# HG changeset patch
# Parent 5a1a0398f8503451582602525c3e7b35def5d0b9
# User Timothy B. Terriberry <tterribe@vt.edu>
Fix variance overflow

Upstream Change-Id: I1bad27ea0720067def6d71a6da5f789508cec265

diff --git a/media/libvpx/vp8/encoder/arm/armv6/vp8_variance16x16_armv6.asm b/media/libvpx/vp8/encoder/arm/armv6/vp8_variance16x16_armv6.asm
--- a/media/libvpx/vp8/encoder/arm/armv6/vp8_variance16x16_armv6.asm
+++ b/media/libvpx/vp8/encoder/arm/armv6/vp8_variance16x16_armv6.asm
@@ -139,16 +139,16 @@ loop
     subs    r12, r12, #1
 
     bne     loop
 
     ; return stuff
     ldr     r6, [sp, #40]       ; get address of sse
     mul     r0, r8, r8          ; sum * sum
     str     r11, [r6]           ; store sse
-    sub     r0, r11, r0, asr #8 ; return (sse - ((sum * sum) >> 8))
+    sub     r0, r11, r0, lsr #8 ; return (sse - ((sum * sum) >> 8))
 
     ldmfd   sp!, {r4-r12, pc}
 
     ENDP
 
     END
 
diff --git a/media/libvpx/vp8/encoder/arm/armv6/vp8_variance_halfpixvar16x16_h_armv6.asm b/media/libvpx/vp8/encoder/arm/armv6/vp8_variance_halfpixvar16x16_h_armv6.asm
--- a/media/libvpx/vp8/encoder/arm/armv6/vp8_variance_halfpixvar16x16_h_armv6.asm
+++ b/media/libvpx/vp8/encoder/arm/armv6/vp8_variance_halfpixvar16x16_h_armv6.asm
@@ -164,17 +164,17 @@ loop
     subs    r12, r12, #1
 
     bne     loop
 
     ; return stuff
     ldr     r6, [sp, #40]       ; get address of sse
     mul     r0, r8, r8          ; sum * sum
     str     r11, [r6]           ; store sse
-    sub     r0, r11, r0, asr #8 ; return (sse - ((sum * sum) >> 8))
+    sub     r0, r11, r0, lsr #8 ; return (sse - ((sum * sum) >> 8))
 
     ldmfd   sp!, {r4-r12, pc}
 
     ENDP
 
 c80808080
     DCD     0x80808080
 
diff --git a/media/libvpx/vp8/encoder/arm/armv6/vp8_variance_halfpixvar16x16_hv_armv6.asm b/media/libvpx/vp8/encoder/arm/armv6/vp8_variance_halfpixvar16x16_hv_armv6.asm
--- a/media/libvpx/vp8/encoder/arm/armv6/vp8_variance_halfpixvar16x16_hv_armv6.asm
+++ b/media/libvpx/vp8/encoder/arm/armv6/vp8_variance_halfpixvar16x16_hv_armv6.asm
@@ -205,17 +205,17 @@ loop
     smlad   r11, r7, r7, r11    ; dual signed multiply, add and accumulate (2)
 
     bne     loop
 
     ; return stuff
     ldr     r6, [sp, #40]       ; get address of sse
     mul     r0, r8, r8          ; sum * sum
     str     r11, [r6]           ; store sse
-    sub     r0, r11, r0, asr #8 ; return (sse - ((sum * sum) >> 8))
+    sub     r0, r11, r0, lsr #8 ; return (sse - ((sum * sum) >> 8))
 
     ldmfd   sp!, {r4-r12, pc}
 
     ENDP
 
 c80808080
     DCD     0x80808080
 
diff --git a/media/libvpx/vp8/encoder/arm/armv6/vp8_variance_halfpixvar16x16_v_armv6.asm b/media/libvpx/vp8/encoder/arm/armv6/vp8_variance_halfpixvar16x16_v_armv6.asm
--- a/media/libvpx/vp8/encoder/arm/armv6/vp8_variance_halfpixvar16x16_v_armv6.asm
+++ b/media/libvpx/vp8/encoder/arm/armv6/vp8_variance_halfpixvar16x16_v_armv6.asm
@@ -166,17 +166,17 @@ loop
     subs    r12, r12, #1
 
