"private" symbols which the assember shouldn't strip, but which the linker may
remove after evaluation. This is mostly useful for Objective-C metadata.
This is plumbing, so we don't have a use of it yet. More to come, etc.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@76385 91177308-0d34-0410-b5e6-96231b3b80d8
Inline asm instructions may have additional <imp-def,kill> register operands.
These operands are not marked with a flag like the normal asm operands, so we
must not assert that there is a flag.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@76373 91177308-0d34-0410-b5e6-96231b3b80d8
starting in getCurrentFunctionEHName. Among other problems,
we would try to privative a "foo.eh" label, but end up emitting
the label as _Lfoo.eh instead of L_foo.eh on darwin. This is really
bad, and the linker has always tolerated these labels existing.
For now, just emit them as _foo.eh.
This patch also fixes problems with ".eh" labels on unnamed
functions and eliminates two strangely defined TargetAsmInfo
hooks.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@76231 91177308-0d34-0410-b5e6-96231b3b80d8
stack alignment right when it is. This is not
ideal but conservatively correct. Adjust a test
to compensate for changed stack offset value.
gcc.apple/asm-block-57.c
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@76120 91177308-0d34-0410-b5e6-96231b3b80d8
call to the MachineCodeEmitter interface and made copying the start
line of a function not conditional on whether we're emitting Dwarf
debug information. I'll propagate the processDebugLoc() calls to the
non-X86 targets in a followup patch.
In the long run, it'll probably be better to gather this information
through the DwarfWriter, but the DwarfWriter currently depends on the
AsmPrinter and TargetAsmInfo, and fixing that would be out of the way
for this patch.
There's a bug in OProfile 0.9.4 that makes it ignore line numbers for
addresses above 4G, and a patch fixing it at
http://thread.gmane.org/gmane.linux.oprofile/7634
Sample output:
$ sudo opcontrol --reset; sudo opcontrol --start-daemon; sudo opcontrol --start; `pwd`/Debug/bin/lli fib.bc; sudo opcontrol --stop
Signalling daemon... done
Profiler running.
fib(40) == 165580141
Stopping profiling.
$ opreport -g -d -l `pwd`/Debug/bin/lli|head -60
Overflow stats not available
CPU: Core 2, speed 1998 MHz (estimated)
Counted CPU_CLK_UNHALTED events (Clock cycles when not halted) with a unit mask of 0x00 (Unhalted core cycles) count 100000
vma samples % linenr info image name symbol name
00007f67a30370b0 25489 61.2554 fib.c:24 10946.jo fib_left
00007f67a30370b0 1634 6.4106 fib.c:24
00007f67a30370b1 83 0.3256 fib.c:24
00007f67a30370b9 1997 7.8348 fib.c:24
00007f67a30370c6 2080 8.1604 fib.c:27
00007f67a30370c8 988 3.8762 fib.c:27
00007f67a30370cd 1315 5.1591 fib.c:27
00007f67a30370cf 251 0.9847 fib.c:27
00007f67a30370d3 1191 4.6726 fib.c:27
00007f67a30370d6 975 3.8252 fib.c:27
00007f67a30370db 1010 3.9625 fib.c:27
00007f67a30370dd 242 0.9494 fib.c:27
00007f67a30370e1 2782 10.9145 fib.c:28
00007f67a30370e5 3768 14.7828 fib.c:28
00007f67a30370eb 615 2.4128 (no location information)
00007f67a30370f3 6558 25.7287 (no location information)
00007f67a3037100 15603 37.4973 fib.c:29 10946.jo fib_right
00007f67a3037100 1646 10.5493 fib.c:29
00007f67a3037101 45 0.2884 fib.c:29
00007f67a3037109 2372 15.2022 fib.c:29
00007f67a3037116 2234 14.3178 fib.c:32
00007f67a3037118 612 3.9223 fib.c:32
00007f67a303711d 622 3.9864 fib.c:32
00007f67a303711f 385 2.4675 fib.c:32
00007f67a3037123 404 2.5892 fib.c:32
00007f67a3037126 634 4.0633 fib.c:32
00007f67a303712b 870 5.5759 fib.c:32
00007f67a303712d 62 0.3974 fib.c:32
00007f67a3037131 1848 11.8439 fib.c:33
00007f67a3037135 2840 18.2016 fib.c:33
00007f67a303713a 1 0.0064 fib.c:33
00007f67a303713b 1023 6.5564 (no location information)
00007f67a3037143 5 0.0320 (no location information)
000000000080c1e4 15 0.0360 MachineOperand.h:150 lli llvm::MachineOperand::isReg() const
000000000080c1e4 6 40.0000 MachineOperand.h:150
000000000080c1ec 2 13.3333 MachineOperand.h:150
...
