There is no needed for neither 1-dimensional nor higher dimensional arrays to
require positive offsets in the outermost array dimension.
We originally introduced this assumption with the support for delinearizing
multi-dimensional arrays.
llvm-svn: 214665
+ Split all reduction dependences and map them to the causing memory accesses.
+ Print the types & base addresses of broken reductions for each "reduction
parallel" marked loop (OpenMP style).
+ 3 test cases to show how reductions are now represented in the isl ast.
The mapping "(ast) loops -> broken reductions" is also needed to find the
memory accesses we need to privatize in a loop.
llvm-svn: 214489
+ Introduced dependency type TYPE_TC_RED to represent the transitive closure
(& the reverse) of reduction dependences. These are used when we check for
reduction parallel loops.
+ Test cases including loop reversals and modulo schedules which compute
reductions in a alternated order.
llvm-svn: 213019
As our delinearization works optimistically, we need in some cases run-time
checks that verify our optimistic assumptions. A simple example is the
following code:
void foo(long n, long m, long o, double A[n][m][o]) {
for (long i = 0; i < 100; i++)
for (long j = 0; j < 150; j++)
for (long k = 0; k < 200; k++)
A[i][j][k] = 1.0;
}
After clang linearized the access to A and we delinearized it again to
A[i][j][k] we need to ensure that we do not access the delinearized array
out of bounds (this information is not available in LLVM-IR). Hence, we
need to verify the following constraints at run-time:
CHECK: Assumed Context:
CHECK: [o, m] -> { : m >= 150 and o >= 200 }
llvm-svn: 212198
This change is particularly useful in the code generation as we need
to know which binary operator/identity element we need to combine/initialize
the privatization locations.
+ Print the reduction type for each memory access
+ Adjusted the test cases to comply with the new output format and
to test for the right reduction type
llvm-svn: 212126
Iterate over all store memory accesses and check for valid binary reduction
candidate loads by following the operands of the stored value. For each
candidate pair we check if they have the same base address and there are no
other accesses which may overlap with them. This ensures that no intermediate
value can escape into other memory locations or is overwritten at some point.
+ 17 test cases for reduction detection and reduction dependency modeling
llvm-svn: 211957
Enabling -keep-going in ScopDetection causes expansion to an invalid
Scop candidate.
Region A <- Valid candidate
|
Region B <- Invalid candidate
If -keep-going is enabled, ScopDetection would expand A to A+B because
the RejectLog is never checked for errors during expansion.
With this patch only A becomes a valid Scop.
llvm-svn: 211875
This change will ease the transision to multiple reductions per statement as
we can now distinguish the effects of multiple reductions in the same
statement.
+ Wrapped reduction dependences are used to compute privatization dependences
+ Modified test cases to account for the change
llvm-svn: 211795
This dependency analysis will keep track of memory accesses if they might be
part of a reduction. If not, the dependences are tracked on a statement level.
The main reason to do this is to reduce the compile time while beeing able to
distinguish the effects of reduction and non-reduction accesses.
+ Adjusted two test cases
llvm-svn: 211794
Use a container class to store the reject logs. Delegating most calls to
the internal std::map and add a few convenient shortcuts (e.g.,
hasErrors()).
llvm-svn: 211780
Add support for generating optimization remarks after completing the
detection of Scops.
The goal is to provide end-users with useful hints about opportunities that
help to increase the size of the detected Scops in their code.
By default the remark is unspecified and the debug location is empty. Future
patches have to expand on the messages generated.
This patch brings a simple test case for ReportFuncCall to demonstrate the
feature.
Reports all missed opportunities to increase the size/number of valid
Scops:
clang <...> -Rpass-missed="polly-detect" <...>
opt <...> -pass-remarks-missed="polly-detect" <...>
Reports beginning and end of all valid Scops:
clang <...> -Rpass="polly-detect" <...>
opt <...> -pass-remarks="polly-detect" <...>
Differential Revision: http://reviews.llvm.org/D4171
llvm-svn: 211769
+ Collect reduction dependences
+ Introduced TYPE_RED in Dependences.h which can be used to obtain the
reduction dependences
+ Used TYPE_RED to prevent parallelization while we do not have a privatizing
code generation
+ Relax the dependences for non-parallel code generation
+ Add privatization dependences to ensure correctness
+ 12 Test cases to check for reduction and privatization dependences
llvm-svn: 211369
+ Flag to indicate reduction like statements
+ Command line option to (dis)allow multiplicative reduction opcodes
+ Two simple positive test cases, one fp test case w and w/o fast math
+ One "negative" test case (only reduction like but no reduction)
llvm-svn: 211114
+ Added const iterator version
+ Changed name to begin/end to allow range loops
+ Changed call sites to range loops
+ Changed typename to (const_)iterator
llvm-svn: 210927
Fixes#19976.
