Make it possible to pass NULL through variadic functions on 64-bit
Windows targets. The Visual C++ headers define NULL to 0, when they
should define it to 0LL on Win64 so that NULL is a pointer-sized
integer.
Fixes PR20949.
Reviewers: thakis, rsmith
Differential Revision: http://reviews.llvm.org/D5480
llvm-svn: 219456
This adds support for the align_value attribute. This attribute is supported by
Intel's compiler (versions 14.0+), and several of my HPC users have requested
support in Clang. It specifies an alignment assumption on the values to which a
pointer points, and is used by numerical libraries to encourage efficient
generation of vector code.
Of course, we already have an aligned attribute that can specify enhanced
alignment for a type, so why is this additional attribute important? The
problem is that if you want to specify that an input array of T is, say,
64-byte aligned, you could try this:
typedef double aligned_double attribute((aligned(64)));
void foo(aligned_double *P) {
double x = P[0]; // This is fine.
double y = P[1]; // What alignment did those doubles have again?
}
the access here to P[1] causes problems. P was specified as a pointer to type
aligned_double, and any object of type aligned_double must be 64-byte aligned.
But if P[0] is 64-byte aligned, then P[1] cannot be, and this access causes
undefined behavior. Getting round this problem requires a lot of awkward
casting and hand-unrolling of loops, all of which is bad.
With the align_value attribute, we can accomplish what we'd like in a well
defined way:
typedef double *aligned_double_ptr attribute((align_value(64)));
void foo(aligned_double_ptr P) {
double x = P[0]; // This is fine.
double y = P[1]; // This is fine too.
}
This attribute does not create a new type (and so it not part of the type
system), and so will only "propagate" through templates, auto, etc. by
optimizer deduction after inlining. This seems consistent with Intel's
implementation (thanks to Alexey for confirming the various Intel-compiler
behaviors).
As a final note, I would have chosen to call this aligned_value, not
align_value, for better naming consistency with the aligned attribute, but I
think it would be more useful to users to adopt Intel's name.
llvm-svn: 218910
This is the last piece of CGCall code that had implicit assumptions about
the order in which Clang arguments are translated to LLVM ones (positions
of inalloca argument, sret, this, padding arguments etc.) Now all of
this data is encapsulated in ClangToLLVMArgsMapping. If this information
would be required somewhere else, this class can be moved to a separate
header or pulled into CGFunctionInfo.
llvm-svn: 218634
Add a method to calculate the number of arguments given QualType
expnads to. Use this method in ClangToLLVMArgMapping calculation.
This number may be cached in CodeGenTypes for efficiency, if needed.
llvm-svn: 218623
Hoist the logic which determines the way QualType is expanded
into a separate method. Remove a bunch of copy-paste and simplify
getTypesFromArgs() / ExpandTypeFromArgs() / ExpandTypeToArgs() methods.
llvm-svn: 218615
In addition to __builtin_assume_aligned, GCC also supports an assume_aligned
attribute which specifies the alignment (and optional offset) of a function's
return value. Here we implement support for the assume_aligned attribute by making
use of the @llvm.assume intrinsic.
llvm-svn: 218500
Summary:
This patch implements a new UBSan check, which verifies
that function arguments declared to be nonnull with __attribute__((nonnull))
are actually nonnull in runtime.
To implement this check, we pass FunctionDecl to CodeGenFunction::EmitCallArgs
(where applicable) and if function declaration has nonnull attribute specified
for a certain formal parameter, we compare the corresponding RValue to null as
soon as it's calculated.
Test Plan: regression test suite
Reviewers: rsmith
Reviewed By: rsmith
Subscribers: cfe-commits, rnk
Differential Revision: http://reviews.llvm.org/D5082
llvm-svn: 217389
There were code paths that are duplicated for constructors and destructors just
because we have both CXXCtorType and CXXDtorsTypes.
This patch introduces an unified enum and reduces code deplication a bit.
llvm-svn: 217383
For naked functions with parameters, Clang would still emit stores in the prologue
that would clobber the stack, because LLVM doesn't set up a stack frame. (This
shows up in -O0 compiles, because the stores are optimized away otherwise.)
For example:
__attribute__((naked)) int f(int x) {
asm("movl $42, %eax");
asm("retl");
}
Would result in:
_Z1fi:
movl 12(%esp), %eax
movl %eax, (%esp) <--- Oops.
movl $42, %eax
retl
Differential Revision: http://reviews.llvm.org/D5183
llvm-svn: 217198
This avoids encoding information about the function prototype into the
thunk at the cost of some function prototype bitcast gymnastics.
Fixes PR20653.
llvm-svn: 216782
Previously, EnterStructPointerForCoercedAccess used Alloc size when determining how to convert. This was problematic, because there were situations were the alloc size was larger than the store size. For example, if the first element of a structure were i24 and the destination type were i32, the old code would generate a GEP and a load i24. The code should compare store sizes to ensure the whole object is loaded. I have attached a test case.
This patch modifies the output of arm64-be-bitfield.c test case, but the new IR seems to be equivalent, and after -O3, the compiler generates identical ARM assembly. (asr x0, x0, #54)
Patch by Thomas Jablin!
llvm-svn: 216722
This tidies up some ARM-specific code added by r208417 to move it out
of the target-independent parts of clang into TargetInfo.cpp. This
also has the advantage that we can now flatten struct arguments to
variadic AAPCS functions.
llvm-svn: 216535
Summary:
This refactoring introduces ClangToLLVMArgMapping class, which
encapsulates the information about the order in which function arguments listed
in CGFunctionInfo should be passed to actual LLVM IR function, such as:
1) positions of sret, if there is any
2) position of inalloca argument, if there is any
3) position of helper padding argument for each call argument
4) positions of regular argument (there can be many if it's expanded).
