Commit Graph

107 Commits

Author SHA1 Message Date
Eric Christopher 4e7d1e7e7b Fundamentally change the MipsSubtarget replacement machinery:
a) Move the replacement level decision to the target machine.
b) Create additional subtargets at the TargetMachine level to
   cache and make replacement easy.
c) Make the mips16 features obvious.
d) Remove the override logic as it no longer does anything.
e) Have MipsModuleDAGToDAGISel take only the target machine.
f) Have the constant islands pass grab the current subtarget
   from the MachineFunction (via the TargetMachine) instead
   of caching it.
g) Unconditionally initialize TLOF.
h) Remove the old complicated subtarget based resetting and
   replace it with simple conditionals.

llvm-svn: 213430
2014-07-18 23:41:32 +00:00
Eric Christopher e54f10ee77 FrameLowering depends only upon the Subtarget, so only take a subtarget
during initialization.

llvm-svn: 213429
2014-07-18 23:33:47 +00:00
Eric Christopher 8924d27c02 In preparation for replacing the whole subtarget on the target machine,
have target lowering take the subtarget explicitly.

llvm-svn: 213426
2014-07-18 23:25:04 +00:00
Eric Christopher 675cb4dab8 Make InstrInfo depend only upon the Subtarget getting passed in
rather than the TargetMachine.

llvm-svn: 213425
2014-07-18 23:25:00 +00:00
Eric Christopher f74faf42fe Avoid caching the relocation model on the subtarget, this is for
two reasons:

a) we're already caching the target machine which contains it,
b) which relocation model you get is dependent upon whether or
not you ask before MCCodeGenInfo is constructed on the target
machine, so avoid any latent issues there.

llvm-svn: 213420
2014-07-18 22:34:20 +00:00
Eric Christopher 7394e23423 Avoid resetting the UseSoftFloat and FloatABIType on the TargetMachine
Options struct and move the comment to inMips16HardFloat. Use the
fact that we now know whether or not we cared about soft float to
set the libcalls.
Accordingly rename mipsSEUsesSoftFloat to abiUsesSoftFloat and
propagate since it's no longer CPU specific.

llvm-svn: 213335
2014-07-18 00:08:50 +00:00
Sanjay Patel a2f658d69d Move Post RA Scheduling flag bit into SchedMachineModel
Refactoring; no functional changes intended

    Removed PostRAScheduler bits from subtargets (X86, ARM).
    Added PostRAScheduler bit to MCSchedModel class.
    This bit is set by a CPU's scheduling model (if it exists).
    Removed enablePostRAScheduler() function from TargetSubtargetInfo and subclasses.
    Fixed the existing enablePostMachineScheduler() method to use the MCSchedModel (was just returning false!).
    Added methods to TargetSubtargetInfo to allow overrides for AntiDepBreakMode, CriticalPathRCs, and OptLevel for PostRAScheduling.
    Added enablePostRAScheduler() function to PostRAScheduler class which queries the subtarget for the above values.
    Preserved existing scheduler behavior for ARM, MIPS, PPC, and X86: 
       a. ARM overrides the CPU's postRA settings by enabling postRA for any non-Thumb or Thumb2 subtarget. 
       b. MIPS overrides the CPU's postRA settings by enabling postRA for everything. 
       c. PPC overrides the CPU's postRA settings by enabling postRA for everything. 
       d. X86 is the only target that actually has postRA specified via sched model info.

Differential Revision: http://reviews.llvm.org/D4217

llvm-svn: 213101
2014-07-15 22:39:58 +00:00
Daniel Sanders 7ddb0ab85f [mips] For the FP64A ABI, odd-numbered double-precision moves must not use mtc1/mfc1.
Summary:
This is because the FP64A the hardware will redirect 32-bit reads/writes
from/to odd-numbered registers to the upper 32-bits of the corresponding
even register. In effect, simulating FR=0 mode when FR=0 mode is not
available.

Unfortunately, we have to make the decision to avoid mfc1/mtc1 before
register allocation so we currently do this for even registers too.

FPXX has a similar requirement on 32-bit architectures that lack
mfhc1/mthc1 so this patch also handles the affected moves from the FPU for
FPXX too. Moves to the FPU were supported by an earlier commit.