The error log does not contain an error, in case we reject a candidate
without generating a diagnostic message by using invalid<>(...). This is
the case for the top-level region of a function.
The patch comes without a test-case because adding a useful one requires
additional code just for triggering it. Before the patch it would only trigger,
if we try to print the CFG with Scop error annotations.
llvm-svn: 210753
Without this patch, the testcase would fail on the delinearization of the second
array:
; void foo(long n, long m, long o, double A[n][m][o]) {
; for (long i = 0; i < n; i++)
; for (long j = 0; j < m; j++)
; for (long k = 0; k < o; k++) {
; A[i+3][j-4][k+7] = 1.0;
; A[i][0][k] = 2.0;
; }
; }
; CHECK: [n, m, o] -> { Stmt_for_body6[i0, i1, i2] -> MemRef_A[3 + i0, -4 + i1, 7 + i2] };
; CHECK: [n, m, o] -> { Stmt_for_body6[i0, i1, i2] -> MemRef_A[i0, 0, i2] };
Here is the output of FileCheck on the testcase without this patch:
; CHECK: [n, m, o] -> { Stmt_for_body6[i0, i1, i2] -> MemRef_A[i0, 0, i2] };
^
<stdin>:26:2: note: possible intended match here
[n, m, o] -> { Stmt_for_body6[i0, i1, i2] -> MemRef_A[o0] };
^
It is possible to find a good delinearization for A[i][0][k] only in the context
of the delinearization of both array accesses.
There are two ways to delinearize together all array subscripts touching the
same base address: either duplicate the code from scop detection to first gather
all array references and then run the delinearization; or as implemented in this
patch, use the same delinearization info that we computed during scop detection.
llvm-svn: 210117
Instead of relying on the delinearization to infer the size of an element,
compute the element size from the base address type. This is a much more precise
way of computing the element size than before, as we would have mixed together
the size of an element with the strides of the innermost dimension.
llvm-svn: 209695
Support a 'keep-going' mode for the ScopDetection. In this mode, we just keep
on detecting, even if we encounter an error.
This is useful for diagnosing SCoP candidates. Sometimes you want all the
errors. Invalid SCoPs will still be refused in the end, we just refuse to
abort on the first error.
llvm-svn: 209574
This stores all RejectReasons created for one region
in a RejectLog inside the DetectionContext. For now
this only keeps track of the last error.
A separate patch will enable the tracking of all errors.
This patch itself does no harm (yet).
llvm-svn: 209572
definition below all of the header #include lines, Polly edition.
If you want to know more details about this, you can see the recent
commits to Debug.h in LLVM. This is just the Polly segment of a cleanup
I'm doing globally for this macro.
llvm-svn: 206852
The following example shows a non-parallel loop
void f(int a[]) {
int i;
for (i = 0; i < 10; ++i)
A[i] = A[i+5];
}
which, in case we import a schedule that limits the iteration domain
to 0 <= i < 5, becomes parallel. Previously we crashed in such cases, now we
just recognize it as parallel.
This fixes http://llvm.org/PR19435
Reported-by: Jeremy Huddleston Sequoia <jeremyhu@apple.com>
llvm-svn: 206318
We update to a newer version of isl, which includes changes to the compute
out facility that make it a lot more predicable. With our new value, we can
reliably bail out for all reported bugs, while still being able to compute
dependences for all but two test cases in the LLVM test suite. For the remaining
two test cases, the dependence problem we construct is unnecessarily complex,
so there is hope we can improve on this. However, to avoid any future issues,
having a reliable compute out facility in place is important.
llvm-svn: 206106
This replaces the ancient INVALID/INVALID_NOVERIFY macros with a real
function.
The new invalid(..) function uses small diagnostic objects that are
generated on demand. We can store arbitrary additional information per
error type and generate useful debug/error messages on the fly.
Use it as follows:
if (/* Some error condition (ReportFoo) */)
invalid<ReportFoo>(Context, /*Assert=*/true/false,
(/* List of helpful diagnostic objects */));
Where ReportFoo is a subclass of RejectReason that is able to take the
list of helpful diagnostic objects in its constructor.
The implementation of invalid will create the report and fire
an assertion, if necessary.
llvm-svn: 205414
For complex examples it may happen that we do not compute dependences. In this
case we do not want to crash, but just not detect parallel loops.
llvm-svn: 204470
llvm.org/PR19081 reports that the polly dependence analysis causes some h264
compilation to hang. We adjust the compute out, to ensure we do not block on
expensive dependence calculations.
llvm-svn: 204168
Value::user_iterator changes in LLVM r203364. Converts several of these
loops to nice range based loops in the process.
