Commit Graph

4922 Commits

Author SHA1 Message Date
Mohammed Agabaria 2c96c43388 [X86] updating TTI costs for arithmetic instructions on X86\SLM arch.
updated instructions:
pmulld, pmullw, pmulhw, mulsd, mulps, mulpd, divss, divps, divsd, divpd, addpd and subpd.

special optimization case which replaces pmulld with pmullw\pmulhw\pshuf seq. 
In case if the real operands bitwidth <= 16.

Differential Revision: https://reviews.llvm.org/D28104 

llvm-svn: 291657
2017-01-11 08:23:37 +00:00
Tony Jiang 3a2f00b024 [PowerPC] Implement missing ISA 2.06 instructions.
Instructions: fctidu[.], fctiwu[.], ftdiv, ftsqrt are not implemented. Implement
them and add corresponding test cases in this patch.

llvm-svn: 291116
2017-01-05 15:00:45 +00:00
Hal Finkel b2f951d87a [PowerPC] Fix logic dealing with nop after calls (and tail-call eligibility)
This change aims to unify and correct our logic for when we need to allow for
the possibility of the linker adding a TOC restoration instruction after a
call. This comes up in two contexts:

 1. When determining tail-call eligibility. If we make a tail call (i.e.
    directly branch to a function) then there is no place for the linker to add
    a TOC restoration.
 2. When determining when we need to add a nop instruction after a call.
    Likewise, if there is a possibility that the linker might need to add a
    TOC restoration after a call, then we need to put a nop after the call
    (the bl instruction).

First problem: We were using similar, but different, logic to decide (1) and
(2). This is just wrong. Both the resideInSameModule function (used when
determining tail-call eligibility) and the isLocalCall function (used when
deciding if the post-call nop is needed) were supposed to be determining the
same underlying fact (i.e. might a TOC restoration be needed after the call).
The same logic should be used in both places.

Second problem: The logic in both places was wrong. We only know that two
functions will share the same TOC when both functions come from the same
section of the same object. Otherwise the linker might cause the functions to
use different TOC base addresses (unless the multi-TOC linker option is
disabled, in which case only shared-library boundaries are relevant). There are
a number of factors that can cause functions to be placed in different sections
or come from different objects (-ffunction-sections, explicitly-specified
section names, COMDAT, weak linkage, etc.). All of these need to be checked.
The existing logic only checked properties of the callee, but the properties of
the caller must also be checked (for example, calling from a function in a
COMDAT section means calling between sections).

There was a conceptual error in the resideInSameModule function in that it
allowed tail calls to functions with weak linkage and protected/hidden
visibility. While protected/hidden visibility does prevent the function
implementation from being replaced at runtime (via interposition), it does not
prevent the linker from using an alternate implementation at link time (i.e.
using some strong definition to replace the provided weak one during linking).
If this happens, then we're still potentially looking at a required TOC
restoration upon return.

Otherwise, in general, the post-call nop is needed wherever ELF interposition
needs to be supported. We don't currently support ELF interposition at the IR
level (see http://lists.llvm.org/pipermail/llvm-dev/2016-November/107625.html
for more information), and I don't think we should try to make it appear to
work in the backend in spite of that fact. Unfortunately, because of the way
that the ABI works, we need to generate code as if we supported interposition
whenever the linker might insert stubs for the purpose of supporting it.

Differential Revision: https://reviews.llvm.org/D27231

llvm-svn: 291003
2017-01-04 21:05:13 +00:00
Ehsan Amiri 6c17bb0eb7 [Power9] Processor Model for Scheduling
PWR9 processor model for instruction scheduling. A subsequent patch will migrate
PWR9 to Post RA MIScheduler.
https://reviews.llvm.org/D24525

llvm-svn: 290102
2016-12-19 13:35:45 +00:00
Chandler Carruth 05e80d31bd Revert r289638: [PowerPC] Fix logic dealing with nop after calls (and tail-call eligibility)
This patch appears to result in trampolines in vtables being miscompiled
when they in turn tail call a method.

I've posted some preliminary details about the failure on the thread for
this commit and talked to Hal. He was comfortable going ahead and
reverting until we sort out what is wrong.

llvm-svn: 289928
2016-12-16 07:31:20 +00:00
Nemanja Ivanovic 552c8e960e [Power9] Allow AnyExt immediates for XXSPLTIB
In some situations, the BUILD_VECTOR node that builds a v18i8 vector by
a splat of an i8 constant will end up with signed 8-bit values and other
situations, it'll end up with unsigned ones. Handle both situations.