Differential Revision: http://reviews.llvm.org/D4484

llvm-svn: 212938
2014-07-14 13:08:14 +00:00
Sasa Stankovic b976fee83c [mips] Expand BuildPairF64 to a spill and reload when the O32 FPXX ABI is
enabled and mthc1 and dmtc1 are not available (e.g. on MIPS32r1)

This prevents the upper 32-bits of a double precision value from being moved to
the FPU with mtc1 to an odd-numbered FPU register. This is necessary to ensure
that the code generated executes correctly regardless of the current FPU mode.

MIPS32r2 and above continues to use mtc1/mthc1, while MIPS-IV and above continue
to use dmtc1.

Differential Revision: http://reviews.llvm.org/D4465

llvm-svn: 212930
2014-07-14 09:40:29 +00:00
Zoran Jovanovic 255d00dc23 [mips] Added FPXX modeless calling convention.
Differential Revision: http://reviews.llvm.org/D4293

llvm-svn: 212726
2014-07-10 15:36:12 +00:00
Daniel Sanders 7e527423f5 [mips] Add support for -modd-spreg/-mno-odd-spreg
Summary:
When -mno-odd-spreg is in effect, 32-bit floating point values are not
permitted in odd FPU registers. The option also prohibits 32-bit and 64-bit
floating point comparison results from being written to odd registers.

This option has three purposes:
* It allows support for certain MIPS implementations such as loongson-3a that
  do not allow the use of odd registers for single precision arithmetic.
* When using -mfpxx, -mno-odd-spreg is the default and this allows us to
  statically check that code is compliant with the O32 FPXX ABI since mtc1/mfc1
  instructions to/from odd registers are guaranteed not to appear for any
  reason. Once this has been established, the user can then re-enable
  -modd-spreg to regain the use of all 32 single-precision registers.
* When using -mfp64 and -mno-odd-spreg together, an O32 extension named
  O32 FP64A is used as the ABI. This is intended to provide almost all
  functionality of an FR=1 processor but can also be executed on a FR=0 core
  with the assistance of a hardware compatibility mode which emulates FR=0
  behaviour on an FR=1 processor.

* Added '.module oddspreg' and '.module nooddspreg' each of which update
  the .MIPS.abiflags section appropriately
* Moved setFpABI() call inside emitDirectiveModuleFP() so that the caller
  doesn't have to remember to do it.
* MipsABIFlags now calculates the flags1 and flags2 member on demand rather
  than trying to maintain them in the same format they will be emitted in.

There is one portion of the -mfp64 and -mno-odd-spreg combination that is not
implemented yet. Moves to/from odd-numbered double-precision registers must not
use mtc1. I will fix this in a follow-up.

Differential Revision: http://reviews.llvm.org/D4383

llvm-svn: 212717
2014-07-10 13:38:23 +00:00
Eric Christopher daa9dbbbd5 Move subtarget dependent features into the subtarget from the target
machine. Includes a fix for a subtarget initialization for
hard floating point on mips16.

llvm-svn: 212240
2014-07-03 00:10:24 +00:00
Eric Christopher 5f9fd210b3 Move the data layout and selection dag info from the mips target machine
down to the subtarget.

llvm-svn: 212224
2014-07-02 21:29:23 +00:00
Eric Christopher 5b336a242c Break out subtarget initialization that dependent variables need into
a separate function and clean up calling convention for helper function.

llvm-svn: 212153
2014-07-02 01:14:43 +00:00
Eric Christopher a4d901f599 Unify these two lines.
llvm-svn: 212152
2014-07-02 01:02:28 +00:00
Eric Christopher 1f51ddda98 Move MipsJITInfo to the subtarget rather than the target machine.
llvm-svn: 212151
2014-07-02 00:54:12 +00:00
Daniel Sanders 387fc15d2c [mips] Marked up instructions added in MIPS32r2 and tested that IAS for -mcpu=mips(2|32) does not accept them
Summary:
This required a new instruction group representing the 32-bit subset of
MIPS-3 that was available in MIPS32R2.

To limit the number of tests required, only one 32-bit and one 64-bit ISA
prior to MIPS32/MIPS64 are tested.

rdhwr has been deliberately left without an ISA annotation for now. This is
because the assembler and CodeGen disagree on when the instruction is
available. Strictly speaking, it is only available in MIPS32r2 and
MIPS64r2. However, it is emulated by a kernel trap on earlier ISA's and is
necessary for TLS so CodeGen should emit it on older ISA's too.