     bne     loop
 
     ; return stuff
     ldr     r6, [sp, #40]       ; get address of sse
     mul     r0, r8, r8          ; sum * sum
     str     r11, [r6]           ; store sse
-    sub     r0, r11, r0, asr #8 ; return (sse - ((sum * sum) >> 8))
+    sub     r0, r11, r0, lsr #8 ; return (sse - ((sum * sum) >> 8))
 
     ldmfd   sp!, {r4-r12, pc}
 
     ENDP
 
 c80808080
     DCD     0x80808080
 
diff --git a/media/libvpx/vp8/encoder/arm/neon/variance_neon.asm b/media/libvpx/vp8/encoder/arm/neon/variance_neon.asm
--- a/media/libvpx/vp8/encoder/arm/neon/variance_neon.asm
+++ b/media/libvpx/vp8/encoder/arm/neon/variance_neon.asm
@@ -72,24 +72,24 @@ variance16x16_neon_loop
     vpaddl.u32      q1, q10
     vadd.s64        d0, d0, d1
     vadd.u64        d1, d2, d3
 
     ;vmov.32        r0, d0[0]                   ;this instruction costs a lot
     ;vmov.32        r1, d1[0]
     ;mul            r0, r0, r0
     ;str            r1, [r12]
-    ;sub            r0, r1, r0, asr #8
+    ;sub            r0, r1, r0, lsr #8
 
-    ;sum is in [-255x256, 255x256]. sumxsum is 32-bit. Shift to right should
-    ;have sign-bit exension, which is vshr.s. Have to use s32 to make it right.
+    ; while sum is signed, sum * sum is always positive and must be treated as
+    ; unsigned to avoid propagating the sign bit.
     vmull.s32       q5, d0, d0
     vst1.32         {d1[0]}, [r12]              ;store sse
-    vshr.s32        d10, d10, #8
-    vsub.s32        d0, d1, d10
+    vshr.u32        d10, d10, #8
+    vsub.u32        d0, d1, d10
 
     vmov.32         r0, d0[0]                   ;return
     bx              lr
 
     ENDP
 
 ;================================
 ;unsigned int vp8_variance16x8_c(
@@ -140,18 +140,18 @@ variance16x8_neon_loop
     ldr             r12, [sp]                   ;load *sse from stack
 
     vpaddl.u32      q1, q10
     vadd.s64        d0, d0, d1
     vadd.u64        d1, d2, d3
 
     vmull.s32       q5, d0, d0
     vst1.32         {d1[0]}, [r12]              ;store sse
-    vshr.s32        d10, d10, #7
-    vsub.s32        d0, d1, d10
+    vshr.u32        d10, d10, #7
+    vsub.u32        d0, d1, d10
 
     vmov.32         r0, d0[0]                   ;return
     bx              lr
 
     ENDP
 
 ;=================================
 ;unsigned int vp8_variance8x16_c(
@@ -195,18 +195,18 @@ variance8x16_neon_loop
     ldr             r12, [sp]                   ;load *sse from stack
 
     vpaddl.u32      q1, q10
     vadd.s64        d0, d0, d1
     vadd.u64        d1, d2, d3
 
     vmull.s32       q5, d0, d0
     vst1.32         {d1[0]}, [r12]              ;store sse
-    vshr.s32        d10, d10, #7
-    vsub.s32        d0, d1, d10
+    vshr.u32        d10, d10, #7
+    vsub.u32        d0, d1, d10
 
     vmov.32         r0, d0[0]                   ;return
     bx              lr
 
     ENDP
 
 ;==================================
 ; r0    unsigned char *src_ptr
@@ -260,17 +260,17 @@ variance8x8_neon_loop
     ldr             r12, [sp]                   ;load *sse from stack
 
     vpaddl.u32      q1, q10
     vadd.s64        d0, d0, d1
     vadd.u64        d1, d2, d3
 
     vmull.s32       q5, d0, d0
     vst1.32         {d1[0]}, [r12]              ;store sse
-    vshr.s32        d10, d10, #6
-    vsub.s32        d0, d1, d10
+    vshr.u32        d10, d10, #6
+    vsub.u32        d0, d1, d10
 
     vmov.32         r0, d0[0]                   ;return
     bx              lr
 
     ENDP
 
     END
diff --git a/media/libvpx/vp8/encoder/arm/neon/vp8_subpixelvariance16x16_neon.asm b/media/libvpx/vp8/encoder/arm/neon/vp8_subpixelvariance16x16_neon.asm
--- a/media/libvpx/vp8/encoder/arm/neon/vp8_subpixelvariance16x16_neon.asm
+++ b/media/libvpx/vp8/encoder/arm/neon/vp8_subpixelvariance16x16_neon.asm
@@ -400,18 +400,18 @@ sub_pixel_variance16x16_neon_loop
     vpaddl.s32      q0, q8                      ;accumulate sum
 
