use the zero-undefined variants of CTTZ and CTLZ. These are just simple
patterns for now, there is more to be done to make real world code using
these constructs be optimized and codegen'ed properly on X86.

The existing tests are spiffed up to check that we no longer generate
unnecessary cmov instructions, and that we generate the very important
'xor' to transform bsr which counts the index of the most significant
one bit to the number of leading (most significant) zero bits. Also they
now check that when the variant with defined zero result is used, the
cmov is still produced.

llvm-svn: 146974

Patch by Sanjoy Das.

llvm-svn: 143064

MORESTACK_RET_RESTORE_R10; which are lowered to a RET and a RET
followed by a MOV respectively.  Having a fake instruction prevents
the verifier from seeing a MachineBasicBlock end with a
non-terminator (MOV).  It also prevents the rather eccentric case of a
MachineBasicBlock ending with RET but having successors nevertheless.

Patch by Sanjoy Das.

llvm-svn: 143062

Fix the assembler strings for a couple of atomic instructions.  Doesn't really matter much in practice, but it's a bit cleaner.

llvm-svn: 139563

Fix atomic load and store on x86 to pass -verify-machineinstrs (and possibly fix some subtle bugs involving passes which check mayStore()).

This isn't exactly ideal, but it is good enough for the moment.

llvm-svn: 139245

The explanation about a 0 argument being materialized as xor is no
longer valid.  Rematerialization will check if EFLAGS is live before
clobbering it.

The code produced by X86TargetLowering::EmitLoweredSelect does not
clobber EFLAGS.

This causes one less testb instruction to be generated in the cmov.ll
test case.

llvm-svn: 139057

from DYNAMIC_STACKALLOC.

Two new pseudo instructions (SEG_ALLOCA_32 and SEG_ALLOCA_64) which
will match X86SegAlloca (based on word size) are also added.  They
will be custom emitted to inject the actual stack handling code.

Patch by Sanjoy Das.

llvm-svn: 138814

llvm-svn: 138660

llvm-svn: 138478

llvm-svn: 137179

llvm-svn: 137160

X86ISD::MEMBARRIER does not require SSE2; it doesn't actually generate any code, and all x86 processors will honor the required semantics.

llvm-svn: 136249

considered safe enough in this context.

llvm-svn: 133159

llvm-svn: 131801

rdar://problem/8614450

llvm-svn: 131746

llvm-svn: 131654

pseudos.  rdar://problem/8614450

llvm-svn: 131641

Finishes off rdar://8470697

llvm-svn: 131458

Next up: xor and and.

Part of rdar://8470697

llvm-svn: 131171

cut and paste.

llvm-svn: 131139

"b + ((a < b) ? 1 : 0)" compiles into
	cmpl	%esi, %edi
	adcl	$0, %esi
instead of
	cmpl	%esi, %edi
	sbbl	%eax, %eax
	andl	$1, %eax
	addl	%esi, %eax

This saves a register, a false dependency on %eax
(Intel's CPUs still don't ignore it) and it's shorter.

llvm-svn: 131070

these patterns.

llvm-svn: 125759

llvm-svn: 124272

llvm-svn: 124270

the flags.

llvm-svn: 123712

doesn't, match it back to setb.

On a 64-bit version of the testcase before we'd get:

	movq	%rdi, %rax
	addq	%rsi, %rax
	sbbb	%dl, %dl
	andb	$1, %dl
	ret

now we get:

	movq	%rdi, %rax
	addq	%rsi, %rax
	setb	%dl
	ret

llvm-svn: 122217

consistently by moving it out of lowering into dag combine.

Add some missing patterns for matching away extended versions of setcc_c.

llvm-svn: 122201

llvm-svn: 121908

llvm-svn: 121328

llvm-svn: 120263

llvm-svn: 120225

various X86 and ARM instructions that are bitten by this as isCodeGenOnly,
as they are.

llvm-svn: 117884

and make it a hard error for instructions to not have an asm string.
These instructions should be marked isCodeGenOnly.

llvm-svn: 117861

llvm-svn: 116984

llvm-svn: 116972

immediates instead of 8 bits ones.

llvm-svn: 116410

8 bit constants can be used.

llvm-svn: 116403

llvm-svn: 116319

reapply: reimplement the second half of the or/add optimization.  We should now

with no changes.  Turns out that one missing "Defs = [EFLAGS]" can upset things
a bit.

llvm-svn: 116040

"Reimplement (part of) the or -> add optimization.  Matching 'or' into 'add'"

With a critical fix: the add pseudos clobber EFLAGS.

llvm-svn: 116039