Fixes PR31340.

llvm-svn: 289804
2016-12-15 11:16:20 +00:00
Joerg Sonnenberger 400e7b7811 Use PIC relocation model as default for PowerPC64 ELF.
Most of the PowerPC64 code generation for the ELF ABI is already PIC.
There are four main exceptions:
(1) Constant pointer arrays etc. should in writeable sections.
(2) The TOC restoration NOP after a call is needed for all global
symbols. While GNU ld has a workaround for questionable GCC self-calls,
we trigger the checks for calls from COMDAT sections as they cross input
sections and are therefore not considered self-calls. The current
decision is questionable and suboptimal, but outside the scope of the
change.
(3) TLS access can not use the initial-exec model.
(4) Jump tables should use relative addresses. Note that the current
encoding doesn't work for the large code model, but it is more compact
than the default for any non-trivial jump table. Improving this is again
beyond the scope of this change.

At least (1) and (3) are assumptions made in target-independent code and
introducing additional hooks is a bit messy. Testing with clang shows
that a -fPIC binary is 600KB smaller than the corresponding -fno-pic
build. Separate testing from improved jump table encodings would explain
only about 100KB or so. The rest is expected to be a result of more
aggressive immediate forming for -fno-pic, where the -fPIC binary just
uses TOC entries.

This change brings the LLVM output in line with the GCC output, other
PPC64 compilers like XLC on AIX are known to produce PIC by default
as well. The relocation model can still be provided explicitly, i.e.
when using MCJIT.

One test case for case (1) is included, other test cases with relocation
mode sensitive behavior are wired to static for now. They will be
reviewed and adjusted separately.

Differential Revision: https://reviews.llvm.org/D26566

llvm-svn: 289743
2016-12-15 00:01:53 +00:00
Hal Finkel 065b756528 [PowerPC] Fix logic dealing with nop after calls (and tail-call eligibility)
This change aims to unify and correct our logic for when we need to allow for
the possibility of the linker adding a TOC restoration instruction after a
call. This comes up in two contexts:

 1. When determining tail-call eligibility. If we make a tail call (i.e.
    directly branch to a function) then there is no place for the linker to add
    a TOC restoration.
 2. When determining when we need to add a nop instruction after a call.
    Likewise, if there is a possibility that the linker might need to add a
    TOC restoration after a call, then we need to put a nop after the call
    (the bl instruction).

First problem: We were using similar, but different, logic to decide (1) and
(2). This is just wrong. Both the resideInSameModule function (used when
determining tail-call eligibility) and the isLocalCall function (used when
deciding if the post-call nop is needed) were supposed to be determining the
same underlying fact (i.e. might a TOC restoration be needed after the call).
The same logic should be used in both places.

Second problem: The logic in both places was wrong. We only know that two
functions will share the same TOC when both functions come from the same
section of the same object. Otherwise the linker might cause the functions to
use different TOC base addresses (unless the multi-TOC linker option is
disabled, in which case only shared-library boundaries are relevant). There are
a number of factors that can cause functions to be placed in different sections
or come from different objects (-ffunction-sections, explicitly-specified
section names, COMDAT, weak linkage, etc.). All of these need to be checked.
The existing logic only checked properties of the callee, but the properties of
the caller must also be checked (for example, calling from a function in a
COMDAT section means calling between sections).

There was a conceptual error in the resideInSameModule function in that it
allowed tail calls to functions with weak linkage and protected/hidden
visibility. While protected/hidden visibility does prevent the function
implementation from being replaced at runtime (via interposition), it does not
prevent the linker from using an alternate implementation at link time (i.e.
using some strong definition to replace the provided weak one during linking).
If this happens, then we're still potentially looking at a required TOC
restoration upon return.

Otherwise, in general, the post-call nop is needed wherever ELF interposition
needs to be supported. We don't currently support ELF interposition at the IR
level (see http://lists.llvm.org/pipermail/llvm-dev/2016-November/107625.html
for more information), and I don't think we should try to make it appear to
work in the backend in spite of that fact. This will yield subtle bugs if
interposition is attempted. As a result, regardless of whether we're in PIC
mode, we don't assume that we need to add the nop to support the possibility of
ELF interposition. However, the necessary check is in place (i.e. calling
GV->isInterposable and TM.shouldAssumeDSOLocal) so when we have functions for
which interposition is allowed at the IR level, we'll add the nop as necessary.
In the mean time, we'll generate more tail calls and fewer nops when compiling
position-independent code.

