937058 - Paper over debug-mode checks of stack depth for unreachable bytecode

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Andy Wingo [:wingo]]

In a number of cases, Ion somehow computes a stack depth for unreachable bytecode.  This is bug 937046.  It then does a sanity check to see that the stack depth is the same as the depth that the decompiler computes, which fails as the decompiler's parser doesn't visit unreachable code, and anyway the stack depth at  unreachable code is meaningless.

This fix will paper over the Ion problems by only asserting that stack depths match for reachable bytecode.

Comment 1

[Andy Wingo [:wingo]]

Attachment: Paper over debug-mode checks of stack depth for unreachable bytecode

Comment 2

[Jan de Mooij [:jandem]]

Comment on attachment 830119 [details] [diff] [review]
Paper over debug-mode checks of stack depth for unreachable bytecode

Review of attachment 830119 [details] [diff] [review]:
-----------------------------------------------------------------

Thanks!

::: js/src/jit/shared/CodeGenerator-shared.cpp
@@ +288,5 @@
> +                    JS_ASSERT(stackDepth - exprStack <= 1);
> +                } else if (JSOp(*bailPC) != JSOP_FUNAPPLY &&
> +                           !IsGetPropPC(bailPC) && !IsSetPropPC(bailPC))
> +                    {
> +                        // For fun.apply({}, arguments) the reconstructStackDepth will

Nit: unindent this block

::: js/src/jsopcode.cpp
@@ +715,5 @@
> +
> +    return true;
> +}
> +
> +

Micro-nit: remove one of these two blank lines

Comment 3

[Andy Wingo [:wingo]]

Attachment: Paper over debug-mode checks of stack depth for unreachable bytecode r=jandem

Comment 4

[Andy Wingo [:wingo]]

Comment on attachment 830181 [details] [diff] [review]
Paper over debug-mode checks of stack depth for unreachable bytecode r=jandem

Nits fixed, r=jandem, thanks for the review!

Comment 5

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/2c7ad2dabeb8

Comment 6

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/2c7ad2dabeb8