Imported Upstream version 6.0.0.172

Former-commit-id: f3cc9b82f3e5bd8f0fd3ebc098f789556b44e9cd

external/llvm/test/Bitcode/mdnodes-distinct-in-post-order.ll

@@ -0,0 +1,30 @@
+; RUN: llvm-as <%s -bitcode-mdindex-threshold=0 | llvm-bcanalyzer -dump | FileCheck %s -check-prefix=CHECK  -check-prefix=MDINDEX
+; RUN: llvm-as <%s | llvm-bcanalyzer -dump | FileCheck %s -check-prefix=CHECK
+; Check that distinct nodes are emitted in post-order to avoid unnecessary
+; forward references.
+
+; Nodes in this testcase are numbered to match how they are referenced in
+; bitcode.  !3 is referenced as opN=3.
+
+; The leafs should come first (in either order).
+; CHECK:       <DISTINCT_NODE/>
+; CHECK-NEXT:  <DISTINCT_NODE/>
+!1 = distinct !{}
+!2 = distinct !{}
+
+; CHECK-NEXT:  <DISTINCT_NODE op0=1 op1=2/>
+!3 = distinct !{!1, !2}
+
+; CHECK-NEXT:  <DISTINCT_NODE op0=1 op1=3 op2=2/>
+!4 = distinct !{!1, !3, !2}
+
+; Before the named records we emit the index containing the position of the
+; previously emitted records, but only if we have a number of record above
+; a threshold (can be controlled through `-bitcode-mdindex-threshold`).
+; MDINDEX:  <INDEX {{.*}} (offset match)
+
+; Note: named metadata nodes are not cannot reference null so their operands
+; are numbered off-by-one.
+; CHECK-NEXT:  <NAME
+; CHECK-NEXT:  <NAMED_NODE op0=3/>
+!named = !{!4}