tree 53455e1113b8eb6badb628d1bf418cff1a06a72f
parent cb29f9cdbceace4e8ea3a9701e421acea3ff9c6d
author bmeurer <bmeurer@chromium.org> 1456484722 -0800
committer Commit bot <commit-bot@chromium.org> 1456484790 +0000

[turbofan] Bailout if LoadBuffer typing assumption doesn't hold.

The LoadBuffer operator that is used for asm.js heap access claims to
return only the appropriate typed array type, but out of bounds access
could make it return undefined. So far we tried to "repair" the graph
later if we see that our assumption was wrong, and for various reasons
that worked for some time. But now that wrong type information that is
propagated earlier is picked up appropriately and thus we generate wrong
code, i.e. we in the repro case we feed NaN into ChangeFloat64Uint32 and
thus get 2147483648 instead of 0 (with proper JS truncation).

This was always considered a temporary hack until we have a proper
asm.js pipeline, but since we still run asm.js through the generic
JavaScript pipeline, we have to address this now. Quickfix is to just
bailout from the pipeline when we see that the LoadBuffer type was
wrong, i.e. the result of LoadBuffer is not properly truncated and thus
undefined or NaN would be observable.

R=mstarzinger@chromium.org, jarin@chromium.org
BUG=chromium:589792
LOG=y

Review URL: https://codereview.chromium.org/1740123002

Cr-Commit-Position: refs/heads/master@{#34322}