Fix mem2reg to correctly handle allocas only used in a single block
Currently, a load from an alloca that is used in as single block and is not preceded
by a store is replaced by undef. This is not always correct if the single block is
inside a loop.
Fix the logic so that:
1) If there are no stores in the block, replace the load with an undef, as before.
2) If there is a store (regardless of where it is in the block w.r.t the load), bail
out, and let the rest of mem2reg handle this alloca.
Kuba Brecka [Wed, 22 Jul 2015 10:25:38 +0000 (10:25 +0000)]
[asan] Improve moving of non-instrumented allocas
In r242510, non-instrumented allocas are now moved into the first basic block. This patch limits that to only move allocas that are present *after* the first instrumented one (i.e. only move allocas up). A testcase was updated to show behavior in these two cases. Without the patch, an alloca could be moved down, and could cause an invalid IR.
[PM/AA] Remove all of the dead AliasAnalysis pointers being threaded
through APIs that are no longer necessary now that the update API has
been removed.
This will make changes to the AA interfaces significantly less
disruptive (I hope). Either way, it seems like a really nice cleanup.
[PM/AA] Remove the last of the legacy update API from AliasAnalysis as
part of simplifying its interface and usage in preparation for porting
to work with the new pass manager.
Note that this will likely expose that we have dead arguments, members,
and maybe even pass requirements for AA. I'll be cleaning those up in
seperate patches. This just zaps the actual update API.
[PM/AA] Switch to an early-exit. NFC. This was split out of another
change because the diff is *useless*. I assure you, I just switched to
early-return in this function.
Cleanup in preparation for my next commit, as requested in code review!
[PM/AA] Replace the only use of the AliasAnalysis::deleteValue API (in
GlobalsModRef) with CallbackVHs that trigger the same behavior.
This is technically more expensive, but in benchmarking some LTO runs,
it seems unlikely to even be above the noise floor. The only way I was
able to measure the performance of GMR at all was to run nothing else
but this one analysis on a linked clang bitcode file. The call graph
analysis still took 5x more time than GMR, and this change at most made
GMR 2% slower (this is well within the noise, so its hard for me to be
sure that this is an actual change). However, in a real LTO run over the
same bitcode, the GMR run takes so little time that the pass timers
don't measure it.
With this, I can remove the last update API from the AliasAnalysis
interface, but I'll actually remove the interface hook point in
a follow-up commit.
Chen Li [Wed, 22 Jul 2015 05:26:29 +0000 (05:26 +0000)]
[LoopUnswitch] Code refactoring to separate trivial loop unswitch and non-trivial loop unswitch in processCurrentLoop()
Summary: The current code in LoopUnswtich::processCurrentLoop() mixes trivial loop unswitch and non-trivial loop unswitch together. It goes over all basic blocks in the loop and checks if a condition is trivial or non-trivial unswitch condition. However, trivial unswitch condition can only occur in the loop header basic block (where it controls whether or not the loop does something at all). This refactoring separate trivial loop unswitch and non-trivial loop unswitch. Before going over all basic blocks in the loop, it checks if the loop header contains a trivial unswitch condition. If so, unswitch it. Otherwise, go over all blocks like before but don't check trivial condition any more since they are not possible to be in the other blocks. This code has no functionality change.
[SROA] Fix a nasty pile of bugs to do with big-endian, different alloca
types and loads, loads or stores widened past the size of an alloca,
etc.
This started off with a bug report about big-endian behavior with
bitfields and loads and stores to a { i32, i24 } struct. An initial
attempt to fix this was sent for review in D10357, but that didn't
really get to the root of the problem.
The core issue was that canConvertValue and convertValue in SROA were
handling different bitwidth integers by doing a zext of the integer. It
wouldn't do a trunc though, only a zext! This would in turn lead SROA to
form an i24 load from an i24 alloca, zext it to i32, and then use it.
This would at least produce the wrong value for big-endian systems.
One of my many false starts here was to correct the computation for
big-endian systems by shifting. But this doesn't actually work because
the original code has a 64-bit store to the entire 8 bytes, and a 32-bit
load of the last 4 bytes, and because the alloc size is 8 bytes, we
can't lose that last (least significant if bigendian) byte! The real
problem here is that we're forming an i24 load in SROA which is actually
not sufficiently wide to load all of the necessary bits here. The source
has an i32 load, and SROA needs to form that as well.
The straightforward way to do this is to disable the zext logic in
canConvertValue and convertValue, forcing us to actually load all
32-bits. This seems like a really good change, but it in turn breaks
several other parts of SROA.
