Approval in here http://lists.cs.uiuc.edu/pipermail/llvmdev/2013-July/064169.html

llvm-svn: 187145

llvm-svn: 187141

The previous change to local live range allocation also suppressed
eviction of local ranges. In rare cases, this could result in more
expensive register choices. This commit actually revives a feature
that I added long ago: check if live ranges can be reassigned before
eviction. But now it only happens in rare cases of evicting a local
live range because another local live range wants a cheaper register.

The benefit is improved code size for some benchmarks on x86 and armv7.

I measured no significant compile time increase and performance
changes are noise.

llvm-svn: 187140

Also avoid locals evicting locals just because they want a cheaper register.

Problem: MI Sched knows exactly how many registers we have and assumes
they can be colored. In cases where we have large blocks, usually from
unrolled loops, greedy coloring fails. This is a source of
"regressions" from the MI Scheduler on x86. I noticed this issue on
x86 where we have long chains of two-address defs in the same live
range. It's easy to see this in matrix multiplication benchmarks like
IRSmk and even the unit test misched-matmul.ll.

A fundamental difference between the LLVM register allocator and
conventional graph coloring is that in our model a live range can't
discover its neighbors, it can only verify its neighbors. That's why
we initially went for greedy coloring and added eviction to deal with
the hard cases. However, for singly defined and two-address live
ranges, we can optimally color without visiting neighbors simply by
processing the live ranges in instruction order.

Other beneficial side effects:

It is much easier to understand and debug regalloc for large blocks
when the live ranges are allocated in order. Yes, global allocation is
still very confusing, but it's nice to be able to comprehend what
happened locally.

Heuristics could be added to bias register assignment based on
instruction locality (think late register pairing, banks...).

Intuituvely this will make some test cases that are on the threshold
of register pressure more stable.

llvm-svn: 187139

llvm-svn: 187138

llvm-svn: 187135

llvm-svn: 187130

Better to have tests run even on non-AArch64 platforms.

llvm-svn: 187128

The last patch corrected some issues, but constant-pool entries had actual
codegen bugs in the large memory model (which MCJIT uses).

llvm-svn: 187126

llvm-svn: 187124

This should actually make the MCJIT tests pass again on AArch64. I don't know
how I missed their failure before.

llvm-svn: 187120

Fix a bug in TableGen where the intrinsic function name recognizer could mis-identify names if one was a prefix substring of the other

For two intrinsics 'llvm.nvvm.texsurf.handle' and 'llvm.nvvm.texsurf.handle.internal',
TableGen was emitting matching code like:

  if (Name.startswith("llvm.nvvm.texsurf.handle")) ...
  if (Name.startswith("llvm.nvvm.texsurf.handle.internal")) ...

We can never match "llvm.nvvm.texsurf.handle.internal" here because it will
always be erroneously matched by the first condition.

The fix is to sort the intrinsic names and emit them in reverse order.

llvm-svn: 187119

llvm-svn: 187117

Before the patch we took advantage of the fact that the compare and
branch are glued together in the selection DAG and fused them together
(where possible) while emitting them.  This seemed to work well in practice.
However, fusing the compare so early makes it harder to remove redundant
compares in cases where CC already has a suitable value.  This patch
therefore uses the peephole analyzeCompare/optimizeCompareInstr pair of
functions instead.

No behavioral change intended, but it paves the way for a later patch.

llvm-svn: 187116

llvm-svn: 187113

As with the stores, these instructions can trap when the condition is false,
so they are only used for things like (cond ? x : *ptr).

llvm-svn: 187112

These instructions are allowed to trap even if the condition is false,
so for now they are only used for "*ptr = (cond ? x : *ptr)"-style
constructs.

llvm-svn: 187111

Consider which set is being increased or decreased before comparing.

llvm-svn: 187110

llvm-svn: 187109

This lets heuristics easily pick the most important set to follow.

llvm-svn: 187108

llvm-svn: 187107

Make sure the context and type fields are MDNodes. We will generate
verification errors if those fields are non-empty strings.
Fix testing cases to make them pass the verifier.

llvm-svn: 187106

The language reference says that:

"If a symbol appears in the @llvm.used list, then the compiler,
assembler, and linker are required to treat the symbol as if there is
a reference to the symbol that it cannot see"

Since even the linker cannot see the reference, we must assume that
the reference can be using the symbol table. For example, a user can add
__attribute__((used)) to a debug helper function like dump and use it from
a debugger.

llvm-svn: 187103

llvm-svn: 187099

Thanks to Nick Lewycky for noticing it.

llvm-svn: 187098

There's no need to specify a flag to omit frame pointer elimination on non-leaf
nodes...(Honestly, I can't parse that option out.) Use the function attribute
stuff instead.

llvm-svn: 187093

llvm-svn: 187088

llvm-svn: 187083

llvm-svn: 187076

Prior to this patch, IfConverter may widen the cases where a sequence of
instructions were executed because of the way it uses nested predicates. This
result in incorrect execution.

For instance, Let A be a basic block that flows conditionally into B and B be a
predicated block.
B can be predicated with A.BrToBPredicate into A iff B.Predicate is less
"permissive" than A.BrToBPredicate, i.e., iff A.BrToBPredicate subsumes
B.Predicate.

The IfConverter was checking the opposite: B.Predicate subsumes
A.BrToBPredicate.

<rdar://problem/14379453>

llvm-svn: 187071

llvm-svn: 187066

llvm-svn: 187064

when there wasn't a match. This behavior is consistent with other register
parsing methods.

llvm-svn: 187063

Patch by Hafiz Abid!

llvm-svn: 187056

The change r187019 has fixed multiple relocations in dynamic linker for
MIPS, so now this test passes for MIPS.

llvm-svn: 187053

Improve the Finder to handle context of a DIVariable used by DbgValueInst.
Fix testing cases to make them pass the verifier.

llvm-svn: 187052

While there shrink a dangerously large SmallPtrSet.

llvm-svn: 187050

llvm-svn: 187049

Found by running the test with pipefail enabled.

llvm-svn: 187046

Before this patch we would strdup each argument. If one was a response file,
we would replace it with the response file contents, leaking the original
strdup result.

We now don't strdup the originals and let StringSaver free any memory it
allocated. This also saves a bit of malloc traffic when response files are
not used.

Leak found by the valgrind build bot.

llvm-svn: 187042