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@76102 91177308-0d34-0410-b5e6-96231b3b80d8
The inline asm operands must be parsed from the first flag, you cannot assume
that an immediate operand preceeding a register use operand is the flag.
PowerPC "m" operands are represented as (flag, imm, reg) triples.
isRegTiedToDefOperand() would incorrectly interpret the imm as the flag.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@76101 91177308-0d34-0410-b5e6-96231b3b80d8
Avoid remat'ing instructions whose def have sub-register indices for now. It's just really really hard to get all the cases right.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75900 91177308-0d34-0410-b5e6-96231b3b80d8
This prefix is used by LLVM to inform the asm printer to not emit usual global symbol prefix before the symbol name.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75875 91177308-0d34-0410-b5e6-96231b3b80d8
This extra check is not trigged when runnning "make check" on top-of-tree.
Change error message to better match llvm_unreachable() grammar.
Don't call llvm_unreachable() when writing error messages to a file, but keep going.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75860 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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75847 91177308-0d34-0410-b5e6-96231b3b80d8
additional bug fixes:
1. The bug that everyone hit was a problem in the asmprinter where it
would remove $stub but keep the L prefix on a name when emitting the
indirect symbol. This is easy to fix by keeping the name of the stub
and the name of the symbol in a StringMap instead of just keeping a
StringSet and trying to reconstruct it late.
2. There was a problem printing the personality function. The current
logic to print out the personality function from the DWARF information
is a bit of a cesspool right now that duplicates a bunch of other
logic in the asm printer. The short version of it is that it depends
on emitting both the L and _ prefix for symbols (at least on darwin)
and until I can untangle it, it is best to switch the mangler back to
emitting both prefixes.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75646 91177308-0d34-0410-b5e6-96231b3b80d8
This adds location info for all llvm_unreachable calls (which is a macro now) in
!NDEBUG builds.
In NDEBUG builds location info and the message is off (it only prints
"UREACHABLE executed").
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75640 91177308-0d34-0410-b5e6-96231b3b80d8
--- Reverse-merging r75619 into '.':
U lib/Target/DarwinTargetAsmInfo.cpp
U lib/CodeGen/AsmPrinter/AsmPrinter.cpp
--- Reverse-merging r75618 into '.':
U lib/CodeGen/ELFWriter.cpp
U lib/CodeGen/MachOCodeEmitter.cpp
U lib/CodeGen/MachOWriter.cpp
--- Reverse-merging r75617 into '.':
U lib/Target/CBackend/CBackend.cpp
--- Reverse-merging r75616 into '.':
U tools/bugpoint/Miscompilation.cpp
U tools/lto/LTOCodeGenerator.cpp
U tools/lto/LTOModule.cpp
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75638 91177308-0d34-0410-b5e6-96231b3b80d8
indicates whether the label is private or not, instead of taking
prefix stuff. One effect of this is that symbols will be generated
with *just* the private prefix, instead of both the private prefix
*and* the user-label-prefix, but this doesn't matter as long as it
is consistent. For example we'll now get "Lfoo" instead of "L_foo".
These are just assembler temporary labels anyway, so they never even
make it into the .o file.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75607 91177308-0d34-0410-b5e6-96231b3b80d8
and related functions out of LoopBase and into Loop, since they
are specific to BasicBlock-based loops. This also allows the code
to be moved out-of-line.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75523 91177308-0d34-0410-b5e6-96231b3b80d8
using the Curiously Recurring Template Pattern with LoopBase.
This will help further refactoring, and future functionality for
Loop. Also, Headers can now foward-declare Loop, instead of pulling
in LoopInfo.h or doing tricks.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75519 91177308-0d34-0410-b5e6-96231b3b80d8
We'll eventually use this to print comments in asm files and do other
fun things.