First in the chain of knock-on failures, we had places where we were
doing integer-widening promotion even though some of the integer loads
or stores extended *past the end* of the alloca's memory! There was even
a comment about preventing this, but it only prevented the case where
the type had a different bit size from its store size. So I added checks
to handle the cases where we actually have a widened load or store and
to avoid trying to special integer widening promotion in those cases.
Second, we actually rely on the ability to promote in the face of loads
past the end of an alloca! This is important so that we can (for
example) speculate loads around PHI nodes to do more promotion. The bits
loaded are garbage, but as long as they aren't used and the alignment is
suitable high (which it wasn't in the test case!) this is "fine". And we
can't stop promoting here, lots of things stop working well if we do. So
we need to add specific logic to handle the extension (and truncation)
case, but *only* where that extension or truncation are over bytes that
*are outside the alloca's allocated storage* and thus totally bogus to
load or store.
And of course, once we add back this correct handling of extension or
truncation, we need to correctly handle bigendian systems to avoid
re-introducing the exact bug that started us off on this chain of misery
in the first place, but this time even more subtle as it only happens
along speculated loads atop a PHI node.
I've ported an existing test for PHI speculation to the big-endian test
file and checked that we get that part correct, and I've added several
more interesting big-endian test cases that should help check that we're
getting this correct.
This optimization allows the DWARF linker to reuse definition of
types it has emitted in previous CUs rather than reemitting them
in each CU that references them. The size and link time gains are
huge. For example when linking the DWARF for a debug build of
clang, this generates a ~150M dwarf file instead of a ~700M one
(the numbers date back a bit and must not be totally accurate
these days).
As with all the other parts of the llvm-dsymutil codebase, the
goal is to keep bit-for-bit compatibility with dsymutil-classic.
The code is littered with a lot of FIXMEs that should be
addressed once we can get rid of the compatibilty goal.
Nick Lewycky [Tue, 21 Jul 2015 21:56:26 +0000 (21:56 +0000)]
Fix a performance problem in memcpyopt by removing a linear scan over ranges when inserting a new range. No functionality change intended. Patch by Anthony Pesch!
[MDA] change BlockScanLimit into a command line option.
Summary:
In the benchmark (https://github.com/vetter/shoc) we are researching,
the duplicated load is not eliminated because MemoryDependenceAnalysis
hit the BlockScanLimit. This patch change it into a command line option
instead of a hardcoded value.
Patched by Xuetian Weng.
Test Plan: test/Analysis/MemoryDependenceAnalysis/memdep-block-scan-limit.ll
Bill Schmidt [Tue, 21 Jul 2015 21:40:17 +0000 (21:40 +0000)]
[PPC64LE] More vector swap optimization TLC
This makes one substantive change and a few stylistic changes to the
VSX swap optimization pass.
The substantive change is to permit LXSDX and LXSSPX instructions to
participate in swap optimization computations. The previous change to
insert a swap following a SUBREG_TO_REG widening operation makes this
almost trivial.
I experimented with also permitting STXSDX and STXSSPX instructions.
This can be done using similar techniques: we could insert a swap
prior to a narrowing COPY operation, and then permit these stores to
participate. I prototyped this, but discovered that the pattern of a
narrowing COPY followed by an STXSDX does not occur in any of our
test-suite code. So instead, I added commentary indicating that this
could be done.
Other TLC:
- I changed SH_COPYSCALAR to SH_COPYWIDEN to more clearly indicate
the direction of the copy.
- I factored the insertion of swap instructions into a separate
function.
Finally, I added a new test case to check that the scalar-to-vector
loads are working properly with swap optimization.
MergeFunc: Transfer the callee's attributes when replacing a direct caller
We insert a bitcast which obfuscates the getCalledFunction for the utility
function which looks up attributes from the called function. Loosing ABI
changing parameter attributes is a bad thing.
Philip Reames [Tue, 21 Jul 2015 16:51:17 +0000 (16:51 +0000)]
[RewriteStatepointsForGC] Delete trivial code
A bit more code cleanup: delete some a trivial true assertion and supporting code, remove a redundant cast, and use count in assertions where feasible.
Alex Lorenz [Tue, 21 Jul 2015 16:50:35 +0000 (16:50 +0000)]
IR: Extract a function 'printLLVMNameWithoutPrefix' from 'PrintLLVMName'. NFC.
This commit extracts the code that prints out a name of an LLVM value without a
prefix from a function 'PrintLLVMName' into a publicly accessible function named
'printLLVMNameWithoutPrefix'.
This change would be useful for MIR serialization, as it would allow the MIR
printer to reuse this function to print out the names of the external symbol
machine operands.
Chris Bieneman [Tue, 21 Jul 2015 15:53:09 +0000 (15:53 +0000)]
[CMake] Projects supported via LLVM_EXTERNAL_*_SOURCE_DIR need to be explicitly specified.
