There are cases of AVX-512 instructions that have two possible encodings. This is the case with instructions that use vector registers with low indexes of 0 - 15 and do not use the zmm registers or the mask k registers.
The EVEX encoding prefix requires 4 bytes whereas the VEX prefix can take only up to 3 bytes. Consequently, using the VEX encoding for these instructions results in a code size reduction of ~2 bytes even though it is compiled with the AVX-512 features enabled.
Reviewers: Craig Topper, Zvi Rackoover, Elena Demikhovsky
Differential Revision: https://reviews.llvm.org/D27901
llvm-svn: 290663
These nodes are only emitted for lowering FABS/FNEG/FNABS/FCOPYSIGN. Ideally we just wouldn't create these nodes if SSE2 or higher is available, but it was simple to just convert them in DAG combine.
For SSE2, AVX, and AVX512 with DQI this is no functional change as the execution domain fixing pass ensures the right domain is selected regardless of the ISD opcode.
For AVX-512 without DQI we end up using integer instructions since the floating point versions aren't available. But we were already doing that for any logical operations in code that didn't come from FABS/FNEG/FNABS/FCOPYSIGN so this seems no worse. And we get the benefit of being able to fold broadcasts now.
llvm-svn: 290060
FP logic instructions are supported in DQ extension on AVX-512 target.
I use integer operations instead.
Added tests.
I also enabled FABS in this patch in order to check ANDPS.
The operations are FOR, FXOR, FAND, FANDN.
The instructions, that supported for 512-bit vector under DQ are:
VORPS/PD, VXORPS/PD, VANDPS/PD, FANDNPS/PD.
Differential Revision: http://reviews.llvm.org/D15110
llvm-svn: 254913
This is a follow-up to the FIXME that was added with D7474 ( http://reviews.llvm.org/rL229531 ).
I thought this load folding bug had been made hard-to-hit, but it turns out to be very easy
when targeting 32-bit x86 and causes a miscompile/crash in Wine:
https://bugs.winehq.org/show_bug.cgi?id=38826https://llvm.org/bugs/show_bug.cgi?id=22371#c25
The quick fix is to simply remove the scalar FP logical instructions from the load folding table
in X86InstrInfo, but that causes us to miss load folds that should be possible when lowering fabs,
fneg, fcopysign. So the majority of this patch is altering those lowerings to use *vector* FP
logical instructions (because that's all x86 gives us anyway). That lets us do the load folding
legally.
Differential Revision: http://reviews.llvm.org/D11477
llvm-svn: 243361
Allow vector fabs operations on bitcasted constant integer values to be optimized
in the same way that we already optimize scalar fabs.
So for code like this:
%bitcast = bitcast i64 18446744069414584320 to <2 x float> ; 0xFFFF_FFFF_0000_0000
%fabs = call <2 x float> @llvm.fabs.v2f32(<2 x float> %bitcast)
%ret = bitcast <2 x float> %fabs to i64
Instead of generating something like this:
movabsq (constant pool loadi of mask for sign bits)
vmovq (move from integer register to vector/fp register)
vandps (mask off sign bits)
vmovq (move vector/fp register back to integer return register)
We should generate:
mov (put constant value in return register)
I have also removed a redundant clause in the first 'if' statement:
N0.getOperand(0).getValueType().isInteger()
is the same thing as:
IntVT.isInteger()
Testcases for x86 and ARM added to existing files that deal with vector fabs.
One existing testcase for x86 removed because it is no longer ideal.
For more background, please see:
http://reviews.llvm.org/D4770
And:
http://llvm.org/bugs/show_bug.cgi?id=20354
Differential Revision: http://reviews.llvm.org/D4785
llvm-svn: 214892
Fundamentally, there isn't a really portable way to test the constant
pool contents. Instead, pin this test to the bare-metal triple. This
also makes it a 64-bit triple which allows us to only match a single
constant pool rather than two. It can also just hard code the '.' prefix
as the format should be stable now that it has a fixed triple. Finally,
I've switched it to use CHECK-NEXT to be more precise in the instruction
sequence expected and to use variables rather than hard coding decisions
by the register allocator.
llvm-svn: 214679
This is intended to be the minimal change needed to fix PR20354 ( http://llvm.org/bugs/show_bug.cgi?id=20354 ). The check for a vector operation was wrong; we need to check that the fabs itself is not a vector operation.
This patch will not generate the optimal code. A constant pool load and 'and' op will be generated instead of just returning a value that we can calculate in advance (as we do for the scalar case). I've put a 'TODO' comment for that here and expect to have that patch ready soon.
There is a very similar optimization that we can do in visitFNEG, so I've put another 'TODO' there and expect to have another patch for that too.
llvm-svn: 214670
Gadi Haber