[LTO] Record whether LTOUnit splitting is enabled in index

Summary:
Records in the module summary index whether the bitcode was compiled
with the option necessary to enable splitting the LTO unit
(e.g. -fsanitize=cfi, -fwhole-program-vtables, or -fsplit-lto-unit).

The information is passed down to the ModuleSummaryIndex builder via a
new module flag "EnableSplitLTOUnit", which is propagated onto a flag
on the summary index.

This is then used during the LTO link to check whether all linked
summaries were built with the same value of this flag. If not, an error
is issued when we detect a situation requiring whole program visibility
of the class hierarchy. This is the case when both of the following
conditions are met:
1) We are performing LowerTypeTests or Whole Program Devirtualization.
2) There are type tests or type checked loads in the code.

Note I have also changed the ThinLTOBitcodeWriter to also gate the
module splitting on the value of this flag.

Reviewers: pcc

Subscribers: ormris, mehdi_amini, Prazek, inglorion, eraman, steven_wu, dexonsmith, arphaman, dang, llvm-commits

Differential Revision: https://reviews.llvm.org/D53890

llvm-svn: 350948

33 files changed, 113 insertions, 27 deletions

diff --git a/llvm/test/Bitcode/thinlto-alias.ll b/llvm/test/Bitcode/thinlto-alias.ll
index 835d720c69e..f3896d2baba 100644
--- a/llvm/test/Bitcode/thinlto-alias.ll
+++ b/llvm/test/Bitcode/thinlto-alias.ll
@@ -18,6 +18,7 @@
 ; CHECK-NEXT: <FUNCTION op0=4 op1=7
 ; CHECK:       <GLOBALVAL_SUMMARY_BLOCK
 ; CHECK-NEXT:    <VERSION
+; CHECK-NEXT:    <FLAGS
 ; See if the call to func is registered.
 ; The value id 1 matches the second FUNCTION record above.
 ; CHECK-NEXT:    <PERMODULE {{.*}} op6=1/>
diff --git a/llvm/test/Bitcode/thinlto-alias2.ll b/llvm/test/Bitcode/thinlto-alias2.ll
index 3d68e3fd4ba..8b04ee75ac5 100644
--- a/llvm/test/Bitcode/thinlto-alias2.ll
+++ b/llvm/test/Bitcode/thinlto-alias2.ll
@@ -4,6 +4,7 @@
 
 ; CHECK:       <GLOBALVAL_SUMMARY_BLOCK
 ; CHECK-NEXT:    <VERSION
+; CHECK-NEXT:    <FLAGS
 ; CHECK-NEXT:    <PERMODULE {{.*}} op4=0 op5=0 op6=[[ALIASID:[0-9]+]]/>
 ; CHECK-NEXT:    <PERMODULE {{.*}} op0=[[ALIASEEID:[0-9]+]]
 ; CHECK-NEXT:    <ALIAS {{.*}} op0=[[ALIASID]] {{.*}} op2=[[ALIASEEID]]/>
diff --git a/llvm/test/Bitcode/thinlto-function-summary-callgraph-cast.ll b/llvm/test/Bitcode/thinlto-function-summary-callgraph-cast.ll
index 79644403d38..d4b4d5491c1 100644
--- a/llvm/test/Bitcode/thinlto-function-summary-callgraph-cast.ll
+++ b/llvm/test/Bitcode/thinlto-function-summary-callgraph-cast.ll
@@ -5,6 +5,7 @@
 
 ; CHECK:       <GLOBALVAL_SUMMARY_BLOCK
 ; CHECK-NEXT:    <VERSION
+; CHECK-NEXT:    <FLAGS
 ; "op7" is a call to "callee" function.
 ; CHECK-NEXT:    <PERMODULE {{.*}} op8=3 op9=[[ALIASID:[0-9]+]]/>
 ; "another_caller" has only references but no calls.
diff --git a/llvm/test/Bitcode/thinlto-function-summary-callgraph-pgo.ll b/llvm/test/Bitcode/thinlto-function-summary-callgraph-pgo.ll
index e332224343e..b9613f732ed 100644
--- a/llvm/test/Bitcode/thinlto-function-summary-callgraph-pgo.ll
+++ b/llvm/test/Bitcode/thinlto-function-summary-callgraph-pgo.ll
@@ -16,6 +16,7 @@
 ; CHECK-NEXT: <FUNCTION op0=4 op1=4
 ; CHECK:       <GLOBALVAL_SUMMARY_BLOCK
 ; CHECK-NEXT:    <VERSION
+; CHECK-NEXT:    <FLAGS
 ; See if the call to func is registered, using the expected hotness type.
 ; CHECK-NEXT:    <PERMODULE_PROFILE {{.*}} op6=1 op7=2/>
 ; CHECK-NEXT:  </GLOBALVAL_SUMMARY_BLOCK>
diff --git a/llvm/test/Bitcode/thinlto-function-summary-callgraph-profile-summary.ll b/llvm/test/Bitcode/thinlto-function-summary-callgraph-profile-summary.ll
index 31c99c189ac..0cd10982dd5 100644
--- a/llvm/test/Bitcode/thinlto-function-summary-callgraph-profile-summary.ll
+++ b/llvm/test/Bitcode/thinlto-function-summary-callgraph-profile-summary.ll
@@ -46,6 +46,7 @@
 ; CHECK-NEXT: <FUNCTION op0=42 op1=5
 ; CHECK-LABEL:       <GLOBALVAL_SUMMARY_BLOCK
 ; CHECK-NEXT:    <VERSION
+; CHECK-NEXT:    <FLAGS
 ; CHECK-NEXT:    <VALUE_GUID op0=25 op1=123/>
 ; op4=hot1 op6=cold op8=hot2 op10=hot4 op12=none1 op14=hot3 op16=none2 op18=none3 op20=123
 ; CHECK-NEXT:    <PERMODULE_PROFILE {{.*}} op6=1 op7=3 op8=5 op9=1 op10=2 op11=3 op12=4 op13=1 op14=6 op15=2 op16=3 op17=3 op18=7 op19=2 op20=8 op21=2 op22=25 op23=4/>
diff --git a/llvm/test/Bitcode/thinlto-function-summary-callgraph-relbf.ll b/llvm/test/Bitcode/thinlto-function-summary-callgraph-relbf.ll
index 6c144652225..7c7a6f6c924 100644
--- a/llvm/test/Bitcode/thinlto-function-summary-callgraph-relbf.ll
+++ b/llvm/test/Bitcode/thinlto-function-summary-callgraph-relbf.ll
@@ -12,6 +12,7 @@
 ; CHECK-NEXT: <FUNCTION op0=17 op1=4
 ; CHECK:       <GLOBALVAL_SUMMARY_BLOCK
 ; CHECK-NEXT:    <VERSION
+; CHECK-NEXT:    <FLAGS
 ; See if the call to func is registered.
 ; CHECK-NEXT:    <PERMODULE_RELBF {{.*}} op4=1 {{.*}} op8=256
 ; CHECK-NEXT:  </GLOBALVAL_SUMMARY_BLOCK>
diff --git a/llvm/test/Bitcode/thinlto-function-summary-callgraph-sample-profile-summary.ll b/llvm/test/Bitcode/thinlto-function-summary-callgraph-sample-profile-summary.ll
index d1f980ab5f6..8bf65ab5e21 100644
--- a/llvm/test/Bitcode/thinlto-function-summary-callgraph-sample-profile-summary.ll
+++ b/llvm/test/Bitcode/thinlto-function-summary-callgraph-sample-profile-summary.ll
@@ -29,6 +29,7 @@
 
 ; CHECK-LABEL:       <GLOBALVAL_SUMMARY_BLOCK
 ; CHECK-NEXT:    <VERSION
+; CHECK-NEXT:    <FLAGS
 ; CHECK-NEXT:    <VALUE_GUID op0=26 op1=123/>
 ; op4=none1 op6=hot1 op8=cold1 op10=none2 op12=hot2 op14=cold2 op16=none3 op18=hot3 op20=cold3 op22=123
 ; CHECK-NEXT:    <PERMODULE_PROFILE {{.*}} op6=7 op7=0 op8=1 op9=3 op10=4 op11=1 op12=8 op13=0 op14=2 op15=3 op16=5 op17=1 op18=9 op19=0 op20=3 op21=3 op22=6 op23=1 op24=26 op25=4/>
diff --git a/llvm/test/Bitcode/thinlto-function-summary-callgraph.ll b/llvm/test/Bitcode/thinlto-function-summary-callgraph.ll
index a605b7ec221..0969b849bc0 100644
--- a/llvm/test/Bitcode/thinlto-function-summary-callgraph.ll
+++ b/llvm/test/Bitcode/thinlto-function-summary-callgraph.ll
@@ -17,6 +17,7 @@
 ; CHECK-NEXT: <FUNCTION op0=17 op1=4
 ; CHECK:       <GLOBALVAL_SUMMARY_BLOCK
 ; CHECK-NEXT:    <VERSION
+; CHECK-NEXT:    <FLAGS
 ; See if the call to func is registered
 ; CHECK-NEXT:    <PERMODULE {{.*}} op4=1
 ; CHECK-NEXT:  </GLOBALVAL_SUMMARY_BLOCK>
diff --git a/llvm/test/Bitcode/thinlto-function-summary.ll b/llvm/test/Bitcode/thinlto-function-summary.ll
index be7e9749086..67c50379e7a 100644
--- a/llvm/test/Bitcode/thinlto-function-summary.ll
+++ b/llvm/test/Bitcode/thinlto-function-summary.ll
@@ -19,6 +19,7 @@
 ; BC-NEXT: <ALIAS op0=67 op1=1
 ; BC: <GLOBALVAL_SUMMARY_BLOCK
 ; BC-NEXT: <VERSION
+; BC-NEXT: <FLAGS
 ; BC-NEXT: <PERMODULE {{.*}} op0=1 op1=0
 ; BC-NEXT: <PERMODULE {{.*}} op0=2 op1=0
 ; BC-NEXT: <PERMODULE {{.*}} op0=3 op1=7
diff --git a/llvm/test/LTO/Resolution/X86/export-jumptable.ll b/llvm/test/LTO/Resolution/X86/export-jumptable.ll
index d6cce854c1b..8ced9d96292 100644
--- a/llvm/test/LTO/Resolution/X86/export-jumptable.ll
+++ b/llvm/test/LTO/Resolution/X86/export-jumptable.ll
@@ -2,7 +2,7 @@
 ; the full LTO object file; any such functions will be referenced by the jump
 ; table.
 
-; RUN: opt -thinlto-bc -o %t %s
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t %s
 ; RUN: llvm-lto2 run -o %t2 -r %t,f1,p -r %t,f2,p -r %t,_start,px %t -save-temps
 ; RUN: llvm-dis %t2.1.2.internalize.bc -o - | FileCheck %s
 
diff --git a/llvm/test/LTO/Resolution/X86/local-def-dllimport.ll b/llvm/test/LTO/Resolution/X86/local-def-dllimport.ll
index ddb78fbd9a6..c97e4b7e14c 100644
--- a/llvm/test/LTO/Resolution/X86/local-def-dllimport.ll
+++ b/llvm/test/LTO/Resolution/X86/local-def-dllimport.ll
@@ -1,4 +1,4 @@
-; RUN: opt -thinlto-bc -o %t0.bc %s
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t0.bc %s
 ; RUN: llvm-lto2 run -r %t0.bc,__imp_f,l \
 ; RUN:               -r %t0.bc,g,p \
 ; RUN:               -r %t0.bc,g,l \
diff --git a/llvm/test/LTO/Resolution/X86/lowertypetests.ll b/llvm/test/LTO/Resolution/X86/lowertypetests.ll
index b87452c8e7a..e5be4b98cbf 100644
--- a/llvm/test/LTO/Resolution/X86/lowertypetests.ll
+++ b/llvm/test/LTO/Resolution/X86/lowertypetests.ll
@@ -1,4 +1,4 @@
-; RUN: opt -thinlto-bc -o %t %s
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t %s
 ; RUN: llvm-lto2 run -r %t,f,plx -r %t,g_alias,plx -r %t,foo,lx -r %t,foo,plx -r %t,bar,lx -r %t,bar,plx -o %t1 %t
 ; RUN: llvm-nm %t1.0 | FileCheck --check-prefix=MERGED %s
 ; RUN: llvm-nm %t1.1 | FileCheck %s
diff --git a/llvm/test/LTO/Resolution/X86/lto-unit-check.ll b/llvm/test/LTO/Resolution/X86/lto-unit-check.ll
new file mode 100644
index 00000000000..1736a5b216a
--- /dev/null
+++ b/llvm/test/LTO/Resolution/X86/lto-unit-check.ll
@@ -0,0 +1,55 @@
+; Test to ensure that the Enable Split LTO Unit flag is set properly in the
+; summary, and that we correctly silently handle linking bitcode files with
+; different values of this flag.
+
+; Linking bitcode both with EnableSplitLTOUnit set should work
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t1 %s
+; RUN: llvm-bcanalyzer -dump %t1 | FileCheck %s --check-prefix=SPLITLTOUNIT
+; RUN: llvm-dis -o - %t1 | FileCheck %s --check-prefix=ENABLESPLITFLAG
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t2 %s
+; RUN: llvm-bcanalyzer -dump %t2 | FileCheck %s --check-prefix=SPLITLTOUNIT
+; RUN: llvm-dis -o - %t2 | FileCheck %s --check-prefix=ENABLESPLITFLAG
+; RUN: llvm-lto2 run -o %t3 %t1 %t2
+
+; Linking bitcode both without EnableSplitLTOUnit set should work
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit=false -o %t1 %s
+; RUN: llvm-bcanalyzer -dump %t1 | FileCheck %s --check-prefix=NOSPLITLTOUNIT
+; RUN: llvm-dis -o - %t1 | FileCheck %s --check-prefix=NOENABLESPLITFLAG
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit=false -o %t2 %s
+; RUN: llvm-bcanalyzer -dump %t2 | FileCheck %s --check-prefix=NOSPLITLTOUNIT
+; RUN: llvm-dis -o - %t2 | FileCheck %s --check-prefix=NOENABLESPLITFLAG
+; RUN: llvm-lto2 run -o %t3 %t1 %t2
+
+; Linking bitcode with different values of EnableSplitLTOUnit should succeed
+; (silently skipping any optimizations like whole program devirt that rely
+; on all modules being split).
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t1 %s
+; RUN: llvm-bcanalyzer -dump %t1 | FileCheck %s --check-prefix=SPLITLTOUNIT
+; RUN: llvm-dis -o - %t1 | FileCheck %s --check-prefix=ENABLESPLITFLAG
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit=false -o %t2 %s
+; RUN: llvm-bcanalyzer -dump %t2 | FileCheck %s --check-prefix=NOSPLITLTOUNIT
+; RUN: llvm-dis -o - %t2 | FileCheck %s --check-prefix=NOENABLESPLITFLAG
+; RUN: llvm-lto2 run -o %t3 %t1 %t2
+
+; Linking bitcode with different values of EnableSplitLTOUnit (reverse order)
+; should succeed (silently skipping any optimizations like whole program devirt
+; that rely on all modules being split).
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit=false -o %t1 %s
+; RUN: llvm-bcanalyzer -dump %t1 | FileCheck %s --check-prefix=NOSPLITLTOUNIT
+; RUN: llvm-dis -o - %t1 | FileCheck %s --check-prefix=NOENABLESPLITFLAG
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t2 %s
+; RUN: llvm-bcanalyzer -dump %t2 | FileCheck %s --check-prefix=SPLITLTOUNIT
+; RUN: llvm-dis -o - %t2 | FileCheck %s --check-prefix=ENABLESPLITFLAG
+; RUN: llvm-lto2 run -o %t3 %t1 %t2
+
+; The flag should be set when splitting is disabled (for backwards compatibility
+; with older bitcode where it was always enabled).
+; SPLITLTOUNIT: <FLAGS op0=8/>
+; NOSPLITLTOUNIT: <FLAGS op0=0/>
+
+; Check that the corresponding module flag is set when expected.
+; ENABLESPLITFLAG: !{i32 1, !"EnableSplitLTOUnit", i32 1}
+; NOENABLESPLITFLAG-NOT: !{i32 1, !"EnableSplitLTOUnit", i32 1}
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/ThinLTO/X86/cache-icall.ll b/llvm/test/ThinLTO/X86/cache-icall.ll
index 5e64a713ffa..034ff97cede 100644
--- a/llvm/test/ThinLTO/X86/cache-icall.ll
+++ b/llvm/test/ThinLTO/X86/cache-icall.ll
@@ -4,8 +4,8 @@
 ; This affects code generated for any users of f(). Make sure that we don't pull a stale object
 ; file for %t.o from the cache.
 
-; RUN: opt -module-hash -module-summary -thinlto-bc %s -o %t.bc
-; RUN: opt -module-hash -module-summary -thinlto-bc %p/Inputs/cache-icall.ll -o %t2.bc
+; RUN: opt -module-hash -module-summary -thinlto-bc -thinlto-split-lto-unit %s -o %t.bc
+; RUN: opt -module-hash -module-summary -thinlto-bc -thinlto-split-lto-unit %p/Inputs/cache-icall.ll -o %t2.bc
 
 ; RUN: rm -Rf %t.cache && mkdir %t.cache
 
diff --git a/llvm/test/ThinLTO/X86/cfi-devirt.ll b/llvm/test/ThinLTO/X86/cfi-devirt.ll
index 7ade794d498..45d6960b505 100644
--- a/llvm/test/ThinLTO/X86/cfi-devirt.ll
+++ b/llvm/test/ThinLTO/X86/cfi-devirt.ll
@@ -2,7 +2,7 @@
 
 ; Test CFI devirtualization through the thin link and backend.
 
-; RUN: opt -thinlto-bc -o %t.o %s
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t.o %s
 
 ; Legacy PM
 ; FIXME: Fix machine verifier issues and remove -verify-machineinstrs=0. PR39436.
@@ -44,6 +44,27 @@
 
 ; REMARK: single-impl: devirtualized a call to _ZN1A1nEi
 
+; Next check that we emit an error when trying to LTO link this module
+; containing an llvm.type.checked.load (with a split LTO Unit) with one
+; that does not have a split LTO Unit.
+; RUN: opt -thinlto-bc -o %t2.o %S/Inputs/empty.ll
+; RUN: not llvm-lto2 run %t.o %t2.o -save-temps -pass-remarks=. \
+; RUN:   -verify-machineinstrs=0 \
+; RUN:   -o %t3 \
+; RUN:   -r=%t.o,test,px \
+; RUN:   -r=%t.o,_ZN1A1nEi,p \
+; RUN:   -r=%t.o,_ZN1B1fEi,p \
+; RUN:   -r=%t.o,_ZN1C1fEi,p \
+; RUN:   -r=%t.o,empty,p \
+; RUN:   -r=%t.o,_ZTV1B, \
+; RUN:   -r=%t.o,_ZTV1C, \
+; RUN:   -r=%t.o,_ZN1A1nEi, \
+; RUN:   -r=%t.o,_ZN1B1fEi, \
+; RUN:   -r=%t.o,_ZN1C1fEi, \
+; RUN:   -r=%t.o,_ZTV1B,px \
+; RUN:   -r=%t.o,_ZTV1C,px 2>&1 | FileCheck %s --check-prefix=ERROR
+; ERROR: LLVM ERROR: inconsistent LTO Unit splitting with llvm.type.test or llvm.type.checked.load
+
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-grtev4-linux-gnu"
 
diff --git a/llvm/test/ThinLTO/X86/cfi-distributed.ll b/llvm/test/ThinLTO/X86/cfi-distributed.ll
index 94f3f95c298..53392285154 100644
--- a/llvm/test/ThinLTO/X86/cfi-distributed.ll
+++ b/llvm/test/ThinLTO/X86/cfi-distributed.ll
@@ -3,8 +3,8 @@
 ; Test to ensure that only referenced type ID records are emitted into
 ; each distributed index file.
 
