Auto merge of #108446 - Zoxc:named-allocs, r=oli-obk

Name LLVM anonymous constants by a hash of their contents

This makes the names stable between different versions of a crate unlike the `AllocId` naming, making LLVM IR comparisons with `llvm-diff` more practical.

1 files changed, 8 insertions, 2 deletions

diff --git a/compiler/rustc_codegen_llvm/src/common.rs b/compiler/rustc_codegen_llvm/src/common.rs
index edb1c160626..b0a9a30ab46 100644
--- a/compiler/rustc_codegen_llvm/src/common.rs
+++ b/compiler/rustc_codegen_llvm/src/common.rs
@@ -10,6 +10,7 @@ use crate::value::Value;
 use rustc_ast::Mutability;
 use rustc_codegen_ssa::mir::place::PlaceRef;
 use rustc_codegen_ssa::traits::*;
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_hir::def_id::DefId;
 use rustc_middle::bug;
 use rustc_middle::mir::interpret::{ConstAllocation, GlobalAlloc, Scalar};
@@ -252,8 +253,13 @@ impl<'ll, 'tcx> ConstMethods<'tcx> for CodegenCx<'ll, 'tcx> {
                             Mutability::Mut => self.static_addr_of_mut(init, alloc.align, None),
                             _ => self.static_addr_of(init, alloc.align, None),
                         };
-                        if !self.sess().fewer_names() {
-                            llvm::set_value_name(value, format!("{:?}", alloc_id).as_bytes());
+                        if !self.sess().fewer_names() && llvm::get_value_name(value).is_empty() {
+                            let hash = self.tcx.with_stable_hashing_context(|mut hcx| {
+                                let mut hasher = StableHasher::new();
+                                alloc.hash_stable(&mut hcx, &mut hasher);
+                                hasher.finish::<u128>()
+                            });
+                            llvm::set_value_name(value, format!("alloc_{hash:032x}").as_bytes());
                         }
                         (value, AddressSpace::DATA)
                     }