1368 Commits

Author SHA1 Message Date
Haojian Wu
efa9aaad70 [clang] Suppress "follow-up" diagnostics on recovery call expressions.
Because of typo-correction, the AST can be transformed, and the transformed
AST is marginally useful for diagnostics purpose, the following
diagnostics usually do harm than good (easily cause confusions).

Given the following code:

```
void abcc();
void test() {
  if (abc());
  // diagnostic 1 (for the typo-correction): the typo is correct to `abcc()`, so the code is treate as `if (abcc())` in AST perspective;
  // diagnostic 2 (for mismatch type): we perform an type-analysis on `if`, discover the type is not match
}
```

The secondary diagnostic "convertable to bool" is likely bogus to users.

The idea is to use RecoveryExpr (clang's dependent mechanism) to preserve the
recovery behavior but suppress all follow-up diagnostics.

Differential Revision: https://reviews.llvm.org/D89946
2020-10-26 12:40:00 +01:00
Richard Smith
7b3515880c For P0732R2, P1907R1: ensure that template parameter objects don't refer
to disallowed objects or have non-constant destruction.
2020-10-24 22:11:43 -07:00
Richard Smith
ba4768c966 [c++20] For P0732R2 / P1907R1: Basic frontend support for class types as
non-type template parameters.

Create a unique TemplateParamObjectDecl instance for each such value,
representing the globally unique template parameter object to which the
template parameter refers.

No IR generation support yet; that will follow in a separate patch.
2020-10-21 13:21:41 -07:00
Yaxun (Sam) Liu
52bcd691cb Recommit "[CUDA][HIP] Defer overloading resolution diagnostics for host device functions"
This recommits 7f1f89ec8d9944559042bb6d3b1132eabe3409de and
40df06cdafc010002fc9cfe1dda73d689b7d27a6 with bug fixes for
memory sanitizer failure and Tensile build failure.
2020-10-19 17:48:04 -04:00
Haojian Wu
31dc908017 [clang] Use isCompoundAssignmentOp to simplify the code, NFC. 2020-10-07 09:50:43 +02:00
Haojian Wu
7f05fe1aee [AST][RecoveryExpr] Fix a crash on undeduced type.
We should not capture the type if the function return type is undeduced.

Reviewed By: adamcz

Differential Revision: https://reviews.llvm.org/D87350
2020-10-05 12:52:04 +02:00
Mark de Wever
0ce6d6b46e [Sema] List conversion validate character array.
The function `TryListConversion` didn't properly validate the following
part of the standard:

    Otherwise, if the parameter type is a character array [... ]
    and the initializer list has a single element that is an
    appropriately-typed string literal (8.5.2 [dcl.init.string]), the
    implicit conversion sequence is the identity conversion.

This caused the following call to `f()` to be ambiguous.
    void f(int(&&)[1]);
    void f(unsigned(&&)[1]);

    void g(unsigned i) {
      f({i});
    }

This issue only occurs when the initializer list had one element.

Differential Revision: https://reviews.llvm.org/D87561
2020-10-03 14:33:28 +02:00
Reid Kleckner
3453b6928d Revert "Recommit "[CUDA][HIP] Defer overloading resolution diagnostics for host device functions""
This reverts commit e39da8ab6a286ac777d5fe7799f1eb782cf99938.

This depends on a change that needs additional design review and needs
to be reverted.
2020-09-24 11:16:54 -07:00
Yaxun (Sam) Liu
e39da8ab6a Recommit "[CUDA][HIP] Defer overloading resolution diagnostics for host device functions"
This recommits 7f1f89ec8d9944559042bb6d3b1132eabe3409de and
40df06cdafc010002fc9cfe1dda73d689b7d27a6 after fixing memory
sanitizer failure.
2020-09-24 08:44:37 -04:00
Yaxun (Sam) Liu
772bd8a7d9 Revert "[CUDA][HIP] Defer overloading resolution diagnostics for host device functions"
This reverts commit 7f1f89ec8d9944559042bb6d3b1132eabe3409de.

This reverts commit 40df06cdafc010002fc9cfe1dda73d689b7d27a6.
2020-09-17 13:55:31 -04:00
Yaxun (Sam) Liu
40df06cdaf [CUDA][HIP] Defer overloading resolution diagnostics for host device functions
In CUDA/HIP a function may become implicit host device function by
pragma or constexpr. A host device function is checked in both
host and device compilation. However it may be emitted only
on host or device side, therefore the diagnostics should be
deferred until it is known to be emitted.

