This patch improves the compiler where "case" statements are concerned, using jump tables more often and creating more efficient machine code in some situations:
* If a case block only contains one branch (not including the else block), the initial range check is removed, since this becomes wasted effort.
* If the else block is empty, the else label is set to the end label - though this doesn't decrease the code size, it takes a bit of strain off the peephole optimizer.
* On -O2 and above, some node analysis is now done on the branch labels. Most of the time this just redirects it to the end
label for empty blocks, but if the block contains a goto statement, it will redirect it to its destination instead,
thus increasing performance by not having multiple jumps (this won't get picked up by the peephole optimiser if the label addresses are in a jump table).
* Some checks now use what I call the 'true count' rather than the 'label count'. The true count includes each
individual value in a range - for example, 0..2 counts as 3. This increases the chance that a jump table will be
utilised in situations where it is more efficient than a linear list.
* For jump tables, if the case block almost covers the entire range (32 entries or fewer from full coverage),
the initial range check is removed and the gaps included in the jump table (pointing to the else label).
git-svn-id: trunk@40676 -
* disable matching volatile references in the assembler optimisers, so they
can't be removed (more conservative than needed, but better than removing
too many)
o the CSE optimiser will ignore them by default, because they're an unknown
inline node for it
* also removed no longer used fpc_in_move_x and fpc_in_fillchar_x inline node
identifiers from rtl/inc/innr.inc, and placed fpc_in_unaligned_x at the
right place
git-svn-id: trunk@40465 -
in the i8086-msdos 'ports' unit, but will be enabled on other targets (e.g.
go32v2) in the future as well. 32-bit 'in' and 'out' not inlined on i8086, but
will be on i386 and x86_64.
git-svn-id: trunk@39362 -
registers to -1 in x86reg.dat. The values that used to be there weren't used
at all (most were just copies of the 32-bit version of the register). This can
be easily demonstrated by the fact that running 'make regdat' in the compiler
directory doesn't change any of the generated files for i8086/i386/x86_64.
git-svn-id: trunk@39098 -
and filled it with the dwarf register mapping, used by Open Watcom (Watcom
also uses this mapping on i386, but we don't need to support their debugger on
i386 for now)
git-svn-id: trunk@39097 -
calling conventions on i386
* generated code at the caller side for pocall_pascal routines on i386 no longer
assumes the routine destroys all registers (except ebp) - instead now it
assumes that it preserves the ebx,esi,edi and ebp registers. This is
compatible with the pascal calling convention of 32-bit delphi and was already
honoured by FPC on the callee side.
* updated the list of calling conventions that save all registers, used in
tx86callnode.can_call_ref, so it is accurate on all x86 platforms - i8086,
i386 and x86_64.
git-svn-id: trunk@38904 -
