optimize a call to a llvm intrinsic to something that invovles a call to a C
library call, make sure it sets the right calling convention on the call.
e.g.
extern double pow(double, double);
double t(double x) {
return pow(10, x);
}
Compiles to something like this for AAPCS-VFP:
define arm_aapcs_vfpcc double @t(double %x) #0 {
entry:
%0 = call double @llvm.pow.f64(double 1.000000e+01, double %x)
ret double %0
}
declare double @llvm.pow.f64(double, double) #1
Simplify libcall (part of instcombine) will turn the above into:
define arm_aapcs_vfpcc double @t(double %x) #0 {
entry:
%__exp10 = call double @__exp10(double %x) #1
ret double %__exp10
}
declare double @__exp10(double)
The pre-instcombine code works because calls to LLVM builtins are special.
Instruction selection will chose the right calling convention for the call.
However, the code after instcombine is wrong. The call to __exp10 will use
the C calling convention.
I can think of 3 options to fix this.
1. Make "C" calling convention just work since the target should know what CC
is being used.
This doesn't work because each function can use different CC with the "pcs"
attribute.
2. Have Clang add the right CC keyword on the calls to LLVM builtin.
This will work but it doesn't match the LLVM IR specification which states
these are "Standard C Library Intrinsics".
3. Fix simplify libcall so the resulting calls to the C routines will have the
proper CC keyword. e.g.
%__exp10 = call arm_aapcs_vfpcc double @__exp10(double %x) #1
This works and is the solution I implemented here.
Both solutions #2 and #3 would work. After carefully considering the pros and
cons, I decided to implement #3 for the following reasons.
1. It doesn't change the "spec" of the intrinsics.
2. It's a self-contained fix.
There are a couple of potential downsides.
1. There could be other places in the optimizer that is broken in the same way
that's not addressed by this.
2. There could be other calling conventions that need to be propagated by
simplify-libcall that's not handled.
But for now, this is the fix that I'm most comfortable with.
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This requires a number of steps.
1) Move value_use_iterator into the Value class as an implementation
detail
2) Change it to actually be a *Use* iterator rather than a *User*
iterator.
3) Add an adaptor which is a User iterator that always looks through the
Use to the User.
4) Wrap these in Value::use_iterator and Value::user_iterator typedefs.
5) Add the range adaptors as Value::uses() and Value::users().
6) Update *all* of the callers to correctly distinguish between whether
they wanted a use_iterator (and to explicitly dig out the User when
needed), or a user_iterator which makes the Use itself totally
opaque.
Because #6 requires churning essentially everything that walked the
Use-Def chains, I went ahead and added all of the range adaptors and
switched them to range-based loops where appropriate. Also because the
renaming requires at least churning every line of code, it didn't make
any sense to split these up into multiple commits -- all of which would
touch all of the same lies of code.
The result is still not quite optimal. The Value::use_iterator is a nice
regular iterator, but Value::user_iterator is an iterator over User*s
rather than over the User objects themselves. As a consequence, it fits
a bit awkwardly into the range-based world and it has the weird
extra-dereferencing 'operator->' that so many of our iterators have.
I think this could be fixed by providing something which transforms
a range of T&s into a range of T*s, but that *can* be separated into
another patch, and it isn't yet 100% clear whether this is the right
move.
However, this change gets us most of the benefit and cleans up
a substantial amount of code around Use and User. =]
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source file had already been moved. Also move the unittest into the IR
unittest library.
This may seem an odd thing to put in the IR library but we only really
use this with instructions and it needs the LLVM context to work, so it
is intrinsically tied to the IR library.
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business.
This header includes Function and BasicBlock and directly uses the
interfaces of both classes. It has to do with the IR, it even has that
in the name. =] Put it in the library it belongs to.
This is one step toward making LLVM's Support library survive a C++
modules bootstrap.
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Summary:
The only current use of this flag is to mark the alloca as dynamic, even
if its in the entry block. The stack adjustment for the alloca can
never be folded into the prologue because the call may clear it and it
has to be allocated at the top of the stack.
Reviewers: majnemer
CC: llvm-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D2571
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We need to ensure that StackSlotColoring.cpp does not reuse stack
spill slots in functions that call "returns_twice" functions such as
setjmp(), otherwise this can lead to miscompiled code, because a stack
slot would be clobbered when it's still live.
This was already handled correctly for functions that call setjmp()
(though this wasn't covered by a test), but not for functions that
invoke setjmp().
We fix this by changing callsFunctionThatReturnsTwice() to check for
invoke instructions.
This fixes PR18244.
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The inalloca attribute is designed to support passing C++ objects by
value in the Microsoft C++ ABI. It behaves the same as byval, except
that it always implies that the argument is in memory and that the bytes
are never copied. This attribute allows the caller to take the address
of an outgoing argument's memory and execute arbitrary code to store
into it.
This patch adds basic IR support, docs, and verification. It does not
attempt to implement any lowering or fix any possibly broken transforms.
When this patch lands, a complete description of this feature should
appear at http://llvm.org/docs/InAlloca.html .
Differential Revision: http://llvm-reviews.chandlerc.com/D2173
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Patch by Ana Pazos.
1.Added support for v1ix and v1fx types.
2.Added Scalar Pairwise Reduce instructions.
3.Added initial implementation of Scalar Arithmetic instructions.
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functions. Make the function attributes pass add it to known library functions
and when it can deduce it.
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This reduces the time actually spent doing string to ID conversion and shows a 10% improvement in compile time for a particularly bad case that involves ARM Neon intrinsics (these have many overloads).
Patch by Jean-Luc Duprat!
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The slot that we're adding/removing the attribute from may not be the same as
the attribute coming in. Make sure that they match up before we try to
add/remove them.
PR15313
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Collections of attributes are handled via the AttributeSet class now. This
finally frees us up to make significant changes to how attributes are structured.
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Use the AttributeSet when we're talking about more than one attribute. Add a
function that adds a single attribute. No functionality change intended.
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code that includes Intrinsics.gen directly.
This never showed up in my testing because the old Intrinsics.gen was
still kicking around in the make build system and was correct there. =[
Thankfully, some of the bots to clean rebuilds and that caught this.
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into their new header subdirectory: include/llvm/IR. This matches the
directory structure of lib, and begins to correct a long standing point
of file layout clutter in LLVM.
There are still more header files to move here, but I wanted to handle
them in separate commits to make tracking what files make sense at each
layer easier.
The only really questionable files here are the target intrinsic
tablegen files. But that's a battle I'd rather not fight today.
I've updated both CMake and Makefile build systems (I think, and my
tests think, but I may have missed something).
I've also re-sorted the includes throughout the project. I'll be
committing updates to Clang, DragonEgg, and Polly momentarily.
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Aside from moving the actual files, this patch only updates the build
system and the source file comments under lib/... that are relevant.
I'll be updating other docs and other files in smaller subsequnet
commits.
While I've tried to test this, but it is entirely possible that there
will still be some build system fallout.
Also, note that I've not changed the library name itself: libLLVMCore.a
is still the library name. I'd be interested in others' opinions about
whether we should rename this as well (I think we should, just not sure
what it might break)
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