register allocation.
Process all of the clobber lists at the end of the function, marking the
registers as used in MachineRegisterInfo.
This is necessary in case the calls clobber callee-saved registers (sic).
llvm-svn: 105473
replace an OpA with a widened OpB, it is possible to get new uses of OpA due to CSE
when recursively updating nodes. Since OpA has been processed, the new uses are
not examined again. The patch checks if this occurred and it it did, updates the
new uses of OpA to use OpB.
llvm-svn: 105453
VECTOR_SHUFFLEs to REG_SEQUENCE instructions. The standard ISD::BUILD_VECTOR
node corresponds closely to REG_SEQUENCE but I couldn't use it here because
its operands do not get legalized. That is pretty awful, but I guess it
makes sense for other targets. Instead, I have added an ARM-specific version
of BUILD_VECTOR that will have its operands properly legalized.
This fixes the rest of Radar 7872877.
llvm-svn: 105439
Check that all the instructions are in the same basic block, that the
EXTRACT_SUBREGs write to the same subregs that are being extracted, and that
the source and destination registers are in the same regclass. Some of
these constraints can be relaxed with a bit more work. Jakob suggested
that the loop that checks for subregs when NewSubIdx != 0 should use the
"nodbg" iterator, so I made that change here, too.
llvm-svn: 105437
A temporary flag -arm-tail-calls defaults to off,
so there is no functional change by default.
Intrepid users may try this; simple cases work
but there are bugs.
llvm-svn: 105413
registers it defines then interfere with an existing preg live range.
For instance, if we had something like these machine instructions:
BB#0
... = imul ... EFLAGS<imp-def,dead>
test ..., EFLAGS<imp-def>
jcc BB#2 EFLAGS<imp-use>
BB#1
... ; fallthrough to BB#2
BB#2
... ; No code that defines EFLAGS
jcc ... EFLAGS<imp-use>
Machine sink will come along, see that imul implicitly defines EFLAGS, but
because it's "dead", it assumes that it can move imul into BB#2. But when it
does, imul's "dead" imp-def of EFLAGS is raised from the dead (a zombie) and
messes up the condition code for the jump (and pretty much anything else which
relies upon it being correct).
The solution is to know which pregs are live going into a basic block. However,
that information isn't calculated at this point. Nor does the LiveVariables pass
take into account non-allocatable physical registers. In lieu of this, we do a
*very* conservative pass through the basic block to determine if a preg is live
coming out of it.
llvm-svn: 105387
expansion is the same as that used by LegalizeDAG.
The resulting code sucks in terms of performance/codesize on x86-32 for a
64-bit operation; I haven't looked into whether different expansions might be
better in general.
llvm-svn: 105378
