Revert upstream 18bfb3a.

The commit in question causes miscompiliation of VirtualBox.  Efforts to
create a reproducer are underway, but quite complicated.

Submitted by:	kevans
Sponsored by:	DARPA

devel/llvm10/Makefile

@@ -2,7 +2,7 @@
 
 PORTNAME=	llvm
 DISTVERSION=	10.0.0
-PORTREVISION=	0
+PORTREVISION=	1
 CATEGORIES=	devel lang
 MASTER_SITES=	https://github.com/llvm/llvm-project/releases/download/llvmorg-${DISTVERSION:S/rc/-rc/}/ \
 		https://${PRE_}releases.llvm.org/${LLVM_RELEASE}/${RCDIR}

devel/llvm10/files/patch-llvm-revert-18bfb3a

@@ -0,0 +1,16 @@
+--- lib/CodeGen/Analysis.cpp.orig	2020-03-26 15:48:08 UTC
++++ lib/CodeGen/Analysis.cpp
+@@ -538,11 +538,10 @@ bool llvm::isInTailCallPosition(ImmutableCallSite CS, 
+       // Debug info intrinsics do not get in the way of tail call optimization.
+       if (isa<DbgInfoIntrinsic>(BBI))
+         continue;
+-      // A lifetime end or assume intrinsic should not stop tail call
++      // An assume intrinsic should not stop tail call
+       // optimization.
+       if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(BBI))
+-        if (II->getIntrinsicID() == Intrinsic::lifetime_end ||
+-            II->getIntrinsicID() == Intrinsic::assume)
++        if (II->getIntrinsicID() == Intrinsic::assume)
+           continue;
+       if (BBI->mayHaveSideEffects() || BBI->mayReadFromMemory() ||
+           !isSafeToSpeculativelyExecute(&*BBI))