Revert "Outline non returning functions unless a longjmp"

This reverts commit 2079798.

This patch (https://reviews.llvm.org/D69257) cannot complete a stage2
build due to the change:

```
CI->getCalledFunction()->getName().contains("longjmp")
```

There are several concrete issues here:

  - The callee may not be a function, so `getCalledFunction` can assert.
  - The called value may not have a name, so `getName` can assert.
  - There's no distinction made between "my_longjmp_test_helper" and the
    actual longjmp libcall.

At a higher level, there's a serious layering problem here. The
splitting pass makes policy decisions in a general way (e.g. based on
attributes or profile data). Special-casing certain names breaks the
layering. It subverts the work of library maintainers (who may now need
to opt-out of unexpected optimization behavior for any affected
functions) and can lead to inconsistent optimization behavior (as not
all llvm passes special-case ".*longjmp.*" in the same way).

The patch may need significant revision to address these issues.

But the immediate issue is that this crashes while compiling llvm's unit
tests in a stage2 build (due to the `getName` problem).

Author: vedantk

llvm/lib/Transforms/IPO/HotColdSplitting.cpp

@@ -113,8 +113,7 @@ bool blockEndsInUnreachable(const BasicBlock &BB) {
   return !(isa<ReturnInst>(I) || isa<IndirectBrInst>(I));
 }
 
-bool unlikelyExecuted(BasicBlock &BB, ProfileSummaryInfo *PSI,
-                      BlockFrequencyInfo *BFI) {
+bool unlikelyExecuted(BasicBlock &BB) {
   // Exception handling blocks are unlikely executed.
   if (BB.isEHPad() || isa<ResumeInst>(BB.getTerminator()))
     return true;
@@ -127,19 +126,12 @@ bool unlikelyExecuted(BasicBlock &BB, ProfileSummaryInfo *PSI,
         return true;
 
   // The block is cold if it has an unreachable terminator, unless it's
-  // preceded by a call to a (possibly warm) noreturn call (e.g. longjmp);
-  // in the case of a longjmp, if the block is cold according to
-  // profile information, we mark it as unlikely to be executed as well.
+  // preceded by a call to a (possibly warm) noreturn call (e.g. longjmp).
   if (blockEndsInUnreachable(BB)) {
     if (auto *CI =
             dyn_cast_or_null<CallInst>(BB.getTerminator()->getPrevNode()))
-      if (CI->hasFnAttr(Attribute::NoReturn)) {
-        if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI))
-          return (II->getIntrinsicID() != Intrinsic::eh_sjlj_longjmp) ||
-                 (BFI && PSI->isColdBlock(&BB, BFI));
-        return !CI->getCalledFunction()->getName().contains("longjmp") ||
-               (BFI && PSI->isColdBlock(&BB, BFI));
-      }
+      if (CI->hasFnAttr(Attribute::NoReturn))
+        return false;
     return true;
   }
 
@@ -599,7 +591,7 @@ bool HotColdSplitting::outlineColdRegions(Function &F, bool HasProfileSummary) {
       continue;
 
     bool Cold = (BFI && PSI->isColdBlock(BB, BFI)) ||
-                (EnableStaticAnalysis && unlikelyExecuted(*BB, PSI, BFI));
+                (EnableStaticAnalysis && unlikelyExecuted(*BB));
     if (!Cold)
       continue;