[llvm] [GVN] Teach GVN simple masked load/store forwarding (PR #157689)

[Matthew Devereau via llvm-commits]

================
@@ -36,6 +36,152 @@ define <128 x i8> @f1(ptr %a0, <128 x i8> %a1, <128 x i8> %a2) {
   ret <128 x i8> %v4
 }
 
-declare <128 x i8> @llvm.masked.load.v128i8.p0(ptr, i32, <128 x i1>, <128 x i8>)
-declare void @llvm.masked.store.v128i8.p0(<128 x i8>, ptr, i32, <128 x i1>)
+define <4 x float> @forward_masked_load(ptr %0, ptr %1) {
----------------
MDevereau wrote:

I've added `forward_masked_load_arbitrary_mask`

https://github.com/llvm/llvm-project/pull/157689