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Auto merge of #111007 - JakobDegen:nrvo, r=tmiasko
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Disable nrvo mir opt

See #111005 and #110902 . The ICE can definitely be hit on stable, the miscompilation I'm not sure about. The pass makes some pretty sketchy assumptions though, and we should not have it on while that's the case.

I'm not going to work on actually fixing this, it's probably not excessively difficult though.

r? rust-lang/mir-opt
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@bors
bors committed May 8, 2023
2 parents a0111af + 8e2da80 commit dfe3188
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Showing 20 changed files with 247 additions and 574 deletions.
3 changes: 2 additions & 1 deletion compiler/rustc_mir_transform/src/nrvo.rs
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Expand Up @@ -34,7 +34,8 @@ pub struct RenameReturnPlace;

impl<'tcx> MirPass<'tcx> for RenameReturnPlace {
fn is_enabled(&self, sess: &rustc_session::Session) -> bool {
sess.mir_opt_level() > 0
// #111005
sess.mir_opt_level() > 0 && sess.opts.unstable_opts.unsound_mir_opts
}

fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut mir::Body<'tcx>) {
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14 changes: 7 additions & 7 deletions tests/codegen/fewer-names.rs
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Expand Up @@ -7,14 +7,14 @@

#[no_mangle]
pub fn sum(x: u32, y: u32) -> u32 {
// YES-LABEL: define{{.*}}i32 @sum(i32 noundef %0, i32 noundef %1)
// YES-NEXT: %3 = add i32 %1, %0
// YES-NEXT: ret i32 %3
// YES-LABEL: define{{.*}}i32 @sum(i32 noundef %0, i32 noundef %1)
// YES-NEXT: %3 = add i32 %1, %0
// YES-NEXT: ret i32 %3

// NO-LABEL: define{{.*}}i32 @sum(i32 noundef %x, i32 noundef %y)
// NO-NEXT: start:
// NO-NEXT: %0 = add i32 %y, %x
// NO-NEXT: ret i32 %0
// NO-LABEL: define{{.*}}i32 @sum(i32 noundef %x, i32 noundef %y)
// NO-NEXT: start:
// NO-NEXT: %z = add i32 %y, %x
// NO-NEXT: ret i32 %z
let z = x + y;
z
}
18 changes: 10 additions & 8 deletions tests/codegen/mem-replace-big-type.rs
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Expand Up @@ -13,7 +13,8 @@ pub struct Big([u64; 7]);
pub fn replace_big(dst: &mut Big, src: Big) -> Big {
// Back in 1.68, this emitted six `memcpy`s.
// `read_via_copy` in 1.69 got that down to three.
// `write_via_move` has it down to just the two essential ones.
// `write_via_move` it was originally down to the essential two, however
// with nrvo disabled it is back at 3
std::mem::replace(dst, src)
}

Expand All @@ -22,13 +23,14 @@ pub fn replace_big(dst: &mut Big, src: Big) -> Big {

// CHECK-NOT: call void @llvm.memcpy

// For a large type, we expect exactly two `memcpy`s
// For a large type, we expect exactly three `memcpy`s
// CHECK-LABEL: define internal void @{{.+}}mem{{.+}}replace{{.+}}sret(%Big)
// CHECK-NOT: alloca
// CHECK-NOT: call void @llvm.memcpy
// CHECK: call void @llvm.memcpy.{{.+}}({{i8\*|ptr}} align 8 %0, {{i8\*|ptr}} align 8 %dest, i{{.*}} 56, i1 false)
// CHECK-NOT: call void @llvm.memcpy
// CHECK: call void @llvm.memcpy.{{.+}}({{i8\*|ptr}} align 8 %dest, {{i8\*|ptr}} align 8 %src, i{{.*}} 56, i1 false)
// CHECK-NOT: call void @llvm.memcpy
// CHECK-NOT: call void @llvm.memcpy
// CHECK: call void @llvm.memcpy.{{.+}}({{i8\*|ptr}} align 8 %result, {{i8\*|ptr}} align 8 %dest, i{{.*}} 56, i1 false)
// CHECK-NOT: call void @llvm.memcpy
// CHECK: call void @llvm.memcpy.{{.+}}({{i8\*|ptr}} align 8 %dest, {{i8\*|ptr}} align 8 %src, i{{.*}} 56, i1 false)
// CHECK-NOT: call void @llvm.memcpy
// CHECK: call void @llvm.memcpy.{{.+}}({{i8\*|ptr}} align 8 %0, {{i8\*|ptr}} align 8 %result, i{{.*}} 56, i1 false)
// CHECK-NOT: call void @llvm.memcpy