Depends on D3696

Reviewers: vmedic

Reviewed By: vmedic

Differential Revision: http://reviews.llvm.org/D3697

llvm-svn: 208690
2014-05-13 11:45:36 +00:00
Daniel Sanders 07cdea2baa [mips] Marked up instructions added in MIPS-V and tested that IAS for -mcpu=mips[1234] does not accept them
Summary:
This required a new instruction group representing the 32-bit subset of
MIPS-V that was available in MIPS32R2

Most of these instructions are correctly rejected but with the wrong error
message. These have been placed in a separate test for now. It happens
because many of the MIPS V instructions have not been implemented.

Depends on D3694

Reviewers: vmedic

Reviewed By: vmedic

Differential Revision: http://reviews.llvm.org/D3695

llvm-svn: 208546
2014-05-12 12:52:44 +00:00
Daniel Sanders 070fd1c42a [mips] Fold FeatureBitCount into FeatureMips32 and FeatureMips64
Summary:
DCL[ZO] are now correctly marked as being MIPS64 instructions. This has no
effect on the CodeGen tests since expansion of i64 prevented their use
anyway.

The check for MIPS16 to prevent the use of CLZ no longer prevents DCLZ as
well. This is not a functional change since DCLZ is still prohibited by
being a MIPS64 instruction (MIPS16 is only compatible with MIPS32).

No functional change

Reviewers: vmedic

Reviewed By: vmedic

Differential Revision: http://reviews.llvm.org/D3694

llvm-svn: 208544
2014-05-12 12:41:59 +00:00
Daniel Sanders fcea8102e8 [mips] Fold FeatureSEInReg into FeatureMips32r2
Summary: No functional change

Reviewers: vmedic

Reviewed By: vmedic

Differential Revision: http://reviews.llvm.org/D3693

llvm-svn: 208543
2014-05-12 12:28:15 +00:00
Daniel Sanders 39d0051847 [mips] Fold FeatureSwap into FeatureMips32r2 and FeatureMips64r2
Summary:
dsbh and dshd are not available on Mips32r2. No codegen test changes
required since expansion of i64 prevented the use of these instructions
anyway.

Depends on D3690

Reviewers: vmedic

Reviewed By: vmedic

Differential Revision: http://reviews.llvm.org/D3692

llvm-svn: 208542
2014-05-12 12:15:41 +00:00
Daniel Sanders 94eda2e1ab [mips] Replace FeatureFPIdx with FeatureMips4_32r2
Summary:
No functional change.

The minor change to the MIPS16 code is in preparation for a patch that will handle 32-bit FPIdx instructions separately to 64-bit (because they were added in different revisions)

Depends on D3677

Reviewers: rkotler, vmedic

Reviewed By: vmedic

Differential Revision: http://reviews.llvm.org/D3690

llvm-svn: 208541
2014-05-12 11:56:16 +00:00
Daniel Sanders e57d866ed0 [mips] Marked up instructions added in MIPS-IV and tested that IAS for -mcpu=mips[123] does not accept them
Summary:
This required a new instruction group representing the 32-bit subset of
MIPS-IV that was available in MIPS32

A small number of instructions are correctly rejected but with the wrong error
message. These have been placed in a separate test for now.

Depends on D3676

Reviewers: vmedic

Reviewed By: vmedic

Differential Revision: http://reviews.llvm.org/D3677

llvm-svn: 208414
2014-05-09 14:06:17 +00:00
Daniel Sanders 395b8181ec [mips] Remove unused CondMov feature bit
Summary:
No functional change

Depends on D3675

Reviewers: vmedic

Reviewed By: vmedic

Differential Revision: http://reviews.llvm.org/D3676

llvm-svn: 208410
2014-05-09 13:15:07 +00:00
Daniel Sanders f2056bef32 [mips] Marked up instructions added in MIPS-III and tested that IAS for -mcpu=mips[12] does not accept them
Summary:
This required a new instruction group representing the 32-bit subset of
MIPS-III that was available in MIPS32

A small number of instructions are correctly rejected but with the wrong error
message. These have been placed in a separate test for now.

There's some obvious InstAlias's that ought to be marked MIPS-III but arent.
This is because they are not currently tested. I intend to catch these with
a final pass through the tablegen records to find tablegen records without
ISA annotations.

Depends on D3674

Reviewers: vmedic

Reviewed By: vmedic

Differential Revision: http://reviews.llvm.org/D3675

llvm-svn: 208408
2014-05-09 13:02:27 +00:00
Daniel Sanders b7f1c6ff3e [mips][mips64r6] Add experimental support for MIPS32r6 and MIPS64r6
Summary:
Adds MIPS32r6/MIPS64r6 and checks the compatibility requirements for these
processors.