-; RUN: opt -thinlto-bc -o %t1.o %s
-; RUN: opt -thinlto-bc -o %t2.o %p/Inputs/cfi-distributed.ll
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t1.o %s
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t2.o %p/Inputs/cfi-distributed.ll
 
 ; RUN: llvm-lto2 run -thinlto-distributed-indexes %t1.o %t2.o \
 ; RUN:   -o %t3 \
diff --git a/llvm/test/ThinLTO/X86/cfi-icall.ll b/llvm/test/ThinLTO/X86/cfi-icall.ll
index 1ab184f1f19..42c26f15893 100644
--- a/llvm/test/ThinLTO/X86/cfi-icall.ll
+++ b/llvm/test/ThinLTO/X86/cfi-icall.ll
@@ -1,4 +1,4 @@
-; RUN: opt -thinlto-bc %s -o %t1.bc
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit %s -o %t1.bc
 ; RUN: llvm-lto2 run  -thinlto-distributed-indexes %t1.bc -o %t.out -save-temps \
 ; RUN:   -r %t1.bc,foo,plx \
 ; RUN:   -r %t1.bc,bar,x \
diff --git a/llvm/test/ThinLTO/X86/cfi.ll b/llvm/test/ThinLTO/X86/cfi.ll
index 9b1bde3b615..0edddb82be9 100644
--- a/llvm/test/ThinLTO/X86/cfi.ll
+++ b/llvm/test/ThinLTO/X86/cfi.ll
@@ -2,7 +2,7 @@
 
 ; Test CFI through the thin link and backend.
 
-; RUN: opt -thinlto-bc -o %t.o %s
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t.o %s
 
 ; Legacy PM
 ; RUN: llvm-lto2 run -save-temps %t.o \
diff --git a/llvm/test/ThinLTO/X86/devirt-after-icp.ll b/llvm/test/ThinLTO/X86/devirt-after-icp.ll
index 987221787e2..fd5dcb728aa 100644
--- a/llvm/test/ThinLTO/X86/devirt-after-icp.ll
+++ b/llvm/test/ThinLTO/X86/devirt-after-icp.ll
@@ -42,7 +42,7 @@
 ; will use the same vtable pointer. Without a dominance check, we could
 ; incorrectly devirtualize a->foo() to B::foo();
 
-; RUN: opt -thinlto-bc -o %t.o %s
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t.o %s
 
 ; Legacy PM
 ; FIXME: Fix machine verifier issues and remove -verify-machineinstrs=0. PR39436.
diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/circular-reference.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/circular-reference.ll
index eeda7932449..fb239b0a8a2 100644
--- a/llvm/test/Transforms/ThinLTOBitcodeWriter/circular-reference.ll
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/circular-reference.ll
@@ -1,4 +1,4 @@
-; RUN: opt -thinlto-bc -o %t %s
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t %s
 ; RUN: llvm-modextract -b -n 0 -o - %t | llvm-dis | FileCheck --check-prefix=M0 %s
 ; RUN: llvm-modextract -b -n 1 -o - %t | llvm-dis | FileCheck --check-prefix=M1 %s
 
diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/comdat.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/comdat.ll
index caea48e0a54..a43fa1cf3eb 100644
--- a/llvm/test/Transforms/ThinLTOBitcodeWriter/comdat.ll
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/comdat.ll
@@ -1,4 +1,4 @@
-; RUN: opt -thinlto-bc -o %t %s
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t %s
 ; RUN: llvm-modextract -n 0 -o - %t | llvm-dis | FileCheck --check-prefix=THIN %s
 ; RUN: llvm-modextract -n 1 -o - %t | llvm-dis | FileCheck --check-prefix=MERGED %s
 
diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/filter-alias.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/filter-alias.ll
index eb0cbe78a73..200d494f247 100644
--- a/llvm/test/Transforms/ThinLTOBitcodeWriter/filter-alias.ll
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/filter-alias.ll
@@ -1,4 +1,4 @@
-; RUN: opt -thinlto-bc -o %t %s
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t %s
 ; RUN: llvm-modextract -n 0 -o - %t | llvm-dis | FileCheck --check-prefix=CHECK0 %s
 ; RUN: llvm-modextract -n 1 -o - %t | llvm-dis | FileCheck --check-prefix=CHECK1 %s
 ; CHECK0-NOT: @{{.*}}anon{{.*}}=
diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/function-alias.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/function-alias.ll
index 119b8219bab..a1dbd963296 100644
--- a/llvm/test/Transforms/ThinLTOBitcodeWriter/function-alias.ll
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/function-alias.ll
@@ -1,4 +1,4 @@
-; RUN: opt -thinlto-bc -o %t %s
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t %s
 ; RUN: llvm-modextract -n 1 -o - %t | llvm-dis | FileCheck --check-prefix=CHECK1 %s
 
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/pr33536.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/pr33536.ll
index 661d0739401..c405c369e05 100644
--- a/llvm/test/Transforms/ThinLTOBitcodeWriter/pr33536.ll
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/pr33536.ll
@@ -1,7 +1,7 @@
 ; Test for a bug specific to the new pass manager where we may build a domtree
 ; to make more precise AA queries for functions.
 ;
-; RUN: opt -aa-pipeline=default -passes='no-op-module' -debug-pass-manager -thinlto-bc -o %t %s
+; RUN: opt -aa-pipeline=default -passes='no-op-module' -debug-pass-manager -thinlto-bc -thinlto-split-lto-unit -o %t %s
 ; RUN: llvm-modextract -b -n 0 -o - %t | llvm-dis | FileCheck --check-prefix=M0 %s
 ; RUN: llvm-modextract -b -n 1 -o - %t | llvm-dis | FileCheck --check-prefix=M1 %s
 
diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/split-internal-typeid.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/split-internal-typeid.ll
index a43db9a3755..290df00fa9e 100644
--- a/llvm/test/Transforms/ThinLTOBitcodeWriter/split-internal-typeid.ll
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/split-internal-typeid.ll
@@ -1,4 +1,4 @@
-; RUN: opt -thinlto-bc -o %t %s
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -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
diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/split-internal1.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/split-internal1.ll
index 6d18c4f6f65..42a06bdf2bf 100644
--- a/llvm/test/Transforms/ThinLTOBitcodeWriter/split-internal1.ll
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/split-internal1.ll
@@ -1,4 +1,4 @@
-; RUN: opt -thinlto-bc -o %t %s
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -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
diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/split-internal2.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/split-internal2.ll
index fbe618f08e3..02fc3d18850 100644
--- a/llvm/test/Transforms/ThinLTOBitcodeWriter/split-internal2.ll
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/split-internal2.ll
@@ -1,4 +1,4 @@
-; RUN: opt -thinlto-bc -o %t %s
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -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
diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/split-vfunc-internal.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/split-vfunc-internal.ll
index 087796b5031..7ebb30ae1aa 100644
--- a/llvm/test/Transforms/ThinLTOBitcodeWriter/split-vfunc-internal.ll
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/split-vfunc-internal.ll
@@ -1,4 +1,4 @@
-; RUN: opt -thinlto-bc -o %t %s
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t %s
 ; RUN: llvm-modextract -b -n 0 -o - %t | llvm-dis | FileCheck --check-prefix=M0 %s
 ; RUN: llvm-modextract -b -n 1 -o - %t | llvm-dis | FileCheck --check-prefix=M1 %s
 
diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/split-vfunc.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/split-vfunc.ll
index 66d37d5e8ae..fcf575188f7 100644
--- a/llvm/test/Transforms/ThinLTOBitcodeWriter/split-vfunc.ll
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/split-vfunc.ll
@@ -1,4 +1,4 @@
-; RUN: opt -thinlto-bc -o %t %s
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t %s
 ; RUN: llvm-modextract -b -n 0 -o - %t | llvm-dis | FileCheck --check-prefix=M0 %s
 ; RUN: llvm-modextract -b -n 1 -o - %t | llvm-dis | FileCheck --check-prefix=M1 %s
 
diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/split.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/split.ll
index 08ed92e7ebe..5502f7a2632 100644
--- a/llvm/test/Transforms/ThinLTOBitcodeWriter/split.ll
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/split.ll
@@ -1,6 +1,6 @@
 ; Generate bitcode files with summary, as well as minimized bitcode without
 ; the debug metadata for the thin link.
-; RUN: opt -thinlto-bc -thin-link-bitcode-file=%t2 -o %t %s
+; RUN: opt -thinlto-bc -thin-link-bitcode-file=%t2 -thinlto-split-lto-unit -o %t %s
 ; RUN: llvm-modextract -b -n 0 -o %t0.bc %t
 ; RUN: llvm-modextract -b -n 1 -o %t1.bc %t
 ; RUN: llvm-modextract -b -n 0 -o %t0.thinlink.bc %t2
diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/symver.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/symver.ll
index 078825cf468..8acdd0c6a68 100644
--- a/llvm/test/Transforms/ThinLTOBitcodeWriter/symver.ll
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/symver.ll
@@ -1,4 +1,4 @@
-; RUN: opt -thinlto-bc -o %t %s
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t %s
 ; RUN: llvm-modextract -n 1 -o - %t | llvm-dis | FileCheck %s
 
 ; The target assembly parser is required to parse the symver directives
diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/unsplittable.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/unsplittable.ll
index 5413e0f6188..46c87bc4e1f 100644
--- a/llvm/test/Transforms/ThinLTOBitcodeWriter/unsplittable.ll
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/unsplittable.ll
@@ -1,4 +1,4 @@
-; RUN: opt -thinlto-bc -thin-link-bitcode-file=%t2 -o %t %s
+; RUN: opt -thinlto-bc -thin-link-bitcode-file=%t2 -thinlto-split-lto-unit -o %t %s
 ; RUN: llvm-dis -o - %t | FileCheck %s
 ; RUN: llvm-bcanalyzer -dump %t | FileCheck --check-prefix=BCA %s
 ; When not splitting the module, the thin link bitcode file should simply be a
@@ -28,7 +28,8 @@ define void @h() comdat {
   ret void
 }
 
-; CHECK: !llvm.module.flags = !{![[FLAG:[0-9]+]]}
-; CHECK: ![[FLAG]] = !{i32 1, !"ThinLTO", i32 0}
+; CHECK: !llvm.module.flags = !{![[FLAG1:[0-9]+]], ![[FLAG2:[0-9]+]]}
+; CHECK: ![[FLAG1]] = !{i32 1, !"EnableSplitLTOUnit", i32 1}
+; CHECK: ![[FLAG2]] = !{i32 1, !"ThinLTO", i32 0}
 
 !0 = !{i32 0, !"typeid"}
diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/x86/module-asm.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/x86/module-asm.ll
index 15e47785cbe..587ab3fbb50 100644
--- a/llvm/test/Transforms/ThinLTOBitcodeWriter/x86/module-asm.ll
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/x86/module-asm.ll
@@ -1,4 +1,4 @@
-; RUN: opt -thinlto-bc -o %t %s
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t %s
 ; RUN: llvm-modextract -b -n 0 -o - %t | llvm-dis | FileCheck --check-prefix=M0 %s
 ; RUN: llvm-modextract -b -n 1 -o - %t | llvm-dis | FileCheck --check-prefix=M1 %s