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Fix a Wxor-used-as-pow false positive

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Since people seem to write "2 ^ X" hoping that it means "1 << X", clang
recently added a warning for this pattern.

It incorrectly fires on this file. To suppress it, restructure the code
to be less clever. (Alternatively we could use "xor" instead of "^" or
write "0x2" instead of "2" but both seem worse.)

No intended behavior change.

Bug: chromium:995200
Change-Id: I64744345be5f5a8cd1f4aaeaf0982da239b378a7
This commit is contained in:
Nico Weber 2019-09-04 10:42:47 -04:00 committed by James Zern
parent 601ef17cf6
commit af650c0bd2
1 changed files with 10 additions and 6 deletions
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16
src/enc/picture_csp_enc.c
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@ -29,11 +29,15 @@
#define USE_INVERSE_ALPHA_TABLE
#ifdef WORDS_BIGENDIAN
#define ALPHA_OFFSET 0 // uint32_t 0xff000000 is 0xff,00,00,00 in memory
// uint32_t 0xff000000 is 0xff,00,00,00 in memory
#define CHANNEL_OFFSET(i) (i)
#else
#define ALPHA_OFFSET 3 // uint32_t 0xff000000 is 0x00,00,00,ff in memory
// uint32_t 0xff000000 is 0x00,00,00,ff in memory
#define CHANNEL_OFFSET(i) (3-(i))
#endif
#define ALPHA_OFFSET CHANNEL_OFFSET(0)
//------------------------------------------------------------------------------
// Detection of non-trivial transparency
@ -997,10 +1001,10 @@ static int PictureARGBToYUVA(WebPPicture* picture, WebPEncCSP colorspace,
return WebPEncodingSetError(picture, VP8_ENC_ERROR_INVALID_CONFIGURATION);
} else {
const uint8_t* const argb = (const uint8_t*)picture->argb;
const uint8_t* const a = argb + (0 ^ ALPHA_OFFSET);
const uint8_t* const r = argb + (1 ^ ALPHA_OFFSET);
const uint8_t* const g = argb + (2 ^ ALPHA_OFFSET);
const uint8_t* const b = argb + (3 ^ ALPHA_OFFSET);
const uint8_t* const a = argb + CHANNEL_OFFSET(0);
const uint8_t* const r = argb + CHANNEL_OFFSET(1);
const uint8_t* const g = argb + CHANNEL_OFFSET(2);
const uint8_t* const b = argb + CHANNEL_OFFSET(3);
picture->colorspace = WEBP_YUV420;
return ImportYUVAFromRGBA(r, g, b, a, 4, 4 * picture->argb_stride,