(OP (trunc x), (trunc y)) -> (trunc (OP x, y))
Unfortunately this simple change causes dag combine to infinite looping. The problem is the shrink demanded ops optimization tend to canonicalize expressions in the opposite manner. That is badness. This patch disable those optimizations in dag combine but instead it is done as a late pass in sdisel.
This also exposes some deficiencies in dag combine and x86 setcc / brcond lowering. Teach them to look pass ISD::TRUNCATE in various places.
llvm-svn: 92849
phi nodes when deciding which pointers point to local memory.
I actually checked long ago how useful this is, and it isn't
very: it hardly ever fires in the testsuite, but since Chris
wants it here it is!
llvm-svn: 92836
memcpy, memset and other intrinsics that only access their arguments
to be readnone if the intrinsic's arguments all point to local memory.
This improves the testcase in the README to readonly, but it could in
theory be made readnone, however this would involve more sophisticated
analysis that looks through the memcpy.
llvm-svn: 92829
Previously, instcombine would only promote an expression tree to
the larger type if doing so eliminated two casts. This is because
a need to manually do the sign extend after the promoted expression
tree with two shifts. Now, we keep track of whether the result of
the computation is going to be properly sign extended already. If
so, we can unconditionally promote the expression, which allows us
to zap more sext's.
This implements rdar://6598839 (aka gcc pr38751)
llvm-svn: 92815
An instruction like this:
%reg1097:1<def> = VMOVSR %R3<kill>, 14, %reg0
Must be replaced with this when substituting physical registers:
%S0<def> = VMOVSR %R3<kill>, 14, %reg0, %D0<imp-def>
llvm-svn: 92812
It is enough to give the super registers CR0, CR1, ..., and specifying the
sub-registers as well causes confusion in the liveness computations.
llvm-svn: 92778
A phi operand that is implicitly defined in a predecessor becomes an undefined
register after phi elimination. This causes a lot of false positives when the
verifier is checking if live-in registers are live-out from all predecessors.
Removing the verifier checks seems like a better solution than insisting on
IMPLICIT_DEF instructions in predecessor blocks.
llvm-svn: 92769
