and the RegisterScavenger not to expect traditional liveness
techniques are applicable to these registers, since we don't fully
modify the effects of push and pop after stackification.
llvm-svn: 61179
my last patch to this file.
The issue there was that all uses of an IV inside a loop
are actually references to Base[IV*2], and there was one
use outside that was the same but LSR didn't see the base
or the scaling because it didn't recurse into uses outside
the loop; thus, it used base+IV*scale mode inside the loop
instead of pulling base out of the loop. This was extra bad
because register pressure later forced both base and IV into
memory. Doing that recursion, at least enough
to figure out addressing modes, is a good idea in general;
the change in AddUsersIfInteresting does this. However,
there were side effects....
It is also possible for recursing outside the loop to
introduce another IV where there was only 1 before (if
the refs inside are not scaled and the ref outside is).
I don't think this is a common case, but it's in the testsuite.
It is right to be very aggressive about getting rid of
such introduced IVs (CheckForIVReuse and the handling of
nonzero RewriteFactor in StrengthReduceStridedIVUsers).
In the testcase in question the new IV produced this way
has both a nonconstant stride and a nonzero base, neither
of which was handled before. (This patch does not handle
all the cases where this can happen.) And when inserting
new code that feeds into a PHI, it's right to put such
code at the original location rather than in the PHI's
immediate predecessor(s) when the original location is outside
the loop (a case that couldn't happen before)
(RewriteInstructionToUseNewBase); better to avoid making
multiple copies of it in this case.
Everything above is exercised in
CodeGen/X86/lsr-negative-stride.ll (and ifcvt4 in ARM which is
the same IR).
llvm-svn: 61178
- ability to insert previously created instructions using a builder
- creation of aliases
- creation of inline asm constants
Patch by Zoltan Varga!
llvm-svn: 61153
nodes. This allows it to do fairly general phi insertion if a
load from a pointer global wants to be SRAd but the load is used
by (recursive) phi nodes. This fixes a pessimization on ppc
introduced by Load PRE.
llvm-svn: 61123
temporary workaround for an obscure bug. When node cloning is
used, it is possible that more SUnits will be created, and
if the SUnits std::vector has to reallocate, it will
invalidate all the graph edges.
llvm-svn: 61122
consistently for deleting branches. In addition to being slightly
more readable, this makes SimplifyCFG a bit better
about cleaning up after itself when it makes conditions unused.
llvm-svn: 61100