     vpaddl.u32      q1, q10
     vadd.s64        d0, d0, d1
     vadd.u64        d1, d2, d3
 
     vmull.s32       q5, d0, d0
     vst1.32         {d1[0]}, [r6]               ;store sse
-    vshr.s32        d10, d10, #8
-    vsub.s32        d0, d1, d10
+    vshr.u32        d10, d10, #8
+    vsub.u32        d0, d1, d10
 
     add             sp, sp, #528
     vmov.32         r0, d0[0]                   ;return
 
     pop             {r4-r6,pc}
 
     ENDP
 
diff --git a/media/libvpx/vp8/encoder/arm/neon/vp8_subpixelvariance16x16s_neon.asm b/media/libvpx/vp8/encoder/arm/neon/vp8_subpixelvariance16x16s_neon.asm
--- a/media/libvpx/vp8/encoder/arm/neon/vp8_subpixelvariance16x16s_neon.asm
+++ b/media/libvpx/vp8/encoder/arm/neon/vp8_subpixelvariance16x16s_neon.asm
@@ -107,18 +107,18 @@ vp8_filt_fpo16x16s_4_0_loop_neon
     vpaddl.s32      q0, q8                      ;accumulate sum
 
     vpaddl.u32      q1, q10
     vadd.s64        d0, d0, d1
     vadd.u64        d1, d2, d3
 
     vmull.s32       q5, d0, d0
     vst1.32         {d1[0]}, [lr]               ;store sse
-    vshr.s32        d10, d10, #8
-    vsub.s32        d0, d1, d10
+    vshr.u32        d10, d10, #8
+    vsub.u32        d0, d1, d10
 
     vmov.32         r0, d0[0]                   ;return
     pop             {pc}
     ENDP
 
 ;================================================
 ;unsigned int vp8_variance_halfpixvar16x16_v_neon
 ;(
@@ -203,18 +203,18 @@ vp8_filt_spo16x16s_0_4_loop_neon
     vpaddl.s32      q0, q8                      ;accumulate sum
 
     vpaddl.u32      q1, q10
     vadd.s64        d0, d0, d1
     vadd.u64        d1, d2, d3
 
     vmull.s32       q5, d0, d0
     vst1.32         {d1[0]}, [lr]               ;store sse
-    vshr.s32        d10, d10, #8
-    vsub.s32        d0, d1, d10
+    vshr.u32        d10, d10, #8
+    vsub.u32        d0, d1, d10
 
     vmov.32         r0, d0[0]                   ;return
     pop             {pc}
     ENDP
 
 ;================================================
 ;unsigned int vp8_variance_halfpixvar16x16_hv_neon
 ;(
@@ -322,18 +322,18 @@ vp8_filt16x16s_4_4_loop_neon
     vpaddl.s32      q0, q13                      ;accumulate sum
 
     vpaddl.u32      q1, q15
     vadd.s64        d0, d0, d1
     vadd.u64        d1, d2, d3
 
     vmull.s32       q5, d0, d0
     vst1.32         {d1[0]}, [lr]               ;store sse
-    vshr.s32        d10, d10, #8
-    vsub.s32        d0, d1, d10
+    vshr.u32        d10, d10, #8
+    vsub.u32        d0, d1, d10
 
     vmov.32         r0, d0[0]                   ;return
     pop             {pc}
     ENDP
 
 ;==============================
 ; r0    unsigned char  *src_ptr,
 ; r1    int  src_pixels_per_line,
@@ -555,18 +555,18 @@ sub_pixel_variance16x16s_neon_loop
     vpaddl.s32      q0, q8                      ;accumulate sum
 
     vpaddl.u32      q1, q10
     vadd.s64        d0, d0, d1
     vadd.u64        d1, d2, d3
 
     vmull.s32       q5, d0, d0
     vst1.32         {d1[0]}, [lr]               ;store sse
-    vshr.s32        d10, d10, #8
-    vsub.s32        d0, d1, d10
+    vshr.u32        d10, d10, #8
+    vsub.u32        d0, d1, d10
 
