show how to fix the Arc problem

[web.git] / personal / _posts / 2017-07-14-undefined-behavior.md

diff --git a/personal/_posts/2017-07-14-undefined-behavior.md b/personal/_posts/2017-07-14-undefined-behavior.md
index e93a6081d8b13ca136028952ca0a3b9c708c26bf..46356689dfa90848d28f5d5b387758fc334bc2b3 100644 (file)
--- a/personal/_posts/2017-07-14-undefined-behavior.md
+++ b/personal/_posts/2017-07-14-undefined-behavior.md
@@ -8,7 +8,7 @@ So, finally, just one year later, this post is my take at what the purpose of th
 <!-- MORE -->
 Warning:  This post may contain opinions.  You have been warned.
 
 <!-- MORE -->
 Warning:  This post may contain opinions.  You have been warned.
 

-## When are optimizations legal?
+## When are Optimizations Legal?

 
 Currently, we have a pretty good understanding of what the intended behavior of *safe* Rust is.
 That is, there is general agreement (modulo some [bugs](https://github.com/rust-lang/rust/issues/27868)) about the order in which operations are to be performed, and about what each individual operation does.
 
 Currently, we have a pretty good understanding of what the intended behavior of *safe* Rust is.
 That is, there is general agreement (modulo some [bugs](https://github.com/rust-lang/rust/issues/27868)) about the order in which operations are to be performed, and about what each individual operation does.


@@ -37,9 +37,9 @@ After all, if there is any execution for which the assumption does *not* hold, t
 Now, it turns out that it is often really hard to obtain precise aliasing information.
 This could be the end of the game:  No alias information, no way to verify our assumptions, no optimizations.
 
 Now, it turns out that it is often really hard to obtain precise aliasing information.
 This could be the end of the game:  No alias information, no way to verify our assumptions, no optimizations.
 

-## Shifting responsibility
+## Shifting Responsibility

 
 

-However, it turns out that compilers writers consider these optimizations important enough that they came up with an alternative solution:
+However, it turns out that compiler writers consider these optimizations important enough that they came up with an alternative solution:

 Instead of having the compiler verify such assumptions, they declared the programmer responsible.
 
 For example, the C standard says that memory accesses have to happen with the right "effective type":  If data was stored with a `float` pointer, it must not be read with an `int` pointer.
 Instead of having the compiler verify such assumptions, they declared the programmer responsible.
 
 For example, the C standard says that memory accesses have to happen with the right "effective type":  If data was stored with a `float` pointer, it must not be read with an `int` pointer.


@@ -87,4 +87,6 @@ Such a specification would describe the additional state that is needed at run-t
 It is with such considerations in my mind that I have previously written about [miri as an executable specification]({{ site.baseurl }}{% post_url 2017-06-06-MIR-semantics %}).
 
 Coming up next on this channel:  During my [internship]({{ site.baseurl }}{% post_url 2017-05-23-internship-starting %}), I am working on such a specification.
 It is with such considerations in my mind that I have previously written about [miri as an executable specification]({{ site.baseurl }}{% post_url 2017-06-06-MIR-semantics %}).
 
 Coming up next on this channel:  During my [internship]({{ site.baseurl }}{% post_url 2017-05-23-internship-starting %}), I am working on such a specification.

-I have a draft ready now, and I will share it with the world to see what the world thinks about it.
+My ideas are concrete enough now that I can write down a draft, which I will share with the world to see what the world thinks about it.
+
+**Uodate:** [Writing down has happened]({{ site.baseurl }}{% post_url 2017-07-17-types-as-contracts %}).