when inlining a readonly function.

llvm-svn: 46393

void bork() {
  int *address = 0;
  *address = 0;
}

It's compiled into LLVM code that looks like this:

define void @bork() noreturn nounwind  {
entry:
        unreachable
}

This is bad on some platforms (like PPC) because it will generate the label for
the function but no body. The label could end up being associated with some
non-code related stuff, like a section. This places a "trap" instruction if the
SimplifyCFG pass removed all code from the function leaving only one
"unreachable" instruction.

llvm-svn: 46387

llvm-svn: 46385

delete a node even if it was not dead in some cases.  Instead, just add it to
the worklist.  Also, make sure to use the CombineTo methods, as it was doing
things that were unsafe: the top level combine loop could touch dangling memory.

This fixes CodeGen/Generic/2008-01-25-dag-combine-mul.ll

llvm-svn: 46384

don't bother making x&-1 only to simplify it in dag combine.  This commonly occurs expanding i64 ops.

llvm-svn: 46383

llvm-svn: 46382

llvm-svn: 46377

llvm-svn: 46372

llvm-svn: 46369

may require a clean rebuild on leopard. :(

llvm-svn: 46360

llvm-svn: 46357

llvm-svn: 46355

was actually passing a completely incorrect size to sys_icache_invalidate.
Instead of having the JITEmitter do this (which doesn't have the correct 
size), just make the target sync its own stubs.

llvm-svn: 46354

arrays.  Also, as a convenience, don't barf, just
return false, if someone calls isTruncStoreLegal
or isLoadXLegal with an extended type for the in
memory type.

llvm-svn: 46352

DeadStoreElimination can treat byval parameters as if there were alloca's for the purpose of removing end-of-function stores.

llvm-svn: 46351

llvm-svn: 46350

we can infer it.  This will eventually help stuff, though it doesn't
do much right now because all fixed FI's have an alignment of 1.

llvm-svn: 46349

a reference to TargetFrameInfo.  Rearrange order of fields in StackObject to
save a word.

llvm-svn: 46348

llvm-svn: 46347

llvm-svn: 46346

llvm-svn: 46345

us to compile:

double test(double X) {
  return copysign(0.0, X);
}

into:

_test:
	andpd	LCPI1_0(%rip), %xmm0
	ret

instead of:
_test:
	pxor	%xmm1, %xmm1
	andpd	LCPI1_0(%rip), %xmm1
	movapd	%xmm0, %xmm2
	andpd	LCPI1_1(%rip), %xmm2
	movapd	%xmm1, %xmm0
	orpd	%xmm2, %xmm0
	ret

llvm-svn: 46344

This should fix bunch of issues.

llvm-svn: 46337

llvm-svn: 46333

llvm-svn: 46320

llvm-svn: 46318

APInt.

While some operators were already specifically overloaded for APSInt, others
resulted in using the overloaded operator methods in APInt, which would result
in the signedness bit being lost.

Modified the APSInt(APInt&) constructor to be "explicit" and to take an
extra (optional) flag to indicate the signedness.  Making the ctor explicit
will catch any implicit conversations between APSInt -> APInt -> APSInt that
results in the signedness flag being lost.

llvm-svn: 46316

can't be aliased to other known objects.  This allows us to know that byval 
pointer args don't alias globals, etc.

llvm-svn: 46315

llvm-svn: 46314

llvm-svn: 46313

This case returns the value in ST(0) and then has to convert it to an SSE
register.  This causes significant codegen ugliness in some cases.  For 
example in the trivial fp-stack-direct-ret.ll testcase we used to generate:

_bar:
	subl	$28, %esp
	call	L_foo$stub
	fstpl	16(%esp)
	movsd	16(%esp), %xmm0
	movsd	%xmm0, 8(%esp)
	fldl	8(%esp)
	addl	$28, %esp
	ret

because we move the result of foo() into an XMM register, then have to
move it back for the return of bar.

Instead of hacking ever-more special cases into the call result lowering code
we take a much simpler approach: on x86-32, fp return is modeled as always 
returning into an f80 register which is then truncated to f32 or f64 as needed.
Similarly for a result, we model it as an extension to f80 + return.

This exposes the truncate and extensions to the dag combiner, allowing target
independent code to hack on them, eliminating them in this case.  This gives 
us this code for the example above:

_bar:
	subl	$12, %esp
	call	L_foo$stub
	addl	$12, %esp
	ret

The nasty aspect of this is that these conversions are not legal, but we want
the second pass of dag combiner (post-legalize) to be able to hack on them.
To handle this, we lie to legalize and say they are legal, then custom expand
them on entry to the isel pass (PreprocessForFPConvert).  This is gross, but
less gross than the code it is replacing :)

This also allows us to generate better code in several other cases.  For 
example on fp-stack-ret-conv.ll, we now generate:

_test:
	subl	$12, %esp
	call	L_foo$stub
	fstps	8(%esp)
	movl	16(%esp), %eax
	cvtss2sd	8(%esp), %xmm0
	movsd	%xmm0, (%eax)
	addl	$12, %esp
	ret

where before we produced (incidentally, the old bad code is identical to what
gcc produces):

_test:
	subl	$12, %esp
	call	L_foo$stub
	fstpl	(%esp)
	cvtsd2ss	(%esp), %xmm0
	cvtss2sd	%xmm0, %xmm0
	movl	16(%esp), %eax
	movsd	%xmm0, (%eax)
	addl	$12, %esp
	ret

Note that we generate slightly worse code on pr1505b.ll due to a scheduling 
deficiency that is unrelated to this patch.

llvm-svn: 46307

1. we already know the value is dead, so don't bother replacing 
   it with undef.
2. The very case the comment describes actually makes the load
   live which asserts in deletenode.  If we do the replacement
   and the node becomes live, just treat it as new.  This fixes
   a failure on X86/2008-01-16-InvalidDAGCombineXform.ll with
   some local changes in my tree.

llvm-svn: 46306

dead stuff around.  This gets fed into the isel pass and causes certain foldings from
happening because nodes have extraneous uses floating around.  For example, if we turned
foo(bar(x)) -> baz(x), we sometimes left bar(x) around.

llvm-svn: 46305

llvm-svn: 46304

llvm-svn: 46303

llvm-svn: 46302

llvm-svn: 46296

Move some functionality for adding flags to MachineInstr's into methods on MachineInstr rather than LiveVariables.

llvm-svn: 46295

llvm-svn: 46292

Let each target decide byval alignment. For X86, it's 4-byte unless the aggregare contains SSE vector(s). For x86-64, it's max of 8 or alignment of the type.

llvm-svn: 46286