Built and tested cleanly for me, yay for being able to fully build and
test Polly changes!
llvm-svn: 203381
The module LLVMPolly.so links to that. There is really no reason to build a
large number of mini-libraries here, especially as we do have dependences
between the libraries that are not properly handled and that make linking fail
on darwin.
Submitted-by: David Fang <fang@csl.cornell.edu>
llvm-svn: 202743
We mostly iterate over read-only values. Following a suggestion by Duncan P.N
Exons Smith, we use the construct 'const auto &' for this.
llvm-svn: 202651
clang-format requires a space before the ":" in the foreach loop. Even though
this is surprising to me, we follow this style to make our formatting
consistent with clang-format. I found that this clang-format style is used in a
couple of C++11 examples, hence I believe the fact that clang-format adds a
colon is not a bug but just something I was not used to yet.
llvm-svn: 202648
In case we do not have valid dependences, we do not run dead code elimination or
the schedule optimizer. This fixes an infinite loop in the dead code
elimination (PR12110).
llvm-svn: 201982
In case the domain of a statement is empty, the schedule optimizer set by
accident the schedule to a NULL pointer. This is incorrect. Instead, we set
it to an empty isl_map with zero schedule dimensions. We already checked for
this in our test cases, but unfortunately the test cases did not fail as
expected. The assert we add in this commit now ensures that the test cases
fail properly in case we regress on this again.
llvm-svn: 201886
This pass eliminates loop iterations that compute results that are not used
later on. This can help e.g. in D, where the default zero-initialization is
often unnecessary if right after new values are assigned to an array.
Contributed-by: Peter Conn <conn.peter@gmail.com>
llvm-svn: 201817
We do not have a use for this information at the moment. If we need this at some
point, the "instruction -> access" mapping needs to be enhanced as a single
instruction could then possibly perform multiple accesses.
This patch allows us to build the polyhedral information for scops with scalar
dependences.
llvm-svn: 201815
In rare cases the modification of one scop can effect the validity of other
scops, as code generation of an earlier scop may make the scalar evolution
functions derived for later scops less precise. The example that triggered this
patch was a scop that contained an 'or' expression as follows:
%add13710 = or i32 %j.19, 1
--> {(1 + (4 * %l)),+,2}<nsw><%for.body81>
Scev could only analyze the 'or' as it knew %j.19 is a multiple of 2. This
information was not available after the first scop was code generated (or
independent-blocks was run on it) and SCEV could not derive a precise SCEV
expression any more. This means we could not any more code generate this SCoP.
My current understanding is that there is always the risk that an earlier code
generation change invalidates later scops. As the example we have seen here is
difficult to avoid, we use this occasion to guard us against all such
invalidations.
This patch "solves" this issue by verifying right before we start working on
a detected scop, if this scop is in fact still valid. This adds a certain
overhead. However the verification we run is anyways very fast and secondly
it is only run on detected scops. So the overhead should not be very large. As
a later optimization we could detect scops only on demand, such that we need
to run scop-detections always only a single time.
This should fix the single last failure in the LLVM test-suite for the new
scev-based code generation.
llvm-svn: 201593
The MayAliasSet class is currently not used and just confuses people. We can
reintroduce it in case need a more precise tracking of alias sets.
llvm-svn: 201191
In rare cases, a region R which is itself not valid has an indirect child region
that is valid. When R becomes part of a valid region by expansion of another
region, then all children of R have to be erased from the set of valid regions.
This patch ensures that indirect children are erased in addition to direct
children.
Contributed-by: Armin Groesslinger <armin.groesslinger@uni-passau.de>
Tobias: I added a reduced test case and adjusted the logic of the patch to
only recurse until the first child is found.
llvm-svn: 200411
Verification of base addresses is difficult as the independent blocks pass may
introduce aliasing that was not there during scop detection. As a midterm
solution -polly-codegen-scev will remove the need for the independent blocks
pass. For now, we do not verify at compile time that the independent blocks pass
does not make the base addresses loop invariant. Disabling this just removes
one of the multiple safety layers we have. We still can check for correctness
in our regression tests.
llvm-svn: 200315
Array base addresses need to be invariant in the region considered. The base
address has to be computed outside the region, or, when it is computed inside,
the value must not change with the iterations of the loops. For example, when a
two-dimensional array is represented as a pointer to pointers the base address
A[i] in an access A[i][j] changes with i; therefore, such regions have to be
rejected.
Contributed by: Armin Größlinger <armin.groesslinger@uni-passau.de>
llvm-svn: 200314
Count the number of computational steps that have been used to solve the
dependence problem and abort in case we reach the "compute-out". This ensures we
do not hang forever in cases the dependence problem is too difficult to solve.
