llvm-6502/test/TableGen
Petr Pavlu d2e1e42c1a [TableGen] Improve decoding options for non-orthogonal instructions
When FixedLenDecoder matches an input bitpattern of form [01]+ with an
instruction bitpattern of form [01?]+ (where 0/1 are static bits and ? are
mixed/variable bits) it passes the input bitpattern to a specific instruction
decoder method which then makes a final decision whether the bitpattern is a
valid instruction or not. This means the decoder must handle all possible
values of the variable bits which sometimes leads to opcode rewrites in the
decoder method when the instructions are not fully orthogonal.

The patch provides a way for the decoder method to say that when it returns
Fail it does not necessarily mean the bitpattern is invalid, but rather that
the bitpattern is definitely not an instruction that is recognized by the
decoder method. The decoder can then try to match the input bitpattern with
other possible instruction bitpatterns.

For example, this allows to solve a situation on AArch64 where the `MSR
(immediate)` instruction has form:
1101 0101 0000 0??? 0100 ???? ???1 1111
but not all values of the ? bits are allowed. The rejected values should be
handled by the `extended MSR (register)` instruction:
1101 0101 000? ???? ???? ???? ???? ????

The decoder will first try to decode an input bitpattern that matches both
bitpatterns as `MSR (immediate)` but currently this puts the decoder method of
`MSR (immediate)` into a situation when it must be able to decode all possible
values of the ? bits, i.e. it would need to rewrite the instruction to `MSR
(register)` when it is not `MSR (immediate)`.

The patch allows to specify that the decoder method cannot determine if the
instruction is valid for all variable values. The decoder method can simply
return Fail when it knows it is definitely not `MSR (immediate)`. The decoder
will then backtrack the decoding and find that it can match the input
bitpattern with the more generic `MSR (register)` bitpattern too.

Differential Revision: http://reviews.llvm.org/D7174


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242274 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-15 08:04:27 +00:00
..
2003-08-03-PassCode.td
2006-09-18-LargeInt.td
2010-03-24-PrematureDefaults.td
AnonDefinitionOnDemand.td
AsmPredicateCondsEmission.td Use std::bitset for SubtargetFeatures. 2015-05-26 10:47:10 +00:00
BitOffsetDecoder.td Update test case to match minor formatting change introduced in r218563. 2014-09-27 05:36:53 +00:00
BitsInit.td Tablegen fixes for new syntax when initializing bits from variables. 2014-08-29 19:41:04 +00:00
BitsInitOverflow.td
cast.td
ClassInstanceValue.td [TableGen] Fully resolve class-instance values before defs in multiclasses 2014-09-16 17:14:13 +00:00
CStyleComment.td
Dag.td
defmclass.td
DefmInherit.td
DefmInsideMultiClass.td
eq.td
eqbit.td
FieldAccess.td
foreach.td
ForeachList.td llvm/test/TableGen/*Foreach*.td: Remove XFAIL:vg_leak. They have not been failing since r215176. 2014-08-12 14:06:21 +00:00
ForeachLoop.td llvm/test/TableGen/*Foreach*.td: Remove XFAIL:vg_leak. They have not been failing since r215176. 2014-08-12 14:06:21 +00:00
ForwardRef.td
GeneralList.td
if-empty-list-arg.td
if.td Change BitsInit to inherit from TypedInit. 2014-08-07 05:47:04 +00:00
ifbit.td Update BitRecTy::convertValue to allow if expressions with bit values on both sides of the if 2014-08-07 05:47:10 +00:00
Include.inc
Include.td
IntBitInit.td
intrinsic-long-name.td [TABLEGEN] Do not crash on intrinsics with names longer than 40 characters 2014-07-17 11:23:29 +00:00
intrinsic-order.td
intrinsic-varargs.td Add support for v1i128 type. 2015-04-17 16:11:05 +00:00
LazyChange.td
LetInsideMultiClasses.td
lisp.td
list-element-bitref.td Change BitsInit to inherit from TypedInit. 2014-08-07 05:47:04 +00:00
ListArgs.td
ListArgsSimple.td
listconcat.td
ListConversion.td
ListManip.td
ListOfList.td
ListSlices.td
lit.local.cfg
LoLoL.td
math.td Allow binary and for tblgen math. 2014-08-05 09:43:25 +00:00
MultiClass.td
MultiClassDefName.td [TableGen] Resolve complex def names inside multiclasses 2015-05-21 04:32:56 +00:00
MultiClassInherit.td
MultiPat.td
nested-comment.td
NestedForeach.td llvm/test/TableGen/*Foreach*.td: Remove XFAIL:vg_leak. They have not been failing since r215176. 2014-08-12 14:06:21 +00:00
Paste.td
pr8330.td
SetTheory.td
SiblingForeach.td llvm/test/TableGen/*Foreach*.td: Remove XFAIL:vg_leak. They have not been failing since r215176. 2014-08-12 14:06:21 +00:00
Slice.td
strconcat.td
String.td
subst2.td
subst.td
SuperSubclassSameName.td
TargetInstrInfo.td
TargetInstrSpec.td
TemplateArgRename.td
Tree.td
TreeNames.td
trydecode-emission2.td [TableGen] Improve decoding options for non-orthogonal instructions 2015-07-15 08:04:27 +00:00
trydecode-emission3.td [TableGen] Improve decoding options for non-orthogonal instructions 2015-07-15 08:04:27 +00:00
trydecode-emission.td [TableGen] Improve decoding options for non-orthogonal instructions 2015-07-15 08:04:27 +00:00
TwoLevelName.td
UnsetBitInit.td
UnterminatedComment.td
usevalname.td
ValidIdentifiers.td