Currently clang is only able to defer certain diagnostics. This causes
false alarms and limits the usefulness of host device functions.

This patch lets clang defer all overloading resolution diagnostics for host device functions.

An option -fgpu-defer-diag is added to control this behavior. By default
it is off.

It is NFC for other languages.

Differential Revision: https://reviews.llvm.org/D84364
2020-09-17 11:30:42 -04:00
Serge Pavlov
f1cd6593da [AST][FPEnv] Keep FP options in trailing storage of CastExpr
This is recommit of 6c8041aa0f, reverted in de044f7562 because of some
fails. Original commit message is below.

This change allow a CastExpr to have optional FPOptionsOverride object,
stored in trailing storage. Of all cast nodes only ImplicitCastExpr,
CStyleCastExpr, CXXFunctionalCastExpr and CXXStaticCastExpr are allowed
to have FPOptions.

Differential Revision: https://reviews.llvm.org/D85960
2020-09-14 12:15:21 +07:00
Serge Pavlov
de044f7562 Revert "[AST][FPEnv] Keep FP options in trailing storage of CastExpr"
This reverts commit 6c8041aa0ffed827636935e59c489b1e390c8542.
It caused some fails on buildbots.
2020-09-12 17:06:42 +07:00
Serge Pavlov
6c8041aa0f [AST][FPEnv] Keep FP options in trailing storage of CastExpr
This change allow a CastExpr to have optional FPOptionsOverride object,
stored in trailing storage. Of all cast nodes only ImplicitCastExpr,
CStyleCastExpr, CXXFunctionalCastExpr and CXXStaticCastExpr are allowed
to have FPOptions.

Differential Revision: https://reviews.llvm.org/D85960
2020-09-12 14:30:44 +07:00
Richard Smith
052dbe226c Remove unused and dangerous overload of PerformImplicitConversion.
Previously we had two overloads where the only real difference beyond
parameter order was whether a reference parameter is const, where one
overload treated the reference parameter as an in-parameter and the
other treated it as an out-parameter!
2020-09-03 15:35:12 -07:00
Aaron Puchert
b4a2d36c3f [Sema] ICK_Function_Conversion is a third kind conversion
Not sure if this has any effect, but it was inconsistent before.

Reviewed By: rsmith

Differential Revision: https://reviews.llvm.org/D67113
2020-08-29 18:42:36 +02:00
Cullen Rhodes
feed5a7239 [Sema][AArch64] Support arm_sve_vector_bits attribute
This patch implements the semantics for the 'arm_sve_vector_bits' type
attribute, defined by the Arm C Language Extensions (ACLE) for SVE [1].
The purpose of this attribute is to define vector-length-specific (VLS)
versions of existing vector-length-agnostic (VLA) types.

The semantics were already implemented by D83551, although the
implementation approach has since changed to represent VLSTs as
VectorType in the AST and fixed-length vectors in the IR everywhere
except in function args/returns. This is described in the prototype
patch D85128 demonstrating the new approach.

The semantic changes added in D83551 are changed since the
AttributedType is replaced by VectorType in the AST. Minimal changes
were necessary in the previous patch as the canonical type for both VLA
and VLS was the same (i.e. sizeless), except in constructs such as
globals and structs where sizeless types are unsupported. This patch
reverts the changes that permitted VLS types that were represented as
sizeless types in such circumstances, and adds support for implicit
casting between VLA <-> VLS types as described in section 3.7.3.2 of the
ACLE.

Since the SVE builtin types for bool and uint8 are both represented as
BuiltinType::UChar in VLSTs, two new vector kinds are implemented to
distinguish predicate and data vectors.

[1] https://developer.arm.com/documentation/100987/latest

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D85736
2020-08-27 10:38:32 +00:00
Richard Smith
c1c1bed5d0 [c++14] Implement missed piece of N3323: use "converted constant" rules
for array bounds, not "integer constant" rules.

