This PR blocklist instructions that are unsafe for masked-load folding.
Folding with the same mask is only safe if every active destination
element reads only from source elements that are also active under the
same mask. These instructions perform element rearrangement or
broadcasting, which may cause active destination elements to read from
masked-off source elements.
VPERMILPD and VPERMILPS are safe only in the rrk form, the rik form
needs to be blocklisted. In the rrk form, the masked source operand is a
control mask, while in the rik form the masked source operand is the
data/value. This is also why VPSHUFB is safe to fold, while other
shuffles such as VSHUFPS are not.
Examples:
```
EVEX.128.66.0F.WIG 67 /r VPACKUSWB xmm1{k1}{z}, xmm2, xmm3/m128
A: 00010203 7F000001 80000002 DEADBEEF
E : 00000000 00000001 00000002 00000003
D: 11111111 22222222 33333333 44444444
k = 0x0400
Masked_e = 00000000 00000000 00000000 00000000 (vmovdqu8{k}{z} Masked_e E)
res1 = 00000000 00000000 00010000 00000000 (VPACKUSWB D{k}{z}, A, E)
res2 = 00000000 00000000 00000000 00000000 (VPACKUSWB D{k}{z}, A, Masked_e)
EVEX.128.66.0F38.W0 C4 /r VPCONFLICTD xmm1 {k1}{z}, xmm2/m128/m32bcst
A: DAA66D2B FFFFFFFC FFFFFFFC D9A0643C
E : 7DDF743F 00000000 5FD99E73 4ED634C9
D: 2629AB38 9E37782F 67BB800F AD66764A
k = 0x0002
Masked_e = (vmovdqu32 {k}{z} Masked_e E)
res1 = 00000000 00000000 00000000 00000000 (VPCONFLICTD D{k}{z}, E)
res2 = 00000000 00000001 00000000 00000000 (VPCONFLICTD D{k}{z}, Masked_e)
EVEX.128.66.0F38.W1 8D /r VPERMW xmm1 {k1}{z}, xmm2, xmm3/m128
A: 00010203 7F000001 80000002 DEADBEEF
E : 00000000 00000001 00000002 00000003
D: 11111111 22222222 33333333 44444444
k = 0x0010
Masked_e = 00000000 00000000 00000002 00000000 (vmovdqu16 {k}{z} Masked_e E)
res1 = 00000000 00000000 00000001 00000000 (vpermw D{k}{z}, A, E)
res2 = 00000000 00000000 00000000 00000000 (vpermw D{k}{z}, A, Masked_e)
EVEX.128.66.0F38.W0 78 /r VPBROADCASTB xmm1{k1}{z}, xmm2/m8
E : 7F4A7C15 6E490933 5D4C9659 4C433CE3
D: F63F9D36 97F6E2B2 9432E8E6 FAEE7A3E
k = 0x0002
Masked_e = 00007C00 00000000 00000000 00000000 (vmovdqu8{k}{z} Masked_e E)
res = 00001500 00000000 00000000 00000000 (vpbroadcastb D{k}{z}, E)
res = 00000000 00000000 00000000 00000000 (vpbroadcastb D{k}{z}, Masked_e)
```
Baseline: https://github.com/llvm/llvm-project/pull/178411
- Replace manual code to convert a `BitsInit` to a uint64_t by using
`convertInitializerToInt` where applicable.
- Add `BitsInit::convertKnownBitsToInt` to handle existing patterns in
DFAEmitter.cpp and RegisterInfoEmitter.cpp.
- Consolidate 3 copies of the same function in X86 emitters into a
single function.
This code used to use the PadToColumn feature of formatted_raw_ostream,
but no longer does. formatted_raw_ostream is slower than regular
raw_ostream because it has to keep track of the number of character
since the last new line character.
Refactor of the llvm-tblgen source into:
- a "Basic" library, which contains the bare minimum utilities to build
`llvm-min-tablegen`
- a "Common" library which contains all of the helpers for TableGen
backends. Such helpers can be shared by more than one backend, and even
unit tested (e.g. CodeExpander is, maybe we can add more over time)
Fixes#80647
1. Rename the names of tables to simplify the print
2. Align the abbreviation in the same file Instr -> Inst
3. Clang-format
4. Capitalize the first char of the variable name
This patch adds "#include <set>" to several files that are relying on
transitive includes of <set>. It in turn unblocks the removal of
unnecessary includes of llvm/ADT/SmallSet.h in several other files.
X86 don't want to unfold RMW instrs to 1 load + 1 op + 1 store, because
RMW could save code size and benefit RA when reg pressure is high.
And from all the call position analysis, we could find we didn't unfold
RMW in current code.
Add expensive check that Uses, Defs are same for entries in memory folding table.
MemFolding could not change the Uses/Defs.
Reviewed By: skan
Differential Revision: https://reviews.llvm.org/D150633
1. Avoid vulnerable assumption: the enum of reg/memory format are continous
2. Remove redundant inline keyword
3. Replace getValueFromBitsInit with byteFromBitsInit b/c both Form and
Opcode can be represented in 1 byte
1. Use `unsigned` for `KeyOp` and `DstOp` b/c `Opcode` is of type `unsigned`.
2. Align the comparator used in X86FoldTablesEmitter.cpp with the one in
CodeGenTarget::ComputeInstrsByEnum.
