This patch introduces a new function attribute, willreturn, to indicate
that a call of this function will either exhibit undefined behavior or
comes back and continues execution at a point in the existing call stack
that includes the current invocation.
This attribute guarantees that the function does not have any endless
loops, endless recursion, or terminating functions like abort or exit.
Patch by Hideto Ueno (@uenoku)
Reviewers: jdoerfert
Subscribers: mehdi_amini, hiraditya, steven_wu, dexonsmith, lebedev.ri, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D62801
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@364555 91177308-0d34-0410-b5e6-96231b3b80d8
FunctionComparator attempts to produce a stable comparison of two Function
instances by looking at all available properties. Since ByVal attributes now
contain a Type pointer, they are not trivially ordered and FunctionComparator
should use its own Type comparison logic to sort them.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@364523 91177308-0d34-0410-b5e6-96231b3b80d8
Summary: This patch introduces a new heuristic for guiding operand reordering. The new "look-ahead" heuristic can look beyond the immediate predecessors. This helps break ties when the immediate predecessors have identical opcodes (see lit test for an example).
Reviewers: RKSimon, ABataev, dtemirbulatov, Ayal, hfinkel, rnk
Reviewed By: RKSimon, dtemirbulatov
Subscribers: rnk, rcorcs, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D60897
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@364478 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This diff enables address sanitizer on Emscripten.
On Emscripten, real memory starts at the value passed to --global-base.
All memory before this is used as shadow memory, and thus the shadow mapping
function is simply dividing by 8.
Reviewers: tlively, aheejin, sbc100
Reviewed By: sbc100
Subscribers: dschuff, sbc100, jgravelle-google, hiraditya, sunfish, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D63742
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@364468 91177308-0d34-0410-b5e6-96231b3b80d8
This allows later passes (in particular InstCombine) to optimize more
cases.
One that's important to us is `memcmp(p, q, constant) < 0` and memcmp(p, q, constant) > 0.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@364412 91177308-0d34-0410-b5e6-96231b3b80d8
This patch generalizes the UnrollLoop utility to support loops that exit
from the header instead of the latch. Usually, LoopRotate would take care
of must of those cases, but in some cases (e.g. -Oz), LoopRotate does
not kick in.
Codesize impact looks relatively neutral on ARM64 with -Oz + LTO.
Program master patch diff
External/S.../CFP2006/447.dealII/447.dealII 629060.00 627676.00 -0.2%
External/SPEC/CINT2000/176.gcc/176.gcc 1245916.00 1244932.00 -0.1%
MultiSourc...Prolangs-C/simulator/simulator 86100.00 86156.00 0.1%
MultiSourc...arks/Rodinia/backprop/backprop 66212.00 66252.00 0.1%
MultiSourc...chmarks/Prolangs-C++/life/life 67276.00 67312.00 0.1%
MultiSourc...s/Prolangs-C/compiler/compiler 69824.00 69788.00 -0.1%
MultiSourc...Prolangs-C/assembler/assembler 86672.00 86696.00 0.0%
Reviewers: efriedma, vsk, paquette
Reviewed By: paquette
Differential Revision: https://reviews.llvm.org/D61962
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@364398 91177308-0d34-0410-b5e6-96231b3b80d8
This follows up the transform from rL363956 to use the ctpop intrinsic when checking for power-of-2-or-zero.
