It can be necessary to detach a register mask pointer from its
MachineOperand. This method is convenient for checking clobbered
physregs on a detached bitmask pointer.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150261 91177308-0d34-0410-b5e6-96231b3b80d8
It doesn't seem worthwhile to give meaning to a NULL register mask
pointer. It complicates all the code using register mask operands.
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Register masks will be used as a compact representation of large clobber
lists. Currently, an x86 call instruction has some 40 operands
representing call-clobbered registers. That's more than 1kB of useless
operands per call site.
A register mask operand references a bit mask of call-preserved
registers, everything else is clobbered. The bit mask will typically
come from TargetRegisterInfo::getCallPreservedMask().
By abandoning ImplicitDefs for call-clobbered registers, it also becomes
possible to share call instruction descriptions between calling
conventions, and we can get rid of the WINCALL* instructions.
This patch introduces the new operand kind. Future patches will add
RegMask support to target-independent passes before finally the fixed
clobber lists can be removed from call instruction descriptions.
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This flag is used when bundling machine instructions. It indicates
whether the operand reads a value defined inside or outside its bundle.
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The <undef> flag says that a MachineOperand doesn't read its register,
or doesn't depend on the previous value of its register.
A full register def never depends on the previous register value. A
partial register def may depend on the previous value if it is intended
to update part of a register.
For example:
%vreg10:dsub_0<def,undef> = COPY %vreg1
%vreg10:dsub_1<def> = COPY %vreg2
The first copy instruction defines the full %vreg10 register with the
bits not covered by dsub_0 defined as <undef>. It is not considered a
read of %vreg10.
The second copy modifies part of %vreg10 while preserving the rest. It
has an implicit read of %vreg10.
This patch adds a MachineOperand::readsReg() method to determine if an
operand reads its register.
Previously, this was modelled by adding a full-register <imp-def>
operand to the instruction. This approach makes it possible to
determine directly from a MachineOperand if it reads its register. No
scanning of MI operands is required.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@141124 91177308-0d34-0410-b5e6-96231b3b80d8
of using a Location class with the same information.
When making a copy of a MachineOperand that was already stored in a
MachineInstr, it is necessary to clear the parent pointer on the copy. Otherwise
the register use-def lists become inconsistent.
Add MachineOperand::clearParent() to do that. An alternative would be a custom
MachineOperand copy constructor that cleared ParentMI. I didn't want to do that
because of the performance impact.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123109 91177308-0d34-0410-b5e6-96231b3b80d8
Pull an unsigned out of the Contents union such that it has the same size as two
pointers and no padding.
Arrange members such that the Contents union and all pointers can be 8-byte
aligned without padding.
This speeds up code generation by 0.8% on a 64-bit host. 32-bit hosts should be
unaffected.
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implementation that is correct for most targets. Tablegen will override where
needed.
Add MachineOperand::subst{Virt,Phys}Reg methods that correctly handle existing
subreg indices when sustituting registers.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@104985 91177308-0d34-0410-b5e6-96231b3b80d8
Here is a theoretical example that illustrates why the placement is important.
tmp1 =
store tmp1 -> x
...
tmp2 = add ...
...
call
...
store tmp2 -> x
Now mem2reg comes along:
tmp1 =
dbg_value (tmp1 -> x)
...
tmp2 = add ...
...
call
...
dbg_value (tmp2 -> x)
When the debugger examine the value of x after the add instruction but before the call, it should have the value of tmp1.
Furthermore, for dbg_value's that reference constants, they should not be emitted at the beginning of the block (since they do not have "producers").
This patch also cleans up how SDISel manages DbgValue nodes. It allow a SDNode to be referenced by multiple SDDbgValue nodes. When a SDNode is deleted, it uses the information to find the SDDbgValues and invalidate them. They are not deleted until the corresponding SelectionDAG is destroyed.
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are from debug info. Add an iterator to MachineRegisterInfo
to skip Debug operands when walking the use list. No
functional change yet.
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MachineInstr and MachineOperand. This required eliminating a
bunch of stuff that was using DOUT, I hope that bill doesn't
mind me stealing his fun. ;-)
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The register allocator, when it allocates a register to a virtual register defined by an implicit_def, can allocate any physical register without worrying about overlapping live ranges. It should mark all of operands of the said virtual register so later passes will do the right thing.
This is not the best solution. But it should be a lot less fragile to having the scavenger try to track what is defined by implicit_def.
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and add a TargetLowering hook for it to use to determine when this
is legal (i.e. not in PIC mode, etc.)
This allows instruction selection to emit folded constant offsets
in more cases, such as the included testcase, eliminating the need
for explicit arithmetic instructions.
This eliminates the need for the C++ code in X86ISelDAGToDAG.cpp
that attempted to achieve the same effect, but wasn't as effective.
Also, fix handling of offsets in GlobalAddressSDNodes in several
places, including changing GlobalAddressSDNode's offset from
int to int64_t.
The Mips, Alpha, Sparc, and CellSPU targets appear to be
unaware of GlobalAddress offsets currently, so set the hook to
false on those targets.
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RA problem by expanding the live interval of an
earlyclobber def back one slot. Remove
overlap-earlyclobber throughout. Remove
earlyclobber bits and their handling from
live internals.
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with an earlyclobber operand elsewhere. Propagate
this bit and the earlyclobber bit through SDISel.
Change linear-scan RA not to allocate regs in a way
that conflicts with an earlyclobber. See also comments.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@56290 91177308-0d34-0410-b5e6-96231b3b80d8
