Summary:
Update the TBAA section to mention the struct path TBAA that LLVM
implements today. This is not a proposal or change in semantics -- it
is intended only to **document** what LLVM already does today.
This is related to https://reviews.llvm.org/D26438 where I've tried to
implement some of the constraints as verifier checks.
Reviewers: anna, reames, rsmith, chandlerc, hfinkel, rjmccall, mehdi_amini, dexonsmith, manmanren
Reviewed By: manmanren
Subscribers: dberlin, dberris, mcrosier, llvm-commits
Differential Revision: https://reviews.llvm.org/D26831
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294999 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This patch starts the implementation as discuss in the following RFC: http://lists.llvm.org/pipermail/llvm-dev/2016-October/106532.html
When optimization duplicates code that will scale down the execution count of a basic block, we will record the duplication factor as part of discriminator so that the offline process tool can find the duplication factor and collect the accurate execution frequency of the corresponding source code. Two important optimization that fall into this category is loop vectorization and loop unroll. This patch records the duplication factor for these 2 optimizations.
The recording will be guarded by a flag encode-duplication-in-discriminators, which is off by default.
Reviewers: probinson, aprantl, davidxl, hfinkel, echristo
Reviewed By: hfinkel
Subscribers: mehdi_amini, anemet, mzolotukhin, llvm-commits
Differential Revision: https://reviews.llvm.org/D26420
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294782 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
The intrinsic, marked as returning it's first argument, has no code
generation effect (though currently not every optimization pass knows
that intrinsics with the returned attribute can be looked through).
It is about to be used to by the PredicateInfo pass to attach
predicate information to existing operands, and be able to tell what
the predicate information affects.
We deliberately do not attach any info through a second operand so
that the intrinsics do not need to dominate the comparisons/etc (since
in the case of assume, we may want to push them up the post-dominator
tree).
Reviewers: davide, sanjoy
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D29517
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294341 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Some frontends emit a speculate-and-select idiom for sqrt, wherein they compute
sqrt(x), check if x is negative, and select NaN if it is:
%cmp = fcmp olt double %a, -0.000000e+00
%sqrt = call double @llvm.sqrt.f64(double %a)
%ret = select i1 %cmp, double 0x7FF8000000000000, double %sqrt
This is technically UB as the LangRef is written today if %a is ever less than
-0. But emitting code that's compliant with the current definition of sqrt
would require a branch, which would then prevent us from matching this idiom in
SelectionDAG (which we do today -- ISD::FSQRT has defined behavior on negative
inputs), because SelectionDAG looks at one BB at a time.
Nothing in LLVM takes advantage of this undefined behavior, as far as we can
tell, and the fact that llvm.sqrt has UB dates from its initial addition to the
LangRef.
Reviewers: arsenm, mehdi_amini, hfinkel
Subscribers: wdng, llvm-commits
Differential Revision: https://reviews.llvm.org/D28797
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@293242 91177308-0d34-0410-b5e6-96231b3b80d8
This commit introduces a set of experimental intrinsics intended to prevent
optimizations that make assumptions about the rounding mode and floating point
exception behavior. These intrinsics will later be extended to specify
flush-to-zero behavior. More work is also required to model instruction
dependencies in machine code and to generate these instructions from clang
(when required by pragmas and/or command line options that are not currently
supported).
Differential Revision: https://reviews.llvm.org/D27028
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@293226 91177308-0d34-0410-b5e6-96231b3b80d8
This is already documented on the call instruction, but
not in the list of supported instructions in the fast math
flag section.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@291578 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
gep 0, 0 is equivalent to bitcast. LLVM canonicalizes it
to getelementptr because it make SROA can then handle it.
Simple case like
void g(A &a) {
z(a);
if (glob)
a.foo();
}
void testG() {
A a;
g(a);
}
was not devirtualized with -fstrict-vtable-pointers because luck of
handling for gep 0 in Memory Dependence Analysis
Reviewers: dberlin, nlewycky, chandlerc
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D28126
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@290763 91177308-0d34-0410-b5e6-96231b3b80d8
This change adds a new intrinsic which is intended to provide memcpy functionality
with additional atomicity guarantees. Please refer to the review thread
or language reference for further details.
Differential Revision: https://reviews.llvm.org/D27133
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@290708 91177308-0d34-0410-b5e6-96231b3b80d8
There was an efficiency problem with how we processed @llvm.assume in
ValueTracking (and other places). The AssumptionCache tracked all of the
assumptions in a given function. In order to find assumptions relevant to
computing known bits, etc. we searched every assumption in the function. For
ValueTracking, that means that we did O(#assumes * #values) work in InstCombine
and other passes (with a constant factor that can be quite large because we'd
repeat this search at every level of recursion of the analysis).