     add             sp, sp, #256
     vmov.32         r0, d0[0]                   ;return
 
     pop             {r4, pc}
     ENDP
 
     END
diff --git a/media/libvpx/vp8/encoder/arm/neon/vp8_subpixelvariance8x8_neon.asm b/media/libvpx/vp8/encoder/arm/neon/vp8_subpixelvariance8x8_neon.asm
--- a/media/libvpx/vp8/encoder/arm/neon/vp8_subpixelvariance8x8_neon.asm
+++ b/media/libvpx/vp8/encoder/arm/neon/vp8_subpixelvariance8x8_neon.asm
@@ -201,18 +201,18 @@ sub_pixel_variance8x8_neon_loop
     vpaddl.s32      q0, q8                      ;accumulate sum
 
     vpaddl.u32      q1, q10
     vadd.s64        d0, d0, d1
     vadd.u64        d1, d2, d3
 
     vmull.s32       q5, d0, d0
     vst1.32         {d1[0]}, [lr]               ;store sse
-    vshr.s32        d10, d10, #6
-    vsub.s32        d0, d1, d10
+    vshr.u32        d10, d10, #6
+    vsub.u32        d0, d1, d10
 
     vmov.32         r0, d0[0]                   ;return
     pop             {r4-r5, pc}
 
     ENDP
 
 ;-----------------
 
diff --git a/media/libvpx/vp8/encoder/variance_c.c b/media/libvpx/vp8/encoder/variance_c.c
--- a/media/libvpx/vp8/encoder/variance_c.c
+++ b/media/libvpx/vp8/encoder/variance_c.c
@@ -70,82 +70,82 @@ unsigned int vp8_variance16x16_c(
     unsigned int *sse)
 {
     unsigned int var;
     int avg;
 
 
     variance(src_ptr, source_stride, ref_ptr, recon_stride, 16, 16, &var, &avg);
     *sse = var;
-    return (var - ((avg * avg) >> 8));
+    return (var - ((unsigned int)(avg * avg) >> 8));
 }
 
 unsigned int vp8_variance8x16_c(
     const unsigned char *src_ptr,
     int  source_stride,
     const unsigned char *ref_ptr,
     int  recon_stride,
     unsigned int *sse)
 {
     unsigned int var;
     int avg;
 
 
     variance(src_ptr, source_stride, ref_ptr, recon_stride, 8, 16, &var, &avg);
     *sse = var;
-    return (var - ((avg * avg) >> 7));
+    return (var - ((unsigned int)(avg * avg) >> 7));
 }
 
 unsigned int vp8_variance16x8_c(
     const unsigned char *src_ptr,
     int  source_stride,
     const unsigned char *ref_ptr,
     int  recon_stride,
     unsigned int *sse)
 {
     unsigned int var;
     int avg;
 
 
     variance(src_ptr, source_stride, ref_ptr, recon_stride, 16, 8, &var, &avg);
     *sse = var;
-    return (var - ((avg * avg) >> 7));
+    return (var - ((unsigned int)(avg * avg) >> 7));
 }
 
 
 unsigned int vp8_variance8x8_c(
     const unsigned char *src_ptr,
     int  source_stride,
     const unsigned char *ref_ptr,
     int  recon_stride,
     unsigned int *sse)
 {
     unsigned int var;
     int avg;
 
 
     variance(src_ptr, source_stride, ref_ptr, recon_stride, 8, 8, &var, &avg);
     *sse = var;
-    return (var - ((avg * avg) >> 6));
+    return (var - ((unsigned int)(avg * avg) >> 6));
 }
 
 unsigned int vp8_variance4x4_c(
     const unsigned char *src_ptr,
     int  source_stride,
     const unsigned char *ref_ptr,
     int  recon_stride,
     unsigned int *sse)
 {
     unsigned int var;
     int avg;
 
 
     variance(src_ptr, source_stride, ref_ptr, recon_stride, 4, 4, &var, &avg);
     *sse = var;
-    return (var - ((avg * avg) >> 4));
+    return (var - ((unsigned int)(avg * avg) >> 4));
 }
 
 
 unsigned int vp8_mse16x16_c(
     const unsigned char *src_ptr,
     int  source_stride,
     const unsigned char *ref_ptr,
     int  recon_stride,
diff --git a/media/libvpx/vp8/encoder/x86/variance_mmx.c b/media/libvpx/vp8/encoder/x86/variance_mmx.c
--- a/media/libvpx/vp8/encoder/x86/variance_mmx.c
+++ b/media/libvpx/vp8/encoder/x86/variance_mmx.c
@@ -86,34 +86,34 @@ unsigned int vp8_variance4x4_mmx(
     int  recon_stride,
     unsigned int *sse)
 {
     unsigned int var;
     int avg;
 
     vp8_get4x4var_mmx(src_ptr, source_stride, ref_ptr, recon_stride, &var, &avg) ;
     *sse = var;
-    return (var - ((avg * avg) >> 4));
+    return (var - ((unsigned int)(avg * avg) >> 4));
 
