint32_t pred = Average2_SSE2(left, top[0]);
+static uint32_t Predictor7_SSE2(const uint32_t* const left,
+                                const uint32_t* const top) {
+  const uint32_t pred = Average2_SSE2(*left, top[0]);
   return pred;
 }
-static uint32_t Predictor8_SSE2(uint32_t left, const uint32_t* const top) {
+static uint32_t Predictor8_SSE2(const uint32_t* const left,
+                                const uint32_t* const top) {
   const uint32_t pred = Average2_SSE2(top[-1], top[0]);
   (void)left;
   return pred;
 }
-static uint32_t Predictor9_SSE2(uint32_t left, const uint32_t* const top) {
+static uint32_t Predictor9_SSE2(const uint32_t* const left,
+                                const uint32_t* const top) {
   const uint32_t pred = Average2_SSE2(top[0], top[1]);
   (void)left;
   return pred;
 }
-static uint32_t Predictor10_SSE2(uint32_t left, const uint32_t* const top) {
-  const uint32_t pred = Average4_SSE2(left, top[-1], top[0], top[1]);
+static uint32_t Predictor10_SSE2(const uint32_t* const left,
+                                 const uint32_t* const top) {
+  const uint32_t pred = Average4_SSE2(*left, top[-1], top[0], top[1]);
   return pred;
 }
-static uint32_t Predictor11_SSE2(uint32_t left, const uint32_t* const top) {
-  const uint32_t pred = Select_SSE2(top[0], left, top[-1]);
+static uint32_t Predictor11_SSE2(const uint32_t* const left,
+                                 const uint32_t* const top) {
+  const uint32_t pred = Select_SSE2(top[0], *left, top[-1]);
   return pred;
 }
-static uint32_t Predictor12_SSE2(uint32_t left, const uint32_t* const top) {
-  const uint32_t pred = ClampedAddSubtractFull_SSE2(left, top[0], top[-1]);
+static uint32_t Predictor12_SSE2(const uint32_t* const left,
+                                 const uint32_t* const top) {
+  const uint32_t pred = ClampedAddSubtractFull_SSE2(*left, top[0], top[-1]);
   return pred;
 }
-static uint32_t Predictor13_SSE2(uint32_t left, const uint32_t* const top) {
-  const uint32_t pred = ClampedAddSubtractHalf_SSE2(left, top[0], top[-1]);
+static uint32_t Predictor13_SSE2(const uint32_t* const left,
+                                 const uint32_t* const top) {
+  const uint32_t pred = ClampedAddSubtractHalf_SSE2(*left, top[0], top[-1]);
   return pred;
 }
 
diff --git a/src/enc/predictor_enc.c b/src/enc/predictor_enc.c
index 2e6762ea..2b5c7672 100644
--- a/src/enc/predictor_enc.c
+++ b/src/enc/predictor_enc.c
@@ -249,7 +249,7 @@ static WEBP_INLINE void GetResidual(
       } else if (x == 0) {
         predict = upper_row[x];  // Top.
       } else {
-        predict = pred_func(current_row[x - 1], upper_row + x);
+        predict = pred_func(&current_row[x - 1], upper_row + x);
       }
 #if (WEBP_NEAR_LOSSLESS == 1)
       if (max_quantization == 1 || mode == 0 || y == 0 || y == height - 1 ||