Differential Revision: https://reviews.llvm.org/D27231

llvm-svn: 289638
2016-12-14 07:24:50 +00:00
Eugene Zelenko 6a9226d9b8 [AMDGPU, PowerPC, TableGen] Fix some Clang-tidy modernize and Include What You Use warnings; other minor fixes (NFC).
llvm-svn: 289475
2016-12-12 22:23:53 +00:00
Guozhi Wei 1fd553c934 [PPC] Prefer direct move on power8 if load 1 or 2 bytes to VSR
Power8 has MTVSRWZ but no LXSIBZX/LXSIHZX, so move 1 or 2 bytes to VSR through MTVSRWZ is much faster than store the extended value into stack and load it with LXSIWZX.
This patch fixes pr31144.

Differential Revision: https://reviews.llvm.org/D27287

llvm-svn: 289473
2016-12-12 22:09:02 +00:00
Eugene Zelenko 2bc2f33ba2 [AMDGPU, PowerPC, TableGen] Fix some Clang-tidy modernize and Include What You Use warnings; other minor fixes (NFC).
llvm-svn: 289282
2016-12-09 22:06:55 +00:00
Sean Fertile 1c4109b4c2 [PPC] Add intrinsics for vector extract word and vector insert word.
Revision: https://reviews.llvm.org/D26547
llvm-svn: 289227
2016-12-09 17:21:42 +00:00
Nemanja Ivanovic 15748f4921 [PowerPC] Improvements for BUILD_VECTOR Vol. 4
This is the final patch in the series of patches that improves
BUILD_VECTOR handling on PowerPC. This adds a few peephole optimizations
to remove redundant instructions. It also adds a large test case which
encompasses a large set of code patterns that build vectors - this test
case was the motivator for this series of patches.

Differential Revision: https://reviews.llvm.org/D26066

llvm-svn: 288800
2016-12-06 11:47:14 +00:00
Nirav Dave d6642c1163 [PPC] Slightly Improve Assembly Parsing errors and add EOL comment
parsing tests.

NFC intended.

llvm-svn: 288667
2016-12-05 14:11:03 +00:00
Guozhi Wei 835de1f3ab [ppc] Correctly compute the cost of loading 32/64 bit memory into VSR
VSX has instructions lxsiwax/lxsdx that can load 32/64 bit value into VSX register cheaply. That patch makes it known to memory cost model, so the vectorization of the test case in pr30990 is beneficial.

Differential Revision: https://reviews.llvm.org/D26713

llvm-svn: 288560
2016-12-03 00:41:43 +00:00
Peter Collingbourne ab85225be4 IR: Change the gep_type_iterator API to avoid always exposing the "current" type.
Instead, expose whether the current type is an array or a struct, if an array
what the upper bound is, and if a struct the struct type itself. This is
in preparation for a later change which will make PointerType derive from
Type rather than SequentialType.

Differential Revision: https://reviews.llvm.org/D26594

llvm-svn: 288458
2016-12-02 02:24:42 +00:00
Matthias Braun f23ef437cc Move FrameInstructions from MachineModuleInfo to MachineFunction
This is per function data so it is better kept at the function instead
of the module.

This is a necessary step to have machine module passes work properly.

Differential Revision: https://reviews.llvm.org/D27185

llvm-svn: 288291
2016-11-30 23:48:42 +00:00
Krzysztof Parzyszek 31095d2ff5 [PowerPC] Preserve machine dominator tree in PPCVSXFMAMutate
It is needed by LiveIntervalAnalysis.

llvm-svn: 288243
2016-11-30 13:31:09 +00:00
Nemanja Ivanovic f9b191f135 [PowerPC] Improvements for BUILD_VECTOR Vol. 2
This patch corresponds to review:
https://reviews.llvm.org/D26023

This patch adds support for converting a vector of loads into a single load if
the loads are consecutive (in either direction).

llvm-svn: 288219
2016-11-29 23:57:54 +00:00
Nemanja Ivanovic 8c11e79b17 [PowerPC] Improvements for BUILD_VECTOR Vol. 2
This patch corresponds to review:
https://reviews.llvm.org/D25980

