[NewPM][Hexagon] Add HexagonPassRegistry.def

[paperchalice]

Prepare for dag-isel, also migrate some test case

[paperchalice]

The test case hvx-loopidiom-memcpy.ll may be invalid. There is no different between opt -march=hexagon -hexagon-loop-idiom -S and opt -mtriple=hexagon-- -p no-op-loop -S.

llvm-project/llvm/lib/Target/Hexagon/HexagonLoopIdiomRecognition.cpp

Lines 2413 to 2416 in 90454a6

	bool HexagonLoopIdiomRecognize::run(Loop *L) {
	const Module &M = *L->getHeader()->getParent()->getParent();
	if (Triple(M.getTargetTriple()).getArch() != Triple::hexagon)
	return false;

The condition is always true when invoke opt -march=hexagon -hexagon-loop-idiom. 😕

[aeubanks]

yeah it does seem like we should remove that check. the pass should only be added for hexagon backends anyway

[aeubanks]

the existing tests don't seem to great, but this patch on its own is good

[aeubanks]

this REQUIRES doesn't make sense, we should run it under all configurations...

same for the other tests here

[iajbar]

Yes, this test should be run under all configurations. REQUIRES should be removed.

[aeubanks]

agreed, but should be done in a separate PR

[iajbar]

Sure, I'll push a patch to remove REQUIRES.

[aeubanks]

this is an issue. the new PM loop infra assumes that loops are always in LCSSA form. either the pass needs to ensure the loops are in LCSSA form, or perhaps it can just call a helper method

[iajbar]

I'll push a patch to make sure LCSSA form is preserved.

[iajbar]

Same here. Please remove REQUIRES.