For an array bound of class type, this causes us to perform an implicit
conversion to size_t, instead of looking for a unique conversion to
integral or unscoped enumeration type. This affects which cases are
valid when a class has multiple implicit conversion functions to
different types.
2020-08-19 15:45:51 -07:00
Haojian Wu
031738a561 [AST][RecoveryExpr] Don't preserve the return type if the FunctionDecl is invalid.
If a functionDecl is invalid (e.g. return type cannot be formed), int is
use as he fallback type, which may lead to some bogus diagnostics.

Reviewed By: sammccall

Differential Revision: https://reviews.llvm.org/D85714
2020-08-11 13:49:57 +02:00
Richard Smith
ed5a18fc03 PR30738: Implement two-phase name lookup for fold-expressions. 2020-08-06 16:56:39 -07:00
Bruno Ricci
eb10b065f2
[clang] Pass the NamedDecl* instead of the DeclarationName into many diagnostics.
Background:
-----------
There are two related argument types which can be sent into a diagnostic to
display the name of an entity: DeclarationName (ak_declarationname) or
NamedDecl* (ak_nameddecl) (there is also ak_identifierinfo for
IdentifierInfo*, but we are not concerned with it here).

A DeclarationName in a diagnostic will just be streamed to the output,
which will directly result in a call to DeclarationName::print.

A NamedDecl* in a diagnostic will also ultimately result in a call to
DeclarationName::print, but with two customisation points along the way:

The first customisation point is NamedDecl::getNameForDiagnostic which is
overloaded by FunctionDecl, ClassTemplateSpecializationDecl and
VarTemplateSpecializationDecl to print the template arguments, if any.

The second customisation point is NamedDecl::printName. By default it just
streams the stored DeclarationName into the output but it can be customised
to provide a user-friendly name for an entity. It is currently overloaded by
DecompositionDecl and MSGuidDecl.

What this patch does:
---------------------
For many diagnostics a DeclarationName is used instead of the NamedDecl*.
This bypasses the two customisation points mentioned above. This patches fix
this for diagnostics in Sema.cpp, SemaCast.cpp, SemaChecking.cpp, SemaDecl.cpp,
SemaDeclAttr.cpp, SemaDecl.cpp, SemaOverload.cpp and SemaStmt.cpp.

I have only modified diagnostics where I could construct a test-case which
demonstrates that the change is appropriate (either with this patch or the next
one).

Reviewed By: erichkeane, aaron.ballman

Differential Revision: https://reviews.llvm.org/D84656
2020-07-28 10:30:35 +01:00
Serge Pavlov
70e7aa4a4e [AST][FPEnv] Keep FP options in trailing storage of CallExpr
This change allow a CallExpr to have optional FPOptionsOverride object,
stored in trailing storage. The implementaion is made similar to the way
used in BinaryOperator.

Differential Revision: https://reviews.llvm.org/D84343
2020-07-24 12:04:19 +07:00
David Blaikie
36036aa70e Reapply "Rename/refactor isIntegerConstantExpression to getIntegerConstantExpression"
Reapply 49e5f603d40083dce9c05796e3cde3a185c3beba
which had been reverted in c94332919bd922032e979b3ae3ced5ca5bdf9650.

Originally reverted because I hadn't updated it in quite a while when I
got around to committing it, so there were a bunch of missing changes to
new code since I'd written the patch.

Reviewers: aaron.ballman

Differential Revision: https://reviews.llvm.org/D76646
2020-07-21 20:57:12 -07:00
David Blaikie
c94332919b Revert "Rename/refactor isIntegerConstantExpression to getIntegerConstantExpression"
Broke buildbots since I hadn't updated this patch in a while. Sorry for
the noise.

This reverts commit 49e5f603d40083dce9c05796e3cde3a185c3beba.
2020-07-12 20:29:19 -07:00
David Blaikie
49e5f603d4 Rename/refactor isIntegerConstantExpression to getIntegerConstantExpression
There is a version that just tests (also called
isIntegerConstantExpression) & whereas this version is specifically used
when the value is of interest (a few call sites were actually refactored
to calling the test-only version) so let's make the API look more like
it.

Reviewers: aaron.ballman

Differential Revision: https://reviews.llvm.org/D76646
2020-07-12 19:43:24 -07:00
Haojian Wu
96a5cfff20 [AST][RecoveryExpr] Fix the value category for recovery expr.
RecoveryExpr was always lvalue, but it is wrong if we use it to model
broken function calls, function call expression has more compliated rules:

- a call to a function whose return type is an lvalue reference yields an lvalue;
- a call to a function whose return type is an rvalue reference yields an xvalue;
- a call to a function whose return type is nonreference type yields a prvalue;

This patch makes the recovery-expr align with the function call if it is
modeled a broken call.

