Set max atomic size for PowerPC.

32-bit PowerPC doesn't have instructions for lock-free atomic ops on
8-byte values, and needs libcalls like __atomic_fetch_add_8().  In
code like "_Atomic long long a; a++;", clang doesn't emit a libcall.
This was causing linker errors on symbols like __sync_fetch_and_add_8.

Now that LLVM knows the max atomic size, its AtomicExpandPass changes
these 8-byte ops into libcalls.

ok mortimer@

1 files changed, 4 insertions, 1 deletions

diff --git a/gnu/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/gnu/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index 60fa5e4afef..8fd8548b99d 100644
--- a/gnu/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/gnu/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -1034,7 +1034,10 @@ PPCTargetLowering::PPCTargetLowering(const PPCTargetMachine &TM,
 
   setOperationAction(ISD::READCYCLECOUNTER, MVT::i64, isPPC64 ? Legal : Custom);
 
-  if (!isPPC64) {
+  if (isPPC64)
+    setMaxAtomicSizeInBitsSupported(64);
+  else {
+    setMaxAtomicSizeInBitsSupported(32);
     setOperationAction(ISD::ATOMIC_LOAD,  MVT::i64, Expand);
     setOperationAction(ISD::ATOMIC_STORE, MVT::i64, Expand);
   }