Currently ARM is the only backend that supports FMA instructions (for at least some subtargets) but does not implement this virtual, so FMAs are never generated except from explicit fma intrinsic calls. Apparently this is due to the fact that it supports both fused (one rounding step) and unfused (two rounding step) multiply + add instructions. This patch clarifies that this the case without changing behavior by implementing the virtual function to simply return false, as the default TargetLoweringBase version does.
It is possible that some cpus perform the fused version faster than the unfused version and vice-versa, so the function implementation should be revisited if hard data is found.
llvm-svn: 185994
Propagate the fix from r185712 to Thumb2 codegen as well. Original
commit message applies here as well:
A "pkhtb x, x, y asr #num" uses the lower 16 bits of "y asr #num" and
packs them in the bottom half of "x". An arithmetic and logic shift are
only equivalent in this context if the shift amount is 16. We would be
shifting in ones into the bottom 16bits instead of zeros if "y" is
negative.
rdar://14338767
llvm-svn: 185982
A "pkhtb x, x, y asr #num" uses the lower 16 bits of "y asr #num" and packs them
in the bottom half of "x". An arithmetic and logic shift are only equivalent in
this context if the shift amount is 16. We would be shifting in ones into the
bottom 16bits instead of zeros if "y" is negative.
radar://14338767
llvm-svn: 185712
In the SelectionDAG immediate operands to inline asm are constructed as
two separate operands. The first is a constant of value InlineAsm::Kind_Imm
and the second is a constant with the value of the immediate.
In ARMDAGToDAGISel::SelectInlineAsm, if we reach an operand of Kind_Imm we
should skip over the next operand too.
llvm-svn: 185688
This adds a new decoder table/namespace 'VFPV8', as these instructions have their
top 4 bits as 0b1111, while other Thumb instructions have 0b1110.
llvm-svn: 185642
This is purely academic because GHC calls are always tail calls so the register mask will never be used; however, this change makes the code clearer and brings the ARM implementation of the GHC calling convention in line with the X86 implementation. Also, it might save someone else some time trying to figuring out what is happening...
llvm-svn: 185592
In the ARM back-end, build_vector nodes are lowered to a target specific
build_vector that uses floating point type.
This works well, unless the inserted bitcasts survive until instruction
selection. In that case, they incur moves between integer unit and floating
point unit that may result in inefficient code.
In other words, this conversion may introduce artificial dependencies when the
code leading to the build vector cannot be completed with a floating point type.
In particular, this happens when loads are not aligned.
Before this patch, in that case, the compiler generates general purpose loads
and creates the floating point vector from them, instead of directly using the
vector unit.
The patch uses a vector friendly sequence of code when the inserted bitcasts to
floating point survived DAGCombine.
This is done by a target specific DAGCombine that changes the target specific
build_vector into a sequence of insert_vector_elt that get rid of the bitcasts.
<rdar://problem/14170854>
llvm-svn: 185587
Before the fix Thumb2 instructions of type "add rD, rN, #imm" (T3 encoding, see ARM ARM A8.8.4) with rD and rN both being low registers (r0-r7) were classified as having the T4 encoding.
The T4 encoding doesn't have a cc_out operand so for above instructions the operand gets erroneously removed, corrupting the token stream and leading to parse errors later in the process.
This bug prevented "add r1, r7, #0xcbcbcbcb" from being assembled correctly.
Fixes <rdar://problem/14224440>.
llvm-svn: 185575
1. it should accept only 4-byte aligned addresses
2. the maximum offset should be 1020
3. it should be encoded with the offset scaled by two bits
llvm-svn: 185528
Swift cores implement store barriers that are stronger than the ARM
specification but weaker than general barriers. They are, in fact, just about
enough to provide the ordering needed for atomic operations with release
semantics.
This patch makes use of that quirk.
llvm-svn: 185527
This is dead code since PIC16 was removed in 2010. The result was an odd mix,
where some parts would carefully pass it along and others would assert it was
zero (most of the object streamer for example).
llvm-svn: 185436
According to ARM EHABI section 9.2, if the
__aeabi_unwind_cpp_pr1() or __aeabi_unwind_cpp_pr2() is
used, then the handler data must be emitted after the unwind
opcodes. The handler data consists of several words, and
should be terminated by zero.
In case that the .handlerdata directive is not specified by
the programmer, we should emit zero to terminate the handler
data.
llvm-svn: 185422
Turns out I'd misread the architecture reference manual and thought
that was a load/store-store barrier, when it's not.
Thanks for pointing it out Eli!
llvm-svn: 185356
I believe the full "dmb ish" barrier is not required to guarantee release
semantics for atomic operations. The weaker "dmb ishst" prevents previous
operations being reordered with a store executed afterwards, which is enough.
A key point to note (fortunately already correct) is that this barrier alone is
*insufficient* for sequential consistency, no matter how liberally placed.
llvm-svn: 185339
This patch assigns paired GPRs for inline asm with
64-bit data on ARM. It's enabled for both ARM and Thumb to support modifiers
like %H, %Q, %R.
llvm-svn: 185169
We were generating intrinsics for NEON fixed-point conversions that didn't
exist (e.g. float -> i16). There are two cases to consider:
+ iN is smaller than float. In this case we can do the conversion but need an
extend or truncate as well.
+ iN is larger than float. In this case using the NEON conversion would be
incorrect so we don't perform any combining.
llvm-svn: 185158
The mapping between SRS pseudo-instructions and SRS native instructions was incorrect, the correct mapping is:
srsfa -> srsib
srsea -> srsia
srsfd -> srsdb
srsed -> srsda
This fixes <rdar://problem/14214734>.
llvm-svn: 185155
(Currently, ARM 'this'-returns are handled in the standard calling convention case by treating R0 as preserved and doing some extra magic in LowerCallResult; this may not apply to calling conventions added in the future so this patch provides and documents an interface for indicating such)
llvm-svn: 185024
Unfortunately this addresses two issues (by the time I'd disentangled the logic
it wasn't worth putting it back to half-broken):
+ Coprocessor instructions should all be predicable in Thumb mode.
+ BKPT should never be predicable.
llvm-svn: 184965
Craig Topper