One part of my refactoring from r242705 is untenable due to how CMake caches variables. There is no way other than caching to allow variables to be set in one directory and globally readable, but we really don't want to cache the temporary value marking that a directory has already been included.
Constfold trunc,rint,nearbyint,ceil and floor using APFloat
A patch by Chakshu Grover!
This patch allows constfolding of trunc,rint,nearbyint,ceil and floor intrinsics using APFloat class.
Differential Revision: http://reviews.llvm.org/D11144
[ARM] Define subtarget feature "reserve-r9", which is used to decide
whether register r9 should be reserved.
This recommits r242737, which broke bots because the number of subtarget
features went over the limit of 64.
This change is needed because we cannot use a backend option to set
cl::opt "arm-reserve-r9" when doing LTO.
Out-of-tree projects currently using cl::opt option "-arm-reserve-r9" to
reserve r9 should make changes to add subtarget feature "reserve-r9" to
the IR.
Philip Reames [Tue, 21 Jul 2015 00:49:55 +0000 (00:49 +0000)]
[RewriteStatepointsForGC] Minor code cleanup [NFC]
We can use builders to simplify part of the code and we only check for the existance of the metadata value; this enables us to delete some redundant code.
Andrew Wilkins [Tue, 21 Jul 2015 00:46:23 +0000 (00:46 +0000)]
[cmake] pass GO_EXECUTABLE to llgo-go
Summary:
When calling llgo-go from the llvm_add_go_executable
cmake function, specify $GO_EXECUTABLE as the go
command to call. Without this, llgo-go searches $PATH
which may be inconsistent with $GO_EXECUTABLE.
ARMLoadStoreOpt: Merge subs/adds into LDRD/STRD; Factor out common code
Re-apply of r241928 which had to be reverted because of the r241926
revert.
This commit factors out common code from MergeBaseUpdateLoadStore() and
MergeBaseUpdateLSMultiple() and introduces a new function
MergeBaseUpdateLSDouble() which merges adds/subs preceding/following a
strd/ldrd instruction into an strd/ldrd instruction with writeback where
possible.
Re-apply r241926 with an additional check that r13 and r15 are not used
for LDRD/STRD. See http://llvm.org/PR24190. This also already includes
the fix from r241951.
[ARM] Define subtarget feature "reserve-r9", which is used to decide
whether register r9 should be reserved.
This change is needed because we cannot use a backend option to set
cl::opt "arm-reserve-r9" when doing LTO.
Out-of-tree projects currently using cl::opt option "-arm-reserve-r9" to
reserve r9 should make changes to add subtarget feature "reserve-r9" to
the IR.
This patch does the following:
* Fix FIXME on `needsStackRealignment`: it is now shared between multiple targets, implemented in `TargetRegisterInfo`, and isn't `virtual` anymore. This will break out-of-tree targets, silently if they used `virtual` and with a build error if they used `override`.
* Factor out `canRealignStack` as a `virtual` function on `TargetRegisterInfo`, by default only looks for the `no-realign-stack` function attribute.
Multiple targets duplicated the same `needsStackRealignment` code:
- Aarch64.
- ARM.
- Mips almost: had extra `DEBUG` diagnostic, which the default implementation now has.
- PowerPC.
- WebAssembly.
- x86 almost: has an extra `-force-align-stack` option, which the default implementation now has.
The default implementation of `needsStackRealignment` used to just return `false`. My current patch changes the behavior by simply using the above shared behavior. This affects:
- AMDGPU
- BPF
- CppBackend
- MSP430
- NVPTX
- Sparc
- SystemZ
- XCore
- Out-of-tree targets
This is a breaking change! `make check` passes.
The only implementation of the `virtual` function (besides the slight different in x86) was Hexagon (which did `MF.getFrameInfo()->getMaxAlignment() > 8`), and potentially some out-of-tree targets. Hexagon now uses the default implementation.
`needsStackRealignment` was being overwritten in `<Target>GenRegisterInfo.inc`, to return `false` as the default also did. That was odd and is now gone.
Don't try to instrument allocas used by outlined SEH funclets
Summary:
Arguments to llvm.localescape must be static allocas. They must be at
some statically known offset from the frame or stack pointer so that
other functions can access them with localrecover.
If we ever want to instrument these, we can use more indirection to
recover the addresses of these local variables. We can do it during
clang irgen or with the asan module pass.
MachineScheduler: Restrict macroop fusion to data-dependent instructions.
Before creating a schedule edge to encourage MacroOpFusion check that:
- The predecessor actually writes a register that the branch reads.
- The predecessor has no successors in the ScheduleDAG so we can
schedule it in front of the branch.
This avoids skewing the scheduling heuristic in cases where macroop
fusion cannot happen.
