From 74d7bd100b742a803c8de82c9c997308cf871038 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Wed, 8 Dec 2010 15:27:37 +0100 Subject: Optimize addition of a small integer to a variable Introduce a new i_increment/4 to optimize the addition of a register and a small integer. This instruction saves two instruction words compared to the standard instructions (an i_fetch/2 instruction followed by a i_plus/3 instruction) and will also be slightly faster. --- erts/emulator/beam/beam_emu.c | 46 ++++++++++++++++++++++++++++++ erts/emulator/beam/beam_load.c | 46 ++++++++++++++++++++++++++++++ erts/emulator/beam/ops.tab | 20 ++++++++++++- erts/emulator/test/beam_literals_SUITE.erl | 37 ++++++++++++++++++++++-- 4 files changed, 146 insertions(+), 3 deletions(-) (limited to 'erts') diff --git a/erts/emulator/beam/beam_emu.c b/erts/emulator/beam/beam_emu.c index afba17f7bd..741ba8fb93 100644 --- a/erts/emulator/beam/beam_emu.c +++ b/erts/emulator/beam/beam_emu.c @@ -1276,6 +1276,52 @@ void process_main(void) #define STORE_ARITH_RESULT(res) StoreBifResult(2, (res)); #define ARITH_FUNC(name) erts_gc_##name + { + Eterm increment_reg_val; + Eterm increment_val; + Uint live; + Eterm result; + + OpCase(i_increment_yIId): + increment_reg_val = yb(Arg(0)); + goto do_increment; + + OpCase(i_increment_xIId): + increment_reg_val = xb(Arg(0)); + goto do_increment; + + OpCase(i_increment_rIId): + increment_reg_val = r(0); + I--; + + do_increment: + increment_val = Arg(1); + if (is_small(increment_reg_val)) { + Sint i = signed_val(increment_reg_val) + increment_val; + ASSERT(MY_IS_SSMALL(i) == IS_SSMALL(i)); + if (MY_IS_SSMALL(i)) { + result = make_small(i); + store_result: + StoreBifResult(3, result); + } + } + + live = Arg(2); + SWAPOUT; + reg[0] = r(0); + reg[live] = increment_reg_val; + reg[live+1] = make_small(increment_val); + result = erts_gc_mixed_plus(c_p, reg, live); + r(0) = reg[0]; + SWAPIN; + ERTS_HOLE_CHECK(c_p); + if (is_value(result)) { + goto store_result; + } + ASSERT(c_p->freason != BADMATCH || is_value(c_p->fvalue)); + goto find_func_info; + } + OpCase(i_plus_jId): { Eterm result; diff --git a/erts/emulator/beam/beam_load.c b/erts/emulator/beam/beam_load.c index 2d57c8a218..e6448931eb 100644 --- a/erts/emulator/beam/beam_load.c +++ b/erts/emulator/beam/beam_load.c @@ -2787,6 +2787,52 @@ gen_skip_bits2(LoaderState* stp, GenOpArg Fail, GenOpArg Ms, return op; } +static GenOp* +gen_increment(LoaderState* stp, GenOpArg Reg, GenOpArg Integer, + GenOpArg Live, GenOpArg Dst) +{ + GenOp* op; + + NEW_GENOP(stp, op); + op->op = genop_i_increment_4; + op->arity = 4; + op->next = NULL; + op->a[0] = Reg; + op->a[1].type = TAG_u; + op->a[1].val = Integer.val; + op->a[2] = Live; + op->a[3] = Dst; + return op; +} + +static GenOp* +gen_increment_from_minus(LoaderState* stp, GenOpArg Reg, GenOpArg Integer, + GenOpArg Live, GenOpArg Dst) +{ + GenOp* op; + + NEW_GENOP(stp, op); + op->op = genop_i_increment_4; + op->arity = 4; + op->next = NULL; + op->a[0] = Reg; + op->a[1].type = TAG_u; + op->a[1].val = -Integer.val; + op->a[2] = Live; + op->a[3] = Dst; + return op; +} + +/* + * Test whether the negation of the given number is small. + */ +static int +negation_is_small(LoaderState* stp, GenOpArg Int) +{ + return Int.type == TAG_i && IS_SSMALL(-Int.val); +} + + static