The greedy register allocator revealed some problems with the value mapping in
SplitKit. We would sometimes start mapping values before all defs were known,
and that could change a value from a simple 1-1 mapping to a multi-def mapping
that requires ssa update.

The new approach collects all defs and register assignments first without
filling in any live intervals. Only when finish() is called, do we compute
liveness and mapped values. At this time we know with certainty which values map
to multiple values in a split range.

This also has the advantage that we can compute live ranges based on the
remaining uses after rematerializing at split points.

The current implementation has many opportunities for compile time optimization.

llvm-svn: 124765

llvm-svn: 124759

llvm-svn: 124755

llvm-svn: 124752

overflow (nsw flag), which was disabled because it breaks 254.gap.  I have
informed the GAP authors of the mistake in their code, and arranged for the
testsuite to use -fwrapv when compiling this benchmark.

llvm-svn: 124746

llvm-svn: 124725

This makes the job of the later optzn passes easier, allowing the vast amount of
icmp transforms to chew on it.

We transform 840 switches in gcc.c, leading to a 16k byte shrink of the resulting
binary on i386-linux.

The testcase from README.txt now compiles into
  decl  %edi
  cmpl  $3, %edi
  sbbl  %eax, %eax
  andl  $1, %eax
  ret

llvm-svn: 124724

llvm-svn: 124722

may be useful to understand "none", this is not the place for it.  Tweak
the fix to Normalize while there: the fix added in 123990 works correctly,
but I like this way better.  Finally, now that Triple understands some
non-trivial environment values, teach the unittests about them.

llvm-svn: 124720

that might have changed been affected by a merge elsewhere will have been
removed from the function set, and it isn't needed for performance because we
call grow() ahead of time to prevent reallocations.

llvm-svn: 124717

reassociation. No testcase, because I wasn't able to create a testcase
which actually demonstrates a problem.

llvm-svn: 124713

llvm-svn: 124712

prefix would be misinterpreted in some cases on 32-bit
x86 platforms.  Thanks to Olivier Meurant for identifying
the bug.

llvm-svn: 124709

the load, then it may be legal to transform the load and store to integer
load and store of the same width.

This is done if the target specified the transformation as profitable. e.g.
On arm, this can transform:
vldr.32 s0, []
vstr.32 s0, []

to

ldr r12, []
str r12, []

rdar://8944252

llvm-svn: 124708

This is completely untested but pretty straightforward, so hopefully I
got it right.

llvm-svn: 124694

llvm-svn: 124688

Patch by Brian G. Lucas!

llvm-svn: 124679

llvm-svn: 124659

pattern matching can also pattern match undef, creating a more uniform
style.

llvm-svn: 124657

llvm-svn: 124656

llvm-svn: 124655

llvm-svn: 124652

different visibilities.

llvm-svn: 124650

llvm-svn: 124645

llvm-svn: 124641

llvm-svn: 124639

llvm-svn: 124611

Enumerate .code16/32/64 instead of checking .code prefix. This
unbreaks some ARM tests.

llvm-svn: 124608

all lead to a silent miscompilation of code.

llvm-svn: 124603

Fix vector sign extend to put the source and destination types in the
correct places.

llvm-svn: 124601

llvm-svn: 124599

llvm-svn: 124587

llvm-svn: 124570

llvm-svn: 124569

(A+B) == A  ->  B == 0
A == (A+B)  ->  B == 0

llvm-svn: 124567

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

by PR9088 fixes things.

llvm-svn: 124561

to do this and more, but would only do it if X/Y had only one use.  Spotted as the
most common missed simplification in SPEC by my auto-simplifier, now that it knows
about nuw/nsw/exact flags.  This removes a bunch of multiplications from 447.dealII
and 483.xalancbmk.  It also removes a lot from tramp3d-v4, which results in much
more inlining.

llvm-svn: 124560

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

llvm-svn: 124557