[AARCH64] vector zext hangs/crashes with NEON disabled

[llvmbot]

Bugzilla Link	43719
Version	trunk
OS	All
Reporter	LLVM Bugzilla Contributor
CC	@Arnaud-de-Grandmaison-ARM,@smithp35

Extended Description

define @​zext_v2xi32(<2 x i32> %vec) { %extended = zext <2 x i32> %vec to <2 x i64> ret <2 x i64> %extended }

llc -march=aarch64 -mattr=-neon

I would expect something like this (if I am correct in that <2 x i32> is passed as i32 *):

zext_v2xi32: ldp w0, w1, [x0] ret

But instead, I either get a segfault (on Termux's 8.0.1 build), or an infinite loop (9.0.0 on archlinuxarm or trunk w/debug). With every other known architecture, SIMD types still scalarize properly with SIMD disabled, given that llvm intrinsics aren't used.

Enabling debug output in llc spams this:

Combining: t7: i64 = Constant<0>

Combining: t6: v2i64 = zero_extend t5 Creating new node: tNNNNN: v1i64 = extract_subvector t6, Constant:i64<0> Creating new node: tNNNNN+1: v1i64 = extract_subvector t6, Constant:i64<1>

[llvmbot]

And the assembly should probably output this

zext_v2i32: mov w0, w0 mov w1, w1 ret

[llvmbot]

Typo: If it wasn't clear, the code should be this.

define <2 x i64> @​zext_v2xi32(<2 x i32> %vec) { %extended = zext <2 x i32> %vec to <2 x i64> ret <2 x i64> %extended }