Auto merge of rust-lang#123949 - scottmcm:debug-no-means-no-debug-info-when-inlined, r=oli-obk,onur-ozkan

At debuginfo=0, don't inline debuginfo when inlining

See rust-lang#123949 (comment) for info.

Author: bors

compiler/rustc_mir_transform/src/inline.rs

@@ -11,7 +11,7 @@ use rustc_middle::mir::visit::*;
 use rustc_middle::mir::*;
 use rustc_middle::ty::TypeVisitableExt;
 use rustc_middle::ty::{self, Instance, InstanceDef, ParamEnv, Ty, TyCtxt};
-use rustc_session::config::OptLevel;
+use rustc_session::config::{DebugInfo, OptLevel};
 use rustc_span::source_map::Spanned;
 use rustc_span::sym;
 use rustc_target::abi::FieldIdx;
@@ -699,7 +699,19 @@ impl<'tcx> Inliner<'tcx> {
         // Insert all of the (mapped) parts of the callee body into the caller.
         caller_body.local_decls.extend(callee_body.drain_vars_and_temps());
         caller_body.source_scopes.extend(&mut callee_body.source_scopes.drain(..));
-        caller_body.var_debug_info.append(&mut callee_body.var_debug_info);
+        if self
+            .tcx
+            .sess
+            .opts
+            .unstable_opts
+            .inline_mir_preserve_debug
+            .unwrap_or(self.tcx.sess.opts.debuginfo != DebugInfo::None)
+        {
+            // Note that we need to preserve these in the standard library so that
+            // people working on rust can build with or without debuginfo while
+            // still getting consistent results from the mir-opt tests.
+            caller_body.var_debug_info.append(&mut callee_body.var_debug_info);
+        }
         caller_body.basic_blocks_mut().extend(callee_body.basic_blocks_mut().drain(..));
 
         caller_body[callsite.block].terminator = Some(Terminator {

compiler/rustc_session/src/options.rs

@@ -1717,6 +1717,9 @@ options! {
         "enable MIR inlining (default: no)"),
     inline_mir_hint_threshold: Option<usize> = (None, parse_opt_number, [TRACKED],
         "inlining threshold for functions with inline hint (default: 100)"),
+    inline_mir_preserve_debug: Option<bool> = (None, parse_opt_bool, [TRACKED],
+        "when MIR inlining, whether to preserve debug info for callee variables \
+        (default: preserve for debuginfo != None, otherwise remove)"),
     inline_mir_threshold: Option<usize> = (None, parse_opt_number, [TRACKED],
         "a default MIR inlining threshold (default: 50)"),
     input_stats: bool = (false, parse_bool, [UNTRACKED],

src/bootstrap/src/core/builder.rs

@@ -2102,6 +2102,14 @@ impl<'a> Builder<'a> {
             // break when incremental compilation is enabled. So this overrides the "no inlining
             // during incremental builds" heuristic for the standard library.
             rustflags.arg("-Zinline-mir");
+
+            // FIXME: always pass this after the next `#[cfg(bootstrap)]` update.
+            if compiler.stage != 0 {
+                // Similarly, we need to keep debug info for functions inlined into other std functions,
+                // even if we're not going to output debuginfo for the crate we're currently building,
+                // so that it'll be available when downstream consumers of std try to use it.
+                rustflags.arg("-Zinline-mir-preserve-debug");
+            }
         }
 
         if self.config.rustc_parallel

tests/codegen/mem-replace-simple-type.rs

@@ -34,18 +34,20 @@ pub fn replace_ref_str<'a>(r: &mut &'a str, v: &'a str) -> &'a str {
 
 #[no_mangle]
 // CHECK-LABEL: @replace_short_array_3(
+// CHECK-SAME: ptr{{.+}}sret{{.+}}%[[RET:.+]], ptr{{.+}}%r, ptr{{.+}}%v
 pub fn replace_short_array_3(r: &mut [u32; 3], v: [u32; 3]) -> [u32; 3] {
     // CHECK-NOT: alloca
-    // CHECK: call void @llvm.memcpy.p0.p0.i64(ptr align 4 %result, ptr align 4 %r, i64 12, i1 false)
+    // CHECK: call void @llvm.memcpy.p0.p0.i64(ptr align 4 %[[RET]], ptr align 4 %r, i64 12, i1 false)
     // CHECK: call void @llvm.memcpy.p0.p0.i64(ptr align 4 %r, ptr align 4 %v, i64 12, i1 false)
     std::mem::replace(r, v)
 }
 