This adds interfaces to the AsmPrinter and changes TableGen to invoke
the postInstructionAction when appropriate. It also add parameters to
TargetAsmInfo to control comment layout.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75490 91177308-0d34-0410-b5e6-96231b3b80d8
This involves temporarily hard wiring some parts to use the global context. This isn't ideal, but it's
the only way I could figure out to make this process vaguely incremental.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75445 91177308-0d34-0410-b5e6-96231b3b80d8
implemented in codegen, have no frontend to generate them, and are
better implemented with pattern matching (like the ppc backend does
to generate rlwimi/rlwinm etc).
PR4543
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75430 91177308-0d34-0410-b5e6-96231b3b80d8
Make llvm_unreachable take an optional string, thus moving the cerr<< out of
line.
LLVM_UNREACHABLE is now a simple wrapper that makes the message go away for
NDEBUG builds.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75379 91177308-0d34-0410-b5e6-96231b3b80d8
hooks as they're no longer needed.
The major change with this patch is to make formatted_raw_ostream usable
by any client of raw_ostream.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75283 91177308-0d34-0410-b5e6-96231b3b80d8
value. Adjust other code to deal with that correctly. Make
DAGTypeLegalizer::PromoteIntRes_EXTRACT_VECTOR_ELT take advantage of
this new flexibility to simplify the code and make it deal with unusual
vectors (like <4 x i1>) correctly. Fixes PR3037.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75176 91177308-0d34-0410-b5e6-96231b3b80d8
registers based on dynamic conditions. For example, X86 EBP/RBP, when used as
frame register has to be spilled in the first fixed object. It should inform
PEI this so it doesn't get allocated another stack object. Also, it should not
be spilled as other callee-saved registers but rather its spilling and restoring
are being handled by emitPrologue and emitEpilogue. Avoid spilling it twice.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75116 91177308-0d34-0410-b5e6-96231b3b80d8
as an (index,bool) pair. The bool flag records whether the kill is a
PHI kill or not. This code will be used to enable splitting of live
intervals containing PHI-kills.
A slight change to live interval weights introduced an extra spill
into lsr-code-insertion (outside the critical sections). The test
condition has been updated to reflect this.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75097 91177308-0d34-0410-b5e6-96231b3b80d8
nodes with operand types that differ from the result type. (This
doesn't normally happen right now, because
SelectionDAGLowering::visitShuffleVector normalizes vector shuffles.)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75081 91177308-0d34-0410-b5e6-96231b3b80d8
number of elements. Make some simplifications based
on this (in particular SplitVecRes_SETCC). Tighten
up some checking while there.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75050 91177308-0d34-0410-b5e6-96231b3b80d8
VSETCC must define all bits, which is different than it was documented
to before. Since all targets that implement VSETCC already have this
behavior, and we don't optimize based on this, just change the
documentation. We now get nice code for vec_compare.ll
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74978 91177308-0d34-0410-b5e6-96231b3b80d8
as "X" constraint and "P" modifier on x86. Make this work.
(Change may not be sufficient to fix it for non-Darwin, but
I'm pretty sure it won't break anything.)
gcc.apple/asm-block-32.c
gcc.apple/asm-block-33.c
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74967 91177308-0d34-0410-b5e6-96231b3b80d8
finishes off enough support for vector compares to get the icmp/fcmp
version of 2008-07-23-VSetCC.ll passing.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74961 91177308-0d34-0410-b5e6-96231b3b80d8
previous cmp; a copy can not be inserted here if the copy insn also has
side effects. We don't have access to the attributes of copy insn here;
so just play safe by finding a safe locations for branch terminators.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74898 91177308-0d34-0410-b5e6-96231b3b80d8
With the SVR4 ABI on PowerPC, vector arguments for vararg calls are passed differently depending on whether they are a fixed or a variable argument. Variable vector arguments always go into memory, fixed vector arguments are put
into vector registers. If there are no free vector registers available, fixed vector arguments are put on the stack.
