[IROutliner] Do not outline from regions that are marked with OptNone

[AndrewLitteken]

Summary

Since the IROutliner is performing an optimization, it should not outline from functions explicitly marked with optnone. This adds an extra check and test to make sure this does not occur.

[paquette]

LGTM

FWIW I think we could shave off some compile time if we could make some sort of interface to the similarity identifier that tells it "this is for outlining". That may just be a subclass or something of the similarity identifier.

llvm/lib/Transforms/IPO/IROutliner.cpp

for (IRSimilarityCandidate &IRSC : CandidateVec) {
     // taken for use somewhere else, we do not outline that block.
     bool BBHasAddressTaken = any_of(IRSC, [](IRInstructionData &ID){
       return ID.Inst->getParent()->hasAddressTaken();
     });
 
     if (BBHasAddressTaken)
       continue;
 
+    if (IRSC.getFunction()->hasOptNone())
+      continue;
+
     if (IRSC.front()->Inst->getFunction()->hasLinkOnceODRLinkage() &&
         !OutlineFromLinkODRs)
       continue;
 
     // Greedily prune out any regions that will overlap with already chosen
     // regions.
     if (CurrentEndIdx != 0 && StartIdx <= CurrentEndIdx)
       continue;

llvm/test/Transforms/IROutliner/no-outlining-optnone.ll

+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --include-generated-funcs
+; RUN: opt -S -verify -iroutliner -ir-outlining-no-cost < %s | FileCheck %s
+
+; Ensure that a function is not outlined if a function has the optnone
+; attribute.
+
+define void @outline_constants1() optnone noinline {
+entry:
+  %a = alloca i32, align 4
+  %b = alloca i32, align 4
+  %c = alloca i32, align 4
+  store i32 3, i32* %a, align 4
+  store i32 4, i32* %b, align 4
+  store i32 5, i32* %c, align 4
+  %al = load i32, i32* %a
+  %bl = load i32, i32* %b
+  %cl = load i32, i32* %c
+  ret void
+}
+
+define void @outline_constants2() optnone noinline {
+entry:
+  %a = alloca i32, align 4
+  %b = alloca i32, align 4
+  %c = alloca i32, align 4
+  store i32 2, i32* %a, align 4
+  store i32 3, i32* %b, align 4
+  store i32 4, i32* %c, align 4
+  %al = load i32, i32* %a
+  %bl = load i32, i32* %b
+  %cl = load i32, i32* %c
+  ret void
+}
+
+; CHECK-LABEL: @outline_constants1(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[A:%.*]] = alloca i32, align 4
+; CHECK-NEXT:    [[B:%.*]] = alloca i32, align 4
+; CHECK-NEXT:    [[C:%.*]] = alloca i32, align 4
+; CHECK-NEXT:    store i32 3, i32* [[A]], align 4
+; CHECK-NEXT:    store i32 4, i32* [[B]], align 4
+; CHECK-NEXT:    store i32 5, i32* [[C]], align 4
+; CHECK-NEXT:    [[AL:%.*]] = load i32, i32* [[A]], align 4
+; CHECK-NEXT:    [[BL:%.*]] = load i32, i32* [[B]], align 4
+; CHECK-NEXT:    [[CL:%.*]] = load i32, i32* [[C]], align 4
+; CHECK-NEXT:    ret void
+;
+;
+; CHECK-LABEL: @outline_constants2(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[A:%.*]] = alloca i32, align 4
+; CHECK-NEXT:    [[B:%.*]] = alloca i32, align 4
+; CHECK-NEXT:    [[C:%.*]] = alloca i32, align 4
+; CHECK-NEXT:    store i32 2, i32* [[A]], align 4
+; CHECK-NEXT:    store i32 3, i32* [[B]], align 4
+; CHECK-NEXT:    store i32 4, i32* [[C]], align 4
+; CHECK-NEXT:    [[AL:%.*]] = load i32, i32* [[A]], align 4
+; CHECK-NEXT:    [[BL:%.*]] = load i32, i32* [[B]], align 4
+; CHECK-NEXT:    [[CL:%.*]] = load i32, i32* [[C]], align 4
+; CHECK-NEXT:    ret void
+;