Early clobbers defining a virtual register were first alocated to a physreg and
then processed as a physreg EC, spilling the virtreg.

This fixes PR7382.

llvm-svn: 105998

Given a copy instruction, CoalescerPair can determine which registers to
coalesce in order to eliminate the copy. It deals with all the subreg fun to
determine a tuple (DstReg, SrcReg, SubIdx) such that:

- SrcReg is a virtual register that will disappear after coalescing.
- DstReg is a virtual or physical register whose live range will be extended.
- SubIdx is 0 when DstReg is a physical register.
- SrcReg can be joined with DstReg:SubIdx.

CoalescerPair::isCoalescable() determines if another copy instruction is
compatible with the same tuple. This fixes some NEON miscompilations where
shuffles are getting coalesced as if they were copies.

The CoalescerPair class will replace a lot of the spaghetti logic in JoinCopy
later.

llvm-svn: 105997

replacing the overly conservative checks that I had introduced recently to
deal with correctness issues.  This makes a pretty noticable difference
in our testcases where reg_sequences are used.  I've updated one test to
check that we no longer emit the unnecessary subreg moves.

llvm-svn: 105991

llvm-svn: 105987

Make sure to skip the dbg_value instructions when moving dups out of the
diamond. rdar://7797940

llvm-svn: 105965

- Rename ExactHazardRecognizer to PostRAHazardRecognizer and move its header to include to allow targets to extend it.

llvm-svn: 105959

llvm-svn: 105955

llvm-svn: 105942

clean-up to a catch-all after inlining, take into account that there could be
filter IDs as well. The presence of filters don't mean that the selector catches
anything. It's just metadata information.

llvm-svn: 105872

llvm-svn: 105862

llvm-svn: 105861

llvm-svn: 105828

llvm-svn: 105775

This is a bit of a hack to make inline asm look more like call instructions.
It would be better to produce correct dead flags during isel.

llvm-svn: 105749

Allow target to place 2-address pass inserted copies in better spots. Thumb2 will use this to try to avoid breaking up IT blocks.

llvm-svn: 105745

   %reg1025 = <sext> %reg1024
    ...
   %reg1026 = SUBREG_TO_REG 0, %reg1024, 4

into this:

   %reg1025 = <sext> %reg1024
    ...
   %reg1027 = EXTRACT_SUBREG %reg1025, 4
   %reg1026 = SUBREG_TO_REG 0, %reg1027, 4

The problem here is that SUBREG_TO_REG is there to assert that an implicit zext
occurs. It doesn't insert a zext instruction. If we allow the EXTRACT_SUBREG
here, it will give us the value after the <sext>, not the original value of
%reg1024 before <sext>.

llvm-svn: 105741

llvm-svn: 105665

that it is an immediate before checking that the instruction is an
EXTRACT_SUBREG.

llvm-svn: 105585

llvm-svn: 105561

llvm-svn: 105554

llvm-svn: 105541

llvm-svn: 105511

I don't think this ever resulted in problems on x86, but it
would on ARM.

llvm-svn: 105509

llvm-svn: 105502

llvm-svn: 105498

llvm-svn: 105492

llvm-svn: 105481

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

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

llvm-svn: 105435

needs to demand the high bits because it's asserting that they're zero.

llvm-svn: 105406

llvm-svn: 105399

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

llvm-svn: 105379

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

This affects both llvm-gcc and clang.

llvm-svn: 105372

spills and reloads.

This means that a partial define of a register causes a reload so the other
parts of the register are preserved.

The reload can be prevented by adding an <imp-def> operand for the full
register. This is already done by the coalescer and live interval analysis where
relevant.

llvm-svn: 105369

register updates.

These operands tell the spiller that the other parts of the partially defined
register are don't-care, and a reload is not necessary.

llvm-svn: 105361

llvm-svn: 105359