Hello,
I have an event driven simulator that uses a switch statement for
executing the next event. Currently, the loop is so tight that
removing the bound checks from the switch increased performance by
10%. This I observed halfway in converting from ints to enums for the
reactions. However, there were bugs at that point and with these
removed the checks were there again (I verified this by looking at the
asm).
The code is too big for this post, but I define the reaction type as follows:
enum reaction_T {RDEF=0, R1=1, R2=2, R3=3, R4=4, R5=5, R6=6};
The program has a const array of the above type to store the
dependency graph (that is why I define the values of the enums) and
two switch statements that lists all the cases.
The program compiles without warnings on a x86_64: g++ (Ubuntu
4.3.2-1ubuntu12) 4.3.2 with
g++ -Wall -Winline -ftree-vectorizer-verbose=0 -pedantic -ansi -O3
-mtune=native -march=native -fno-strict-aliasing -lm -c sim.cc
The program seems to by type safe so the bounds checks should be
removed. Is there any way enforce the removal of the bound checks or
some compiler switch that could give a hint of what is wrong?
Best regards,
Henrik Mannerström