The NumFixedArgs attribute allows to decide for an argument in a vararg call whether it belongs to the fixed or variable portion of the parameter list.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74764 91177308-0d34-0410-b5e6-96231b3b80d8
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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74601 91177308-0d34-0410-b5e6-96231b3b80d8
- This more or less amounts to a revert of r65379. I'm curious to know what
happened that caused this variable to become unused.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74579 91177308-0d34-0410-b5e6-96231b3b80d8
have the alignment be calculated up front, and have the back-ends obey whatever
alignment is decided upon.
This allows for future work that would allow for precise no-op placement and the
like.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74564 91177308-0d34-0410-b5e6-96231b3b80d8
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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74518 91177308-0d34-0410-b5e6-96231b3b80d8
the SelectionDAG::getGlobalAddress function properly looks through
aliases to determine thread-localness, but then passes the GV* down
to GlobalAddressSDNode::GlobalAddressSDNode which does not. Instead
of passing down isTarget, just pass down the predetermined node
opcode. This fixes some assertions with out of tree changes I'm
working on.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74325 91177308-0d34-0410-b5e6-96231b3b80d8
to be shared, but how/where to privatize it is not immediately clear to me.
If any SelectionDAG experts see a better solution, please share!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74180 91177308-0d34-0410-b5e6-96231b3b80d8
This change doubles the allowable value for MVT::LAST_VALUETYPE. It does
this by doing several things.
1. Introduces MVT::MAX_ALLOWED_LAST_VALUETYPE which in this change has a
value of 64. This value contains the current maximum for the
MVT::LAST_VALUETYPE.
2. Instead of checking "MVT::LAST_VALUETYPE <= 32", all of those uses
now become "MVT::LAST_VALUETYPE <= MVT::MAX_ALLOWED_LAST_VALUETYPE"
3. Changes the dimension of the ValueTypeActions from 2 elements to four
elements and adds comments ahead of the declaration indicating the it is
"(MVT::MAX_ALLOWED_LAST_VALUETYPE/32) * 2". This at least lets us find
what is affected if and when MVT::MAX_ALLOWED_LAST_VALUETYPE gets
changed.
4. Adds initializers for the new elements of ValueTypeActions.
This does NOT add any types in MVT. That would be done separately.
This doubles the size of ValueTypeActions from 64 bits to 128 bits and
gives us the freedom to add more types for AVX.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74110 91177308-0d34-0410-b5e6-96231b3b80d8
a bunch of code from all the targets, and eliminates nondeterministic
ordering of directives being emitted in the output.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74096 91177308-0d34-0410-b5e6-96231b3b80d8
Only pad when the section size > 0 and move the code that deals
with globals initializers to a place we know for sure the global
is initialized.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73944 91177308-0d34-0410-b5e6-96231b3b80d8
Support for .text relocations, implementing TargetELFWriter overloaded methods for x86/x86_64.
Use a map to track global values to their symbol table indexes
Code cleanup and small fixes
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73894 91177308-0d34-0410-b5e6-96231b3b80d8
- Register allocator should resolve the second part of the hint (register number) before passing it to the target since it knows virtual register to physical register mapping.
- More fixes to get ARM load / store double word working.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73671 91177308-0d34-0410-b5e6-96231b3b80d8
TurnCopyIntoImpDef turns a copy into implicit_def and remove the val# defined by it. This causes an scavenger assertion later if the def reaches other blocks. Disable the transformation if the value live interval extends beyond its def block.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73478 91177308-0d34-0410-b5e6-96231b3b80d8
support for x86, and UMULO/SMULO for many architectures, including PPC
(PR4201), ARM, and Cell. The resulting expansion isn't perfect, but it's
not bad.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73477 91177308-0d34-0410-b5e6-96231b3b80d8
incomming chain of the RETURN node. The incomming chain must
be the outgoing chain of the CALL node. This causes the
backend to identify tail calls that are not tail calls. This
patch fixes this.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73387 91177308-0d34-0410-b5e6-96231b3b80d8
- Change register allocation hint to a pair of unsigned integers. The hint type is zero (which means prefer the register specified as second part of the pair) or entirely target dependent.
- Allow targets to specify alternative register allocation orders based on allocation hint.
Part 2.
- Use the register allocation hint system to implement more aggressive load / store multiple formation.
