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2012-10-09beam_bool: Recognize more safe optimizationsBjörn Gustavsson
The optimizer of boolean expressions can often reject optimizations that it does not recognize as safe. For instance, if a boolean expression was preceded by 'move' instructions that saved x registers into y registers, it would almost certainly reject the optimization because it required the y register not be used in the code that follows. Fix this problem by allowing identical 'move' instructions that assing to y registers at the beginning of the old and the optimized code. While at it, correct the spelling of "preceding".
2010-05-21Merge branch 'bg/compiler-cover-and-clean' into devErlang/OTP
* bg/compiler-cover-and-clean: v3_life: Remove clause that cannot match in match_fail/3 v3_life tests: Cover exception handling code in v3_life:function/1 beam_type: Remove redundant clause v3_core tests: Cover make_bool_switch_guard/5 v3_core tests: Cover handling of pattern aliases v3_core: Remove a clause in is_simple/1 that cannot match v3_core: Remove unused support for generating compilation errors Remove stray support for the put_literal/2 instruction Remove stray support for the bs_bits_to_bytes2/2 instruction Remove the bs_bits_to_bytes/3 instruction Cover handling of 'math' BIFs beam_bool: Remove a clause in live_regs/1 that cannot match beam_bool: Cover handling of bs_context_to_binary in initialized_regs/2 beam_bool: Remove a clause in initialized_regs/2 that cannot match beam_block: Remove a clause that will never be executed erts: Stop supporting non-literal empty tuples compile: Remove code that is only executed on Solaris Do not cover-analyze core_scan core_SUITE_data: Don't ignore *.core files in this directory OTP-8636 bg/compiler-cover-and-clean
2010-05-20beam_bool: Remove a clause in live_regs/1 that cannot matchBjörn Gustavsson
live_regs/1 folds over a list of tuples, so a clause matching an element being an empty list can never match. If the list for some unfathomable reason would contain an empty list, there will be an internal compiler error and no *.beam file will be created. Thus this change is safe.
2010-05-20beam_bool: Remove a clause in initialized_regs/2 that cannot matchBjörn Gustavsson
When scanning a reversed instruction sequence for a function, it is impossible to reach the end of the list, because each function must have a fun_info/4 instruction followed by a label/1 instruction at the beginning, and there is a clause that will handle those instructions. If for some unfathomable reason the end of the list would be reached, with this change there will be an internal compiler error and no *.beam file will be created. Thus this change is safe.
2009-12-11beam_bool: Fix generation of code that does not validateBjörn Gustavsson
The following code (by Simon Cornish) bad(XDo1, XDo2, Do3) -> Do1 = (XDo1 =/= []), Do2 = (XDo2 =/= []), CH1 = if Do1 == true; Do1 == false,Do2==false,Do3 == blah -> ch1; true -> no end, CH2 = if Do1 == true; Do1 == false,Do2==false,Do3 == xx -> ch2; true -> no end, {CH1,CH2}. is optimized by beam_bool even though the optimization is not safe. The trouble is that an assignment to {y,0} no longer occurs on all paths leading to its use. The bug is in dst_regs/2 which is supposed to return a set of all registers assigned in a code block, but it ignores registers assigned in 'move' instructions. Fix the bug by taking 'move' instructions into account. This change is safe since it can only cause more registers to be added to the MustBeKilled and MustBeUnused sets in ensure_opt_safe/6, which means that it can only cause the optimization to be turned off for code that used to be optimized.
2009-12-10Fix crash in beam_boolBjörn Gustavsson
The following code crashes beam_bool: bad(XDo1, XDo2, Do3) -> Do1 = (XDo1 =/= []), Do2 = (XDo2 =/= []), if Do1 =:= true; Do1 =:= false, Do2 =:= false, Do3 =:= delete -> no end. (Reported by Simon Cornish; minimized by Kostis Sagonas.) For the moment fix the bug in the simplest and safest way possible (basically, instead of crashing just don't do the optimization). In a future major release (e.g. R14), the following improvements could be considered: * In beam_bool, it should be possible to move the Do1 and Do2 expressions to the pre-block and still optimize the expression in the 'if' statement. * In sys_core_fold, it should be possible to eliminate the try/catch around the guard expression in the 'if', because none of the guard tests can actually fail.
2009-11-20The R13B03 release.OTP_R13B03Erlang/OTP