BBNumbers. Instead of using a bi-directional mapping, just use a single
densemap. This speeds up mem2reg on 176.gcc by 8%, from 1.3489 to
1.2485s.
llvm-svn: 33940
nondeterminism being bad) could cause some trivial missed optimizations (dead
phi nodes being left around for later passes to clean up).
With this, llvm-gcc4 now bootstraps and correctly compares. I don't know
why I never tried to do it before... :)
llvm-svn: 27984
has a single def. In this case, look for uses that are dominated by the def
and attempt to rewrite them to directly use the stored value.
This speeds up mem2reg on these values and reduces the number of phi nodes
inserted. This should address PR665.
llvm-svn: 24411
BasicBlock's removePredecessor routine. This requires shuffling around
the definition and implementation of hasContantValue from Utils.h,cpp into
Instructions.h,cpp
llvm-svn: 22664
The optimization for locally used allocas was not safe for allocas that
were read before they were written. This change disables that optimization
in that case.
llvm-svn: 22318
unneccesary. This allows us to delete several hundred phi nodes of the
form PHI(x,x,x,undef) from 253.perlbmk and probably other programs as well.
This implements Mem2Reg/UndefValuesMerge.ll
llvm-svn: 17098
whose addresses where used by trivial phi nodes and select instructions. This
is now performed by the instcombine pass, which is more powerful, is much
simpler, and is faster. This allows the deletion of a bunch of code, two
FIXME's and two gotos.
llvm-svn: 16406
Move include/Config and include/Support into include/llvm/Config,
include/llvm/ADT and include/llvm/Support. From here on out, all LLVM
public header files must be under include/llvm/.
llvm-svn: 16137
non-deterministic things like the ordering of blocks in the dominance
frontier of a BB. Unfortunately, I don't know of a better way to solve
this problem than to explicitly sort the BB's in function-order before
processing them. This is guaranteed to slow the pass down a bit, but
is absolutely necessary to get usable diffs between two different tools
executing the mem2reg or scalarrepl pass.
Before this, bazillions of spurious diff failures occurred all over the
place due to the different order of processing PHIs:
- %tmp.111 = getelementptr %struct.Connector_struct* %upcon.0.0, uint 0, uint 0
+ %tmp.111 = getelementptr %struct.Connector_struct* %upcon.0.1, uint 0, uint 0
Now, the diffs match.
llvm-svn: 14244
"minimal" SSA form (in other words, it doesn't insert dead PHIs). This
speeds up the mem2reg pass very significantly because it doesn't have to
do a lot of frivolous work in many common cases.
In the 252.eon function I have been playing with, this doesn't even insert
the 120 PHI nodes that it used to which were trivially dead (in the process
of promoting 356 alloca instructions overall). This speeds up the mem2reg
pass from 1.2459s to 0.1284s. More significantly, the DCE pass used to take
2.4138s to remove the 120 dead PHI nodes that mem2reg constructed, now it
takes 0.0134s (which is the time to scan the function and decide that there
is nothing dead). So overall, on this one function, we speed things up a
total of 3.5179s, which is a 24.8x speedup! :)
This change is tested by the Mem2Reg/2003-10-05-DeadPHIInsertion.ll test,
which now passes.
llvm-svn: 8884
