Imp-def is *not* allowed to redefine a live register.
Imp-use is *not* allowed to use a dead register.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@78106 91177308-0d34-0410-b5e6-96231b3b80d8
killed by another operand.
There is probably a better fix. Either 1) scavenger can look at other operands, or
2) livevariables can be smarter about kill markers. Patches welcome.
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Allow imp-def and imp-use of anything in the scavenger asserts, just like the machine code verifier.
Allow redefinition of a sub-register of a live register.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77904 91177308-0d34-0410-b5e6-96231b3b80d8
Reserved registers are not candidates for scavenging, and they were removed
from the candidate list like this:
CreateRegClassMask(RC, Candidates);
Candidates ^= ReservedRegs;
However, when there are reserved registers outside RC, this causes invalid
bits to be set in Candidates.
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Note, isUndef marker must be placed even on implicit_def def operand or else the scavenger will not ignore it. This is necessary because -O0 path does not use liveintervalanalysis, it treats implicit_def just like any other def.
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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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register destinations that are tied to source operands. The
TargetInstrDescr::findTiedToSrcOperand method silently fails for inline
assembly. The existing MachineInstr::isRegReDefinedByTwoAddr was very
close to doing what is needed, so this revision makes a few changes to
that method and also renames it to isRegTiedToUseOperand (for consistency
with the very similar isRegTiedToDefOperand and because it handles both
two-address instructions and inline assembly with tied registers).
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- When scavenging a register, in addition to the spill, insert a restore before the first use.
- Abort if client is looking to scavenge a register even when a previously scavenged register is still live.
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2. Coalescer can now create an interesting situation where a register def can
reaches itself without being killed.
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%r3<def> = OR %x3<kill>, %x3
We don't want to mark the %r3 as unused even though it's a sub-register of %x3.
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that it is cheap and efficient to get.
Move a variety of predicates from TargetInstrInfo into
TargetInstrDescriptor, which makes it much easier to query a predicate
when you don't have TII around. Now you can use MI->getDesc()->isBranch()
instead of going through TII, and this is much more efficient anyway. Not
all of the predicates have been moved over yet.
Update old code that used MI->getInstrDescriptor()->Flags to use the
new predicates in many places.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@45674 91177308-0d34-0410-b5e6-96231b3b80d8
