in addition to ZERO_EXTEND and SIGN_EXTEND. Fix a bug in the
way it checked for live-out values, and simplify the way it
find users by using SDNode::use_iterator's (relatively) new
features. Also, make it slightly more permissive on targets
with free truncates.
In SelectionDAGBuild, avoid creating ANY_EXTEND nodes that are
larger than necessary. If the target's SwitchAmountTy has
enough bits, use it. This exposes the truncate to optimization
early, enabling more optimizations.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@68670 91177308-0d34-0410-b5e6-96231b3b80d8
eagerly. This helps avoid CopyToReg nodes in some cases where they
aren't needed, and also helps subsequent optimizer heuristics
in cases where the extra nodes would cause the node to appear
to have multiple results. This doesn't have a significant impact
currently; it'll help an upcoming change.
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avoiding sign extension for the top octet. For "negative" chars, we'd print
stuff like:
.asciz "\702...
now we print:
.asciz "\302...
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@68577 91177308-0d34-0410-b5e6-96231b3b80d8
with SUBREG_TO_REG, teach SimpleRegisterCoalescing to coalesce
SUBREG_TO_REG instructions (which are similar to INSERT_SUBREG
instructions), and teach the DAGCombiner to take advantage of this on
targets which support it. This eliminates many redundant
zero-extension operations on x86-64.
This adds a new TargetLowering hook, isZExtFree. It's similar to
isTruncateFree, except it only applies to actual definitions, and not
no-op truncates which may not zero the high bits.
Also, this adds a new optimization to SimplifyDemandedBits: transform
operations like x+y into (zext (add (trunc x), (trunc y))) on targets
where all the casts are no-ops. In contexts where the high part of the
add is explicitly masked off, this allows the mask operation to be
eliminated. Fix the DAGCombiner to avoid undoing these transformations
to eliminate casts on targets where the casts are no-ops.
Also, this adds a new two-address lowering heuristic. Since
two-address lowering runs before coalescing, it helps to be able to
look through copies when deciding whether commuting and/or
three-address conversion are profitable.
Also, fix a bug in LiveInterval::MergeInClobberRanges. It didn't handle
the case that a clobber range extended both before and beyond an
existing live range. In that case, multiple live ranges need to be
added. This was exposed by the new subreg coalescing code.
Remove 2008-05-06-SpillerBug.ll. It was bugpoint-reduced, and the
spiller behavior it was looking for no longer occurrs with the new
instruction selection.
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Note that these are distinct from TargetInstrInfo::INSERT_SUBREG
and TargetInstrInfo::EXTRACT_SUBREG, which are used.
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entered via fall-through. Don't miss fallthroughs from blocks
terminated by conditional branches. Also, move
isOnlyReachableByFallthrough out of line.
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e.g.
%reg1024<def> = MOV r1
%reg1025<def> = ADD %reg1024, %reg1026
r0 = MOV %reg1025
If it's not possible / profitable to commute ADD, then turning ADD into a LEA saves a copy.
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x * 40
=>
shlq $3, %rdi
leaq (%rdi,%rdi,4), %rax
This has the added benefit of allowing more multiply to be folded into addressing mode. e.g.
a * 24 + b
=>
leaq (%rdi,%rdi,2), %rax
leaq (%rsi,%rax,8), %rax
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Also fixes SDISel so it *does not* force promote return value if the function is not marked signext / zeroext.
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stoppoint nodes around until Legalize; doing this
imposed an ordering on a sequence of loads that
came from different lines, interfering with scheduling.
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help out the register pressure reduction heuristics in the case of
nodes with multiple uses. Currently this uses very conservative
heuristics, so it doesn't have a broad impact, but in cases where it
does help it can make a big difference.
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e.g. allocating for GR32, bh is not used, updating bl spill weight.
bl should get the same spill weight otherwise it will be choosen
as a spill candidate since spilling bh doesn't make ebx available.
This fix PR2866.
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same as a normal i80 {low64, high16} rather
than its own {high64, low16}. A depressing number
of places know about this; I think I got them all.
Bitcode readers and writers convert back to the old
form to avoid breaking compatibility.
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a data dependency on the load node, so it really needs a
data-dependence edge to the load node, even if the load previously
existed.
And add a few comments.
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