 }
 
 unsigned int vp8_variance8x8_mmx(
     const unsigned char *src_ptr,
     int  source_stride,
     const unsigned char *ref_ptr,
     int  recon_stride,
     unsigned int *sse)
 {
     unsigned int var;
     int avg;
 
     vp8_get8x8var_mmx(src_ptr, source_stride, ref_ptr, recon_stride, &var, &avg) ;
     *sse = var;
 
-    return (var - ((avg * avg) >> 6));
+    return (var - ((unsigned int)(avg * avg) >> 6));
 
 }
 
 unsigned int vp8_mse16x16_mmx(
     const unsigned char *src_ptr,
     int  source_stride,
     const unsigned char *ref_ptr,
     int  recon_stride,
@@ -148,17 +148,17 @@ unsigned int vp8_variance16x16_mmx(
     vp8_get8x8var_mmx(src_ptr, source_stride, ref_ptr, recon_stride, &sse0, &sum0) ;
     vp8_get8x8var_mmx(src_ptr + 8, source_stride, ref_ptr + 8, recon_stride, &sse1, &sum1);
     vp8_get8x8var_mmx(src_ptr + 8 * source_stride, source_stride, ref_ptr + 8 * recon_stride, recon_stride, &sse2, &sum2) ;
     vp8_get8x8var_mmx(src_ptr + 8 * source_stride + 8, source_stride, ref_ptr + 8 * recon_stride + 8, recon_stride, &sse3, &sum3);
 
     var = sse0 + sse1 + sse2 + sse3;
     avg = sum0 + sum1 + sum2 + sum3;
     *sse = var;
-    return (var - ((avg * avg) >> 8));
+    return (var - ((unsigned int)(avg * avg) >> 8));
 }
 
 unsigned int vp8_variance16x8_mmx(
     const unsigned char *src_ptr,
     int  source_stride,
     const unsigned char *ref_ptr,
     int  recon_stride,
     unsigned int *sse)
@@ -167,17 +167,17 @@ unsigned int vp8_variance16x8_mmx(
     int sum0, sum1, avg;
 
     vp8_get8x8var_mmx(src_ptr, source_stride, ref_ptr, recon_stride, &sse0, &sum0) ;
     vp8_get8x8var_mmx(src_ptr + 8, source_stride, ref_ptr + 8, recon_stride, &sse1, &sum1);
 
     var = sse0 + sse1;
     avg = sum0 + sum1;
     *sse = var;
-    return (var - ((avg * avg) >> 7));
+    return (var - ((unsigned int)(avg * avg) >> 7));
 
 }
 
 
 unsigned int vp8_variance8x16_mmx(
     const unsigned char *src_ptr,
     int  source_stride,
     const unsigned char *ref_ptr,
@@ -189,17 +189,17 @@ unsigned int vp8_variance8x16_mmx(
 
     vp8_get8x8var_mmx(src_ptr, source_stride, ref_ptr, recon_stride, &sse0, &sum0) ;
     vp8_get8x8var_mmx(src_ptr + 8 * source_stride, source_stride, ref_ptr + 8 * recon_stride, recon_stride, &sse1, &sum1) ;
 
     var = sse0 + sse1;
     avg = sum0 + sum1;
     *sse = var;
 
-    return (var - ((avg * avg) >> 7));
+    return (var - ((unsigned int)(avg * avg) >> 7));
 
