of a select instruction, see if doing the compare with the
true and false values of the select gives the same result.
If so, that can be used as the value of the comparison.

llvm-svn: 118378

llvm-svn: 118337

llvm-svn: 115116

llvm-svn: 114304

llvm-svn: 110543

(X >s -1) ? C1 : C2 and (X <s  0) ? C2 : C1
into ((X >>s 31) & (C2 - C1)) + C1, avoiding the conditional.

This optimization could be extended to take non-const C1 and C2 but we better
stay conservative to avoid code size bloat for now.

for
int sel(int n) {
     return n >= 0 ? 60 : 100;
}

we now generate
  sarl  $31, %edi
  andl  $40, %edi
  leal  60(%rdi), %eax

instead of
  testl %edi, %edi
  movl  $60, %ecx
  movl  $100, %eax
  cmovnsl %ecx, %eax

llvm-svn: 107866

llvm-svn: 107569

llvm-svn: 107565

llvm-svn: 107213

llvm-svn: 106102

llvm-svn: 105878

llvm-svn: 104404

llvm-svn: 102906

llvm-svn: 101581

a load/or/and/store sequence into a narrower store when it is
safe.  Daniel tells me that clang will start producing this sort
of thing with bitfields, and this does  trigger a few dozen times
on 176.gcc produced by llvm-gcc even now.

This compiles code like CodeGen/X86/2009-05-28-DAGCombineCrash.ll 
into:

        movl    %eax, 36(%rdi)

instead of:

        movl    $4294967295, %eax       ## imm = 0xFFFFFFFF
        andq    32(%rdi), %rax
        shlq    $32, %rcx
        addq    %rax, %rcx
        movq    %rcx, 32(%rdi)

and each of the testcases into a single store.  Each of them used
to compile into craziness like this:

_test4:
	movl	$65535, %eax            ## imm = 0xFFFF
	andl	(%rdi), %eax
	shll	$16, %esi
	addl	%eax, %esi
	movl	%esi, (%rdi)
	ret

llvm-svn: 101343

llvm-svn: 98194

llvm-svn: 95624

llvm-svn: 94945

indices are safe if the result is known to be within the bounds of the
underlying object.

llvm-svn: 94829

llvm-svn: 94374

llvm-svn: 94373

readme forever.

llvm-svn: 94318

llvm-svn: 94312

llvm-svn: 93797

phi nodes when deciding which pointers point to local memory.
I actually checked long ago how useful this is, and it isn't
very: it hardly ever fires in the testsuite, but since Chris
wants it here it is!

llvm-svn: 92836

memcpy, memset and other intrinsics that only access their arguments
to be readnone if the intrinsic's arguments all point to local memory.
This improves the testcase in the README to readonly, but it could in
theory be made readnone, however this would involve more sophisticated
analysis that looks through the memcpy.

llvm-svn: 92829

on the example in PR4216.  This doesn't trigger in the testsuite,
so I'd really appreciate someone scrutinizing the logic for
correctness.

llvm-svn: 92458

multiply sequence when the power is a constant integer.  Before, our
codegen for std::pow(.., int) always turned into a libcall, which was
really inefficient.

This should also make many gfortran programs happier I'd imagine.

llvm-svn: 92388

on integers as well and codegen should lower them to branch trees.

llvm-svn: 92382

llvm-svn: 91230

merging x >u 5 and x <s 20 because it's impossible to implement.

llvm-svn: 91228

llvm-svn: 90429

llvm-svn: 90428

llvm-svn: 90050

llvm-svn: 90009

the FIXME I added yesterday to be implemented.

llvm-svn: 90008

llvm-svn: 89982

the example in GCC PR16799 to:

LBB1_2:                                                     ## %bb1
	movl	%eax, %eax
	subq	%rax, %rdi
	movq	%rdi, (%rcx)
	movl	(%rdi), %eax
	testl	%eax, %eax
	je	LBB1_2

instead of:

LBB1_2:                                                     ## %bb1
	movl	(%rdi), %ecx
	subq	%rcx, %rdi
	movq	%rdi, (%rax)
	cmpl	$0, (%rdi)
	je	LBB1_2

llvm-svn: 89978

allows us to compile the example in readme.txt into:

LBB1_1:                                                     ## %bb
	movl	4(%rdx,%rax), %ecx
	movl	%ecx, %esi
	imull	(%rdx,%rax), %esi
	imull	%esi, %ecx
	movl	%esi, 8(%rdx,%rax)
	imull	%ecx, %esi
	movl	%ecx, 12(%rdx,%rax)
	movl	%esi, 16(%rdx,%rax)
	imull	%ecx, %esi
	movl	%esi, 20(%rdx,%rax)
	addq	$16, %rax
	cmpq	$4000, %rax
	jne	LBB1_1

instead of:

LBB1_1: 
	movl	(%rdx,%rax), %ecx
	imull	4(%rdx,%rax), %ecx
	movl	%ecx, 8(%rdx,%rax)
	imull	4(%rdx,%rax), %ecx
	movl	%ecx, 12(%rdx,%rax)
	imull	8(%rdx,%rax), %ecx
	movl	%ecx, 16(%rdx,%rax)
	imull	12(%rdx,%rax), %ecx
	movl	%ecx, 20(%rdx,%rax)
	addq	$16, %rax
	cmpq	$4000, %rax
	jne	LBB1_1

GCC (4.2) doesn't seem to be able to eliminate the loads in this 
testcase either, it generates:

L2:
	movl	(%rdx), %eax
	imull	4(%rdx), %eax
	movl	%eax, 8(%rdx)
	imull	4(%rdx), %eax
	movl	%eax, 12(%rdx)
	imull	8(%rdx), %eax
	movl	%eax, 16(%rdx)
	imull	12(%rdx), %eax
	movl	%eax, 20(%rdx)
	addl	$4, %ecx
	addq	$16, %rdx
	cmpl	$1002, %ecx
	jne	L2

llvm-svn: 89952

llvm-svn: 89951