[llvm] [VPlan] Add initial CFG simplification, removing BranchOnCond true. (PR #106748)

[via llvm-commits]

================
@@ -15,7 +15,6 @@ define void @clamped_tc_8(ptr nocapture %dst, i32 %n, i64 %val) vscale_range(1,1
 ; CHECK-NEXT:    [[N_VEC:%.*]] = sub i64 [[N_RND_UP]], [[N_MOD_VF]]
 ; CHECK-NEXT:    [[TMP5:%.*]] = call i64 @llvm.vscale.i64()
 ; CHECK-NEXT:    [[TMP6:%.*]] = mul i64 [[TMP5]], 8
-; CHECK-NEXT:    [[IND_END:%.*]] = getelementptr i8, ptr [[DST]], i64 [[N_VEC]]
----------------
ayalz wrote:

The above branch-on-false from entry to scalar preheader or vector preheader can/should also be eliminated, turning the scalar loop into unreachable dead code?

https://github.com/llvm/llvm-project/pull/106748