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Diffstat (limited to 'lib/hipe/doc/src/hipe_app.xml')
| -rw-r--r-- | lib/hipe/doc/src/hipe_app.xml | 84 |
1 files changed, 75 insertions, 9 deletions
diff --git a/lib/hipe/doc/src/hipe_app.xml b/lib/hipe/doc/src/hipe_app.xml index 9299c6d73f..63bc6ea2d7 100644 --- a/lib/hipe/doc/src/hipe_app.xml +++ b/lib/hipe/doc/src/hipe_app.xml @@ -4,7 +4,7 @@ <appref> <header> <copyright> - <year>1997</year><year>2016</year> + <year>1997</year><year>2018</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -35,6 +35,14 @@ <app>HiPE</app> <appsummary>The HiPE Application</appsummary> <description> + <note> + <p> + HiPE and execution of HiPE compiled code only have limited support by + the OTP team at Ericsson. The OTP team only does limited maintenance + of HiPE and does not actively develop HiPE. HiPE is mainly supported + by the HiPE team at Uppsala University. + </p> + </note> <p> The normal way to native-compile an Erlang module using HiPE is to include the atom native in the Erlang compiler options, as in:</p> @@ -100,16 +108,74 @@ </item> <tag>Optimization for <c>receive</c> with unique references</tag> - <item><p>The BEAM compiler can do an optimization when - a <c>receive</c> statement is <em>only</em> waiting for messages - containing a reference created before the receive. All messages - that existed in the queue when the reference was created will be - bypassed, as they cannot possibly contain the reference. HiPE - does not implement this optimization.</p> - <p>An example of this is when - <c>gen_server:call()</c> waits for the reply message.</p> + <item> + <p> + The BEAM compiler can do an optimization when a receive + statement is only waiting for messages containing a reference + created before the receive. All messages that existed in the + queue when the reference was created will be bypassed, as they + cannot possibly contain the reference. HiPE currently has an + optimization similar this, but it is not guaranteed to + bypass all messages. In the worst case scenario, it cannot + bypass any messages at all. + </p> + <p> + An example of this is when <c>gen_server:call()</c> waits for + the reply message. + </p> </item> + <tag>Garbage collection after BIFs</tag> + <item> + <p> + The condition for determining whether a garbage collection + is needed or not has changed in later releases. HiPE has not + been updated regarding this which may cause premature garbage + collections after BIF calls. + </p> + </item> + + </taglist> + </section> + <section> + <title>Stability Issues</title> + <taglist> + <tag>Not checking reduction count on function returns</tag> + <item> + <p> + BEAM checks the reduction count and schedules out the executing + process if needed both when calling a function and when returning + from a function call that was not called using a tail call. + HiPE only checks the reduction count when calling a function. + </p> + <p> + The runtime system might need to schedule out a process + in order to reclaim memory. If the process isn't scheduled + out soon after the process has entered this state, memory + consumption will quickly grow. Maintaining this state is also + quite expensive performance wise. + </p> + <p> + Processes executing code that performs large recursions and + produce data after returning from recursive calls may have to + be scheduled out when returning from a function call. Since + HiPE does not check reductions on returns, processes executing + such HiPE compiled code may cause huge peeks in memory + consumption as well as severe performance degradation. + </p> + </item> + + <tag>Not bumping appropriate amount of reductions in <c>receive</c> statements</tag> + <item> + <p> + The process signaling improvements made in ERTS version + 10.0 moved potentially significant amounts of work into the + receive statement from other places. In order to account for + this work, the reduction count should be bumped on the + executing process. Reductions are not bumped when entering + the <c>receive</c> statement from HiPE compiled code. + </p> + </item> </taglist> </section> <section> |