- Aggressively form LDRD / STRD. These are formed *before* register allocation. It has to be done this way to shorten live interval of base and offset registers. e.g.
v1025 = LDR v1024, 0
v1026 = LDR v1024, 0
=>
v1025,v1026 = LDRD v1024, 0
If this transformation isn't done before allocation, v1024 will overlap v1025 which means it more difficult to allocate a register pair.
- Even with the register allocation hint, it may not be possible to get the desired allocation. In that case, the post-allocation load / store multiple pass must fix the ldrd / strd instructions. They can either become ldm / stm instructions or back to a pair of ldr / str instructions.
This is work in progress, not yet enabled.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73381 91177308-0d34-0410-b5e6-96231b3b80d8
consecutive addresses togther. This makes it easier for the post-allocation pass
to form ldm / stm.
This is step 1. We are still missing a lot of ldm / stm opportunities because
of register allocation are not done in the desired order. More enhancements
coming.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73291 91177308-0d34-0410-b5e6-96231b3b80d8
Emission for globals, using the correct data sections
Function alignment can be computed for each target using TargetELFWriterInfo
Some small fixes
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73201 91177308-0d34-0410-b5e6-96231b3b80d8
on x86 to handle more cases. Fix a bug in said code that would cause it
to read past the end of an object. Rewrite the code in
SelectionDAGLegalize::ExpandBUILD_VECTOR to be a bit more general.
Remove PerformBuildVectorCombine, which is no longer necessary with
these changes. In addition to simplifying the code, with this change,
we can now catch a few more cases of consecutive loads.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73012 91177308-0d34-0410-b5e6-96231b3b80d8
integer type to be consistent with normal operation legalization. No visible
change because nothing is actually using this at the moment.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72980 91177308-0d34-0410-b5e6-96231b3b80d8
Update code generator to use this attribute and remove NoImplicitFloat target option.
Update llc to set this attribute when -no-implicit-float command line option is used.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72959 91177308-0d34-0410-b5e6-96231b3b80d8
build vectors with i64 elements will only appear on 32b x86 before legalize.
Since vector widening occurs during legalize, and produces i64 build_vector
elements, the dag combiner is never run on these before legalize splits them
into 32b elements.
Teach the build_vector dag combine in x86 back end to recognize consecutive
loads producing the low part of the vector.
Convert the two uses of TLI's consecutive load recognizer to pass LoadSDNodes
since that was required implicitly.
Add a testcase for the transform.
Old:
subl $28, %esp
movl 32(%esp), %eax
movl 4(%eax), %ecx
movl %ecx, 4(%esp)
movl (%eax), %eax
movl %eax, (%esp)
movaps (%esp), %xmm0
pmovzxwd %xmm0, %xmm0
movl 36(%esp), %eax
movaps %xmm0, (%eax)
addl $28, %esp
ret
New:
movl 4(%esp), %eax
pmovzxwd (%eax), %xmm0
movl 8(%esp), %eax
movaps %xmm0, (%eax)
ret
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72957 91177308-0d34-0410-b5e6-96231b3b80d8
integer and floating-point opcodes, introducing
FAdd, FSub, and FMul.
For now, the AsmParser, BitcodeReader, and IRBuilder all preserve
backwards compatability, and the Core LLVM APIs preserve backwards
compatibility for IR producers. Most front-ends won't need to change
immediately.
This implements the first step of the plan outlined here:
http://nondot.org/sabre/LLVMNotes/IntegerOverflow.txt
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72897 91177308-0d34-0410-b5e6-96231b3b80d8
using Promote which won't work because i64 isn't
a legal type. It's easy enough to use Custom, but
then we have the problem that when the type
legalizer is promoting FP_TO_UINT->i16, it has no
way of telling it should prefer FP_TO_SINT->i32
to FP_TO_UINT->i32. I have uncomfortably hacked
this by making the type legalizer choose FP_TO_SINT
when both are Custom.
This fixes several regressions in the testsuite.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72891 91177308-0d34-0410-b5e6-96231b3b80d8
instcombine doesn't know when it's safe. To partially compensate
for this, introduce new code to do this transformation in
dagcombine, which can use UnsafeFPMath.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72872 91177308-0d34-0410-b5e6-96231b3b80d8
