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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 /erts/emulator/beam/beam_load.c | |
| 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.
Diffstat (limited to 'erts/emulator/beam/beam_load.c')
| -rw-r--r-- | erts/emulator/beam/beam_load.c | 6 |
1 files changed, 6 insertions, 0 deletions
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. |