aboutsummaryrefslogtreecommitdiffstats
path: root/lib/compiler/src/beam_ssa_codegen.erl
AgeCommit message (Collapse)Author
2019-01-24compiler: Introduce module-level type optimizationJohn Högberg
This commit lets the type optimization pass work across functions, tracking return and argument types to eliminate redundant tests.
2019-01-18beam_ssa_codegen: Remove forgotten and unreachable clauseBjörn Gustavsson
fd682dd3b1dc corrected label generation for 'or', but forgot to remove the old incorrect clause (that can no longer be reached).
2019-01-11beam_ssa_codegen: Correct label generation for 'or'Björn Gustavsson
Code generation for 'or' with {z,0} destination could generate duplicate new labels. The bug was introduced in eb571f8951bd.
2018-11-19beam_ssa_codegen: Improve optimization of allocate instructionsBjörn Gustavsson
There could be `allocate_zero` instructions where `allocate` would suffice or superfluous `init` instructions because all possible initializations of Y registers were not taken into account. While at it, also add some more comments.
2018-10-01Merge pull request #1965 from bjorng/bjorn/compiler/misc-cleanupsBjörn Gustavsson
Minor cleanups and bug fixes of the compiler
2018-09-28Remove unused instruction bs_context_to_binary from the compilerJohn Högberg
This has been superseded by bs_get_tail/3. Note that it is NOT removed from the emulator or beam_disasm, as old modules are still legal.
2018-09-28Rewrite BSM optimizations in the new SSA-based intermediate formatJohn Högberg
This commit improves the bit-syntax match optimization pass, leveraging the new SSA intermediate format to perform much more aggressive optimizations. Some highlights: * Watch contexts can be reused even after being passed to a function or being used in a try block. * Sub-binaries are no longer eagerly extracted, making it far easier to keep "happy paths" free from binary creation. * Trivial wrapper functions no longer disable context reuse.
2018-09-26Move bif_to_test/3 from beam_utils to beam_ssa_codegenBjörn Gustavsson
The only caller of bif_to_test/3 is beam_ssa_codegen.
2018-09-26Move allocation combining from beam_flatten to beam_ssa_codegenBjörn Gustavsson
Continuing the simplification of beam_flatten, move the optimization that eliminates a test_heap instruction following a binary construction by incorporating the allocation of the heap space into the bs_init* instruction itself. This change does not change the generated code in any way. Also remove beam_utils:combine_heap_needs/2, because beam_flatten was the last user of it.
2018-09-26Move optimization of 'move' from beam_flatten to beam_ssa_codegenBjörn Gustavsson
The purpose of beam_flatten is to eliminate the blocks created by beam_block, but it also does a few optimizations because at the time the optimizations were added, beam_flatten was the most convenient place. Move the optimization that places `{move,Something,{x,0}}` before `call` instructions from beam_flatten to beam_ssa_codegen. This change will very slightly improve compilation times, and it will also apply the optimization in more places. In particular, a `{move,Literal,{x,0}}` would never be moved passed a `trim` instruction before this change. Now it will.
2018-09-20Consistently use #b_var{} instead of var_name()John Högberg
We chose to refer to variables through their var_name() because we anticipated the need to annotate them, but it turned out we didn't really need that, and many things become a lot cleaner if the entire #b_var{} is used to represent variables.
2018-09-17beam_ssa_codegen: Don't emit kill instructions before exit BIFsBjörn Gustavsson
Omitting `kill` instructions before BIFs that throw exceptions will reduce the code size. This optimization supersedes the same optimizations in beam_dead.
2018-09-12Optimize 'and' and 'or' instructionsBjörn Gustavsson
2018-09-03Introduce a put_tuple2 instructionBjörn Gustavsson
Sometimes when building a tuple, there is no way to avoid an extra `move` instruction. Consider this code: make_tuple(A) -> {ok,A}. The corresponding BEAM code looks like this: {test_heap,3,1}. {put_tuple,2,{x,1}}. {put,{atom,ok}}. {put,{x,0}}. {move,{x,1},{x,0}}. return. To avoid overwriting the source register `{x,0}`, a `move` instruction is necessary. The problem doesn't exist when building a list: %% build_list(A) -> [A]. {test_heap,2,1}. {put_list,{x,0},nil,{x,0}}. return. Introduce a new `put_tuple2` instruction that builds a tuple in a single instruction, so that the `move` instruction can be eliminated: %% make_tuple(A) -> {ok,A}. {test_heap,3,1}. {put_tuple2,{x,0},{list,[{atom,ok},{x,0}]}}. return. Note that the BEAM loader already combines `put_tuple` and `put` instructions into an internal instruction similar to `put_tuple2`. Therefore the introduction of the new instruction will not speed up execution of tuple building itself, but it will be less work for the loader to load the new instruction.
2018-08-24Introduce a new SSA-based intermediate formatBjörn Gustavsson
v3_codegen is replaced by three new passes: * beam_kernel_to_ssa which translates the Kernel Erlang format to a new SSA-based intermediate format. * beam_ssa_pre_codegen which prepares the SSA-based format for code generation, including register allocation. Registers are allocated using the linear scan algorithm. * beam_ssa_codegen which generates BEAM assembly code from the SSA-based format. It easier and more effective to optimize the SSA-based format before X and Y registers have been assigned. The current optimization passes constantly have to make sure no "holes" in the X register assignments are created (that is, that no X register becomes undefined that an allocation instruction depends on). This commit also introduces the following optimizations: * Replacing of tuple matching of records with the is_tagged_tuple instruction. (Replacing beam_record.) * Sinking of get_tuple_element instructions to just before the first use of the extracted values. As well as potentially avoiding extracting tuple elements when they are not actually used on all executions paths, this optimization could also reduce the number values that will need to be stored in Y registers. (Similar to beam_reorder, but more effective.) * Live optimizations, removing the definition of a variable that is not subsequently used (provided that the operation has no side effects), as well strength reduction of binary matching by replacing the extraction of value from a binary with a skip instruction. (Used to be done by beam_block, beam_utils, and v3_codegen.) * Removal of redundant bs_restore2 instructions. (Formerly done by beam_bs.) * Type-based optimizations across branches. More effective than the old beam_type pass that only did type-based optimizations in basic blocks. * Optimization of floating point instructions. (Formerly done by beam_type.) * Optimization of receive statements to introduce recv_mark and recv_set instructions. More effective with far fewer restrictions on what instructions are allowed between creating the reference and entering the receive statement. * Common subexpression elimination. (Formerly done by beam_block.)