Differential revision: https://reviews.llvm.org/D83201
2020-07-08 13:55:07 +02:00
Richard Smith
065fc1eafe PR45521: Preserve the value kind when performing a standard conversion
sequence on a glvalue expression.

If the sequence is supposed to perform an lvalue-to-rvalue conversion,
then one will be specified as the first conversion in the sequence.
Otherwise, one should not be invented.
2020-07-07 18:28:28 -07:00
Richard Smith
5a5f5350e1 [c++20] Fix handling of operator rewrites naming consteval operator<=>. 2020-06-29 19:02:47 -07:00
Melanie Blower
f4aaed3bf1 Reland D81869 "Modify FPFeatures to use delta not absolute settings"
This reverts commit defd43a5b393bb63a902042adf578081b03b171d.
with correction to solve msan report

To solve https://bugs.llvm.org/show_bug.cgi?id=46166 where the
floating point settings in PCH files aren't compatible, rewrite
FPFeatures to use a delta in the settings rather than absolute settings.
With this patch, these floating point options can be benign.

Reviewers: rjmccall

Differential Revision: https://reviews.llvm.org/D81869
2020-06-27 01:34:57 -07:00
Melanie Blower
defd43a5b3 Revert "Revert "Revert "Modify FPFeatures to use delta not absolute settings"""
This reverts commit 9518763d710bfbbf9315fa88972c55898be44a0e.
Memory sanitizer fails in CGFPOptionsRAII::CGFPOptionsRAII dtor
2020-06-26 08:47:04 -07:00
Melanie Blower
9518763d71 Revert "Revert "Modify FPFeatures to use delta not absolute settings""
This reverts commit b55d723ed61052b77e720dcffecac43abe873186.
Reapply Modify FPFeatures to use delta not absolute settings

To solve https://bugs.llvm.org/show_bug.cgi?id=46166 where the
floating point settings in PCH files aren't compatible, rewrite
FPFeatures to use a delta in the settings rather than absolute settings.
With this patch, these floating point options can be benign.

Reviewers: rjmccall

Differential Revision: https://reviews.llvm.org/D81869
2020-06-26 08:00:08 -07:00
Melanie Blower
b55d723ed6 Revert "Modify FPFeatures to use delta not absolute settings"
This reverts commit 3a748cbf86cea3844fada04eeff4cc64b01f67e0.
I'm reverting this commit because I forgot to format the commit message
propertly. Sorry for the thrash.
2020-06-26 07:52:57 -07:00
Melanie Blower
3a748cbf86 Modify FPFeatures to use delta not absolute settings 2020-06-26 07:41:09 -07:00
Fangrui Song
b3d10920e1 Restore part of D80450 [CUDA][HIP] Fix implicit HD function resolution
The "if (S.getLangOpts().CUDA && Cand1.Function && Cand2.Function) {"
part is known to be problematic but the root cause isn't clear yet.
2020-06-10 22:33:33 -07:00
Fangrui Song
dfc0d94755 Revert D80450 "[CUDA][HIP] Fix implicit HD function resolution"
This reverts commit 263390d4f5f23967a31af09eb6e0c12e633d6104.

This can still cause bogus errors:

eigen3/Eigen/src/Core/CoreEvaluators.h:94:38: error: call to implicitly-deleted copy constructor of 'unary_evaluator<Eigen::Inverse<Eigen::Matrix<double, 4, 4, 0, 4, 4>>>'

thrust/system/detail/generic/for_each.h:49:3: error: implicit instantiation of undefined template
'thrust::detail::STATIC_ASSERTION_FAILURE<false>'
2020-06-10 17:42:28 -07:00
Florian Hahn
4affc444b4 [Matrix] Implement * binary operator for MatrixType.
This patch implements the * binary operator for values of
MatrixType. It adds support for matrix * matrix, scalar * matrix and
matrix * scalar.

For the matrix, matrix case, the number of columns of the first operand
must match the number of rows of the second. For the scalar,matrix variants,
the element type of the matrix must match the scalar type.