 #[no_mangle]
 // CHECK-LABEL: @replace_short_array_4(
+// CHECK-SAME: ptr{{.+}}sret{{.+}}%[[RET:.+]], ptr{{.+}}%r, ptr{{.+}}%v
 pub fn replace_short_array_4(r: &mut [u32; 4], v: [u32; 4]) -> [u32; 4] {
     // CHECK-NOT: alloca
-    // CHECK: call void @llvm.memcpy.p0.p0.i64(ptr align 4 %result, ptr align 4 %r, i64 16, i1 false)
+    // CHECK: call void @llvm.memcpy.p0.p0.i64(ptr align 4 %[[RET]], ptr align 4 %r, i64 16, i1 false)
     // CHECK: call void @llvm.memcpy.p0.p0.i64(ptr align 4 %r, ptr align 4 %v, i64 16, i1 false)
     std::mem::replace(r, v)
 }

tests/codegen/slice-ref-equality.rs

@@ -43,48 +43,48 @@ pub fn is_zero_array(data: &[u8; 4]) -> bool {
 // equality for non-byte types also just emit a `bcmp`, not a loop.
 
 // CHECK-LABEL: @eq_slice_of_nested_u8(
-// CHECK-SAME: [[USIZE:i16|i32|i64]] noundef %1
-// CHECK-SAME: [[USIZE]] noundef %3
+// CHECK-SAME: [[USIZE:i16|i32|i64]] noundef %x.1
+// CHECK-SAME: [[USIZE]] noundef %y.1
 #[no_mangle]
 fn eq_slice_of_nested_u8(x: &[[u8; 3]], y: &[[u8; 3]]) -> bool {
-    // CHECK: icmp eq [[USIZE]] %1, %3
-    // CHECK: %[[BYTES:.+]] = mul nsw [[USIZE]] %1, 3
+    // CHECK: icmp eq [[USIZE]] %x.1, %y.1
+    // CHECK: %[[BYTES:.+]] = mul nsw [[USIZE]] {{%x.1|%y.1}}, 3
     // CHECK: tail call{{( noundef)?}} i32 @{{bcmp|memcmp}}(ptr
     // CHECK-SAME: , [[USIZE]]{{( noundef)?}} %[[BYTES]])
     x == y
 }
 
 // CHECK-LABEL: @eq_slice_of_i32(
-// CHECK-SAME: [[USIZE:i16|i32|i64]] noundef %1
-// CHECK-SAME: [[USIZE]] noundef %3
+// CHECK-SAME: [[USIZE:i16|i32|i64]] noundef %x.1
+// CHECK-SAME: [[USIZE]] noundef %y.1
 #[no_mangle]
 fn eq_slice_of_i32(x: &[i32], y: &[i32]) -> bool {
-    // CHECK: icmp eq [[USIZE]] %1, %3
-    // CHECK: %[[BYTES:.+]] = shl nsw [[USIZE]] %1, 2
+    // CHECK: icmp eq [[USIZE]] %x.1, %y.1
+    // CHECK: %[[BYTES:.+]] = shl nsw [[USIZE]] {{%x.1|%y.1}}, 2
     // CHECK: tail call{{( noundef)?}} i32 @{{bcmp|memcmp}}(ptr
     // CHECK-SAME: , [[USIZE]]{{( noundef)?}} %[[BYTES]])
     x == y
 }
 
 // CHECK-LABEL: @eq_slice_of_nonzero(
-// CHECK-SAME: [[USIZE:i16|i32|i64]] noundef %1
-// CHECK-SAME: [[USIZE]] noundef %3
+// CHECK-SAME: [[USIZE:i16|i32|i64]] noundef %x.1
+// CHECK-SAME: [[USIZE]] noundef %y.1
 #[no_mangle]
 fn eq_slice_of_nonzero(x: &[NonZero<i32>], y: &[NonZero<i32>]) -> bool {
-    // CHECK: icmp eq [[USIZE]] %1, %3
-    // CHECK: %[[BYTES:.+]] = shl nsw [[USIZE]] %1, 2
+    // CHECK: icmp eq [[USIZE]] %x.1, %y.1
+    // CHECK: %[[BYTES:.+]] = shl nsw [[USIZE]] {{%x.1|%y.1}}, 2
     // CHECK: tail call{{( noundef)?}} i32 @{{bcmp|memcmp}}(ptr
     // CHECK-SAME: , [[USIZE]]{{( noundef)?}} %[[BYTES]])
     x == y
 }
 