Avoid early pipefail exits due to grep failures in stage comparisons.
If objects or executables did not contain any RPATH, grep would return
nonzero, and the whole stage comparison loop would unexpectedly exit.
Fix this by checking the grep result explicitly.
Since BSD cmp(1) does not support the --ignore-initial option, use the
more portable 3rd and 4th arguments to skip the first 16 bytes during
the comparison of Phase2 and Phase3 objects.
[ARM] Refactor the prologue/epilogue emission to be more robust.
This is the first step toward supporting shrink-wrapping for this target.
The changes could be summarized by these items:
- Expand the tail-call return as part of the expand pseudo pass.
- Get rid of the assumptions that the epilogue is the exit block:
* Do not assume which registers are free in the epilogue. (This indirectly
improve the lowering of the code for the segmented stacks, see the test
cases.)
* Take into account that the basic block can be empty.
[NVPTX] make load on global readonly memory to use ldg
Summary:
[NVPTX] make load on global readonly memory to use ldg
Summary:
As describe in [1], ld.global.nc may be used to load memory by nvcc when
__restrict__ is used and compiler can detect whether read-only data cache
is safe to use.
This patch will try to check whether ldg is safe to use and use them to
replace ld.global when possible. This change can improve the performance
by 18~29% on affected kernels (ratt*_kernel and rwdot*_kernel) in
S3D benchmark of shoc [2].
Suppress two warnings from MSVC 2015 that are triggered under /W4. Since we turn off exceptions in the code base, C4577 is moot. C4091 triggers on system headers and is a benign construct.
Alex Lorenz [Mon, 20 Jul 2015 20:51:18 +0000 (20:51 +0000)]
MIR Serialization: Initial serialization of machine constant pools.
This commit implements the initial serialization of machine constant pools and
the constant pool index machine operands. The constant pool is serialized using
a YAML sequence of YAML mappings that represent the constant values.
The target-specific constant pool items aren't serialized by this commit.
Chris Bieneman [Mon, 20 Jul 2015 20:36:06 +0000 (20:36 +0000)]
[CMake] Cleanup tools/CMakeLists.txt to take advantage of the auto-registration that was already partially working.
Re-landing r242059 which re-landed r241621... I'm really bad at this.
Summary (r242059):
This change re-lands r241621, with an additional fix that was required to allow tool sources to live outside the llvm checkout. It also no longer renames LLVM_EXTERNAL_*_SOURCE_DIR. This change was reverted in r241663, because it renamed several variables of the format LLVM_EXTERNAL_*_* to LLVM_TOOL_*_*.
Summary (r241621):
The tools CMakeLists file already had implicit tool registration, but there were a few things off about it that needed to be altered to make it work. This change addresses all that. The changes in this patch are:
* factored out canonicalizing tool names from paths to CMake variables * removed the LLVM_IMPLICIT_PROJECT_IGNORE mechanism in favor of LLVM_EXTERNAL_${nameUPPER}_BUILD which I renamed to LLVM_TOOL_${nameUPPER}_BUILD because it applies to internal and external tools
* removed ignore_llvm_tool_subdirectory() in favor of just setting LLVM_TOOL_${nameUPPER}_BUILD to Off
* Added create_llvm_tool_options() to resolve a bug in add_llvm_external_project() - the old LLVM_EXTERNAL_${nameUPPER}_BUILD would not work on a clean CMake directory because the option could be created after it was set in code.
* Removed all but the minimum required calls to add_llvm_external_project from tools/CMakeLists.txt
Sanjoy Das [Mon, 20 Jul 2015 20:31:39 +0000 (20:31 +0000)]
[ImplicitNullChecks] Work with implicit defs.
Summary:
This change generalizes the implicit null checks pass to work with
instructions that don't have any explicit register defs. This lets us
use X86's `cmp` against memory as faulting load instructions.
Alex Lorenz [Mon, 20 Jul 2015 20:31:01 +0000 (20:31 +0000)]
MIR Parser: Add support for quoted named global value operands.
This commit extends the machine instruction lexer and implements support for
the quoted global value tokens. With this change the syntax for the global value
identifier tokens becomes identical to the syntax for the global identifier
tokens from the LLVM's assembly language.
The MSys 2 version of 'env' cannot be used to set 'TZ' in the
environment due to some portability hacks in the process spawning
compatibility layer[1]. This affects test/Object/archive-toc.test, which
tries to set TZ in the environment.
Other than that, this saves a subprocess invocation of a small unix
utility, which is makes the tests faster.
The internal shell does not support shell variable expansion, so this
idiom in the ASan tests isn't supported yet:
RUN: env ASAN_OPTIONS=$ASAN_OPTIONS:opt=1 ...
projects / llvm / log