Reviewers: rjmccall, anemet, Bigcheese, rsmith, martong

Reviewed By: rjmccall

Differential Revision: https://reviews.llvm.org/D76794
2020-06-07 11:11:27 +01:00
Ties Stuij
ecd682bbf5 [ARM] Add __bf16 as new Bfloat16 C Type
Summary:
This patch upstreams support for a new storage only bfloat16 C type.
This type is used to implement primitive support for bfloat16 data, in
line with the Bfloat16 extension of the Armv8.6-a architecture, as
detailed here:

https://community.arm.com/developer/ip-products/processors/b/processors-ip-blog/posts/arm-architecture-developments-armv8-6-a

The bfloat type, and its properties are specified in the Arm Architecture
Reference Manual:

https://developer.arm.com/docs/ddi0487/latest/arm-architecture-reference-manual-armv8-for-armv8-a-architecture-profile

In detail this patch:
- introduces an opaque, storage-only C-type __bf16, which introduces a new bfloat IR type.

This is part of a patch series, starting with command-line and Bfloat16
assembly support. The subsequent patches will upstream intrinsics
support for BFloat16, followed by Matrix Multiplication and the
remaining Virtualization features of the armv8.6-a architecture.

The following people contributed to this patch:
- Luke Cheeseman
- Momchil Velikov
- Alexandros Lamprineas
- Luke Geeson
- Simon Tatham
- Ties Stuij

Reviewers: SjoerdMeijer, rjmccall, rsmith, liutianle, RKSimon, craig.topper, jfb, LukeGeeson, fpetrogalli

Reviewed By: SjoerdMeijer

Subscribers: labrinea, majnemer, asmith, dexonsmith, kristof.beyls, arphaman, danielkiss, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D76077
2020-06-05 10:32:43 +01:00
Yaxun (Sam) Liu
263390d4f5 [CUDA][HIP] Fix implicit HD function resolution
recommit e03394c6a6ff with fix

When implicit HD function calls a function in device compilation,
if one candidate is an implicit HD function, current resolution rule is:

D wins over HD and H
HD and H are equal

this caused regression when there is an otherwise worse D candidate

This patch changes that to

D, HD and H are all equal

The rationale is that we already know for host compilation there is already
a valid candidate in HD and H candidates that will not cause error. Allowing
HD and H gives us a fall back candidate that will not cause error. If D wins,
that means D has to be a better match otherwise, therefore D should also
be a valid candidate that will not cause error. In this way, we can guarantee
no regression.

Differential Revision: https://reviews.llvm.org/D80450
2020-06-04 16:54:52 -04:00
Florian Hahn
714e84be46 [SemaOverload] Use iterator_range to iterate over VectorTypes (NFC).
We can simplify the code a bit by using iterator_range instead of
plain iterators. Matrix type support here (added in 6f6e91d19337)
already uses an iterator_range.

Reviewers: rjmccall, arphaman, jfb, Bigcheese

Reviewed By: rjmccall

Differential Revision: https://reviews.llvm.org/D81138
2020-06-04 20:47:16 +01:00
Florian Hahn
a7c6bec228 [Sema] Remove unused matrix_begin/end helpers (NFC).
The matrix_types() helper returning an iterator range is used instead.
2020-06-04 11:29:01 +01:00
Richard Smith
b5f2c4e45b PR23029 / C++ DR2233: Allow expanded parameter packs to follow
parameters with default arguments.

Directly follow the wording by relaxing the AST invariant that all
parameters after one with a default arguemnt also have default
arguments, and removing the diagnostic on missing default arguments
on a pack-expanded parameter following a parameter with a default
argument.

Testing also revealed that we need to special-case explicit
specializations of templates with a pack following a parameter with a
default argument, as such explicit specializations are otherwise
impossible to write. The standard wording doesn't address this case; a
issue has been filed.

This exposed a bug where we would briefly consider a parameter to have
no default argument while we parse a delay-parsed default argument for
that parameter, which is also fixed.

Partially incorporates a patch by Raul Tambre.
2020-06-02 13:48:59 -07:00
Florian Hahn
6f6e91d193 [Matrix] Implement + and - operators for MatrixType.
This patch implements the + and - binary operators for values of
MatrixType. It adds support for matrix +/- matrix, scalar +/- matrix and
matrix +/- scalar.