This is the 2nd patch in a series of 4 that improve the lowering and combining
for BUILD_VECTOR nodes on PowerPC. This particular patch combines a build vector
of fp-to-int conversions into an fp-to-int conversion of a build vector of fp
values. For example:
Converts (build_vector (fp_to_[su]i $A), (fp_to_[su]i $B), ...)
Into (fp_to_[su]i (build_vector $A, $B, ...))).
Which is a natural match for much cleaner code.

llvm-svn: 288218
2016-11-29 23:36:03 +00:00
Nemanja Ivanovic f57f150b1b Revert https://reviews.llvm.org/rL287679
This commit caused some miscompiles that did not show up on any of the bots.
Reverting until we can investigate the cause of those failures.

llvm-svn: 288214
2016-11-29 23:00:33 +00:00
Nemanja Ivanovic df1cb520df [PowerPC] Improvements for BUILD_VECTOR Vol. 1
This patch corresponds to review:
https://reviews.llvm.org/D25912

This is the first patch in a series of 4 that improve the lowering and combining
for BUILD_VECTOR nodes on PowerPC.

llvm-svn: 288152
2016-11-29 16:11:34 +00:00
Nemanja Ivanovic 10fc3cfc63 [PowerPC] Remove InstAlias definitions that cause incorrect assembly
In rL283190, I added some InstAlias definitions to generate extended mnemonics
for some uses of the XXPERMDI instruction. However, when the assembler matches
these extended mnemonics, it matches the new instruction in situations where it
should match the old one.
This patch removes these definitions and accomplishes that by defining these
mnemonics with additional instructions that are isCodeGenOnly.

Fixes PR31127.

llvm-svn: 287765
2016-11-23 15:51:52 +00:00
Nemanja Ivanovic b8e30d6db6 [PowerPC] Emit VMX loads/stores for aligned ops to avoid adding swaps on LE
This patch corresponds to review:
https://reviews.llvm.org/D26861

It also fixes PR30730.

Committing on behalf of Lei Huang.

llvm-svn: 287679
2016-11-22 19:02:07 +00:00
Simon Pilgrim fbd2221de5 Fix comment typos. NFC.
Identified by Pedro Giffuni in PR27636.

llvm-svn: 287486
2016-11-20 13:10:51 +00:00
Daniel Sanders 72db2a390a Check that emitted instructions meet their predicates on all targets except ARM, Mips, and X86.
Summary:
* ARM is omitted from this patch because this check appears to expose bugs in this target.
* Mips is omitted from this patch because this check either detects bugs or deliberate
  emission of instructions that don't satisfy their predicates. One deliberate
  use is the SYNC instruction where the version with an operand is correctly
  defined as requiring MIPS32 while the version without an operand is defined
  as an alias of 'SYNC 0' and requires MIPS2.
* X86 is omitted from this patch because it doesn't use the tablegen-erated
  MCCodeEmitter infrastructure.

Patches for ARM and Mips will follow.

Depends on D25617

Reviewers: tstellarAMD, jmolloy

Subscribers: wdng, jmolloy, aemerson, rengolin, arsenm, jyknight, nemanjai, nhaehnle, tstellarAMD, llvm-commits

Differential Revision: https://reviews.llvm.org/D25618

llvm-svn: 287439
2016-11-19 13:05:44 +00:00
Ehsan Amiri 395be572f0 [PPC] limit line width to 80 characters
NFC. Forgot to fix this in the original commit.

llvm-svn: 287350
2016-11-18 16:24:27 +00:00
Ehsan Amiri ff0942e6ea [Power9] Add patterns for vnegd, vnegw
Exploit new instructions by adding patterns to .td file.
https://reviews.llvm.org/D26551

llvm-svn: 287334
2016-11-18 11:05:55 +00:00
Ehsan Amiri 85818684c6 [PPC][DAGCombine] Convert SETCC to subtract when the result is zero extended
When we see a SETCC whose only users are zero extend operations, we can replace
it with a subtraction. This results in doing all calculations in GPRs and
avoids CR use.

Currently we do this only for ULT, ULE, UGT and UGE condition codes. There are
ways that this can be extended. For example for signed condition codes. In that
case we will be introducing additional sign extend instructions, so more careful
profitability analysis may be required.

Another direction to extend this is for equal, not equal conditions. Also when
users of SETCC are any_ext or sign_ext, we might be able to do something 
similar.

llvm-svn: 287329
2016-11-18 10:41:44 +00:00
Joerg Sonnenberger 8c1a9ac52b Always use relative jump table encodings on PowerPC64.
For the default, small and medium code model, use the existing
difference from the jump table towards the label. For all other code
models, setup the picbase and use the difference between the picbase and
the block address.

