The greedy register allocator tries to split a live-range around each
instruction where it is used or defined to relax the constraints on the entire
live-range (this is a last chance split before falling back to spill).
The goal is to have a big live-range that is unconstrained (i.e., that can use
the largest legal register class) and several small local live-range that carry
the constraints implied by each instruction.
E.g.,
Let csti be the constraints on operation i.
V1=
op1 V1(cst1)
op2 V1(cst2)
V1 live-range is constrained on the intersection of cst1 and cst2.
tryInstructionSplit relaxes those constraints by aggressively splitting each
def/use point:
V1=
V2 = V1
V3 = V2
op1 V3(cst1)
V4 = V2
op2 V4(cst2)
Because of how the coalescer infrastructure works, each new variable (V3, V4)
that is alive at the same time as V1 (or its copy, here V2) interfere with V1.
Thus, we end up with an uncoalescable copy for each split point.
To make tryInstructionSplit less aggressive, we check if the split point
actually relaxes the constraints on the whole live-range. If it does not, we do
not insert it.
Indeed, it will not help the global allocation problem:
- V1 will have the same constraints.
- V1 will have the same interference + possibly the newly added split variable
VS.
- VS will produce an uncoalesceable copy if alive at the same time as V1.
<rdar://problem/15570057>
llvm-svn: 198369
This fixes a crash that appeared when generating dotty graphs for functions
without loops (for which we do not calculate polyhedral information).
llvm-svn: 198364
CR logicals (crand, crxor, etc.) on the P7 need to be in the first slot of each
dispatch group. The old itinerary entry was just wrong (but has not mattered
because we don't generate these instructions).
This will matter when, in an upcoming commit, we start generating these
instructions.
llvm-svn: 198359
Several of the 64-bit fixed-point instructions with immediate operands were
using the 32-bit (i32) operand nodes instead of the corresponding 64-bit (i64)
operand definitions (u16imm instead of u16imm64, for example).
This error has had no effect so far, but would have caused type-checking
violations with an upcoming change.
llvm-svn: 198356
As noted in the comment above CodeGenPrepare::OptimizeInst, which aggressively
sinks compares to reduce pressure on the condition register(s), for targets
such as PowerPC with multiple condition registers, this may not be the right
thing to do. This adds an HasMultipleConditionRegisters boolean to TLI, and
CodeGenPrepare::OptimizeInst is skipped when HasMultipleConditionRegisters is
true.
This functionality will be used by the PowerPC backend in an upcoming commit.
Especially when the PowerPC backend starts tracking individual condition
register bits as separate allocatable entities (which will happen in this
upcoming commit), this sinking from CodeGenPrepare::OptimizeInst is
significantly suboptimial.
llvm-svn: 198354
I originally had these using opt -verify, and I never removed the
-verify when converting them to use llvm-as instead, so these were
failing because of using the -verify argument which llvm-as doesn't have
instead of what it's actually supposed to be testing.
llvm-svn: 198352
Use an if statement instead of a pair of ternary operators checking
the same condition.
Use a cheap method call rather than returning the local symbol.
llvm-svn: 198351
Even within a multiclass, we had been generating concrete implicit anonymous
defs when parsing values (generally in value lists). This behavior was
incorrect, and led to errors when multiclass parameters were used in the
parameter list of the implicit anonymous def.
If we had some multiclass:
multiclass mc<string n> {
... : SomeClass<SomeOtherClass<n> >
The capture of the multiclass parameter 'n' would not work correctly, and
depending on how the implicit SomeOtherClass was used, either TableGen would
ignore something it shouldn't, or would crash.
To fix this problem, when inside a multiclass, we generate prototype anonymous
defs for implicit anonymous defs (just as we do for explicit anonymous defs).
Within the multiclass, the current record prototype is populated with a node
that is essentially: !cast<SomeOtherClass>(!strconcat(NAME, anon_value_name)).
This is then resolved to the correct concrete anonymous def, in the usual way,
when NAME is resolved during multiclass instantiation.
llvm-svn: 198348
A ValueType in a pattern dag is a type cast, and GetNumNodeResults should
handle it (the type cast has only one result).
This comes up, for example, during the type checking of pattern fragments, for
example, AArch64's Neon_combine_2d fragment is:
dag Operands = (ops node:$Rm, node:$Rn);
dag Fragment = (v2f64 (concat_vectors (v1f64 node:$Rm), (v1f64 node:$Rn)));
llvm-svn: 198347
Plugins need to go in build/Debug/lib as well (rather than build/lib/Debug).
Also, fix the SHLIBDIR path for Xcode, which by default includes Xcode build
settings rather than a simple %(build_mode)s parameter.
llvm-svn: 198344
TableGen had been generating a different name for an anonymous multiclass's
NAME for every def in the multiclass. This had an unfortunate side effect: it
was impossible to reference one def within the multiclass from another (in the
parameter list, for example). By making sure we only generate an anonymous name
once per multiclass (which, as it turns out, requires only changing the name
parameter to reference type), we can now concatenate NAME within the multiclass
with a def name in order to generate a reference to that def.
This does not matter so much, in and of itself, but is necessary for a
follow-up commit that will fix variable capturing in implicit anonymous
multiclass defs (and that is important).
llvm-svn: 198340
When widening an IV to remove s/zext, we generally try to eliminate
the original narrow IV. However, LCSSA phi nodes outside the loop were
still using the original IV. Clean this up more aggressively to avoid
redundancy in generated code.
llvm-svn: 198338
In a standalone build, Clang binaries should end up in Clang's build folder,
not LLVM's.
Xcode still has a few issues finding auxiliary tools and libraries in the
build folders. I'll fix those next.
llvm-svn: 198328
The separate Xcode project generated for Clang is putting the clang
executables into the same location where the LLVM executables are
going. This is wrong, and breaks the Clang build because we try to
create clang++ and clang-cl symlinks in the wrong place and to the
wrong place.
As a stop-gap to get these builds working again, teach the symlink
generation to point into the LLVM executable directory instead.
llvm-svn: 198319
The backend string is only verified when available as it's possible to run
clang IRGen for targets that haven't been built or don't exist in LLVM.
llvm-svn: 198309
Quentin Colombet