Remove address taken, add optnone

[dblaikie]

Summary

Address taken function may not always be cold.
optnone functions should not be optimized.

[sebpop]

lgtm

[dblaikie]

Test case?

[hiraditya]

Will add one soon!

[hiraditya]

Adding test

[dblaikie]

test/Transforms/HotColdSplit/split-cold-1.ll

29

I'm guessing if this is marked "noinline" then this test wouldn't fail with the patch not applied? (because it'd be caught by the noinline case a few lines later - producing the same behavior)

With the "noinline" removed, does this test fail without the patch applied?

[aeubanks]

test/Transforms/HotColdSplit/split-cold-1.ll

29

This patch shouldn't be necessary, optnone requires noinline:

$ cat /tmp/a.ll
define void @test1() optnone {
  ret void
}
$ bin/opt.exe -verify -disable-output /tmp/a.ll
Attribute 'optnone' requires 'noinline'!
void ()* @test1
C:\src\llvm-project\build\rel\bin\opt.exe: C:/src/tmp/a.ll: error: input module is broken!

[dblaikie]

test/Transforms/HotColdSplit/split-cold-1.ll

29

Great! Given how old the patch is, I'll just commandeer and abandon it.

lib/Transforms/IPO/HotColdSplitting.cpp

 bool HotColdSplitting::shouldOutlineFrom(const Function &F) const {
   // Do not try to outline again from an already outlined cold function.
   if (OutlinedFunctions.count(&F))
     return false;
 
   if (F.size() <= 2)
     return false;
 
-  if (F.hasAddressTaken())
+  if (F.hasFnAttribute(Attribute::OptimizeNone))
     return false;
 
   if (F.hasFnAttribute(Attribute::AlwaysInline))
     return false;
 
   if (F.hasFnAttribute(Attribute::NoInline))
     return false;
 

test/Transforms/HotColdSplit/split-cold-1.ll

 ; RUN: opt -hotcoldsplit -S < %s | FileCheck %s
 
 ; Outlined function is called from a basic block named codeRepl
+; CHECK-LABEL: @foo
 ; CHECK: codeRepl:
 ; CHECK-NEXT: call void @foo
 define void @foo() {
 entry:
   br i1 undef, label %if.then, label %if.end
 
 if.then:                                          ; preds = %entry
   unreachable
 
 if.end:                                           ; preds = %entry
   br label %if.then12
 
 if.then12:                                        ; preds = %if.end
   br label %cleanup40
 
 cleanup40:                                        ; preds = %if.then12
   br label %return
 
 return:                                           ; preds = %cleanup40
   ret void
 }
+
+; CHECK-LABEL: @bar
+; CHECK-NOT: codeRepl:
+define void @bar() noinline optnone {
+entry:
+  br i1 undef, label %if.then, label %if.end
+
+if.then:                                          ; preds = %entry
+  unreachable
+
+if.end:                                           ; preds = %entry
+  br label %if.then12
+
+if.then12:                                        ; preds = %if.end
+  br label %cleanup40
+
+cleanup40:                                        ; preds = %if.then12
+  br label %return
+
+return:                                           ; preds = %cleanup40
+  ret void
+}