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IDProjectCategoryView StatusDate SubmittedLast Update
0038285FPCCompilerpublic2020-12-31 11:062020-12-31 16:53
ReporterChristo Crause Assigned ToFlorian  
PrioritynormalSeverityminorReproducibilityN/A
Status closedResolutionfixed 
Product Version3.3.1 
Fixed in Version3.3.1 
Summary0038285: AVR [patch] Fix missed optimization opportunities
DescriptionSome of the optimizations in PeepHoleOptPass1 do not return true, thus preventing possible further optimizations in short units.

An example of this is shown below. It is expected that the intermediate code generated should trigger the InOriOut2Sbi optimization, however the optimizer didn't perform an extra pass because the previous Lds2In optimization didn't return true. This happens even at -O4.

Attached please find a patch that sets result for all optimizations that previously didn't set result to fix this specific problem and other potential missed opportunities.
Steps To Reproduceprogram sbitest;

begin
  EECR := EECR or 4;
end.

Compile with ~/fpc/3.3.1/compiler/ppcrossavr -Tembedded -Pavr -MObjFPC -Scghim -O2 -gw3 -vewnhibq -n @~/fpc/3.3.1/fpc.cfg -Wpatmega328p -XPavr- -al sbitest.pp

Note generated code:
# [15] EECR := EECR or 4;
    in r18,31
    ori r18,4
    out 31,r18

This isn't the expected sbi instruction.
TagsNo tags attached.
Fixed in Revision47915
FPCOldBugId
FPCTarget-
Attached Files

Activities

Christo Crause

2020-12-31 11:06

reporter  

aoptcpu.patch (1,207 bytes)    
diff --git a/compiler/avr/aoptcpu.pas b/compiler/avr/aoptcpu.pas
index b64a27df71..031633d92f 100644
--- a/compiler/avr/aoptcpu.pas
+++ b/compiler/avr/aoptcpu.pas
@@ -423,7 +423,7 @@ Implementation
 
                             DebugMsg('Peephole LdiOp2Opi performed', p);
 
-                            RemoveCurrentP(p);
+                            result:=RemoveCurrentP(p);
                           end;
                       end;
                   end;
@@ -447,6 +447,7 @@ Implementation
                         taicpu(p).loadconst(0,taicpu(p).oper[0]^.ref^.offset)
                       else
                         taicpu(p).loadconst(0,taicpu(p).oper[0]^.ref^.offset-32);
+                      result:=true;
                     end;
                 A_LDS:
                   if (taicpu(p).oper[1]^.ref^.symbol=nil) and
@@ -468,6 +469,8 @@ Implementation
                         taicpu(p).loadconst(1,taicpu(p).oper[1]^.ref^.offset)
                       else
                         taicpu(p).loadconst(1,taicpu(p).oper[1]^.ref^.offset-32);
+
+                      result:=true;
                     end;
                 A_IN:
                     if GetNextInstruction(p,hp1) then
aoptcpu.patch (1,207 bytes)   

Florian

2020-12-31 16:36

administrator   ~0127975

Thanks, applied.

Christo Crause

2020-12-31 16:53

reporter   ~0127977

Thanks!

Issue History

Date Modified Username Field Change
2020-12-31 11:06 Christo Crause New Issue
2020-12-31 11:06 Christo Crause File Added: aoptcpu.patch
2020-12-31 16:36 Florian Assigned To => Florian
2020-12-31 16:36 Florian Status new => resolved
2020-12-31 16:36 Florian Resolution open => fixed
2020-12-31 16:36 Florian Fixed in Version => 3.3.1
2020-12-31 16:36 Florian Fixed in Revision => 47915
2020-12-31 16:36 Florian FPCTarget => -
2020-12-31 16:36 Florian Note Added: 0127975
2020-12-31 16:53 Christo Crause Status resolved => closed
2020-12-31 16:53 Christo Crause Note Added: 0127977