I've also included comments to describe removed and re-encoded instructions,
along with placeholder def's for the new instructions but there are no
functional changes to codegen at this point.

Reviewers: jkolek, vmedic

Reviewed By: vmedic

Differential Revision: http://reviews.llvm.org/D3622

llvm-svn: 208399
2014-05-09 09:46:21 +00:00
Daniel Sanders d240953db2 [mips] Add highly experimental support for MIPS-I, MIPS-II, MIPS-III, and MIPS-V
Summary:
These processors will only be available for the integrated assembler at
first (CodeGen will emit a fatal error saying they are not implemented).

The intention is to work through the existing instructions and correctly
annotate the ISA they were added in so that we have a sufficiently good
base to start MIPS64r6 development. MIPS64r6 removes/re-encodes certain
instructions and I believe it is best to define ISA's using set-union's
as far as possible rather than using set-subtraction.

Reviewers: vmedic

Subscribers: emaste, llvm-commits

Differential Revision: http://reviews.llvm.org/D3569

llvm-svn: 208221
2014-05-07 16:25:22 +00:00
Chandler Carruth 84e68b2994 [Modules] Fix potential ODR violations by sinking the DEBUG_TYPE
definition below all of the header #include lines, lib/Target/...
edition.

llvm-svn: 206842
2014-04-22 02:41:26 +00:00
Chandler Carruth d174b72a28 [cleanup] Lift using directives, DEBUG_TYPE definitions, and even some
system headers above the includes of generated '.inc' files that
actually contain code. In a few targets this was already done pretty
consistently, but it wasn't done *really* consistently anywhere. It is
strictly cleaner IMO and necessary in a bunch of places where the
DEBUG_TYPE is referenced from the generated code. Consistency with the
necessary places trumps. Hopefully the build bots are OK with the
movement of intrin.h...

llvm-svn: 206838
2014-04-22 02:03:14 +00:00
Matheus Almeida 0051f2dc78 [mips] Add initial support for NaN2008 in the back-end.
This is so that EF_MIPS_NAN2008 is set if we are using IEEE 754-2008
NaN encoding (-mnan=2008). This patch also adds support for parsing
'.nan legacy' and '.nan 2008' assembly directives. The handling of
these directives should match GAS' behaviour i.e., the last directive
in use sets the ELF header bit (EF_MIPS_NAN2008).

Differential Revision: http://reviews.llvm.org/D3346

llvm-svn: 206396
2014-04-16 15:48:55 +00:00
Daniel Sanders a024fb0e04 [mips] Correct r206370 to account for non-Linux targets using the small data section.
This should fix the ninja-x64-msvc-RA-centos6 builder.

I suspect the check in MipsSubtarget.cpp is incorrect and is really trying to
check for a bare-metal target rather and anything other than linux. I'll
investigate this.

llvm-svn: 206385
2014-04-16 12:29:08 +00:00
Daniel Sanders 5e94e68f7b [mips] Some uses of isMips64()/hasMips64() are really tests for 64-bit GPR's
Summary:
No functional change since these predicates are (currently) synonymous.

Extracted from a patch by David Chisnall
His work was sponsored by: DARPA, AFRL

Differential Revision: http://llvm-reviews.chandlerc.com/D3202

llvm-svn: 204943
2014-03-27 16:42:17 +00:00
Kai Nacke 93fe5e810d [MIPS] Add cpu octeon and some instructions
The Octeon cpu from Cavium Networks is mips64r2 based and has an extended
instruction set. In order to utilize this with LLVM, a new cpu feature "octeon"
and a subtarget feature "cnmips" is added. A small set of new instructions
(baddu, dmul, pop, dpop, seq, sne) is also added. LLVM generates dmul, pop and
dpop instructions with option -mcpu=octeon or -mattr=+cnmips.

llvm-svn: 204337
2014-03-20 11:51:58 +00:00
Daniel Sanders 737285e02d [mips] Treat -mcpu=generic the same way as an empty CPU string.
Summary:
This should fix the MCJIT unit tests that were broken by r201792 on the MIPS buildbot.
MIPS currently uses the default implementation of sys::getHostCPUName() which
always returns "generic". For now, we will accept "generic" and coerce it to
"mips32" or "mips64" depending on the target architecture like we do for empty
CPU names.