int smp(LoaderState* stp) { diff --git a/erts/emulator/beam/ops.tab b/erts/emulator/beam/ops.tab index 6db55e1402..029d7b512c 100644 --- a/erts/emulator/beam/ops.tab +++ b/erts/emulator/beam/ops.tab @@ -1371,7 +1371,21 @@ apply I apply_last I P # -# New GCing arithmetic instructions. +# Optimize addition and subtraction of small literals using +# the i_increment/4 instruction (in bodies, not in guards). +# + +gc_bif2 p Live u$bif:erlang:splus/2 Int=i Reg=d Dst => \ + gen_increment(Reg, Int, Live, Dst) +gc_bif2 p Live u$bif:erlang:splus/2 Reg=d Int=i Dst => \ + gen_increment(Reg, Int, Live, Dst) + +gc_bif2 p Live u$bif:erlang:sminus/2 Reg=d Int=i Dst | \ + negation_is_small(Int) => \ + gen_increment_from_minus(Reg, Int, Live, Dst) + +# +# GCing arithmetic instructions. # gc_bif2 Fail I u$bif:erlang:splus/2 S1 S2 Dst=d => i_fetch S1 S2 | i_plus Fail I Dst @@ -1394,6 +1408,10 @@ gc_bif1 Fail I u$bif:erlang:bnot/1 Src Dst=d => i_int_bnot Fail Src I Dst gc_bif1 Fail I u$bif:erlang:sminus/1 Src Dst=d => i_fetch i Src | i_minus Fail I Dst gc_bif1 Fail I u$bif:erlang:splus/1 Src Dst=d => i_fetch i Src | i_plus Fail I Dst +i_increment r I I d +i_increment x I I d +i_increment y I I d + i_plus j I d i_minus j I d i_times j I d diff --git a/erts/emulator/test/beam_literals_SUITE.erl b/erts/emulator/test/beam_literals_SUITE.erl index f56d7ac1c5..1eda939cf8 100644 --- a/erts/emulator/test/beam_literals_SUITE.erl +++ b/erts/emulator/test/beam_literals_SUITE.erl @@ -23,7 +23,8 @@ matching_bigs/1, matching_more_bigs/1, matching_bigs_and_smalls/1, badmatch/1, case_clause/1, receiving/1, literal_type_tests/1, - put_list/1, fconv/1, literal_case_expression/1]). + put_list/1, fconv/1, literal_case_expression/1, + increment/1]). -include("test_server.hrl"). @@ -32,7 +33,7 @@ all(suite) -> matching_bigs, matching_more_bigs, matching_bigs_and_smalls, badmatch, case_clause, receiving, literal_type_tests, - put_list, fconv, literal_case_expression]. + put_list, fconv, literal_case_expression, increment]. putting(doc) -> "Test creating lists and tuples containing big number literals."; putting(Config) when is_list(Config) -> @@ -419,6 +420,38 @@ literal_case_expression(Config) when is_list(Config) -> ?line code:purge(Mod), ok. +%% Test the i_increment instruction. +increment(Config) when is_list(Config) -> + %% In the 32-bit emulator, Neg32 can be represented as a small, + %% but -Neg32 cannot. Therefore the i_increment instruction must + %% not be used in the subtraction that follows (since i_increment + %% cannot handle a bignum literal). + Neg32 = -(1 bsl 27), + Big32 = id(1 bsl 32), + Result32 = (1 bsl 32) + (1 bsl 27), + ?line Result32 = Big32 + (1 bsl 27), + ?line Result32 = Big32 - Neg32, + + %% Same thing, but for the 64-bit emulator. + Neg64 = -(1 bsl 59), + Big64 = id(1 bsl 64), + Result64 = (1 bsl 64) + (1 bsl 59), + ?line Result64 = Big64 + (1 bsl 59), + ?line Result64 = Big64 - Neg64, + + %% Test error handling for the i_increment instruction. + Bad = id(bad), + ?line {'EXIT',{badarith,_}} = (catch Bad + 42), + + %% Small operands, but a big result. + Res32 = 1 bsl 27, + Small32 = id(Res32-1), + ?line Res32 = Small32 + 1, + Res64 = 1 bsl 59, + Small64 = id(Res64-1), + ?line Res64 = Small64 + 1, + ok. + %% Help functions. chksum(Term) -> -- cgit v1.2.3