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| author | Björn Gustavsson <[email protected]> | 2015-06-25 13:21:14 +0200 |
|---|---|---|
| committer | Björn Gustavsson <[email protected]> | 2015-07-03 14:34:58 +0200 |
| commit | 62473daf8169a04a07409f344d938bc51a4536c3 (patch) | |
| tree | 153bf43a5833103f6d368de318288aad692fcedf | |
| parent | 3dc2bee53b4d36f41821a6ab512cf01c958c11f9 (diff) | |
| download | otp-62473daf8169a04a07409f344d938bc51a4536c3.tar.gz otp-62473daf8169a04a07409f344d938bc51a4536c3.tar.bz2 otp-62473daf8169a04a07409f344d938bc51a4536c3.zip | |
Introduce swap_temp/3 and swap/2
Sequences of three move instructionst that effectively swap the
contents of two registers are fairly common. We can replace them
with a swap_temp/3 instruction. The third operand is the temporary
register to be used for swapping, since the temporary register
may actually be used.
If swap_temp/3 instruction is followed by a call, the temporary
register will often (but not always) be killed by the call. If
it is killed, we can replace the swap_temp/3 instruction with a
slightly cheaper swap/2 instruction.
| -rw-r--r-- | erts/emulator/beam/beam_emu.c | 14 | ||||
| -rw-r--r-- | erts/emulator/beam/beam_load.c | 6 | ||||
| -rw-r--r-- | erts/emulator/beam/ops.tab | 28 |
3 files changed, 48 insertions, 0 deletions
diff --git a/erts/emulator/beam/beam_emu.c b/erts/emulator/beam/beam_emu.c index 2c10e7ae7c..4e6e7aa48a 100644 --- a/erts/emulator/beam/beam_emu.c +++ b/erts/emulator/beam/beam_emu.c @@ -545,6 +545,20 @@ void** beam_ops; HTOP += 2; \ } while (0) +#define Swap(R1, R2) \ + do { \ + Eterm V = R1; \ + R1 = R2; \ + R2 = V; \ + } while (0) + +#define SwapTemp(R1, R2, Tmp) \ + do { \ + Eterm V = R1; \ + R1 = R2; \ + R2 = Tmp = V; \ + } while (0) + #define Move(Src, Dst, Store) \ do { \ Eterm term = (Src); \ diff --git a/erts/emulator/beam/beam_load.c b/erts/emulator/beam/beam_load.c index 871c2b1f55..1e3690fcd6 100644 --- a/erts/emulator/beam/beam_load.c +++ b/erts/emulator/beam/beam_load.c @@ -2702,6 +2702,12 @@ same_label(LoaderState* stp, GenOpArg Target, GenOpArg Label) Target.val == Label.val; } +static int +is_killed(LoaderState* stp, GenOpArg Reg, GenOpArg Live) +{ + return Reg.type == TAG_x && Live.type == TAG_u && + Live.val <= Reg.val; +} /* * Generate an instruction for element/2. diff --git a/erts/emulator/beam/ops.tab b/erts/emulator/beam/ops.tab index 97525c3b72..386de0a658 100644 --- a/erts/emulator/beam/ops.tab +++ b/erts/emulator/beam/ops.tab @@ -303,6 +303,34 @@ move_window3 x x x y move_window4 x x x x y move_window5 x x x x x y +# Swap registers. +move R1=x Tmp=x | move R2=xy R1 | move Tmp R2 => swap_temp R1 R2 Tmp + +swap_temp R1 R2 Tmp | line Loc | apply Live | is_killed(Tmp, Live) => \ + swap R1 R2 | line Loc | apply Live + +swap_temp R1 R2 Tmp | line Loc | call Live Addr | is_killed(Tmp, Live) => \ + swap R1 R2 | line Loc | call Live Addr +swap_temp R1 R2 Tmp | call_only Live Addr | \ + is_killed(Tmp, Live) => swap R1 R2 | call_only Live Addr +swap_temp R1 R2 Tmp | call_last Live Addr D | \ + is_killed(Tmp, Live) => swap R1 R2 | call_last Live Addr D + +swap_temp R1 R2 Tmp | line Loc | call_ext Live Addr | is_killed(Tmp, Live) => \ + swap R1 R2 | line Loc | call_ext Live Addr +swap_temp R1 R2 Tmp | line Loc | call_ext_only Live Addr | \ + is_killed(Tmp, Live) => swap R1 R2 | line Loc | call_ext_only Live Addr +swap_temp R1 R2 Tmp | line Loc | call_ext_last Live Addr D | \ + is_killed(Tmp, Live) => swap R1 R2 | line Loc | call_ext_last Live Addr D + +%macro: swap_temp SwapTemp -pack +swap_temp x x x +swap_temp x y x + +%macro: swap Swap -pack +swap x x +swap x y + move Src=x D1=x | move Src=x D2=x => move_dup Src D1 D2 move Src=x SD=x | move SD=x D=x => move_dup Src SD D move Src=x D1=x | move Src=x D2=y => move_dup Src D1 D2 |