This is similar to the -unroll-threshold option. There should be no change in
behavior when -tail-dup-size is not explicit on the llc command line.

llvm-svn: 124564

Teach DAGCombine to fold fold (sra (trunc (sr x, c1)), c2) -> (trunc (sra x, c1+c2) when c1 equals the amount of bits that are truncated off.

This happens all the time when a smul is promoted to a larger type.

On x86-64 we now compile "int test(int x) { return x/10; }" into
  movslq  %edi, %rax
  imulq $1717986919, %rax, %rax
  movq  %rax, %rcx
  shrq  $63, %rcx
  sarq  $34, %rax <- used to be "shrq $32, %rax; sarl $2, %eax"
  addl  %ecx, %eax

This fires 96 times in gcc.c on x86-64.

llvm-svn: 124559

This happens e.g. for code like "X - X%10" where we lower the modulo operation
to a series of multiplies and shifts that are then subtracted from X, leading to
this missed optimization.

llvm-svn: 124532

llvm-svn: 124526

llvm-svn: 124522

Re-commit r124462 with fixes. Tail recursion elim will now dup ret into unconditional predecessor to enable TCE on demand.

llvm-svn: 124518

llvm-svn: 124478

llvm-svn: 124472

llvm-svn: 124468

  branches. PR8575, rdar://5134905, rdar://8911460.
- Allow codegen tail duplication to dup small return blocks after register
  allocation is done.

llvm-svn: 124462

llvm-svn: 124443

rdar://problem/8893967: JM/lencod miscompile at -arch armv7 -mthumb -O3

Added ResurrectKill to remove kill flags after we decide to reused a
physical register. And (hopefully) ensure that we call it in all the
right places.

Sorry, I'm not checking in a unit test given that it's a miscompile I
can't reproduce easily with a toy example. Failures in the rewriter
depend on a series of heuristic decisions maked during one of the many
upstream phases in codegen. This case would require coercing regalloc
to generate a couple of rematerialzations in a way that causes the
scavenger to reuse the same register at just the wrong point.

The general way to test this is to implement kill flags
verification. Then we could have a simple, robust compile-only unit
test. That would be worth doing if the whole pass was not about to
disappear. At this point we focus verification work on the next
generation of regalloc.

llvm-svn: 124442

llvm-svn: 124397

Take 2. This includes fix for dragonegg crash.

llvm-svn: 124380

Linear scan regalloc is currently assuming that any register aliased with
a member of a regclass must also be in at least one regclass.  That is not
always true.  For example, for X86, RIP is in a regclass but IP is not.
If you're unlucky, this can cause a crash by invalidating the iterator.

llvm-svn: 124365

llvm-svn: 124350

llvm-svn: 124346

llvm-svn: 124339

llvm-svn: 124331

llvm-svn: 124327

llvm-svn: 124320

[AVX] Add INSERT_SUBVECTOR and support it on x86.  This provides a
default implementation for x86, going through the stack in a similr
fashion to how the codegen implements BUILD_VECTOR.  Eventually this
will get matched to VINSERTF128 if AVX is available.

llvm-svn: 124307

llvm-svn: 124302

llvm-svn: 124301

llvm-svn: 124300

[AVX] Support EXTRACT_SUBVECTOR on x86.  This provides a default
implementation of EXTRACT_SUBVECTOR for x86, going through the stack
in a similr fashion to how the codegen implements BUILD_VECTOR.
Eventually this will get matched to VEXTRACTF128 if AVX is available.

llvm-svn: 124292

No functional change.

llvm-svn: 124257

llvm-svn: 124245

Resolve DanglingDbgValue of PHI nodes where the use follows dbg.value intrinisic.

llvm-svn: 124203

This assertion is too restrictive, it does not apply for dangling dbg value nodes (nodes where dbg.value intrinsic preceds use of the value). 

llvm-svn: 124202

llvm-svn: 124150

llvm-svn: 124142

llvm-svn: 124138

rdar://problem/8893967

llvm-svn: 124137

llvm-svn: 124077

clang's -Wuninitialized-experimental warning.
While these don't look like real bugs, clang's
-Wuninitialized-experimental analysis is stricter
than GCC's, and these fixes have the benefit
of being general nice cleanups.

llvm-svn: 124073

Add support for SHT_X86_64_UNWIND.

llvm-svn: 124059

llvm-svn: 124056

llvm-svn: 124054

DAG. Disable using "-disable-sched-cycles".

For ARM, this enables a framework for modeling the cpu pipeline and
counting stalls. It also activates several heuristics to drive
scheduling based on the model. Scheduling is inherently imprecise at
this stage, and until spilling is improved it may defeat attempts to
schedule. However, this framework provides greater control over
tuning codegen.

Although the flag is not target-specific, it should have very little
affect on the default scheduler used by x86. The only two changes that
affect x86 are:
- scheduling a high-latency operation bumps the current cycle so independent
  operations can have their latency covered. i.e. two independent 4
  cycle operations can produce results in 4 cycles, not 8 cycles.
- Two operations with equal register pressure impact and no
  latency-based stalls on their uses will be prioritized by depth before height
  (height is irrelevant if no stalls occur in the schedule below this point).

llvm-svn: 123971