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2013-02-22Update copyright yearsBjörn-Egil Dahlberg
2013-02-09Fix unsafe optimization of funsBjörn Gustavsson
Commits 53bd4974a101 and 726f6e4c7afe simplified the handling of match_fail (used to generated exceptions such as 'function_clause') by first rewriting them to a call to erlang/error{1,2} and later rewriting them to specialized BEAM instructions (to reduce the code size). There was one flaw, though, which only was exposed when more aggressive optimizations were added in c3b60f86c622. Here is an example to explain it: t(V) -> fun(get) -> V end. The following BEAM code will be initially generated for the fun: {function, '-t/1-fun-0-', 2, 5}. {label,1}. {line,[{location,"t.erl",5}]}. {func_info,{atom,t},{atom,'-t/1-fun-0-'},2}. {label,2}. {test,is_eq_exact,{f,2},[{x,0},{atom,get}]}. {move,{x,1},{x,0}}. return. {label,2}. {test_heap,2,1}. {put_list,{x,0},nil,{x,1}}. {move,{atom,function_clause},{x,0}}. {line,[{location,"t.erl",5}]}. {call_ext_only,2,{extfunc,erlang,error,2}}. Translating back to Erlang code, that would be roughly: '-t/1-fun-0-'(get, V) -> V; '-t/1-fun-0-'(Arg1, _) -> erlang:error(function_clause, [Arg1]). Note that the second argument (the free variable V) is not included in the call to erlang:error/2. The beam_except pass will simplify the code to: {function, '-t/1-fun-0-', 2, 8}. {label,1}. {line,[{location,"t.erl",5}]}. {func_info,{atom,t},{atom,'-t/1-fun-0-'},2}. {label,2}. {test,is_eq_exact,{f,1},[{x,0},{atom,get}]}. {move,{x,1},{x,0}}. return. The code has been shortened by jumping to the func_info/3 instruction. Translating back to Erlang: '-t/1-fun-0-'(get, V) -> V; '-t/1-fun-0-'(Arg1, Arg2) -> erlang:error(function_clause, [Arg1,Arg2]). it is clear that both arguments are now included in the 'function_clause' exception, even though the initially generated code only included the first argument. That is no problem in this particular case, but for some more complex funs, optimizing the first version based on variable usage could make the second version unsafe. I rejected the following potential solutions: - Including the free arguments in the call to erlang:error/2: '-t/1-fun-0-'(get, V) -> V; '-t/1-fun-0-'(Arg1, Arg2) -> erlang:error(function_clause, [Arg1,Arg2]). Unfortunately, that is tricky. The free variables are only known after the second pass in v3_kernel when variable usage has been calculated. We would need to add a third pass (only for funs) that would the free arguments to the second argument for erlang:error/2 *and* update the variable usage information. - Calling beam_except earlier, from within beam_block before any optimizations based on variable usages are done. But means that the problem could reappear in some other form in the future when other updates are done to the code generator and/or optimization passes. The solution I have chosen is to modify beam_except to only replace a call to erlang:error(function_class, Args) if the length of Args is the same as the arity in the func_info/3 instruction. The code will be slightly larger. Also, the free variables for funs and list comprehensions will no longer be included in the function_clause exception (that could be less confusing, but it also means less information during debugging).
2013-01-09compiler: Remove support for packagesBjörn Gustavsson
2012-10-23compiler: Run testcases in parallelBjörn Gustavsson
Run testcases in parallel will make the test suite run slightly faster. Another reason for this change is that we want more testing of parallel testcase support in common_test.
2012-10-09Improve binary matching of literalsBjörn Gustavsson
The bs_match_string instruction is used to speed up matching of binary literals. For example, given this source code: foo1(<<1,2,3>>) -> ok. The matching part of the code will look like: {test,bs_start_match2,{f,1},1,[{x,0},0],{x,0}}. {test,bs_match_string,{f,3},[{x,0},24,{string,[1,2,3]}]}. {test,bs_test_tail2,{f,3},[{x,0},0]}. Nice. However, if we do a simple change to the source code: foo2(<<1,2,3>>) -> ok; foo2(<<>>) -> error. the resulting matching code will look like (sligthly simplified): {test,bs_start_match2,{f,4},1,[{x,0},0],{x,0}}. {test,bs_get_integer2,{f,7},1,[{x,0},{integer,8},1,Flags],{x,1}}. {test,is_eq_exact,{f,8},[{x,1},{integer,1}]}. {test,bs_match_string,{f,6},[{x,0},16,{string,[2,3]}]}. {test,bs_test_tail2,{f,6},[{x,0},0]}. {move,{atom,ok},{x,0}}. return. {label,6}. {bs_restore2,{x,0},{atom,start}}. {label,7}. {test,bs_test_tail2,{f,8},[{x,0},0]}. That is, matching of the first byte is not combined into the bs_match_string instruction that follows. Fix this problem by allowing a bs_match_string instruction to be used if all clauses will match either the same integer literal or the empty binary.