Reviewers: jacksprat, matheusalmeida

Reviewed By: jacksprat

Differential Revision: http://llvm-reviews.chandlerc.com/D2878

llvm-svn: 202253
2014-02-26 10:20:15 +00:00
Daniel Sanders 5a1449dab4 [mips] Make it impossible to have UnknownABI in CodeGen and Integrated Assembler.
Summary:
This removes the need to coerce UnknownABI to the default ABI (O32 for
MIPS32, N64 for MIPS64 [*]) in both MipsSubtarget and MipsAsmParser.

Clang has been updated to disable both possible default ABI's before enabling
the ABI it intends to use.

[*] N64 being the default for MIPS64 is not actually correct.
    However N32 is not fully implemented/tested yet.

Depends on: D2830

Reviewers: jacksprat, matheusalmeida

Reviewed By: matheusalmeida

Differential Revision: http://llvm-reviews.chandlerc.com/D2832
Differential Revision: http://llvm-reviews.chandlerc.com/D2846

llvm-svn: 201792
2014-02-20 14:58:19 +00:00
Daniel Sanders e70897f3ea [mips] Make mips64 the default CPU for the mips64 architecture
Summary:
This is consistent with the integrated assembler.
All mips64 codegen tests previously passed -mcpu. Removed -mcpu from
blez_bgez.ll and const-mult.ll to cover the default case.

Ideally, the two implementations of selectMipsCPU() will be merged but it's
proven difficult to find a home for the function that doesn't cause link errors.
For now, we'll hoist the common functionality into a function and mark it with
FIXME's.

Reviewers: jacksprat, matheusalmeida

Reviewed By: matheusalmeida

Differential Revision: http://llvm-reviews.chandlerc.com/D2830

llvm-svn: 201782
2014-02-20 13:13:33 +00:00
Petar Jovanovic 9725016af3 [mips] Add NaCl target and forbid indexed loads and stores for it
This patch adds NaCl target for Mips. It also forbids indexed loads and
stores if the target is NaCl.

Patch by Sasa Stankovic.

Differential Revision: http://llvm-reviews.chandlerc.com/D2690

llvm-svn: 200855
2014-02-05 17:19:30 +00:00
Chandler Carruth 8a8cd2bab9 Re-sort all of the includes with ./utils/sort_includes.py so that
subsequent changes are easier to review. About to fix some layering
issues, and wanted to separate out the necessary churn.

Also comment and sink the include of "Windows.h" in three .inc files to
match the usage in Memory.inc.

llvm-svn: 198685
2014-01-07 11:48:04 +00:00
Reed Kotler 0d409e2dfe Check in conditional branches for constant islands. Still need to finish
conditional branches for very large targets. That will be the next small
patch. Everything now should in principle work as good (functionality
wise) as without constant islands so we decided at Mips/Imagination to
make constant islands the default for Mips16 now so that it will get
excercised a lot and this port is still experimentatl though hopefully soon
we will change the status. Some more cleanup and code review is in order
but things are converging fast.

llvm-svn: 195902
2013-11-28 00:56:37 +00:00
Simon Atanasyan 1093afe27a [Mips] Adjust float ABI settings in case of MIPS16 mode.
Hard float for mips16 means essentially to compile as soft float but to
use a runtime library for soft float that is written with native mips32
floating point instructions (those runtime routines run in mips32 hard
float mode).

The patch reviewed by Reed Kotler.

llvm-svn: 195123
2013-11-19 12:20:17 +00:00
Akira Hatanaka 3048b0248a [mips] Compute stack alignment on the fly.
llvm-svn: 193673
2013-10-30 02:29:43 +00:00
Akira Hatanaka 6b2d841975 [mips] Align the stack to 16-bytes for mfp64.
llvm-svn: 193641
2013-10-29 19:29:03 +00:00
Reed Kotler 91ae9829a9 Make first substantial checkin of my port of ARM constant islands code to Mips.
Before I just ported the shell of the pass. I've tried to keep everything
nearly identical to the ARM version. I think it will be very easy to eventually
merge these two and create a new more general pass that other targets can
use. I have some improvements I would like to make to allow pools to 
be shared across functions and some other things. When I'm all done we
can think about making a more general pass. More to be ported but the
basic mechanism works now almost as good as gcc mips16.