There is just a single case in the LLVM test-suite that runs into the
compute-out. Even in this case, we can probably coalesce some of the parameters
(i32 b, i32 b zext i64, ...) to simplify the problem enough to not hit the
compute out. However, for now we set the compute out in place to address the
general issue. The compute out was choosen such that it stops on a recent laptop
after about 8 seconds.
llvm-svn: 200156
This fixes a crash that appeared when generating dotty graphs for functions
without loops (for which we do not calculate polyhedral information).
llvm-svn: 198364
We now report the following:
$ polly-clang -O3 -mllvm -polly -mllvm -polly-report test.c -c \
-gline-tables-only
note: Polly detected an optimizable loop region (scop) in function 'foo'
test.c:2: Start of scop
test.c:3: End of scop
note: Polly detected an optimizable loop region (scop) in function 'bar'
test.c:9: Start of scop
test.c:13: End of scop
llvm-svn: 197558
When constructing a scop sometimes the exact representation of a statement or
condition would be very complex, but there is a common case which is a lot
simpler, but which is only valid under certain assumptions. The assumed context
records the assumptions taken during the construction of this scop and that need
to be code generated as a run-time test.
At the moment, we do not yet model any assumptions, but only added the
AssumedContext as well as the isl-ast generation support. As a next step,
this needs to be hooked up with the isl code generation.
if (1) /* run-time condition */
{ /* optimized code */ }
else
{ /* original code */ }
llvm-svn: 193652
Instead of defining the relevant functions inline, we now just keep the
declarations in the class itself. This makes the class declaration a lot
easier to read as all functions can be seen at once. We also use this
opportunity to privatize all functions not used in the public interface of the
class.
llvm-svn: 190841
Use 0 >= 1 instead of 0 != 0 to represent 'false'. This might be slightly more
efficient as isl may create a union of sets for 0 != 0, whereas this is never
needed for the expression 0 >= 1.
Contributed-by: Alexandre Isoard <alexandre.isoard@gmail.com>
llvm-svn: 190384
SCoP invariant parameters with the different start value would deter parameter
sharing. For example, when compiling the following C code:
void foo(float *input) {
for (long j = 0; j < 8; j++) {
// SCoP begin
for (long i = 0; i < 8; i++) {
float x = input[j * 64 + i + 1];
input[j * 64 + i] = x * x;
}
}
}
Polly would creat two parameters for these memory accesses:
p_0: {0,+,256}
p_2: {4,+,256}
[j * 64 + i + 1] => MemRef_input[o0] : 4o0 = p_1 + 4i0
[j * 64 + i] => MemRef_input[o0] : 4o0 = p_0 + 4i0
These parameters only differ from start value. To enable parameter sharing,
we split the start value from SCEVAddRecExpr, so they would share a single
parameter that always has zero start value:
p0: {0,+,256}<%for.cond1.preheader>
[j * 64 + i + 1] => MemRef_input[o0] : 4o0 = 4 + p_1 + 4i0
[j * 64 + i] => MemRef_input[o0] : 4o0 = p_0 + 4i0
Such translation can make the polly-dependence much faster.
Contributed-by: Star Tan <tanmx_star@yeah.net>
llvm-svn: 187728
String operations resulted by raw_string_ostream in the INVALID macro can lead
to significant compile-time overhead when compiling large size source code.
This is because raw_string_ostream relies on TypeFinder class, whose
compile-time cost increases as the size of the module increases. This patch
targets to ensure that it only track detection failures if actually needed.
In this way, we can avoid expensive string operations in normal execution.
With this patch file, the relative compile-time cost of Polly-detect pass does
not increase even when compiling very large size source code.
Contributed-by: Star Tan <tanmx_star@yeah.net>
llvm-svn: 187102
Ensure that the scalar write access corresponds to the result of a load
instruction appears after the generic read access corresponds to the load
instruction.
llvm-svn: 186419
isl recently introduced isl_val as an abstract interface to represent arbitrary
precision numbers. This interface superseeds the old isl_int interface. In
contrast to the old interface which implemented arbitrary precision arithmetic
using macros that forward to the gmp library, the new library hides the math
library implementation in isl. This allows us to switch the math library used by
isl without affecting users such as Polly.
llvm-svn: 184529
When a region header is part of a loop, then all entering edges of this region
should not come from the loop but outside the region. Otherwise, the loop may be
only partially part of the region, which would cause troubles in handling
induction variables.
Currently, we can only model induction variables that are either fully part of
the scop (loop induction variable) or induction variables that are scop-
invariant (parameter). A loop that is only partially part of the
scop causes troubles, as there is no good way to handle the induction
variable in the independent blocks pass.
Contributed-by: Star Tan <tanmx_star@yeah.net>
llvm-svn: 183800
Tobias Grosser