[Vm-dev] Plugin code generation issues

[Levente Uzonyi]

Hi All,

I wrote a new plugin the other day and found two issues with code 
generation.
The first one, which is less important is related to the inline pragma.
I expected that methods marked with <inline: true> will either not 
be generated at all when the code generator inlines all occurrences of 
them or they'll be generated as inline C functions. But they are 
generated as regular static functions even though they are never used.

The other one, which is more significant is related to type casts.
I've got the following method:

rotateRight64: value by: amount

 	<inline: true>
 	<var: #value type: #'unsigned long long'>
 	<returnTypeC: #'unsigned long long'>

 	^(value >> amount) bitOr: (value << (64 - amount))

The code using the above method has the variable declaration

 	<var: #w declareC: 'unsigned long long w[80]'>

The method is used with individual elements of w:

 	self rotateRight64: (w at: i - 2) by: 61

The generated function gets inlined as expected, but the elements of the 
array are casted to usqInt before right shifts:

 	((((usqInt) (w[i2 - 2])) >> 61) | ((w[i2 - 2]) << (3)))

This is a problem on 32-bit platforms, because usqInt is unsigned int 
there, so the upper 32-bits will be lost by the cast.

When the method is used with non-array variables, then the generator works 
as expected:

 	self rotateRight64: a by: 39

is generated as:

 	((a >> 39) | (a << (25)))

where a is declared as

 	<var: #a type: #'unsigned long long'>

I tried to fix the issue by declaring w as

 	<var: #w type: #'unsigned long long*'>

But is didn't make the usqInt casts go away.
Is it possible that the code generator doesn't know that the type of w[i] 
is unsigned long long, when w is unsigned long long*?


Levente

P.S.: The code is available here 
http://squeaksource.com/Cryptography/CryptographyPlugins-ul.18.mcz .
Generate SHA2Plugin to see the problem.