llvm-svn: 122456

DAGCombine add (sext i1), X into sub X, (zext i1) if sext from i1 is illegal.  The latter usually compiles into smaller code.

example code:
unsigned foo(unsigned x, unsigned y) {
  if (x != 0) y--;
  return y;
}

before:
  _foo:                           ## @foo
    cmpl  $1, 4(%esp)             ## encoding: [0x83,0x7c,0x24,0x04,0x01]
    sbbl  %eax, %eax              ## encoding: [0x19,0xc0]
    notl  %eax                    ## encoding: [0xf7,0xd0]
    addl  8(%esp), %eax           ## encoding: [0x03,0x44,0x24,0x08]
    ret                           ## encoding: [0xc3]

after:
  _foo:                           ## @foo
    cmpl  $1, 4(%esp)             ## encoding: [0x83,0x7c,0x24,0x04,0x01]
    movl  8(%esp), %eax           ## encoding: [0x8b,0x44,0x24,0x08]
    adcl  $-1, %eax               ## encoding: [0x83,0xd0,0xff]
    ret                           ## encoding: [0xc3]

llvm-svn: 122455

llvm-svn: 122453

  int test(unsigned long a, unsigned long b) { return -(a < b); }
compiles to
  _test:                              ## @test
    cmpq  %rsi, %rdi                  ## encoding: [0x48,0x39,0xf7]
    sbbl  %eax, %eax                  ## encoding: [0x19,0xc0]
    ret                               ## encoding: [0xc3]
instead of
  _test:                              ## @test
    xorl  %ecx, %ecx                  ## encoding: [0x31,0xc9]
    cmpq  %rsi, %rdi                  ## encoding: [0x48,0x39,0xf7]
    movl  $-1, %eax                   ## encoding: [0xb8,0xff,0xff,0xff,0xff]
    cmovael %ecx, %eax                ## encoding: [0x0f,0x43,0xc1]
    ret                               ## encoding: [0xc3]

llvm-svn: 122451

fixed.

llvm-svn: 122448

if we have a lame assembler.

llvm-svn: 122446

pick the victim with the lowest total spill weight.

llvm-svn: 122445

llvm-svn: 122444

better name and matches what is used in the MachO writer.

llvm-svn: 122443

llvm-svn: 122441

llvm-svn: 122427

llvm-svn: 122419

the original instruction, half the cases were missed (making it not
wrong but suboptimal).  Also correct a typo (A <-> B) in the second
chunk. 

llvm-svn: 122414

esp. important given that the LOCAL_SECTDIFF enumeration got redefined.

llvm-svn: 122412

MC/Mach-O/ARM: Clone off an ARM version of RecordScatteredRelocation until I figure out how it is supposed to work.

llvm-svn: 122410

llvm-svn: 122409

llvm-svn: 122408

llvm-svn: 122407

llvm-svn: 122406

llvm-svn: 122405

llvm-svn: 122404

RecordRelocation with lots of FIXMEs.

llvm-svn: 122402

llvm-svn: 122401

clear how to keep in the generic path (yet).
 - Will revisit when it actually works.

llvm-svn: 122400

if both A op B and A op C simplify.  This fires fairly often but doesn't
make that much difference.  On gcc-as-one-file it removes two "and"s and
turns one branch into a select.

llvm-svn: 122399

llvm-svn: 122398

instcombine is compared to instsimplify.

llvm-svn: 122397

loads properly.  We miscompiled the testcase into:

_test:                                  ## @test
	movl	$128, (%rdi)
	movzbl	1(%rdi), %eax
	ret

Now we get a proper:

_test:                                  ## @test
	movl	$128, (%rdi)
	movsbl	(%rdi), %eax
	movzbl	%ah, %eax
	ret

This fixes PR8757.

llvm-svn: 122392

unhanded cases faster and simplify code.

llvm-svn: 122391

llvm-svn: 122389

llvm-svn: 122385

llvm-svn: 122384

llvm-svn: 122381

llvm-svn: 122379

I still think that LVI should be handling this, but that capability is some ways off in the future,
and this matters for some significant benchmarks.

llvm-svn: 122378

types, but they're just getting converted to unsigned anyway, so cast first
(and ask questions later).

llvm-svn: 122377

llvm-svn: 122371

the same physical register. Simplifies the fix from the previous
checkin r122211.

llvm-svn: 122370

llvm-svn: 122368

the shift type was needed one place, the shift count
type another.  The transform in 123555 had the same
problem.

llvm-svn: 122366