Overall, this results in smaller data tables at the expensive of one or
two more arithmetic operation at the jump site. Given that we only create
jump tables with a lot more than two entries, it is a net win in size.
For larger code models the assumption remains that individual functions
are no larger than 2GB.

Differential Revision: https://reviews.llvm.org/D26336

llvm-svn: 287059
2016-11-16 00:37:30 +00:00
Zaara Syeda a19c9e60e9 vector load store with length (left justified) llvm portion
llvm-svn: 286993
2016-11-15 17:54:19 +00:00
Tony Jiang 5f850cd1b1 [PowerPC] Implement BE VSX load/store builtins - llvm portion.
This patch implements all the overloads for vec_xl_be and vec_xst_be. On BE,
they behaves exactly the same with vec_xl and vec_xst, therefore they are
simply implemented by defining a matching macro. On LE, they are implemented
by defining new builtins and intrinsics. For int/float/long long/double, it
is just a load (lxvw4x/lxvd2x) or store(stxvw4x/stxvd2x). For char/char/short,
we also need some extra shuffling before or after call the builtins to get the
desired BE order. For int128, simply call vec_xl or vec_xst.

llvm-svn: 286967
2016-11-15 14:25:56 +00:00
Sean Fertile a435e07de8 [PPC] Add intrinsic mapping to the xscvhpsp instruction
add an intrinsic to expose the 'VSX Scalar Convert Half-Precision to
Single-Precision' instruction.

Differential review: https://reviews.llvm.org/D26536

llvm-svn: 286862
2016-11-14 18:43:59 +00:00
Sean Fertile adda5b2d2b [PPC] add intrinsics for vec extract exp/significand and vec test data class.
Differential Revision: https://reviews.llvm.org/D26272

llvm-svn: 286829
2016-11-14 14:42:37 +00:00
Nemanja Ivanovic ec4b0c360f [PowerPC] Add remaining vector permute builtins in altivec.h - LLVM portion
This patch corresponds to review:
https://reviews.llvm.org/D26480

Adds all the intrinsics used for various permute builtins that will
be added to altivec.h.

llvm-svn: 286638
2016-11-11 21:42:01 +00:00
Nemanja Ivanovic 2efc3cb968 [PowerPC] Add vector conversion builtins to altivec.h - LLVM portion
This patch corresponds to review:
https://reviews.llvm.org/D26307

Adds all the intrinsics used for various conversion builtins that will
be added to altivec.h. These are type conversions between various types of
vectors.

llvm-svn: 286596
2016-11-11 14:41:19 +00:00
Sean Fertile e1ca561b0a Add a blank line for a test commit.
llvm-svn: 286550
2016-11-11 02:33:17 +00:00
Evandro Menezes 21f9ce1a0d [DAG Combiner] Fix the native computation of the Newton series for reciprocals
The generic infrastructure to compute the Newton series for reciprocal and
reciprocal square root was conceived to allow a target to compute the series
itself.  However, the original code did not properly consider this condition
if returned by a target.  This patch addresses the issues to allow a target
to compute the series on its own.

Differential revision: https://reviews.llvm.org/D22975

llvm-svn: 286523
2016-11-10 23:31:06 +00:00
Chandler Carruth 651f019297 Sink all of the code relying on the MachO MachineModuleInfo to live
behind the test that the MachineModuleInfo analysis was
actually available and can be used.

While the MachO bits may well be reasonable to assume in the darwin
assembly printer, the analysis isn't constructively guaranteed anywhere
I could find so it seems safest to avoid crashing here.

This issue was found with PVS-Studio. Pretty sure the Clang Static
Anaylzer flags similar issues but we've probably never pointed it at
this code effectively.

llvm-svn: 285972
2016-11-03 23:33:46 +00:00
Tony Jiang 946242b5d2 NFC - Test commit.
Delete an empty line at the end of README.txt file.

llvm-svn: 285964
2016-11-03 20:32:21 +00:00
Joerg Sonnenberger bef3621ad0 Create the virtual register for the global base in the intersection of
GPRC and GPRC_NOR0 (or the 64bit equivalent) and not just the latter.
GPRC_NOR0 contains ZERO as alternative meaning of r0 and is therefore
not a true subclass of GPRC.