For the matrix, matrix case, the types must initially be structurally
equivalent. For the scalar,matrix variants, the element type of the
matrix must match the scalar type.

Reviewers: rjmccall, anemet, Bigcheese, rsmith, martong

Reviewed By: rjmccall

Differential Revision: https://reviews.llvm.org/D76793
2020-05-29 20:42:22 +01:00
Richard Smith
0dfb43deb6 Fix handling of default arguments in __attribute__((enable_if)).
We didn't properly build default argument expressions previously -- we
failed to build the wrapper CXXDefaultArgExpr node, which meant that
std::source_location misbehaved, and we didn't perform default argument
instantiation when necessary, which meant that dependent default
arguments in function templates didn't work at all.
2020-05-28 15:35:22 -07:00
Artem Belevich
ef649e8fd5 Revert "[CUDA][HIP] Workaround for resolving host device function against wrong-sided function"
Still breaks CUDA compilation.

This reverts commit e03394c6a6ff5832aa43259d4b8345f40ca6a22c.
2020-05-18 12:22:55 -07:00
Yaxun (Sam) Liu
e03394c6a6 [CUDA][HIP] Workaround for resolving host device function against wrong-sided function
recommit c77a4078e01033aa2206c31a579d217c8a07569b with fix

https://reviews.llvm.org/D77954 caused regressions due to diagnostics in implicit
host device functions.

For now, it seems the most feasible workaround is to treat implicit host device function and explicit host
device function differently. Basically in device compilation for implicit host device functions, keep the
old behavior, i.e. give host device candidates and wrong-sided candidates equal preference. For explicit
host device functions, favor host device candidates against wrong-sided candidates.

The rationale is that explicit host device functions are blessed by the user to be valid host device functions,
that is, they should not cause diagnostics in both host and device compilation. If diagnostics occur, user is
able to fix them. However, there is no guarantee that implicit host device function can be compiled in
device compilation, therefore we need to preserve its overloading resolution in device compilation.

Differential Revision: https://reviews.llvm.org/D79526
2020-05-12 08:27:50 -04:00
Haojian Wu
8222107aa9 [AST] Preserve the type in RecoveryExprs for broken function calls.
RecoveryExprs are modeled as dependent type to prevent bogus diagnostics
and crashes in clang.

This patch allows to preseve the type for broken calls when the
RecoveryEprs have a known type, e.g. a broken non-overloaded call, a
overloaded call when the all candidates have the same return type, so
that more features (code completion still work on "take2args(x).^") still
work.

However, adding the type is risky, which may result in more clang code being
affected leading to new crashes and hurt diagnostic, and it requires large
effort to minimize the affect (update all sites in clang to handle errorDepend
case), so we add a new flag (off by default) to allow us to develop/test
them incrementally.

This patch also has some trivial fixes to suppress diagnostics (to prevent regressions).

Tested:

all existing tests are passed (when both "-frecovery-ast", "-frecovery-ast-type" flags are flipped on);

Reviewed By: sammccall

Subscribers: rsmith, arphaman, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D79160
2020-05-11 08:46:18 +02:00
Artem Belevich
bf6a26b066 Revert D77954 -- it breaks Eigen & Tensorflow.
This reverts commit 55bcb96f3154808bcb5afc3fb46d8e00bf1db847.
2020-05-05 14:07:31 -07:00
Melanie Blower
f5360d4bb3 Reapply "Add support for #pragma float_control" with buildbot fixes
Add support for #pragma float_control

Reviewers: rjmccall, erichkeane, sepavloff

Differential Revision: https://reviews.llvm.org/D72841

This reverts commit fce82c0ed310174fe48e2402ac731b6340098389.
2020-05-04 05:51:25 -07:00
Melanie Blower
fce82c0ed3 Revert "Reapply "Add support for #pragma float_control" with improvements to"
This reverts commit 69aacaf699922ffe0450f567e21208c10c84731f.
2020-05-01 10:31:09 -07:00
Melanie Blower
69aacaf699 Reapply "Add support for #pragma float_control" with improvements to
test cases
Add support for #pragma float_control

Reviewers: rjmccall, erichkeane, sepavloff

Differential Revision: https://reviews.llvm.org/D72841

This reverts commit 85dc033caccaa6ab919d57f9759290be41240146, and makes
corrections to the test cases that failed on buildbots.
2020-05-01 10:03:30 -07:00