Files
clang-p2996/llvm/test/Transforms/InstCombine
Evan Cheng 319be53a1f Remove a instcombine transform that (no longer?) makes sense:
// C - zext(bool) -> bool ? C - 1 : C
    if (ZExtInst *ZI = dyn_cast<ZExtInst>(Op1))
      if (ZI->getSrcTy()->isIntegerTy(1))
        return SelectInst::Create(ZI->getOperand(0), SubOne(C), C);

This ends up forming sext i1 instructions that codegen to terrible code. e.g.
int blah(_Bool x, _Bool y) {
  return (x - y) + 1;
}
=>
        movzbl  %dil, %eax
        movzbl  %sil, %ecx
        shll    $31, %ecx
        sarl    $31, %ecx
        leal    1(%rax,%rcx), %eax
        ret


Without the rule, llvm now generates:
        movzbl  %sil, %ecx
        movzbl  %dil, %eax
        incl    %eax
        subl    %ecx, %eax
        ret

It also helps with ARM (and pretty much any target that doesn't have a sext i1 :-).

The transformation was done as part of Eli's r75531. He has given the ok to
remove it.

rdar://11748024

llvm-svn: 159230
2012-06-26 22:03:13 +00:00
..
2012-02-29 01:53:13 +00:00
2011-11-08 00:23:01 +00:00
2011-02-11 19:37:55 +00:00
2012-06-08 22:30:05 +00:00
2012-04-23 17:39:52 +00:00
2010-09-02 22:38:56 +00:00

This directory contains test cases for the instcombine transformation.  The
dated tests are actual bug tests, whereas the named tests are used to test
for features that the this pass should be capable of performing.