[2024] linker/inline: use bottom-up inlining to minimize redundancy.

Author: eddyb

crates/rustc_codegen_spirv/src/linker/inline.rs

@@ -4,7 +4,7 @@
 
 use indexmap::IndexSet;
 use rspirv::dr::Module;
-use rspirv::spirv::Op;
+use rspirv::spirv::{Op, Word};
 use rustc_data_structures::fx::FxHashMap;
 
 // FIXME(eddyb) use newtyped indices and `IndexVec`.
@@ -19,6 +19,9 @@ pub struct CallGraph {
 
 impl CallGraph {
     pub fn collect(module: &Module) -> Self {
+        Self::collect_with_func_id_to_idx(module).0
+    }
+    pub fn collect_with_func_id_to_idx(module: &Module) -> (Self, FxHashMap<Word, FuncIdx>) {
         let func_id_to_idx: FxHashMap<_, _> = module
             .functions
             .iter()
@@ -51,10 +54,13 @@ impl CallGraph {
                     .collect()
             })
             .collect();
-        Self {
-            entry_points,
-            callees,
-        }
+        (
+            Self {
+                entry_points,
+                callees,
+            },
+            func_id_to_idx,
+        )
     }
 
     /// Order functions using a post-order traversal, i.e. callees before callers.

crates/rustc_codegen_spirv/src/linker/ipo.rs

@@ -28,14 +28,13 @@ OpLine %5 32 4
 %21 = OpVariable  %12  Function
 OpLine %5 32 23
 %22 = OpCompositeConstruct  %6  %13 %14 %15 %16
-OpLine %5 32 4
+OpLine %5 27 4
 %23 = OpCompositeExtract  %9  %22 0
 %24 = OpCompositeExtract  %9  %22 1
 %25 = OpCompositeExtract  %9  %22 2
 %26 = OpCompositeExtract  %9  %22 3
 %27 = OpCompositeConstruct  %11  %23 %24 %25 %26
 OpStore %21 %27
-OpLine %5 27 4
 %28 = OpULessThan  %17  %18 %10
 OpNoLine
 OpSelectionMerge %29 None

tests/compiletests/ui/dis/panic_builtin_bounds_check.stderr

@@ -1,6 +1,20 @@
-warning: `#[inline(never)]` function `nested_ref::deep_load` needs to be inlined because it has illegal argument or return types
+warning: `#[inline(never)]` function `nested_ref::deep_load` has been inlined
+  --> $DIR/nested-ref.rs:12:4
+   |
+LL | fn deep_load(r: &'static &'static u32) -> u32 {
+   |    ^^^^^^^^^
+   |
+   = note: inlining was required due to illegal parameter type
+   = note: called from `nested_ref::main`
 
-warning: `#[inline(never)]` function `nested_ref::deep_transpose` needs to be inlined because it has illegal argument or return types
+warning: `#[inline(never)]` function `nested_ref::deep_transpose` has been inlined
+  --> $DIR/nested-ref.rs:19:4
+   |
+LL | fn deep_transpose(r: &'static &'static Mat2) -> Mat2 {
+   |    ^^^^^^^^^^^^^^
+   |
+   = note: inlining was required due to illegal parameter type
+   = note: called from `nested_ref::main`
 
 warning: 2 warnings emitted
 

tests/compiletests/ui/lang/consts/nested-ref.stderr

@@ -1,12 +1,44 @@
-warning: `#[inline(never)]` function `member_ref_arg_broken::h` needs to be inlined because it has illegal argument or return types
+warning: `#[inline(never)]` function `member_ref_arg_broken::f` has been inlined
+  --> $DIR/member_ref_arg-broken.rs:20:4
+   |
+LL | fn f(x: &u32) -> u32 {
+   |    ^
+   |
+   = note: inlining was required due to illegal (pointer) argument
+   = note: called from `member_ref_arg_broken::main`
+
+warning: `#[inline(never)]` function `member_ref_arg_broken::g` has been inlined
+  --> $DIR/member_ref_arg-broken.rs:25:4
+   |
+LL | fn g(xy: (&u32, &u32)) -> (u32, u32) {
+   |    ^
+   |
+   = note: inlining was required due to illegal (pointer) argument
+   = note: called from `member_ref_arg_broken::main`
 
-warning: `#[inline(never)]` function `member_ref_arg_broken::h_newtyped` needs to be inlined because it has illegal argument or return types
+warning: `#[inline(never)]` function `member_ref_arg_broken::h` has been inlined
+  --> $DIR/member_ref_arg-broken.rs:30:4
+   |
+LL | fn h(xyz: (&u32, &u32, &u32)) -> (u32, u32, u32) {
+   |    ^
+   |
+   = note: inlining was required due to illegal parameter type
+   = note: called from `member_ref_arg_broken::main`
+
+warning: `#[inline(never)]` function `member_ref_arg_broken::h_newtyped` has been inlined
+  --> $DIR/member_ref_arg-broken.rs:41:4
+   |
+LL | fn h_newtyped(xyz: ((&u32, &u32, &u32),)) -> (u32, u32, u32) {
+   |    ^^^^^^^^^^
+   |
+   = note: inlining was required due to illegal parameter type
+   = note: called from `member_ref_arg_broken::main`
 
 error: error:0:0 - OpLoad Pointer <id> '$ID[%$ID]' is not a logical pointer.
          %39 = OpLoad %uint %38
    |
    = note: spirv-val failed
    = note: module `$TEST_BUILD_DIR/lang/core/ref/member_ref_arg-broken`
 
-error: aborting due to 1 previous error; 2 warnings emitted
+error: aborting due to 1 previous error; 4 warnings emitted
 

tests/compiletests/ui/lang/core/ref/member_ref_arg-broken.stderr

@@ -0,0 +1,20 @@
+warning: `#[inline(never)]` function `member_ref_arg::f` has been inlined
+  --> $DIR/member_ref_arg.rs:14:4
+   |
+LL | fn f(x: &u32) {}
+   |    ^
+   |
+   = note: inlining was required due to illegal (pointer) argument
+   = note: called from `member_ref_arg::main`
+
+warning: `#[inline(never)]` function `member_ref_arg::g` has been inlined
+  --> $DIR/member_ref_arg.rs:17:4
+   |
+LL | fn g(xy: (&u32, &u32)) {}
+   |    ^
+   |
+   = note: inlining was required due to illegal (pointer) argument
+   = note: called from `member_ref_arg::main`
+
+warning: 2 warnings emitted
+

tests/compiletests/ui/lang/core/ref/member_ref_arg.stderr

@@ -0,0 +1,11 @@
+warning: `#[inline(never)]` function `track_caller::track_caller_maybe_panic::panic_cold_explicit` has been inlined
+  --> $DIR/track_caller.rs:10:9
+   |
+LL |         panic!();
+   |         ^^^^^^^^
+   |
+   = note: inlining was required due to panicking
+   = note: called from `track_caller::track_caller_maybe_panic`
+
+warning: 1 warning emitted
+