Simplify several related methods (ConstructAttributeList, EmitFunctionProlog
and EmitCall): now they don't have to maintain iterators over the list
of LLVM IR function arguments, dealing with all the sret/inalloca/this complexities,
and just use expected positions of LLVM IR arguments stored in ClangToLLVMArgMapping.
This may increase the running time of EmitFunctionProlog, as we have to traverse
expandable arguments twice, but in further refactoring we will be able
to speed up EmitCall by passing already calculated CallArgsToIRArgsMapping to
ConstructAttributeList, thus avoiding traversing expandable argument there.
No functionality change.
Test Plan: regression test suite
Reviewers: majnemer, rnk
Reviewed By: rnk
Subscribers: cfe-commits, rjmccall, timurrrr
Differential Revision: http://reviews.llvm.org/D4938
llvm-svn: 216251
Summary:
This patch adds a runtime check verifying that functions
annotated with "returns_nonnull" attribute do in fact return nonnull pointers.
It is based on suggestion by Jakub Jelinek:
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20140623/223693.html.
Test Plan: regression test suite
Reviewers: rsmith
Reviewed By: rsmith
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D4849
llvm-svn: 215485
This moves some memptr specific code into the generic thunk emission
codepath.
Fixes PR20053.
Reviewers: majnemer
Differential Revision: http://reviews.llvm.org/D4613
llvm-svn: 214004
In C99, an array parameter declarator might have the form:
direct-declarator '[' 'static' type-qual-list[opt] assign-expr ']'
where the static keyword indicates that the caller will always provide a
pointer to the beginning of an array with at least the number of elements
specified by the assignment expression. For constant sizes, we can use the
new dereferenceable attribute to pass this information to the optimizer. For
VLAs, we don't know the size, but (for addrspace(0)) do know that the pointer
must be nonnull (and so we can use the nonnull attribute).
llvm-svn: 213444
Because references must be initialized using some evaluated expression, they
must point to something, and a callee can assume the reference parameter is
dereferenceable. Taking advantage of a new attribute just added to LLVM, mark
them as such.
Because dereferenceability in addrspace(0) implies nonnull in the backend, we
don't need both attributes. However, we need to know the size of the object to
use the dereferenceable attribute, so for incomplete types we still emit only
nonnull.
llvm-svn: 213386
We now have an LLVM-level nonnull attribute that can be applied to function
parameters, and we emit it for reference types (as of r209723), but did not
emit it when an __attribute__((nonnull)) was provided. Now we will.
llvm-svn: 212835
Of course, such code is horribly broken and will explode on impact.
That said, ATL does it, and we have to support them, at least a little
bit.
Fixes PR20191.
llvm-svn: 212508
This is a GNU attribute that causes calls within the attributed function
to be inlined where possible. It is implemented by giving such calls the
alwaysinline attribute.
Differential Revision: http://reviews.llvm.org/D3816
llvm-svn: 209217
This is a GNU attribute that allows split stacks to be turned off on a
per-function basis.
Differential Revision: http://reviews.llvm.org/D3817
llvm-svn: 209167
This allows us to perfectly forward non-trivial arguments that use
inalloca.
We still can't forward non-trivial arguments through thunks when we have
a covariant return type with a non-trivial adjustment. This would
require emitting an extra copy, which is non-conforming anyway.
llvm-svn: 208927
Summary:
MSVC always passes 'sret' after 'this', unlike GCC. This required
changing a number of places in Clang that assumed the sret parameter was
always first in LLVM IR.
This fixes win64 MSVC ABI compatibility for methods returning structs.
Reviewers: rsmith, majnemer
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D3618
llvm-svn: 208458
This is the clang counterpart to 208413, which ensures that Homogeneous
Floating-point Aggregates are passed in consecutive registers on ARM.
llvm-svn: 208417
Previously we calculated the shift amount based upon DataLayout::getTypeAllocSizeInBits.
This will only work for legal types - types such as i24 that are created as part of
structs for bitfields will return "32" from that function. Change to using
getTypeSizeInBits.
It turns out that AArch64 didn't run across this problem because it always returned
[1 x i64] as the type for a bitfield, whereas ARM64 returns i64 so goes down this
(better, but wrong) codepath.
llvm-svn: 208231
Passing objects directly (in registers or memory) creates a second copy
of the object in the callee. The callee always destroys its copy, but
we also have to destroy any temporary created in the caller. In other
words, copy elision of these kinds of objects is impossible.
Objects larger than 8 bytes with non-trivial dtors and trivial copy
ctors are still passed indirectly, and we can still elide copies of
them.
Fixes PR19640.
llvm-svn: 207889
We were destroying them in the callee, and then again in the caller. We
should use an EH-only cleanup and disable it at the point of the call
for win64, even though we don't use inalloca.
llvm-svn: 207733
If we crash, we raise a crash handler dialog, and that's really
annoying. Even though we can't emit correct IR until we have musttail,
don't crash.
llvm-svn: 205948
Summary:
The definition of a type later in a translation unit may change it's
type from {}* to (%struct.foo*)*. Earlier function definitions may use
the former while more recent definitions might use the later. This is
fine until they interact with one another (like one calling the other).
In these cases, a bitcast is needed because the inalloca must match the
function call but the store to the lvalue which initializes the argument
slot has to match the rvalue's type.
This technique is along the same lines with what the other,
non-inalloca, codepaths perform.
This fixes PR19287.
Reviewers: rnk
CC: cfe-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D3224
llvm-svn: 205217
r203364: what was use_iterator is now user_iterator, and there is
a use_iterator for directly iterating over the uses.
This also switches to use the range-based APIs where appropriate.
llvm-svn: 203365
Reid Kleckner