Outliner: add "target-cpu" feature from source function to outlined

[t.p.northover]

Summary

The CPU is used to determine which inline asm instructions are allowed, so needs to be copied across in case the outlined function contains any.

[paquette]

LGTM

[t.p.northover]

Thanks. Committed as b586dc21a7e8.

llvm/lib/CodeGen/TargetInstrInfo.cpp

void TargetInstrInfo::mergeOutliningCandidateAttributes(
   // Include target features from an arbitrary candidate for the outlined
   // function. This makes sure the outlined function knows what kinds of
   // instructions are going into it. This is fine, since all parent functions
   // must necessarily support the instructions that are in the outlined region.
   outliner::Candidate &FirstCand = Candidates.front();
   const Function &ParentFn = FirstCand.getMF()->getFunction();
   if (ParentFn.hasFnAttribute("target-features"))
     F.addFnAttr(ParentFn.getFnAttribute("target-features"));
+  if (ParentFn.hasFnAttribute("target-cpu"))
+    F.addFnAttr(ParentFn.getFnAttribute("target-cpu"));
 
   // Set nounwind, so we don't generate eh_frame.
   if (llvm::all_of(Candidates, [](const outliner::Candidate &C) {
         return C.getMF()->getFunction().hasFnAttribute(Attribute::NoUnwind);
       }))
     F.addFnAttr(Attribute::NoUnwind);
 }
 

llvm/test/CodeGen/AArch64/machine-outliner.ll

 ; RUN: llc -verify-machineinstrs -enable-machine-outliner -aarch64-load-store-renaming=true -mtriple=aarch64-apple-darwin < %s | FileCheck %s
 ; RUN: llc -verify-machineinstrs -enable-machine-outliner -aarch64-load-store-renaming=true -mtriple=aarch64-apple-darwin -mcpu=cortex-a53 -enable-misched=false < %s | FileCheck %s
 ; RUN: llc -verify-machineinstrs -enable-machine-outliner -enable-linkonceodr-outlining -mtriple=aarch64-apple-darwin < %s | FileCheck %s -check-prefix=ODR
 ; RUN: llc -verify-machineinstrs -enable-machine-outliner -mtriple=aarch64-apple-darwin -stop-after=machine-outliner < %s | FileCheck %s -check-prefix=TARGET_FEATURES
 
 ; Make sure that we inherit target features from functions and make sure we have
 ; the right function attributes.
 ; TARGET_FEATURES: define internal void @OUTLINED_FUNCTION_{{[0-9]+}}()
 ; TARGET_FEATURES-SAME: #[[ATTR_NUM:[0-9]+]]
 ; TARGET_FEATURES-DAG: attributes #[[ATTR_NUM]] = {
 ; TARGET_FEATURES-SAME: minsize
 ; TARGET_FEATURES-SAME: nounwind
 ; TARGET_FEATURES-SAME: optsize
+; TARGET_FEATURES-SAME: "target-cpu"="cyclone"
 ; TARGET_FEATURES-SAME: "target-features"="+sse"
 
 define linkonce_odr void @fish() #0 {
   ; CHECK-LABEL: _fish:
   ; CHECK-NOT: OUTLINED
   ; ODR: [[OUTLINED:OUTLINED_FUNCTION_[0-9]+]]
   %1 = alloca i32, align 4
   %2 = alloca i32, align 4