DI: Require subprogram definitions to be distinct

As a follow-up to r246098, require `DISubprogram` definitions
(`isDefinition: true`) to be 'distinct'.  Specifically, add an assembler
check, a verifier check, and bitcode upgrading logic to combat testcase
bitrot after the `DIBuilder` change.

While working on the testcases, I realized that
test/Linker/subprogram-linkonce-weak-odr.ll isn't relevant anymore.  Its
purpose was to check for a corner case in PR22792 where two subprogram
definitions match exactly and share the same metadata node.  The new
verifier check, requiring that subprogram definitions are 'distinct',
precludes that possibility.

I updated almost all the IR with the following script:

    git grep -l -E -e '= !DISubprogram\(.* isDefinition: true' |
    grep -v test/Bitcode |
    xargs sed -i '' -e 's/= \(!DISubprogram(.*, isDefinition: true\)/= distinct \1/'

Likely some variant of would work for out-of-tree testcases.

llvm-svn: 246327

1 files changed, 11 insertions, 0 deletions

diff --git a/llvm/test/Bitcode/DISubprogram-distinct-definitions.ll b/llvm/test/Bitcode/DISubprogram-distinct-definitions.ll
new file mode 100644
index 00000000000..5c6fb908be9
--- /dev/null
+++ b/llvm/test/Bitcode/DISubprogram-distinct-definitions.ll
@@ -0,0 +1,11 @@
+; RUN: llvm-dis < %s.bc | FileCheck %s
+; Check that subprogram definitions are correctly upgraded to 'distinct'.
+; Bitcode compiled from r245235 of the 3.7 release branch.
+
+!named = !{!0}
+!0 = distinct !DICompileUnit(language: 12, file: !1, subprograms: !2)
+!1 = !DIFile(filename: "path/to/file", directory: "/path/to/dir")
+!2 = !{!3}
+
+; CHECK: = distinct !DISubprogram({{.*}}, isDefinition: true
+!3 = !DISubprogram(name: "foo", isDefinition: true)