Auto merge of #28354 - dotdash:slow_plat, r=eddyb

When the inliner has to decided if it wants to inline a function A into an
internal function B, it first checks whether it would be more profitable
to inline B into its callees instead. This means that it has to analyze
B, which involves checking the assumption cache. Building the assumption
cache requires scanning the whole function, and because inlining
currently clears the assumption cache, this scan happens again and
again, getting even slower as the function grows from inlining.

As inlining the huge find functions isn't really useful anyway, we can
mark them as noinline, which skips the cost analysis and reduces compile
times by as much as 70%.

cc #28273

3 files changed, 3 insertions, 0 deletions

diff --git a/src/librustc_platform_intrinsics/aarch64.rs b/src/librustc_platform_intrinsics/aarch64.rs
index a3084d903e2..1db5b3cb9ea 100644
--- a/src/librustc_platform_intrinsics/aarch64.rs
+++ b/src/librustc_platform_intrinsics/aarch64.rs
@@ -17,6 +17,7 @@ use {Intrinsic, i, i_, u, u_, f, v, v_, agg, p, void};
 use IntrinsicDef::Named;
 use rustc::middle::ty;
 
+#[inline(never)]
 pub fn find<'tcx>(_tcx: &ty::ctxt<'tcx>, name: &str) -> Option<Intrinsic> {
     if !name.starts_with("aarch64_v") { return None }
     Some(match &name["aarch64_v".len()..] {
diff --git a/src/librustc_platform_intrinsics/arm.rs b/src/librustc_platform_intrinsics/arm.rs
index 89b147027b5..eae5c520883 100644
--- a/src/librustc_platform_intrinsics/arm.rs
+++ b/src/librustc_platform_intrinsics/arm.rs
@@ -17,6 +17,7 @@ use {Intrinsic, i, i_, u, u_, f, v, agg, p};
 use IntrinsicDef::Named;
 use rustc::middle::ty;
 
+#[inline(never)]
 pub fn find<'tcx>(_tcx: &ty::ctxt<'tcx>, name: &str) -> Option<Intrinsic> {
     if !name.starts_with("arm_v") { return None }
     Some(match &name["arm_v".len()..] {
diff --git a/src/librustc_platform_intrinsics/x86.rs b/src/librustc_platform_intrinsics/x86.rs
index 2dfd00e9ce3..19aeb589e70 100644
--- a/src/librustc_platform_intrinsics/x86.rs
+++ b/src/librustc_platform_intrinsics/x86.rs
@@ -17,6 +17,7 @@ use {Intrinsic, i, i_, u, u_, f, v, v_, agg, p, void};
 use IntrinsicDef::Named;
 use rustc::middle::ty;
 
+#[inline(never)]
 pub fn find<'tcx>(_tcx: &ty::ctxt<'tcx>, name: &str) -> Option<Intrinsic> {
     if !name.starts_with("x86_mm") { return None }
     Some(match &name["x86_mm".len()..] {