// CHECK-NOT: call void @llvm.memcpy
2 changes: 1 addition & 1 deletion tests/codegen/nrvo.rs
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Expand Up @@ -8,7 +8,7 @@
pub fn nrvo(init: fn(&mut [u8; 4096])) -> [u8; 4096] {
// CHECK-LABEL: nrvo
// CHECK: @llvm.memset
// CHECK-NOT: @llvm.memcpy
// FIXME: turn on nrvo then check-not: @llvm.memcpy
// CHECK: ret
// CHECK-EMPTY
let mut buf = [0; 4096];
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4 changes: 2 additions & 2 deletions tests/codegen/var-names.rs
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Expand Up @@ -9,7 +9,7 @@ pub fn test(a: u32, b: u32) -> u32 {
// CHECK: %c = add i32 %a, %b
let d = c;
let e = d * a;
// CHECK-NEXT: %0 = mul i32 %c, %a
// CHECK-NEXT: %e = mul i32 %c, %a
e
// CHECK-NEXT: ret i32 %0
// CHECK-NEXT: ret i32 %e
}
12 changes: 8 additions & 4 deletions tests/mir-opt/inline/inline_into_box_place.main.Inline.diff
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Expand Up @@ -16,7 +16,8 @@
+ let mut _4: usize; // in scope 3 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
+ let mut _5: usize; // in scope 3 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
+ let mut _6: *mut u8; // in scope 3 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
+ let mut _7: *const std::vec::Vec<u32>; // in scope 3 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
+ let mut _7: std::boxed::Box<std::vec::Vec<u32>>; // in scope 3 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
+ let mut _8: *const std::vec::Vec<u32>; // in scope 3 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
+ scope 4 {
+ }
+ }
Expand Down Expand Up @@ -65,9 +66,12 @@
bb3: {
- StorageDead(_1); // scope 0 at $DIR/inline_into_box_place.rs:+2:1: +2:2
- return; // scope 0 at $DIR/inline_into_box_place.rs:+2:2: +2:2
+ _1 = ShallowInitBox(move _6, std::vec::Vec<u32>); // scope 3 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
+ _7 = (((_1.0: std::ptr::Unique<std::vec::Vec<u32>>).0: std::ptr::NonNull<std::vec::Vec<u32>>).0: *const std::vec::Vec<u32>); // scope 3 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
+ (*_7) = move _2; // scope 3 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
+ StorageLive(_7); // scope 3 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
+ _7 = ShallowInitBox(move _6, std::vec::Vec<u32>); // scope 3 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
+ _8 = (((_7.0: std::ptr::Unique<std::vec::Vec<u32>>).0: std::ptr::NonNull<std::vec::Vec<u32>>).0: *const std::vec::Vec<u32>); // scope 3 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
+ (*_8) = move _2; // scope 3 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
+ _1 = move _7; // scope 3 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
+ StorageDead(_7); // scope 3 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
+ StorageDead(_2); // scope 0 at $DIR/inline_into_box_place.rs:+1:48: +1:49
+ _0 = const (); // scope 0 at $DIR/inline_into_box_place.rs:+0:11: +2:2
+ drop(_1) -> [return: bb1, unwind: bb2]; // scope 0 at $DIR/inline_into_box_place.rs:+2:1: +2:2
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14 changes: 9 additions & 5 deletions tests/mir-opt/inline/issue_58867_inline_as_ref_as_mut.b.Inline.after.mir
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Expand Up @@ -8,18 +8,22 @@ fn b(_1: &mut Box<T>) -> &mut T {
let mut _4: &mut std::boxed::Box<T>; // in scope 0 at $DIR/issue_58867_inline_as_ref_as_mut.rs:+1:5: +1:15
scope 1 (inlined <Box<T> as AsMut<T>>::as_mut) { // at $DIR/issue_58867_inline_as_ref_as_mut.rs:8:7: 8:15
debug self => _4; // in scope 1 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
let mut _5: std::boxed::Box<T>; // in scope 1 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
let mut _6: *const T; // in scope 1 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
let mut _5: &mut T; // in scope 1 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
let mut _6: std::boxed::Box<T>; // in scope 1 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
let mut _7: *const T; // in scope 1 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
}

