From c022413023855334a9f7cb6718bc20d00b0c6759 Mon Sep 17 00:00:00 2001
From: Nikita Popov <npopov@redhat.com>
Date: Thu, 2 Oct 2025 17:22:15 +0200
Subject: [PATCH] Enable -disable-i2p-p2i-opt flag

---
 compiler/rustc_codegen_llvm/src/llvm_util.rs     | 2 ++
 tests/codegen-llvm/iter-repeat-n-trivial-drop.rs | 3 ++-
 tests/codegen-llvm/try_question_mark_nop.rs      | 4 ++++
 tests/codegen-llvm/vec-iter-collect-len.rs       | 3 ++-
 4 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/compiler/rustc_codegen_llvm/src/llvm_util.rs b/compiler/rustc_codegen_llvm/src/llvm_util.rs
index 3b920168e06dc..6d8c52438f77e 100644
--- a/compiler/rustc_codegen_llvm/src/llvm_util.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm_util.rs
@@ -118,6 +118,8 @@ unsafe fn configure_llvm(sess: &Session) {
         // Use non-zero `import-instr-limit` multiplier for cold callsites.
         add("-import-cold-multiplier=0.1", false);
 
+        add("-disable-i2p-p2i-opt", false);
+
         if sess.print_llvm_stats() {
             add("-stats", false);
         }
diff --git a/tests/codegen-llvm/iter-repeat-n-trivial-drop.rs b/tests/codegen-llvm/iter-repeat-n-trivial-drop.rs
index 6f34097842800..8e6d757756b92 100644
--- a/tests/codegen-llvm/iter-repeat-n-trivial-drop.rs
+++ b/tests/codegen-llvm/iter-repeat-n-trivial-drop.rs
@@ -47,8 +47,9 @@ pub fn iter_repeat_n_next(it: &mut std::iter::RepeatN<NotCopy>) -> Option<NotCop
 #[no_mangle]
 // CHECK-LABEL: @vec_extend_via_iter_repeat_n
 pub fn vec_extend_via_iter_repeat_n() -> Vec<u8> {
+    // FIXME: Has extra inttoptr + ptrtoint pair
     // CHECK: %[[ADDR:.+]] = tail call {{(noalias )?}}noundef dereferenceable_or_null(1234) ptr @{{.*}}__rust_alloc(i64 noundef {{(range\(i64 1, 0\) )?}}1234, i64 noundef {{(range\(i64 1, -9223372036854775807\) )?}}1)
-    // CHECK: tail call void @llvm.memset.p0.i64(ptr noundef nonnull align 1 dereferenceable(1234) %[[ADDR]], i8 42, i64 1234,
+    // CHECK: tail call void @llvm.memset.p0.i64(ptr noundef nonnull align 1 dereferenceable(1234) %[[ADDR2:.+]], i8 42, i64 1234,
 
     let n = 1234_usize;
     let mut v = Vec::with_capacity(n);
diff --git a/tests/codegen-llvm/try_question_mark_nop.rs b/tests/codegen-llvm/try_question_mark_nop.rs
index a09fa0a49019d..4dfa20c852f84 100644
--- a/tests/codegen-llvm/try_question_mark_nop.rs
+++ b/tests/codegen-llvm/try_question_mark_nop.rs
@@ -212,6 +212,8 @@ pub fn control_flow_nop_traits_128(x: ControlFlow<i128, u128>) -> ControlFlow<i1
 #[no_mangle]
 pub fn result_nop_match_ptr(x: Result<usize, Box<()>>) -> Result<usize, Box<()>> {
     // CHECK: start:
+    // CHECK-NEXT: ptrtoint
+    // CHECK-NEXT: inttoptr
     // CHECK-NEXT: insertvalue { i{{[0-9]+}}, ptr }
     // CHECK-NEXT: insertvalue { i{{[0-9]+}}, ptr }
     // CHECK-NEXT: ret
@@ -225,6 +227,8 @@ pub fn result_nop_match_ptr(x: Result<usize, Box<()>>) -> Result<usize, Box<()>>
 #[no_mangle]
 pub fn result_nop_traits_ptr(x: Result<u64, NonNull<()>>) -> Result<u64, NonNull<()>> {
     // CHECK: start:
+    // CHECK-NEXT: ptrtoint
+    // CHECK-NEXT: inttoptr
     // CHECK-NEXT: insertvalue { i{{[0-9]+}}, ptr }
     // CHECK-NEXT: insertvalue { i{{[0-9]+}}, ptr }
     // CHECK-NEXT: ret
diff --git a/tests/codegen-llvm/vec-iter-collect-len.rs b/tests/codegen-llvm/vec-iter-collect-len.rs
index 807548ef883f5..0666ba8f5fb07 100644
--- a/tests/codegen-llvm/vec-iter-collect-len.rs
+++ b/tests/codegen-llvm/vec-iter-collect-len.rs
@@ -3,10 +3,11 @@
 
 #[no_mangle]
 pub fn get_len() -> usize {
+    // FIXME: Allocation no longer optimized away.
     // CHECK-LABEL: @get_len
     // CHECK-NEXT: start:
     // CHECK-NEXT: ; call __rustc::__rust_no_alloc_shim_is_unstable_v2
     // CHECK-NEXT: tail call void @_R{{.+}}__rust_no_alloc_shim_is_unstable_v2()
-    // CHECK-NEXT: ret i{{[0-9]+}} 3
+    // CHECK: ret i{{[0-9]+}} 3
     [1, 2, 3].iter().collect::<Vec<_>>().len()
 }