llvm-svn: 193509
2013-10-27 21:57:36 +00:00
Daniel Sanders 1b1e25b7c5 [mips][msa] MSA requires FR=1 mode (64-bit FPU register file). Report fatal error when using it in FR=0 mode.
llvm-svn: 191498
2013-09-27 10:08:31 +00:00
Reed Kotler c03807a3a5 Fix a problem with dual mips16/mips32 mode. When the underlying processor
has hard float, when you compile the mips32 code you have to make sure
that it knows to compile any mips32 routines as hard float. I need to clean
up the way mips16 hard float is specified but I need to first think through
all the details. Mips16 always has a form of soft float, the difference being
whether the underlying hardware has floating point. So it's not really
necessary to pass the -soft-float to llvm since soft-float is always true
for mips16 by virtue of the fact that it will not register floating point
registers. By using this fact, I can simplify the way this is all handled.

llvm-svn: 189690
2013-08-30 19:40:56 +00:00
Reed Kotler 0eae85fb1f Fix a subtle difference between running clang vs llc for mips16.
This regards how mips16 is viewed. It's not really a target type but
there has always been a target for it in the td files. It's more properly
-mcpu=mips32 -mattr=+mips16 . This is how clang treats it but we have
always had the -mcpu=mips16 which I probably should delete now but it will
require updating all the .ll test cases for mips16. In this case it changed
how we decide if we have a count bits instruction and whether instruction
lowering should then expand ctlz. Now that we have dual mode compilation,
-mattr=+mips16 really just indicates the inital processor mode that
we are compiling for. (It is also possible to have -mcpu=64 -mattr=+mips16
but as far as I know, nobody has even built such a processor, though there
is an architecture manual for this).

llvm-svn: 188586
2013-08-16 23:05:18 +00:00
Jack Carter 3a2c2d42b8 [Mips][msa] Added initial MSA support.
* msa SubtargetFeature
* registers
* ld.[bhwd], and st.[bhwd] instructions

Does not correctly prohibit use of both 32-bit FPU registers and MSA together.

Patch by Daniel Sanders

llvm-svn: 188313
2013-08-13 20:54:07 +00:00
Akira Hatanaka 13e6ccf341 [mips] Rename register classes CPURegs and CPU64Regs.
llvm-svn: 187832
2013-08-06 23:08:38 +00:00
Reed Kotler 783c79446b Checkin in of first of several patches to finish implementation of
mips16/mips32 floating point interoperability. 

This patch fixes returns from mips16 functions so that if the function
was in fact called by a mips32 hard float routine, then values
that would have been returned in floating point registers are so returned.

Mips16 mode has no floating point instructions so there is no way to
load values into floating point registers.

This is needed when returning float, double, single complex, double complex
in the Mips ABI.

Helper functions in libc for mips16 are available to do this.

For efficiency purposes, these helper functions have a different calling
convention from normal Mips calls.

Registers v0,v1,a0,a1 are used to pass parameters instead of
a0,a1,a2,a3.

This is because v0,v1,a0,a1 are the natural registers used to return
floating point values in soft float. These values can then be moved
to the appropriate floating point registers with no extra cost.

The only register that is modified is ra in this call.

The helper functions make sure that the return values are in the floating
point registers that they would be in if soft float was not in effect
(which it is for mips16, though the soft float is implemented using a mips32
library that uses hard float).
 

llvm-svn: 181641
2013-05-10 22:25:39 +00:00
Reed Kotler fe94cc3ea0 This is for an experimental option -mips-os16. The idea is to compile all
Mips32 code as Mips16 unless it can't be compiled as Mips 16. For now this
would happen as long as floating point instructions are not needed.
Probably it would also make sense to compile as mips32 if atomic operations
are needed too. There may be other cases too.

A module pass prescans the IR and adds the mips16 or nomips16 attribute
to functions depending on the functions needs.

Mips 16 mode can result in a 40% code compression by utililizing 16 bit
encoding of many instructions.

The hope is for this to replace the traditional gcc way of dealing with
Mips16 code using floating point which involves essentially using soft float
but with a library implemented using mips32 floating point. This gcc 
method also requires creating stubs so that Mips32 code can interact with
these Mips 16 functions that have floating point needs. My conjecture is
that in reality this traditional gcc method would never win over this
new method.

I will be implementing the traditional gcc method also. Some of it is already
done but I needed to do the stubs to finish the work and those required
this mips16/32 mixed mode capability.

I have more ideas for to make this new method much better and I think the old
method will just live in llvm for anyone that needs the backward compatibility
but I don't for what reason that would be needed.

llvm-svn: 179185
2013-04-10 16:58:04 +00:00