RegisterCoalescer can create sub-register defs when it is joining a
register with a sub-register. Add <undef> flags to these new
sub-register defs where appropriate.
llvm-svn: 141138
It does, after all.
RemoveCopyByCommutingDef rewrites the uses of one particular value
number in A. It doesn't know how to rewrite phi uses, so there can't be
any.
llvm-svn: 139787
Instead, let HasOtherReachingDefs() test for defs in B that overlap any
phi-defs in A as well. This test is slightly different, but almost
identical.
A perfectly precise test would only check those phi-defs in A that are
reachable from AValNo.
llvm-svn: 139782
The source live range is recomputed using shrinkToUses() which does
handle phis correctly. The hasPHIKill() condition was relevant in the
old days when ReMaterializeTrivialDef() tried to recompute the live
range itself.
The shrinkToUses() function will mark the original def as dead when no
more uses and phi kills remain. It is then removed by
runOnMachineFunction().
llvm-svn: 139781
Coalescing can remove copy-like instructions with sub-register operands
that constrained the register class. Examples are:
x86: GR32_ABCD:sub_8bit_hi -> GR32
arm: DPR_VFP2:ssub0 -> DPR
Recompute the register class of any virtual registers that are used by
less instructions after coalescing.
This affects code generation for the Cortex-A8 where we use NEON
instructions for f32 operations, c.f. fp_convert.ll:
vadd.f32 d16, d1, d0
vcvt.s32.f32 d0, d16
The register allocator is now free to use d16 for the temporary, and
that comes first in the allocation order because it doesn't interfere
with any s-registers.
llvm-svn: 137133
These copies would coalesce easily, but the resulting value would be
defined by a deleted instruction. Now we also remove the undefined value
number from the destination register.
This fixes PR10503.
llvm-svn: 136174
copy is a kill") to see if it fixes the i386 dragonegg buildbot, which is timing out
because gcc built with dragonegg is going into an infinite loop.
llvm-svn: 134237
sink them into MC layer.
- Added MCInstrInfo, which captures the tablegen generated static data. Chang
TargetInstrInfo so it's based off MCInstrInfo.
llvm-svn: 134021
EXTRACT_SUBREG no longer appears as a machine instruction. Use COPY instead.
Add isCopy() checks in many places using isMoveInstr() and isExtractSubreg().
The isMoveInstr hook will be removed later.
llvm-svn: 107879
It is OK for an alias live range to overlap if there is a copy to or from the
physical register. CoalescerPair can work out if the copy is coalescable
independently of the alias.
This means that we can join with the actual destination interval instead of
using the getOrigDstReg() hack. It is no longer necessary to merge clobber
ranges into subregisters.
llvm-svn: 107695
CoalescerPair can determine if a copy can be coalesced, and which register gets
merged away. The old logic in SimpleRegisterCoalescing had evolved into
something a bit too convoluted.
llvm-svn: 106701
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
Jakob Stoklund Olesen