Several of us discussed this situation at the last developers' meeting, and
this implements the discussed solution: Make the values that an assume might
affect operands of the assume itself. To avoid exposing this detail to
frontends and passes that need not worry about it, I've used the new
operand-bundle feature to add these extra call "operands" in a way that does
not affect the intrinsic's signature. I think this solution is relatively
clean. InstCombine adds these extra operands based on what ValueTracking, LVI,
etc. will need and then those passes need only search the users of the values
under consideration. This should fix the computational-complexity problem.
At this point, no passes depend on the AssumptionCache, and so I'll remove
that as a follow-up change.
Differential Revision: https://reviews.llvm.org/D27259
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Summary:
Attaching !absolute_symbol to a global variable does two things:
1) Marks it as an absolute symbol reference.
2) Specifies the value range of that symbol's address.
Teach the X86 backend to allow absolute symbols to appear in place of
immediates by extending the relocImm and mov64imm32 matchers. Start using
relocImm in more places where it is legal.
As previously proposed on llvm-dev:
http://lists.llvm.org/pipermail/llvm-dev/2016-October/105800.html
Differential Revision: https://reviews.llvm.org/D25878
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If the inrange keyword is present before any index, loading from or
storing to any pointer derived from the getelementptr has undefined
behavior if the load or store would access memory outside of the bounds of
the element selected by the index marked as inrange.
This can be used, e.g. for alias analysis or to split globals at element
boundaries where beneficial.
As previously proposed on llvm-dev:
http://lists.llvm.org/pipermail/llvm-dev/2016-July/102472.html
Differential Revision: https://reviews.llvm.org/D22793
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DW_TAG_atomic_type was already included in Dwarf.defs and emitted correctly,
however Verifier didn't recognize it as valid.
Thus we introduce the following changes:
* Make DW_TAG_atomic_type valid tag for IR and DWARF (enabled only with -gdwarf-5)
* Add it to related docs
* Add DebugInfo tests
Differential Revision: https://reviews.llvm.org/D26144
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On Windows, it is often applied to the second parameter, and the x86
backend is prepared to deal with sret appearing on any parameter.
Other backends assume it only appears on parameter zero, but those are
target-specific requirements, and not an IR-level rule.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@280951 91177308-0d34-0410-b5e6-96231b3b80d8
I've found this out the hard way; LLVM will not normally catch this
error (unless -verify-machineinstrs is passed), and under certain
very specific circumstances (such as register scavenger running
under pressure) this would result in an opaque crash in codegen.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@280071 91177308-0d34-0410-b5e6-96231b3b80d8
This reverts commit r278048. Something changed between the last time I
built this--it takes awhile on my ridiculously slow and ancient
computer--and now that broke this.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@278053 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Based on two patches by Michael Mueller.
This is a target attribute that causes a function marked with it to be
emitted as "hotpatchable". This particular mechanism was originally
devised by Microsoft for patching their binaries (which they are
constantly updating to stay ahead of crackers, script kiddies, and other
ne'er-do-wells on the Internet), but is now commonly abused by Windows
programs to hook API functions.
This mechanism is target-specific. For x86, a two-byte no-op instruction
is emitted at the function's entry point; the entry point must be
immediately preceded by 64 (32-bit) or 128 (64-bit) bytes of padding.
This padding is where the patch code is written. The two byte no-op is
then overwritten with a short jump into this code. The no-op is usually
a `movl %edi, %edi` instruction; this is used as a magic value
indicating that this is a hotpatchable function.
Reviewers: majnemer, sanjoy, rnk
Subscribers: dberris, llvm-commits
Differential Revision: https://reviews.llvm.org/D19908
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@278048 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This change adds a `ni` specifier in the `datalayout` string to denote
pointers in some given address spaces as "non-integral", and adds some
typing rules around these special pointers.
Reviewers: majnemer, chandlerc, atrick, dberlin, eli.friedman, tstellarAMD, arsenm
Subscribers: arsenm, mcrosier, llvm-commits
Differential Revision: https://reviews.llvm.org/D22488
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@277085 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
The llvm.invariant.start and llvm.invariant.end intrinsics currently
support specifying invariant memory objects only in the default address
space.
With this change, these intrinsics are overloaded for any adddress space
for memory objects
and we can use these llvm invariant intrinsics in non-default address
spaces.
Example: llvm.invariant.start.p1i8(i64 4, i8 addrspace(1)* %ptr)
This overloaded intrinsic is needed for representing final or invariant
memory in managed languages.
Reviewers: apilipenko, reames
Subscribers: llvm-commits
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276447 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
The llvm.invariant.start and llvm.invariant.end intrinsics currently
support specifying invariant memory objects only in the default address space.
With this change, these intrinsics are overloaded for any adddress space for memory objects
and we can use these llvm invariant intrinsics in non-default address spaces.
Example: llvm.invariant.start.p1i8(i64 4, i8 addrspace(1)* %ptr)
This overloaded intrinsic is needed for representing final or invariant memory in managed languages.
Reviewers: tstellarAMD, reames, apilipenko
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D22519
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276316 91177308-0d34-0410-b5e6-96231b3b80d8
