1410622 - TiledRegion.cpp : ccomparison 'uint64_t' (aka 'unsigned long') > 18446744073709551615 is always false [-Werror,-Wtautological-constant-compare]

Status: RESOLVED FIXED

(Core :: Graphics, defect, P3)

Description

[Sylvestre Ledru [:Sylvestre]]

/data/jenkins/workspace/firefox-clang-last/gfx/src/TiledRegion.cpp:143:29: error: comparison 'uint64_t' (aka 'unsigned long') > 18446744073709551615 is always false [-Werror,-Wtautological-constant-compare]
     return ((uint64_t)total > (uint64_t)SIZE_MAX) ? SIZE_MAX : (size_t)total;
             ~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~~~~~

Comment 1

[Andi [:andi]]

Attachment: Bug 1410622 - Prevent warning on 64bit systems when comparing uint64_t with size_t max value.

Review commit: https://reviewboard.mozilla.org/r/191986/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/191986/

Comment 2

[Kartikaya Gupta (email:[e-mail])]

Comment on attachment 8921026 [details]
Bug 1410622 - Prevent warning on 64bit systems when comparing uint64_t with size_t max value.

https://reviewboard.mozilla.org/r/191986/#review197238

::: gfx/src/TiledRegion.cpp:142
(Diff revision 1)
>      int64_t tilesInLastRow = ((int64_t)mEnd.x - (int64_t)mTileBounds.x1) / kTileSize;
>      int64_t tilesInFullRow = ((int64_t)mTileBounds.x2 - (int64_t)mTileBounds.x1) / kTileSize;
>      int64_t total = tilesInFirstRow + (tilesInFullRow * numberOfFullRows) + tilesInLastRow;
>      MOZ_ASSERT(total > 0);
> -    // The total may be larger than what fits in a size_t, so clamp it to
> -    // SIZE_MAX in that case.
> +    // On 32bit systems the total may be larger than what fits in a size_t (4 bytes),
> +    // so clamp it to SIZE_MAX in that case.

Update this comment so it says "size_t's max value" instead of SIZE_MAX since the code is no longer using SIZE_MAX.

Comment 3

[Andi [:andi]]

Comment on attachment 8921026 [details]
Bug 1410622 - Prevent warning on 64bit systems when comparing uint64_t with size_t max value.

Review request updated; see interdiff: https://reviewboard.mozilla.org/r/191986/diff/1-2/

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/7aa291217448
Prevent warning on 64bit systems when comparing uint64_t with size_t max value. r=kats

Comment 5

[Sebastian Hengst [:aryx] (needinfo me if it's about an intermittent or backout)]

https://hg.mozilla.org/mozilla-central/rev/7aa291217448