This is matching the isPowerOf2() patterns used in PR42314:
https://bugs.llvm.org/show_bug.cgi?id=42314
But there's at least 1 instcombine follow-up needed to match the alternate form:
(v & (v - 1)) == 0;
We should have all of the backend expansions handled with:
rL364319
(x86-specific changes still needed for optimal code based on subtarget)
And the larger patterns to exclude zero as a power-of-2 are joining with this change after:
rL364153 ( D63660 )
rL364246
Differential Revision: https://reviews.llvm.org/D63777
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@364341 91177308-0d34-0410-b5e6-96231b3b80d8
This is the Demorgan'd 'not' of the pattern handled in:
D63660 / rL364153
This is another intermediate IR step towards solving PR42314:
https://bugs.llvm.org/show_bug.cgi?id=42314
We can test if a value is not a power-of-2 using ctpop(X) > 1,
so combining that with an is-zero check of the input is the
same as testing if not exactly 1 bit is set:
(X == 0) || (ctpop(X) u> 1) --> ctpop(X) != 1
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@364246 91177308-0d34-0410-b5e6-96231b3b80d8
Prefer the more exact intrinsic to remove a use of the input value
and possibly make further transforms easier (we will still need
to match patterns with funnel-shift of wider types as pieces of
bswap, especially if we want to canonicalize to funnel-shift with
constant shift amount). Discussed in D46760.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@364187 91177308-0d34-0410-b5e6-96231b3b80d8
trunc(lshr) handling - if the shift is out of range (undefined) then bail like we do for non-constant shifts.
Fixes OSS Fuzz #15217
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@364181 91177308-0d34-0410-b5e6-96231b3b80d8
In rL364135, I taught IndVars to fold exiting branches in loops with a zero backedge taken count (i.e. loops that only run one iteration). This extends that to eliminate the dead comparison left around.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@364155 91177308-0d34-0410-b5e6-96231b3b80d8
This turned out to be surprisingly effective. I was originally doing this just for completeness sake, but it seems like there are a lot of cases where SCEV's exit count reasoning is stronger than it's isKnownPredicate reasoning.
Once this is in, I'm thinking about trying to build on the same infrastructure to eliminate provably untaken checks. There may be something generally interesting here.
Differential Revision: https://reviews.llvm.org/D63618
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@364135 91177308-0d34-0410-b5e6-96231b3b80d8
This reverts r364084 (git commit 5698921be2d567f6abf925479ac9f5a376d6d74f)
It caused crashes while compiling a file in Chrome. Reduction
forthcoming.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@364111 91177308-0d34-0410-b5e6-96231b3b80d8
The VM layout on iOS is not stable between releases. On 64-bit iOS and
its derivatives we use a dynamic shadow offset that enables ASan to
search for a valid location for the shadow heap on process launch rather
than hardcode it.
This commit extends that approach for 32-bit iOS plus derivatives and
their simulators.
rdar://50645192
rdar://51200372
rdar://51767702
Reviewed By: delcypher
Differential Revision: https://reviews.llvm.org/D63586
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@364105 91177308-0d34-0410-b5e6-96231b3b80d8
This patch introduces a new heuristic for guiding operand reordering. The new "look-ahead" heuristic can look beyond the immediate predecessors. This helps break ties when the immediate predecessors have identical opcodes (see lit test for an example).
Committed on behalf of @vporpo (Vasileios Porpodas)
Differential Revision: https://reviews.llvm.org/D60897
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@364084 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
The motivation for this was to propagate fast-math flags like nnan and
ninf on vector floating point operations to the corresponding scalar
operations to take advantage of follow-on optimizations. But I think
the same argument applies to all of our IR flags: if they apply to the
vector operation then they also apply to all the individual scalar
operations, and they might enable follow-on optimizations.
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63593
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@364051 91177308-0d34-0410-b5e6-96231b3b80d8
Also, add a FIXME for the unsafe transform on a unary FNeg. A unary FNeg can only be transformed to a FMul by -1.0 when the nnan flag is present. The unary FNeg project is a WIP, so the unsafe transformation is acceptable until that work is complete.
