Auto merge of #117947 - Dirbaio:drop-llvm-15, r=cuviper

Update the minimum external LLVM to 16.

With this change, we'll have stable support for LLVM 16 and 17.
For reference, the previous increase to LLVM 15 was #114148

[Relevant zulip discussion](https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/riscv.20forced-atomics)

1 files changed, 0 insertions, 12 deletions

diff --git a/compiler/rustc_codegen_llvm/src/context.rs b/compiler/rustc_codegen_llvm/src/context.rs
index e6c5085cc0e..92a8c00510b 100644
--- a/compiler/rustc_codegen_llvm/src/context.rs
+++ b/compiler/rustc_codegen_llvm/src/context.rs
@@ -134,18 +134,6 @@ pub unsafe fn create_module<'ll>(
 
     let mut target_data_layout = sess.target.data_layout.to_string();
     let llvm_version = llvm_util::get_version();
-    if llvm_version < (16, 0, 0) {
-        if sess.target.arch == "s390x" {
-            // LLVM 16 data layout changed to always set 64-bit vector alignment,
-            // which is conditional in earlier LLVM versions.
-            // https://reviews.llvm.org/D131158 for the discussion.
-            target_data_layout = target_data_layout.replace("-v128:64", "");
-        } else if sess.target.arch == "riscv64" {
-            // LLVM 16 introduced this change so as to produce more efficient code.
-            // See https://reviews.llvm.org/D116735 for the discussion.
-            target_data_layout = target_data_layout.replace("-n32:64-", "-n64-");
-        }
-    }
     if llvm_version < (17, 0, 0) {
         if sess.target.arch.starts_with("powerpc") {
             // LLVM 17 specifies function pointer alignment for ppc: