PPC: Add CTR-register clobber to builtin setjmp

Because the builtin longjmp implementation uses a CTR-based indirect jump, when
the control flow arrives at the builtin setjmp call, the CTR register has
necessarily been clobbered. Correspondingly, this adds CTR to the list of
implicit definitions of the builtin setjmp pseudo instruction.

We don't need to add CTR to the implicit definitions of builtin longjmp
because, even though it does clobber the CTR register, the control flow cannot
return to inside the loop unless there is also a builtin setjmp call.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186488 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 7 insertions, 0 deletions

diff --git a/lib/Target/PowerPC/PPCCTRLoops.cpp b/lib/Target/PowerPC/PPCCTRLoops.cpp
index 30181a027a..4e30c53764 100644
--- a/lib/Target/PowerPC/PPCCTRLoops.cpp
+++ b/lib/Target/PowerPC/PPCCTRLoops.cpp
@@ -233,6 +233,13 @@ bool PPCCTRLoops::mightUseCTR(const Triple &TT, BasicBlock *BB) {
 #endif
 
           case Intrinsic::longjmp:
+
+          // Exclude eh_sjlj_setjmp; we don't need to exclude eh_sjlj_longjmp
+          // because, although it does clobber the counter register, the
+          // control can't then return to inside the loop unless there is also
+          // an eh_sjlj_setjmp.
+          case Intrinsic::eh_sjlj_setjmp:
+
           case Intrinsic::memcpy:
           case Intrinsic::memmove:
           case Intrinsic::memset: