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| author | Magnus Lång <[email protected]> | 2016-11-09 18:47:12 +0100 |
|---|---|---|
| committer | Magnus Lång <[email protected]> | 2016-11-15 14:58:59 +0100 |
| commit | c91c523f1ca58644267402325b6fb59d65049829 (patch) | |
| tree | c355fdf2a07ff894cbb8f1cc1bea7abcb889dd0b /lib/hipe/rtl | |
| parent | ca0fbe891d0f8278b4824d6b2c5db4cd01fcef5c (diff) | |
| download | otp-c91c523f1ca58644267402325b6fb59d65049829.tar.gz otp-c91c523f1ca58644267402325b6fb59d65049829.tar.bz2 otp-c91c523f1ca58644267402325b6fb59d65049829.zip | |
hipe_rtl: drop alub dest when unused
Diffstat (limited to 'lib/hipe/rtl')
| -rw-r--r-- | lib/hipe/rtl/hipe_rtl.erl | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/lib/hipe/rtl/hipe_rtl.erl b/lib/hipe/rtl/hipe_rtl.erl index e4e857ec43..d39969a0ed 100644 --- a/lib/hipe/rtl/hipe_rtl.erl +++ b/lib/hipe/rtl/hipe_rtl.erl @@ -334,6 +334,7 @@ defines/1, redirect_jmp/3, is_safe/1, + reduce_unused/1, %% highest_var/1, pp/1, pp/2, @@ -1314,6 +1315,24 @@ is_safe(Instr) -> #switch{} -> false %% Maybe this is safe... end. +%% @spec reduce_unused(rtl_instruction()) +%% -> false | [rtl_instruction()]. +%% +%% @doc Produces a simplified instruction sequence that is equivalent to [Instr] +%% under the assumption that all results of Instr are unused, or 'false' if +%% there is no such sequence (other than [Instr] itself). + +reduce_unused(Instr) -> + case Instr of + #alub{dst=Dst} when Dst =/= [] -> + [Instr#alub{dst=[]}]; + _ -> + case is_safe(Instr) of + true -> []; + false -> false + end + end. + %% %% True if argument is an alu-operator %% |