IPO: Introduce ThinLTOBitcodeWriter pass.

This pass prepares a module containing type metadata for ThinLTO by splitting
it into regular and thin LTO parts if possible, and writing both parts to
a multi-module bitcode file. Modules that do not contain type metadata are
written unmodified as a single module.

All globals with type metadata are added to the regular LTO module, and
the rest are added to the thin LTO module.

Differential Revision: https://reviews.llvm.org/D27324

llvm-svn: 289899

1 files changed, 26 insertions, 0 deletions

diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/split.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/split.ll
new file mode 100644
index 00000000000..e08e92328b5
--- /dev/null
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/split.ll
@@ -0,0 +1,26 @@
+; RUN: opt -thinlto-bc -o %t %s
+; RUN: llvm-modextract -b -n 0 -o %t0 %t
+; RUN: llvm-modextract -b -n 1 -o %t1 %t
+; RUN: not llvm-modextract -b -n 2 -o - %t 2>&1 | FileCheck --check-prefix=ERROR %s
+; RUN: llvm-dis -o - %t0 | FileCheck --check-prefix=M0 %s
+; RUN: llvm-dis -o - %t1 | FileCheck --check-prefix=M1 %s
+; RUN: llvm-bcanalyzer -dump %t0 | FileCheck --check-prefix=BCA0 %s
+; RUN: llvm-bcanalyzer -dump %t1 | FileCheck --check-prefix=BCA1 %s
+
+; ERROR: llvm-modextract: error: module index out of range; bitcode file contains 2 module(s)
+
+; BCA0: <GLOBALVAL_SUMMARY_BLOCK
+; BCA1-NOT: <GLOBALVAL_SUMMARY_BLOCK
+
+; M0: @g = external global i8{{$}}
+; M1: @g = global i8 42, !type !0
+@g = global i8 42, !type !0
+
+; M0: define i8* @f()
+; M1-NOT: @f()
+define i8* @f() {
+  ret i8* @g
+}
+
+; M1: !0 = !{i32 0, !"typeid"}
+!0 = !{i32 0, !"typeid"}