2012-03-30Update copyright yearsBjörn-Egil Dahlberg
2012-02-13compiler: Teach the inliner to preserve on_load functionsBjörn Gustavsson
The inliner was ignorant of on_load functions and would discard them (unless they were exported or referenced). Noticed-by: Yiannis Tsiouris <[email protected]>
2012-01-04compilation_SUITE: Compile compiler modules in parallelBjörn Gustavsson
On my Mac Pro with 8 cores, this change make self_compile/1 more than twice as fast, and self_compile_old_inliner/1 more than 4 times faster.
2012-01-04compilation_SUITE: Prevent cover from being run on slave nodesBjörn Gustavsson
In the self compilation test cases, the compiler compiles itself and runs the newly compiled version on a slave node. Having the cover server starting on the slave node defeats the purpose of the test, since it will load the SAME cover-compiled code on the slave node. (It will also be slower, but will not improve coverage since it compiles the same source files again.) Use a shielded node to prevent the cover server from getting started on the slave node.
2012-01-04Eliminate the match_fail primop in v3_kernel and later passesBjörn Gustavsson
In the v3_life pass, it is assumed that a 'match_fail' primop only occur at the top-level and at the end of a function. But this code: do_split_cases(A) -> case A of x -> Z = dummy1; _ -> Z = dummy2, a=b end, Z. will be optimized by sys_core_fold to the following code: 'split_cases'/1 = fun (_cor0) -> let <_cor7,Z> = case _cor0 of <'x'> when 'true' -> < 'dummy1','dummy1' > <_cor6> when 'true' -> %% Here follows a 'match_fail' primop inside %% multiple return values: < primop 'match_fail'({'badmatch','b'}),'dummy2' > end in Z moving the 'match_fail' primop into a "values" construction. In the future, we would like to get rid of the v3_life pass (it is there for historical reasons), so in the mean-time we prefer to not add more code to it by generalizing the handling of 'match_fail'. Since the 'match_fail' primop can be simulated by erlang:error/{1,2}, the simplest solution is to translate 'match_fail' to a call to erlang:error/{1,2} in v3_kernel and remove the handling of 'match_fail' in v3_life and v3_codegen. It is tempting to get rid of 'match_fail' also in the Core Erlang format, but there are two issues: - Removing the support for 'match_fail' completely may break tools that generate Core Erlang code. We should not do that in a minor release. - There is no easy way to generate a 'function_clause' exception that will remain correct if it will be inlined into another function. (Calling "erlang:error(function_clause, Args)" is fine only if it is not inlined into another function.) A good solution probably involves introducing new instructions, which is better done in a major release. Noticed-by: Håkan Matsson Minimized-test-case-by: Erik Søe Sørensen
2011-04-12compiler tests: Reinstate ?MODULE macro in calls to test_lib:recompile/1Björn Gustavsson
In 3d0f4a3085f11389e5b22d10f96f0cbf08c9337f (an update to conform with common_test), in all test_lib:recompile(?MODULE) calls, ?MODULE was changed to the actual name of the module. That would cause test_lib:recompile/1 to compile the module with the incorrect compiler options in cloned modules such as record_no_opt_SUITE, causing worse coverage.
2011-02-23compiler: Eliminate some warningsBjörn Gustavsson
2011-02-17Rename Suite Callback to Common Test HookLukas Larsson
2011-02-17Fix formatting for compilerLukas Larsson
2011-02-17Add init_per_suite and end_per_suiteLukas Larsson
2011-02-17Add ts_install_scb to suite/0Lukas Larsson
2011-02-17Update compiler tests to conform with common_test standardLukas Larsson
2010-12-02beam_utils: Fix check_liveness/3 for receive loopsBjörn Gustavsson
Sometimes the beam_bool pass wants to know whether an y register will be killed by the code that follows and will do (effectively): beam_utils:is_killed({y,Y}, Code, L) When asked to calculate the liveness for an y register, beam_utils:is_killed/3 will loop forever if the code includes a receive loop. Since this rarely occurs, fix the problem in the simplest and most conservative way. Reported-by: Christopher Williams
2010-11-26beam_utils: Fix liveness analysis for gc_bif instructionsBjörn Gustavsson
When gc_bif instructions occurred outside of a block, beam_utils:check_liveness/3 did not take into account that the instruction could do a garbage collection, and could falsely report that an x register would be killed. That could cause the beam_dead pass to make the code unsafe by removing the assignment to an x register that would subsequently be referenced by the garbage collector. Reported-by: Christopher Williams
2010-07-29beam_asm: Simplify string table generation for beamsPaul Guyot
The code for generating the string table (which is now only used for bit syntax matching) in a BEAM file is quite complicated and potentially expensive when compiling modules with many thousands of clauses doing bit syntax matching. Simplify and optimize the code using bit syntax and binary:match/2 instead of the list operations in the original code.
2009-11-20The R13B03 release.OTP_R13B03Erlang/OTP