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This is generally more readable due to the way the assembler aliases
work.
(This causes a lot of test changes, but it's not really as scary as it
looks at first glance; it's just mechanically changing a bunch of checks
for orr to check for mov instead.)
Differential Revision: https://reviews.llvm.org/D59720
llvm-svn: 356954
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Fixes https://bugs.llvm.org/show_bug.cgi?id=35094
The Dead register definition pass should leave alone the atomicrmw
instructions on AArch64 (LTE extension). The reason is the following
statement in the Arm ARM:
"The ST<OP> instructions, and LD<OP> instructions where the destination
register is WZR or XZR, are not regarded as doing a read for the purpose
of a DMB LD barrier."
A good example was given in the gcc thread by Will Deacon (linked in the
bugzilla ticket 35094):
P0 (atomic_int* y,atomic_int* x) {
atomic_store_explicit(x,1,memory_order_relaxed);
atomic_thread_fence(memory_order_release);
atomic_store_explicit(y,1,memory_order_relaxed);
}
P1 (atomic_int* y,atomic_int* x) {
atomic_fetch_add_explicit(y,1,memory_order_relaxed); // STADD
atomic_thread_fence(memory_order_acquire);
int r0 = atomic_load_explicit(x,memory_order_relaxed);
}
P2 (atomic_int* y) {
int r1 = atomic_load_explicit(y,memory_order_relaxed);
}
My understanding is that it is forbidden for r0 == 0 and r1 == 2 after
this test has executed. However, if the relaxed add in P1 compiles to
STADD and the subsequent acquire fence is compiled as DMB LD, then we
don't have any ordering guarantees in P1 and the forbidden result could
be observed.
Change-Id: I419f9f9df947716932038e1100c18d10a96408d0
llvm-svn: 356360
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Armv8.1-A added an atomic load-clear instruction (which performs bitwise
and with the complement of it's operand), but not a load-and
instruction. Our current code-generation for atomic load-and always
inserts an MVN instruction to invert its argument, even if it could be
folded into a constant or another instruction.
This adds lowering early in selection DAG to convert a load-and
operation into an xor with -1 and a load-clear, allowing the normal DAG
optimisations to work on it.
To do this, I've had to add a new ISD opcode, ATOMIC_LOAD_CLR. I don't
see any easy way to do this with an AArch64-specific ISD node, because
the code-generation for atomic operations assumes the SDNodes are of
type AtomicSDNode.
I've left the old tablegen patterns in because they are still needed for
global isel.
Differential revision: https://reviews.llvm.org/D42478
llvm-svn: 324908
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Armv8.1-A added an atomic load-add instruction, but not a load-subtract
instruction. Our current code-generation for atomic load-subtract always
inserts a NEG instruction to negate it's argument, even if it could be
folded into a constant or another instruction.
This adds lowering early in selection DAG to convert a load-subtract
operation into a subtract and a load-add, allowing the normal DAG
optimisations to work on it.
I've left the old tablegen patterns in because they are still needed for
global isel.
Some of the tests in this patch are copied from D35375 by Chad Rosier (which
was abandoned).
Differential revision: https://reviews.llvm.org/D42477
llvm-svn: 324892
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The Large System Extension added an atomic compare-and-swap instruction
that operates on a pair of 64-bit registers, which we can use to
implement a 128-bit cmpxchg.
Because i128 is not a legal type for AArch64 we have to do all of the
instruction selection in C++, and the instruction requires even/odd
register pairs, so we have to wrap it in REG_SEQUENCE and EXTRACT_SUBREG
nodes. This is very similar to what we do for 64-bit cmpxchg in the ARM
backend.
Differential revision: https://reviews.llvm.org/D42104
llvm-svn: 323634
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The code wasn't zero-extending correctly, so the comparison could
spuriously fail.
Adds some AArch64 tests to cover this case.
Inspired by D41791.
Differential Revision: https://reviews.llvm.org/D41798
llvm-svn: 322767
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llvm-svn: 314105
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Add memory synchronization semantics to LSE Atomics.
The memory semantics feature will be added in a subsequent patch.
In this patch, several corrections were added to the existing LSE Atomics
implementation, based on the ARM Errata D11904 from 05/12/2017.
Patch by: steleman
Differential Revision: https://reviews.llvm.org/D35319
llvm-svn: 310167
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This patch is a follow-up to r305893 and adds preliminary support for the
fetch_sub and fetch_and operations.
llvm-svn: 307913
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Added test file for ARMv8.1 LSE Atomics that I forgot to include in
commit r305893.
Patch by Ananth Jasty.
Differential Revision: https://reviews.llvm.org/D33586
Change-Id: Ic1ad8ed87c1b584c4c791b459a686c866a3c3087
llvm-svn: 305918
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