wrong code at -O{2,3} on x86_64-linux-gnu

[zhendongsu]

It appears to be a recent regression as it doesn't reproduce with 18.1.0 and earlier.

Compiler Explorer: https://godbolt.org/z/EGasYh8x1

[691] % clangtk -v
clang version 20.0.0git (https://github.com/llvm/llvm-project.git 223e2efa5e886502a9467b7ef700ebce9b7886e8)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /local/suz-local/software/local/clang-trunk/bin
Build config: +assertions
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/10
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/11
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/9
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/11
Candidate multilib: .;@m64
Selected multilib: .;@m64
[692] % 
[692] % clangtk -O1 small.c; ./a.out
[693] % 
[693] % clangtk -O2 small.c
[694] % ./a.out
Aborted
[695] % 
[695] % cat small.c
char a[8];
int b = 1, c;
int main() {
  for (; c < 8; c++)
    a[c] = !c >> b;
  if (a[0] != 0)
    __builtin_abort();
  return 0;
}

[dtcxzyw]

Reproducer: https://alive2.llvm.org/ce/z/5SkPZS

; bin/opt -passes=vector-combine test.ll -S

target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

define <2 x i32> @test(<2 x i64> %vec.ind16, <2 x i32> %broadcast.splat20) {
  %19 = icmp eq <2 x i64> %vec.ind16, zeroinitializer
  %20 = zext <2 x i1> %19 to <2 x i32>
  %21 = lshr <2 x i32> %20, %broadcast.splat20
  ret <2 x i32> %21
}

define <2 x i32> @test(<2 x i64> %vec.ind16, <2 x i32> %broadcast.splat20) {
  %1 = icmp eq <2 x i64> %vec.ind16, zeroinitializer
  %2 = trunc <2 x i32> %broadcast.splat20 to <2 x i1>
  %3 = lshr <2 x i1> %1, %2
  %4 = zext <2 x i1> %3 to <2 x i32>
  ret <2 x i32> %4
}

[dtcxzyw]

Related PR: #104606