 }
 
 
 unsigned int vp8_sub_pixel_variance4x4_mmx
 (
     const unsigned char  *src_ptr,
     int  src_pixels_per_line,
diff --git a/media/libvpx/vp8/encoder/x86/variance_sse2.c b/media/libvpx/vp8/encoder/x86/variance_sse2.c
--- a/media/libvpx/vp8/encoder/x86/variance_sse2.c
+++ b/media/libvpx/vp8/encoder/x86/variance_sse2.c
@@ -143,34 +143,34 @@ unsigned int vp8_variance4x4_wmt(
     int  recon_stride,
     unsigned int *sse)
 {
     unsigned int var;
     int avg;
 
     vp8_get4x4var_mmx(src_ptr, source_stride, ref_ptr, recon_stride, &var, &avg) ;
     *sse = var;
-    return (var - ((avg * avg) >> 4));
+    return (var - ((unsigned int)(avg * avg) >> 4));
 
 }
 
 unsigned int vp8_variance8x8_wmt
 (
     const unsigned char *src_ptr,
     int  source_stride,
     const unsigned char *ref_ptr,
     int  recon_stride,
     unsigned int *sse)
 {
     unsigned int var;
     int avg;
 
     vp8_get8x8var_sse2(src_ptr, source_stride, ref_ptr, recon_stride, &var, &avg) ;
     *sse = var;
-    return (var - ((avg * avg) >> 6));
+    return (var - ((unsigned int)(avg * avg) >> 6));
 
 }
 
 
 unsigned int vp8_variance16x16_wmt
 (
     const unsigned char *src_ptr,
     int  source_stride,
@@ -215,17 +215,17 @@ unsigned int vp8_variance16x8_wmt
     int sum0, sum1, avg;
 
     vp8_get8x8var_sse2(src_ptr, source_stride, ref_ptr, recon_stride, &sse0, &sum0) ;
     vp8_get8x8var_sse2(src_ptr + 8, source_stride, ref_ptr + 8, recon_stride, &sse1, &sum1);
 
     var = sse0 + sse1;
     avg = sum0 + sum1;
     *sse = var;
-    return (var - ((avg * avg) >> 7));
+    return (var - ((unsigned int)(avg * avg) >> 7));
 
 }
 
 unsigned int vp8_variance8x16_wmt
 (
     const unsigned char *src_ptr,
     int  source_stride,
     const unsigned char *ref_ptr,
@@ -236,17 +236,17 @@ unsigned int vp8_variance8x16_wmt
     int sum0, sum1, avg;
 
     vp8_get8x8var_sse2(src_ptr, source_stride, ref_ptr, recon_stride, &sse0, &sum0) ;
     vp8_get8x8var_sse2(src_ptr + 8 * source_stride, source_stride, ref_ptr + 8 * recon_stride, recon_stride, &sse1, &sum1) ;
 
     var = sse0 + sse1;
     avg = sum0 + sum1;
     *sse = var;
-    return (var - ((avg * avg) >> 7));
+    return (var - ((unsigned int)(avg * avg) >> 7));
 
 }
 
 unsigned int vp8_sub_pixel_variance4x4_wmt
 (
     const unsigned char  *src_ptr,
     int  src_pixels_per_line,
     int  xoffset,
diff --git a/media/libvpx/vp8/encoder/x86/variance_ssse3.c b/media/libvpx/vp8/encoder/x86/variance_ssse3.c
--- a/media/libvpx/vp8/encoder/x86/variance_ssse3.c
+++ b/media/libvpx/vp8/encoder/x86/variance_ssse3.c
@@ -107,17 +107,17 @@ unsigned int vp8_sub_pixel_variance16x16
         vp8_filter_block2d_bil_var_ssse3(
             src_ptr, src_pixels_per_line,
             dst_ptr, dst_pixels_per_line, 16,
             xoffset, yoffset,
             &xsum0, &xxsum0);
     }
 
     *sse = xxsum0;
-    return (xxsum0 - ((xsum0 * xsum0) >> 8));
+    return (xxsum0 - ((unsigned int)(xsum0 * xsum0) >> 8));
 }
 
 unsigned int vp8_sub_pixel_variance16x8_ssse3
 (
     const unsigned char  *src_ptr,
     int  src_pixels_per_line,
     int  xoffset,
     int  yoffset,
@@ -156,10 +156,10 @@ unsigned int vp8_sub_pixel_variance16x8_
         vp8_filter_block2d_bil_var_ssse3(
             src_ptr, src_pixels_per_line,
             dst_ptr, dst_pixels_per_line, 8,
             xoffset, yoffset,
             &xsum0, &xxsum0);
     }
 
     *sse = xxsum0;
-    return (xxsum0 - ((xsum0 * xsum0) >> 7));
+    return (xxsum0 - ((unsigned int)(xsum0 * xsum0) >> 7));
 }