The bogus assert with introduced in D63445.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@363998 91177308-0d34-0410-b5e6-96231b3b80d8
Currently, many profiling tests on Solaris FAIL like
Command Output (stderr):
--
Undefined first referenced
symbol in file
__llvm_profile_register_names_function /tmp/lit_tmp_Nqu4eh/infinite_loop-9dc638.o
__llvm_profile_register_function /tmp/lit_tmp_Nqu4eh/infinite_loop-9dc638.o
Solaris 11.4 ld supports the non-standard GNU ld extension of adding
__start_SECNAME and __stop_SECNAME labels to sections whose names are valid
as C identifiers. Given that we already use Solaris 11.4-only features
like ld -z gnu-version-script-compat and fully working .preinit_array
support in compiler-rt, we don't need to worry about older versions of
Solaris ld.
The patch documents that support (although the comment in
lib/Transforms/Instrumentation/InstrProfiling.cpp
(needsRuntimeRegistrationOfSectionRange) is quite cryptic what it's
actually about), and adapts the affected testcase not to expect the
alternativeq __llvm_profile_register_functions and __llvm_profile_init.
It fixes all affected tests.
Tested on amd64-pc-solaris2.11.
Differential Revision: https://reviews.llvm.org/D41111
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@363984 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
The getClobberingMemoryAccess API checks for clobbering accesses in a loop by walking the backedge. This may check if a memory access is being
clobbered by the loop in a previous iteration, depending how smart AA got over the course of the updates in MemorySSA (it does not occur when built from scratch).
If no clobbering access is found inside the loop, it will optimize to an access outside the loop. This however does not mean that access is safe to sink.
Given:
```
for i
load a[i]
store a[i]
```
The access corresponding to the load can be optimized to outside the loop, and the load can be hoisted. But it is incorrect to sink it.
In order to sink the load, we'd need to check no Def clobbers the Use in the same iteration. With this patch we currently restrict sinking to either
Defs not existing in the loop, or Defs preceding the load in the same block. An easy extension is to ensure the load (Use) post-dominates all Defs.
Caught by PR42294.
This issue also shed light on the converse problem: hoisting stores in this same scenario would be illegal. With this patch we restrict
hoisting of stores to the case when their corresponding Defs are dominating all Uses in the loop.
Reviewers: george.burgess.iv
Subscribers: jlebar, Prazek, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63582
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@363982 91177308-0d34-0410-b5e6-96231b3b80d8
I can't actually come up with a test case this triggers on without an out of tree change, but in theory, it's a bug in the recently added multiple exit LFTR support. The root issue is that an exiting block common to two loops can (in theory) have computable exit counts for both loops. Rewriting the exit of an inner loop in terms of the outer loops IV would cause the inner loop to either a) run forever, or b) terminate on the first iteration.
In practice, we appear to get lucky and not have the exit count computable for the outer loop, except when it's trivially zero. Given we bail on zero exit counts, we don't appear to ever trigger this. But I can't come up with a reason we *can't* compute an exit count for the outer loop on the common exiting block, so this may very well be triggering in some cases.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@363964 91177308-0d34-0410-b5e6-96231b3b80d8
The form that compares against 0 is better because:
1. It removes a use of the input value.
2. It's the more standard form for this pattern: https://graphics.stanford.edu/~seander/bithacks.html#DetermineIfPowerOf2
3. It results in equal or better codegen (tested with x86, AArch64, ARM, PowerPC, MIPS).
This is a root cause for PR42314, but probably doesn't completely answer the codegen request:
https://bugs.llvm.org/show_bug.cgi?id=42314
Alive proof:
https://rise4fun.com/Alive/9kG
Name: is power-of-2
%neg = sub i32 0, %x
%a = and i32 %neg, %x
%r = icmp eq i32 %a, %x
=>
%dec = add i32 %x, -1
%a2 = and i32 %dec, %x
%r = icmp eq i32 %a2, 0
Name: is not power-of-2
%neg = sub i32 0, %x
%a = and i32 %neg, %x
%r = icmp ne i32 %a, %x
=>
%dec = add i32 %x, -1
%a2 = and i32 %dec, %x
%r = icmp ne i32 %a2, 0
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@363956 91177308-0d34-0410-b5e6-96231b3b80d8
