Make llvm undef values generate ISD::UNDEF nodes

llvm-svn: 21261

llvm-svn: 21167

llvm-svn: 21014

llvm-svn: 21011

llvm-svn: 20965

them up after the code has been emitted.  This allows targets to select one
mbb as multiple mbb's as needed.

llvm-svn: 20937

returned integer values all of the way to 64-bits (we only did it to 32-bits
leaving the top bits undefined).  This causes problems for targets like alpha
whose ABI's define the top bits too.

llvm-svn: 20926

llvm-svn: 20842

using Function::arg_{iterator|begin|end}.  Likewise Module::g* -> Module::global_*.

This patch is contributed by Gabor Greif, thanks!

llvm-svn: 20597

llvm-svn: 20231

Don't sink argument loads into loops or other bad places.  This disables folding of argument loads with instructions that are not in the entry block.

llvm-svn: 20228

llvm-svn: 19779

llvm-svn: 19763

llvm-svn: 19707

do it.  This results in better code on X86 for floats (because if strict
precision is not required, we can elide some more expensive double -> float
conversions like the old isel did), and allows other targets to emit
CopyFromRegs that are not legal for arguments.

llvm-svn: 19668

llvm-svn: 19656

X86/reg-pressure.ll again, and allows us to do nice things in other cases.
For example, we now codegen this sort of thing:

int %loadload(int *%X, int* %Y) {
  %Z = load int* %Y
  %Y = load int* %X      ;; load between %Z and store
  %Q = add int %Z, 1
  store int %Q, int* %Y
  ret int %Y
}

Into this:

loadload:
        mov %EAX, DWORD PTR [%ESP + 4]
        mov %EAX, DWORD PTR [%EAX]
        mov %ECX, DWORD PTR [%ESP + 8]
        inc DWORD PTR [%ECX]
        ret

where we weren't able to form the 'inc [mem]' before.  This also lets the
instruction selector emit loads in any order it wants to, which can be good
for register pressure as well.

llvm-svn: 19644

llvm-svn: 19642

the basic block that uses them if possible.  This is a big win on X86, as it
lets us fold the argument loads into instructions and reduce register pressure
(by not loading all of the arguments in the entry block).

For this (contrived to show the optimization) testcase:

int %argtest(int %A, int %B) {
        %X = sub int 12345, %A
        br label %L
L:
        %Y = add int %X, %B
        ret int %Y
}

we used to produce:

argtest:
        mov %ECX, DWORD PTR [%ESP + 4]
        mov %EAX, 12345
        sub %EAX, %ECX
        mov %EDX, DWORD PTR [%ESP + 8]
.LBBargtest_1:  # L
        add %EAX, %EDX
        ret


now we produce:

argtest:
        mov %EAX, 12345
        sub %EAX, DWORD PTR [%ESP + 4]
.LBBargtest_1:  # L
        add %EAX, DWORD PTR [%ESP + 8]
        ret

This also fixes the FIXME in the code.

BTW, this occurs in real code.  164.gzip shrinks from 8623 to 8608 lines of
.s file.  The stack frame in huft_build shrinks from 1644->1628 bytes,
inflate_codes shrinks from 116->108 bytes, and inflate_block from 2620->2612,
due to fewer spills.

Take that alkis. :-)

llvm-svn: 19639

llvm-svn: 19635

llvm-svn: 19612

llvm-svn: 19595

llvm-svn: 19582

llvm-svn: 19579

llvm-svn: 19568

stores/loads.

llvm-svn: 19562

llvm-svn: 19535

llvm-svn: 19531

llvm-svn: 19528

llvm-svn: 19498

same for PHI nodes.

llvm-svn: 19484

llvm-svn: 19463

llvm-svn: 19409

llvm-svn: 19407

llvm-svn: 19404

llvm-svn: 19384

llvm-svn: 19374

llvm-svn: 19369

int GEP indices on 64-bit archs.

llvm-svn: 19354

llvm-svn: 19349