 // CHECK-LABEL: @eq_slice_of_option_of_nonzero(
-// CHECK-SAME: [[USIZE:i16|i32|i64]] noundef %1
-// CHECK-SAME: [[USIZE]] noundef %3
+// CHECK-SAME: [[USIZE:i16|i32|i64]] noundef %x.1
+// CHECK-SAME: [[USIZE]] noundef %y.1
 #[no_mangle]
 fn eq_slice_of_option_of_nonzero(x: &[Option<NonZero<i16>>], y: &[Option<NonZero<i16>>]) -> bool {
-    // CHECK: icmp eq [[USIZE]] %1, %3
-    // CHECK: %[[BYTES:.+]] = shl nsw [[USIZE]] %1, 1
+    // CHECK: icmp eq [[USIZE]] %x.1, %y.1
+    // CHECK: %[[BYTES:.+]] = shl nsw [[USIZE]] {{%x.1|%y.1}}, 1
     // CHECK: tail call{{( noundef)?}} i32 @{{bcmp|memcmp}}(ptr
     // CHECK-SAME: , [[USIZE]]{{( noundef)?}} %[[BYTES]])
     x == y

tests/crashes/121127.rs

@@ -1,5 +1,6 @@
 //@ known-bug: #121127
-//@ compile-flags: -Zpolymorphize=on -Zinline-mir=yes
+//@ compile-flags: -Zpolymorphize=on -Zinline-mir=yes -C debuginfo=2
+// Note that as of PR#123949 this only crashes with debuginfo enabled
 
 #![feature(specialization)]
 

tests/mir-opt/const_prop/inherit_overflow.main.GVN.panic-abort.diff

@@ -9,8 +9,6 @@
       scope 1 {
       }
       scope 2 (inlined #[track_caller] <u8 as Add>::add) {
-          debug self => _2;
-          debug other => _3;
           let mut _4: (u8, bool);
       }
 

tests/mir-opt/const_prop/inherit_overflow.main.GVN.panic-unwind.diff

@@ -9,8 +9,6 @@
       scope 1 {
       }
       scope 2 (inlined #[track_caller] <u8 as Add>::add) {
-          debug self => _2;
-          debug other => _3;
           let mut _4: (u8, bool);
       }
 

tests/mir-opt/dataflow-const-prop/default_boxed_slice.main.DataflowConstProp.32bit.panic-abort.diff

@@ -12,16 +12,13 @@
           let _3: std::ptr::Unique<[bool]>;
           let mut _4: std::ptr::Unique<[bool; 0]>;
           scope 3 {
-              debug ptr => _3;
           }
           scope 4 (inlined Unique::<[bool; 0]>::dangling) {
               let mut _5: std::ptr::NonNull<[bool; 0]>;
               scope 5 (inlined NonNull::<[bool; 0]>::dangling) {
                   let _6: *mut [bool; 0];
                   scope 6 {
-                      debug ptr => _6;
                       scope 10 (inlined NonNull::<[bool; 0]>::new_unchecked) {
-                          debug ptr => _6;
                           let mut _8: bool;
                           let _9: ();
                           let mut _10: *mut ();
@@ -37,7 +34,6 @@
                       scope 8 (inlined align_of::<[bool; 0]>) {
                       }
                       scope 9 (inlined without_provenance_mut::<[bool; 0]>) {
-                          debug addr => _7;
                       }
                   }
               }

tests/mir-opt/dataflow-const-prop/default_boxed_slice.main.DataflowConstProp.32bit.panic-unwind.diff

@@ -12,16 +12,13 @@
           let _3: std::ptr::Unique<[bool]>;
           let mut _4: std::ptr::Unique<[bool; 0]>;
           scope 3 {
-              debug ptr => _3;
           }
           scope 4 (inlined Unique::<[bool; 0]>::dangling) {
               let mut _5: std::ptr::NonNull<[bool; 0]>;
               scope 5 (inlined NonNull::<[bool; 0]>::dangling) {
                   let _6: *mut [bool; 0];
                   scope 6 {
-                      debug ptr => _6;
                       scope 10 (inlined NonNull::<[bool; 0]>::new_unchecked) {
-                          debug ptr => _6;
                           let mut _8: bool;
                           let _9: ();
                           let mut _10: *mut ();
@@ -37,7 +34,6 @@
                       scope 8 (inlined align_of::<[bool; 0]>) {
                       }
                       scope 9 (inlined without_provenance_mut::<[bool; 0]>) {
-                          debug addr => _7;
                       }
                   }
               }