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2011-11-07beam_asm: Fix broken NewIndex in fun entriesBjörn Gustavsson
The calculation of the NewIndex field in fun entries is broken: the sys_pre_expand and v3_kernel modules keep separate index counters starting at zero; thus there is no guarantee that each fun within a module will have its own unique NewIndex. We don't really need the NewIndex any more (see below), but since we do need the NewUniq field, we should fix NewIndex for cleanliness sake. The simplest way is to assign NewIndex as late as possible, namely in beam_asm, and to set it to the same value as Index. Historical Note: Why NewIndex Was Introduced There was once an idea that the debugger should be able to interpret only a single function in a module (for speed). To make sure that interpreted funs could be called from BEAM code and vice versa, the fun identification must be visible in the abstract code. Therefore a NewIndex field was introduced in each fun in the abstract code. However, it turned out that interpreting single functions does not play well with aggressive code optimization. For example, in this code: f() -> X = 1, fun() -> X+2 end. the variable X will seem to be free in the fun, but an aggressive optimizer will replace X with 1 in the fun; thus the fun will no longer have any free variables. Therefore, the debugger will always interpret entire modules.
2011-11-07beam_asm: Strenghten the calculation of Uniq for funsBjörn Gustavsson
Funs are identified by a triple, <Module,Uniq,Index>, where Module is the module name, Uniq is a 27 bit hash value of some intermediate representation of the code for the fun, and index is a small integer. When a fun is loaded, the triple for the fun will be compared to previously loaded funs. If all elements in the triple in the newly loaded fun are the same, the newly loaded fun will replace the previous fun. The idea is that if Uniq are the same, the code for the fun is also the same. The problem is that Uniq is only based on the intermediate representation of the fun itself. If the fun calls local functions in the same module, Uniq may remain the same even if the behavior of the fun has been changed. See http://erlang.org/pipermail/erlang-bugs/2007-June/000368.htlm for an example. As a long-term plan to fix this problem, the NewIndex and NewUniq fields was added to each fun in the R8 release (where NewUniq is the MD5 of the BEAM code for the module). Unfortunately, it turns out that the compiler does not assign unique value to NewIndex (if it isn't tested, it doesn't work), so we cannot use the <Module,NewUniq,NewIndex> triple as identification. It would be possible to use <Module,NewUniq,Index>, but that seems ugly. Therefore, fix the problem by making Uniq more unique by taking 27 bits from the MD5 for the BEAM code. That only requires a change to the compiler. Also update a test case for cover, which now fails because of the stronger Uniq calculation. (The comment in test case about why the Pid2 process survived is not correct.)
2011-08-16Include location information for line instructions in BEAM filesBjörn Gustavsson
2011-08-16compiler: Generate line instructionsBjörn Gustavsson
2011-08-16compiler, emulator: Introduce the line/1 instructionBjörn Gustavsson
Introduce the line/1 instruction in the compiler and the BEAM virtual machine. It will not yet be generated by the compiler and will not actually carry any information.
2010-05-17Add guard BIFs binary_part/2,3Patrik Nyblom
Add the gc_bif's to the VM. Add infrastructure for gc_bif's (guard bifs that can gc) with two and. three arguments in VM (loader and VM). Add compiler support for gc_bif with three arguments. Add compiler (and interpreter) support for new guard BIFs. Add testcases for new guard BIFs in compiler and emulator.
2010-05-12Merge branch 'bg/compiler-attributes' into devErlang/OTP
* bg/compiler-attributes: Remove opaque declarations from the attributes
2010-05-12Remove opaque declarations from the attributesBjörn Gustavsson
-opaque declarations should not be retained in the attributes (because they will be loaded along with the code and are not useful). While at it, filter away those Dialyzer attributes as early as possible - in v3_kernel.
2009-12-09compiler: Teach 'slim' to omit compilation infoBjörn Gustavsson
The original intention for the undocumented 'slim' option was to omit non-essential parts of *.beam files to reduce the size of the primary bootstrap. Therefore, debug information and local function information (only used by xref, not by the loader) are omitted, but information about the compilation time and compiler version are still included. Including compilation information is troublesome, however, when committing the bootstrap into a revision control system, because every beam file is guaranteed to be changed every time the bootstrap is updated. Therefore, change the 'slim' option to also omit compilation information.
2009-11-20The R13B03 release.OTP_R13B03Erlang/OTP