llvm-svn: 285813
2016-11-02 15:00:31 +00:00
Nemanja Ivanovic e70fa63390 [PowerPC] Implement vector shift builtins - llvm portion
This patch corresponds to review https://reviews.llvm.org/D26095.
Committing on behalf of Tony Jiang.

llvm-svn: 285681
2016-11-01 09:42:32 +00:00
Nemanja Ivanovic 60bdfe5a7c [PPC] add absolute difference altivec instructions and matching intrinsics
This patch corresponds to review https://reviews.llvm.org/D26072.
Committing on behalf of Sean Fertile.

llvm-svn: 285627
2016-10-31 19:47:52 +00:00
Nemanja Ivanovic e28a0fc72a Implement vector count leading/trailing bytes with zero lsb and vector parity
builtins - llvm portion

This patch corresponds to review https://reviews.llvm.org/D26003.
Committing on behalf of Zaara Syeda.

llvm-svn: 285434
2016-10-28 19:38:24 +00:00
Nemanja Ivanovic 32b5fed639 [PowerPC] - No SExt/ZExt needed for count trailing zeros
This patch corresponds to review:
https://reviews.llvm.org/D25896

It just eliminates the redundant ZExt after a count trailing zeros instruction.

llvm-svn: 285267
2016-10-27 05:17:58 +00:00
Nemanja Ivanovic 0f45998bc6 [PowerPC] Implement vec_insert_exp builtins - llvm portion
This revision corresponds to review: https://reviews.llvm.org/D25957.
Committing on behalf of Zaara Syeda.

llvm-svn: 285225
2016-10-26 19:03:40 +00:00
Peter Collingbourne 6733564e5a Target: Change various section classifiers in TargetLoweringObjectFile to take a GlobalObject.
These functions are about classifying a global which will actually be
emitted, so it does not make sense for them to take a GlobalValue which may
for example be an alias.

Change the Mach-O object writer and the Hexagon, Lanai and MIPS backends to
look through aliases before using TargetLoweringObjectFile interfaces. These
are functional changes but all appear to be bug fixes.

Differential Revision: https://reviews.llvm.org/D25917

llvm-svn: 285006
2016-10-24 19:23:39 +00:00
Ehsan Amiri c90b02cf50 [PPC] Generate positive FP zero using xor insn instead of loading from constant area
https://reviews.llvm.org/D23614

Currently we load +0.0 from constant area. That can change to be generated using
XOR instruction.

llvm-svn: 284995
2016-10-24 17:31:09 +00:00
Ehsan Amiri 1f31e9157d [PPC] Better codegen for AND, ANY_EXT, SRL sequence
https://reviews.llvm.org/D24924

This improves the code generated for a sequence of AND, ANY_EXT, SRL instructions. This is a targetted fix for this special pattern. The pattern is generated by target independet dag combiner and so a more general fix may not be necessary. If we come across other similar cases, some ideas for handling it are discussed on the code review.

llvm-svn: 284983
2016-10-24 15:46:58 +00:00
Sanjay Patel 0051efcf97 [Target] remove TargetRecip class; 2nd try
This is a retry of r284495 which was reverted at r284513 due to use-after-scope bugs
caused by faulty usage of StringRef.

This version also renames a pair of functions:
getRecipEstimateDivEnabled()
getRecipEstimateSqrtEnabled()
as suggested by Eric Christopher.

original commit msg:

[Target] remove TargetRecip class; move reciprocal estimate isel functionality to TargetLowering

This is a follow-up to https://reviews.llvm.org/D24816 - where we changed reciprocal estimates to be function attributes
rather than TargetOptions.

This patch is intended to be a structural, but not functional change. By moving all of the
TargetRecip functionality into TargetLowering, we can remove all of the reciprocal estimate
state, shield the callers from the string format implementation, and simplify/localize the
logic needed for a target to enable this.

If a function has a "reciprocal-estimates" attribute, those settings may override the target's
default reciprocal preferences for whatever operation and data type we're trying to optimize.
If there's no attribute string or specific setting for the op/type pair, just use the target
default settings.

As noted earlier, a better solution would be to move the reciprocal estimate settings to IR
instructions and SDNodes rather than function attributes, but that's a multi-step job that
requires infrastructure improvements. I intend to work on that, but it's not clear how long
it will take to get all the pieces in place.

Differential Revision: https://reviews.llvm.org/D25440

llvm-svn: 284746
2016-10-20 16:55:45 +00:00