[llvm] d828281 - [AlwaysInliner] Respect noinline call site attribute

[Dávid Bolvanský via llvm-commits]

Author: Dávid Bolvanský
Date: 2022-02-11T19:23:11+01:00
New Revision: d828281e7860b5e812474212bfc49cc57d52dae0

URL: https://github.com/llvm/llvm-project/commit/d828281e7860b5e812474212bfc49cc57d52dae0
DIFF: https://github.com/llvm/llvm-project/commit/d828281e7860b5e812474212bfc49cc57d52dae0.diff

LOG: [AlwaysInliner] Respect noinline call site attribute

```
always_inline foo() { }

bar () {

noinline foo();
}
```

We should prefer call site attribute over attribute on decl. This is fix for AlwaysInliner, similar fix is needed for normal Inliner (follow up).

Related to https://reviews.llvm.org/D119061

Reviewed By: aeubanks

Differential Revision: https://reviews.llvm.org/D119553

Added: 
    

Modified: 
    llvm/lib/Transforms/IPO/AlwaysInliner.cpp
    llvm/test/Transforms/Inline/always-inline.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/IPO/AlwaysInliner.cpp b/llvm/lib/Transforms/IPO/AlwaysInliner.cpp
index a6d9ce1033f3c..e6bccd97e0e78 100644
--- a/llvm/lib/Transforms/IPO/AlwaysInliner.cpp
+++ b/llvm/lib/Transforms/IPO/AlwaysInliner.cpp
@@ -1,4 +1,4 @@
-//===- InlineAlways.cpp - Code to inline always_inline functions ----------===//
+//===- AlwaysInliner.cpp - Code to inline always_inline functions ----------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
@@ -59,9 +59,16 @@ PreservedAnalyses AlwaysInlinerPass::run(Module &M,
 
       for (User *U : F.users())
         if (auto *CB = dyn_cast<CallBase>(U))
-          if (CB->getCalledFunction() == &F &&
-              CB->hasFnAttr(Attribute::AlwaysInline))
-            Calls.insert(CB);
+          if (CB->getCalledFunction() == &F) {
+            if (F.hasFnAttribute(Attribute::AlwaysInline)) {
+              // Avoid inlining if noinline call site attribute.
+              if (!CB->isNoInline())
+                Calls.insert(CB);
+            } else if (CB->hasFnAttr(Attribute::AlwaysInline)) {
+              // Ok, alwaysinline call site attribute.
+              Calls.insert(CB);
+            }
+          }
 
       for (CallBase *CB : Calls) {
         Function *Caller = CB->getCaller();
@@ -210,6 +217,9 @@ InlineCost AlwaysInlinerLegacyPass::getInlineCost(CallBase &CB) {
   if (!CB.hasFnAttr(Attribute::AlwaysInline))
     return InlineCost::getNever("no alwaysinline attribute");
 
+  if (Callee->hasFnAttribute(Attribute::AlwaysInline) && CB.isNoInline())
+    return InlineCost::getNever("noinline call site attribute");
+
   auto IsViable = isInlineViable(*Callee);
   if (!IsViable.isSuccess())
     return InlineCost::getNever(IsViable.getFailureReason());

diff  --git a/llvm/test/Transforms/Inline/always-inline.ll b/llvm/test/Transforms/Inline/always-inline.ll
index f947bdbd87347..37e890532375c 100644
--- a/llvm/test/Transforms/Inline/always-inline.ll
+++ b/llvm/test/Transforms/Inline/always-inline.ll
@@ -314,3 +314,57 @@ define void @outer14() {
   call void @inner14()
   ret void
 }
+
+define internal i32 @inner15() {
+; CHECK: @inner15(
+  ret i32 1
+}
+
+define i32 @outer15() {
+; CHECK-LABEL: @outer15(
+; CHECK: call
+
+   %r = call i32 @inner15() noinline
+   ret i32 %r
+}
+
+define internal i32 @inner16() alwaysinline {
+; CHECK: @inner16(
+  ret i32 1
+}
+
+define i32 @outer16() {
+; CHECK-LABEL: @outer16(
+; CHECK: call
+
+   %r = call i32 @inner16() noinline
+   ret i32 %r
+}
+
+define i32 @inner17() alwaysinline {
+; CHECK: @inner17(
+  ret i32 1
+}
+
+define i32 @outer17() {
+; CHECK-LABEL: @outer17(
+; CHECK: call
+
+   %r = call i32 @inner17() noinline
+   ret i32 %r
+}
+
+define i32 @inner18() noinline {
+; CHECK: @inner18(
+  ret i32 1
+}
+
+define i32 @outer18() {
+; CHECK-LABEL: @outer18(
+; CHECK-NOT: call
+; CHECK: ret
+
+   %r = call i32 @inner18() alwaysinline
+
+   ret i32 %r
+}