[SystemZ] Recognize INLINEASM_BR in backend.

SystemZInstrInfo::analyzeBranch() needs to check for INLINEASM_BR
instructions, or it will crash.

Review: Ulrich Weigand
llvm-svn: 370753

llvm/lib/Target/SystemZ/SystemZInstrInfo.cpp

@@ -462,8 +462,8 @@ bool SystemZInstrInfo::analyzeBranch(MachineBasicBlock &MBB,
       break;
 
     // A terminator that isn't a branch can't easily be handled by this
-    // analysis.
-    if (!I->isBranch())
+    // analysis.  Asm goto is not understood / optimized.
+    if (!I->isBranch() || I->getOpcode() == SystemZ::INLINEASM_BR)
       return true;
 
     // Can't handle indirect branches.

llvm/test/CodeGen/SystemZ/asm-20.ll

@@ -0,0 +1,15 @@
+; Test that asm goto can be compiled.
+;
+; RUN: llc < %s -mtriple=s390x-linux-gnu
+
+define i32 @c() {
+entry:
+  callbr void asm sideeffect "", "X"(i8* blockaddress(@c, %d))
+          to label %asm.fallthrough [label %d]
+
+asm.fallthrough:               ; preds = %entry
+  br label %d
+
+d:                             ; preds = %asm.fallthrough, %entry
+  ret i32 undef
+}