bb0: {
StorageLive(_2); // scope 0 at $DIR/issue_58867_inline_as_ref_as_mut.rs:+1:5: +1:15
StorageLive(_3); // scope 0 at $DIR/issue_58867_inline_as_ref_as_mut.rs:+1:5: +1:15
StorageLive(_4); // scope 0 at $DIR/issue_58867_inline_as_ref_as_mut.rs:+1:5: +1:15
_4 = &mut (*_1); // scope 0 at $DIR/issue_58867_inline_as_ref_as_mut.rs:+1:5: +1:15
_5 = deref_copy (*_4); // scope 1 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
_6 = (((_5.0: std::ptr::Unique<T>).0: std::ptr::NonNull<T>).0: *const T); // scope 1 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
_3 = &mut (*_6); // scope 1 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
StorageLive(_5); // scope 0 at $DIR/issue_58867_inline_as_ref_as_mut.rs:+1:7: +1:15
_6 = deref_copy (*_4); // scope 1 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
_7 = (((_6.0: std::ptr::Unique<T>).0: std::ptr::NonNull<T>).0: *const T); // scope 1 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
_5 = &mut (*_7); // scope 1 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
_3 = _5; // scope 1 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
StorageDead(_5); // scope 0 at $DIR/issue_58867_inline_as_ref_as_mut.rs:+1:7: +1:15
_2 = &mut (*_3); // scope 0 at $DIR/issue_58867_inline_as_ref_as_mut.rs:+1:5: +1:15
StorageDead(_4); // scope 0 at $DIR/issue_58867_inline_as_ref_as_mut.rs:+1:14: +1:15
_0 = &mut (*_2); // scope 0 at $DIR/issue_58867_inline_as_ref_as_mut.rs:+1:5: +1:15
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14 changes: 9 additions & 5 deletions tests/mir-opt/inline/issue_58867_inline_as_ref_as_mut.d.Inline.after.mir
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Expand Up @@ -7,17 +7,21 @@ fn d(_1: &Box<T>) -> &T {
let mut _3: &std::boxed::Box<T>; // in scope 0 at $DIR/issue_58867_inline_as_ref_as_mut.rs:+1:5: +1:15
scope 1 (inlined <Box<T> as AsRef<T>>::as_ref) { // at $DIR/issue_58867_inline_as_ref_as_mut.rs:18:7: 18:15
debug self => _3; // in scope 1 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
let mut _4: std::boxed::Box<T>; // in scope 1 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
let mut _5: *const T; // in scope 1 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
let _4: &T; // in scope 1 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
let mut _5: std::boxed::Box<T>; // in scope 1 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
let mut _6: *const T; // in scope 1 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
}

bb0: {
StorageLive(_2); // scope 0 at $DIR/issue_58867_inline_as_ref_as_mut.rs:+1:5: +1:15
StorageLive(_3); // scope 0 at $DIR/issue_58867_inline_as_ref_as_mut.rs:+1:5: +1:15
_3 = &(*_1); // scope 0 at $DIR/issue_58867_inline_as_ref_as_mut.rs:+1:5: +1:15
_4 = deref_copy (*_3); // scope 1 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
_5 = (((_4.0: std::ptr::Unique<T>).0: std::ptr::NonNull<T>).0: *const T); // scope 1 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
_2 = &(*_5); // scope 1 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
StorageLive(_4); // scope 1 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
_5 = deref_copy (*_3); // scope 1 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
_6 = (((_5.0: std::ptr::Unique<T>).0: std::ptr::NonNull<T>).0: *const T); // scope 1 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
_4 = &(*_6); // scope 1 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
_2 = _4; // scope 1 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
StorageDead(_4); // scope 1 at $SRC_DIR/alloc/src/boxed.rs:LL:COL
_0 = &(*_2); // scope 0 at $DIR/issue_58867_inline_as_ref_as_mut.rs:+1:5: +1:15
StorageDead(_3); // scope 0 at $DIR/issue_58867_inline_as_ref_as_mut.rs:+1:14: +1:15
StorageDead(_2); // scope 0 at $DIR/issue_58867_inline_as_ref_as_mut.rs:+2:1: +2:2
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