[lld][WebAssembly] Implement various thinlto flags

lld/test/wasm/lto/Inputs/thinlto_empty.ll

@@ -0,0 +1,2 @@
+target datalayout = "e-m:e-p:32:32-p10:8:8-p20:8:8-i64:64-n32:64-S128-ni:1:10:20"
+target triple = "wasm32-unknown-unknown"

lld/test/wasm/lto/obj-path.ll

@@ -0,0 +1,94 @@
+;; Copied from testr/ELF/lto/obj-path.ll
+;; Test --lto-obj-path= for regular LTO.
+
+; RUN: rm -rf %t && split-file %s %t && cd %t
+; RUN: mkdir d
+; RUN: opt 1.ll -o 1.bc
+; RUN: opt 2.ll -o d/2.bc
+
+; RUN: rm -f objpath.o
+; RUN: wasm-ld --lto-obj-path=objpath.o -shared 1.bc d/2.bc -o 3
+; RUN: llvm-nm 3 | FileCheck %s --check-prefix=NM
+; RUN: llvm-objdump -d objpath.o | FileCheck %s
+; RUN: ls 3* objpath* | count 2
+
+; RUN: rm -f 3 objpath.o
+; RUN: wasm-ld --thinlto-index-only=3.txt --lto-obj-path=objpath.o -shared 1.bc d/2.bc -o 3
+; RUN: llvm-objdump -d objpath.o | FileCheck %s
+; RUN: not ls 3
+
+; NM: T f
+; NM: T g
+
+; CHECK: file format wasm
+; CHECK: <f>:
+; CHECK: <g>:
+
+;; Test --lto-obj-path= for ThinLTO.
+; RUN: opt -module-summary 1.ll -o 1.bc
+; RUN: opt -module-summary 2.ll -o d/2.bc
+
+; RUN: wasm-ld --lto-obj-path=objpath.o -shared 1.bc d/2.bc -o 3
+; RUN: llvm-nm 3 | FileCheck %s --check-prefix=NM3
+; RUN: llvm-objdump -d objpath.o1 | FileCheck %s --check-prefix=CHECK1
+; RUN: llvm-objdump -d objpath.o2 | FileCheck %s --check-prefix=CHECK2
+
+; NM3:      T f
+; NM3-NEXT: T g
+
+; CHECK1:       file format wasm
+; CHECK1-EMPTY:
+; CHECK1-NEXT:  Disassembly of section CODE:
+; CHECK1:  <f>:
+; CHECK1-EMPTY:
+; CHECK1-NEXT:    end
+; CHECK1-NOT:   {{.}}
+
+; CHECK2:       file format wasm
+; CHECK2-EMPTY:
+; CHECK2-NEXT:  Disassembly of section CODE:
+; CHECK2:  <g>:
+; CHECK2-EMPTY:
+; CHECK2-NEXT:    end
+; CHECK2-NOT:   {{.}}
+
+;; With --thinlto-index-only, --lto-obj-path= creates just one file.
+; RUN: rm -f objpath.o objpath.o1 objpath.o2
+; RUN: wasm-ld --thinlto-index-only --lto-obj-path=objpath.o -shared 1.bc d/2.bc -o /dev/null
+; RUN: llvm-objdump -d objpath.o | FileCheck %s --check-prefix=EMPTY
+; RUN: not ls objpath.o1
+; RUN: not ls objpath.o2
+
+;; Ensure lld emits empty combined module if specific obj-path.
+; RUN: mkdir obj
+; RUN: wasm-ld --lto-obj-path=objpath.o -shared 1.bc d/2.bc -o obj/out --save-temps
+; RUN: ls obj/out.lto.o out.lto.1.o d/out.lto.2.o
+
+;; Ensure lld does not emit empty combined module by default.
+; RUN: rm -fr obj && mkdir obj
+; RUN: wasm-ld -shared 1.bc d/2.bc -o obj/out --save-temps
+; RUN: not test -e obj/out.lto.o
+
+; EMPTY:     file format wasm
+; EMPTY-NOT: {{.}}
+
+;--- 1.ll
+target datalayout = "e-m:e-p:32:32-p10:8:8-p20:8:8-i64:64-n32:64-S128-ni:1:10:20"
+target triple = "wasm32-unknown-unknown"
+
+declare void @g(...)
+
+define void @f() {
+entry:
+  call void (...) @g()
+  ret void
+}
+
+;--- 2.ll
+target datalayout = "e-m:e-p:32:32-p10:8:8-p20:8:8-i64:64-n32:64-S128-ni:1:10:20"
+target triple = "wasm32-unknown-unknown"
+
+define void @g() {
+entry:
+  ret void
+}

lld/test/wasm/lto/parallel.ll

@@ -1,8 +1,8 @@
-; RUN: llvm-as -o %t.bc %s
-; RUN: rm -f %t.lto.o %t1.lto.o
-; RUN: wasm-ld --lto-partitions=2 -save-temps -o %t %t.bc -r
-; RUN: llvm-nm %t.lto.o | FileCheck --check-prefix=CHECK0 %s
-; RUN: llvm-nm %t1.lto.o | FileCheck --check-prefix=CHECK1 %s
+; RUN: rm -rf %t && mkdir %t && cd %t
+; RUN: llvm-as -o a.bc %s
+; RUN: wasm-ld --lto-partitions=2 -save-temps -o out a.bc -r
+; RUN: llvm-nm out.lto.o | FileCheck --check-prefix=CHECK0 %s
+; RUN: llvm-nm out.lto.1.o | FileCheck --check-prefix=CHECK1 %s
 
 target datalayout = "e-m:e-p:32:32-p10:8:8-p20:8:8-i64:64-n32:64-S128-ni:1:10:20"
 target triple = "wasm32-unknown-unknown-wasm"

lld/test/wasm/lto/thinlto-index-only.ll

@@ -0,0 +1,145 @@
+; RUN: rm -rf %t && split-file %s %t && cd %t
+; RUN: mkdir d
+
+;; First ensure that the ThinLTO handling in lld handles
+;; bitcode without summary sections gracefully and generates index file.
+; RUN: llvm-as 1.ll -o 1.o
+; RUN: llvm-as %p/Inputs/thinlto.ll -o d/2.o
+; RUN: wasm-ld --thinlto-index-only -shared 1.o d/2.o -o 3
+; RUN: ls d/2.o.thinlto.bc
+; RUN: not test -e 3
+; RUN: wasm-ld -shared 1.o d/2.o -o 3
+; RUN: llvm-nm 3 | FileCheck %s --check-prefix=NM
+
+;; Basic ThinLTO tests.
+; RUN: llvm-as 0.ll -o 0.o
+; RUN: opt -module-summary 1.ll -o 1.o
+; RUN: opt -module-summary %p/Inputs/thinlto.ll -o d/2.o
+; RUN: opt -module-summary %p/Inputs/thinlto_empty.ll -o 3.o
+; RUN: cp 3.o 4.o
+
+;; Ensure lld doesn't generates index files when --thinlto-index-only is not enabled.
+; RUN: rm -f 1.o.thinlto.bc d/2.o.thinlto.bc
+; RUN: wasm-ld -shared 1.o d/2.o -o /dev/null
+; RUN: not ls 1.o.thinlto.bc
+; RUN: not ls d/2.o.thinlto.bc
+
+;; Ensure lld generates an index and not a binary if requested.
+; RUN: wasm-ld --thinlto-index-only -shared 1.o --start-lib d/2.o 3.o --end-lib 4.o -o 4
+; RUN: not test -e 4
+; RUN: llvm-bcanalyzer -dump 1.o.thinlto.bc | FileCheck %s --check-prefix=BACKEND1
+; RUN: llvm-bcanalyzer -dump d/2.o.thinlto.bc | FileCheck %s --check-prefix=BACKEND2
+; RUN: llvm-dis < 3.o.thinlto.bc | FileCheck %s --check-prefix=BACKEND3
+; RUN: llvm-dis < 4.o.thinlto.bc | FileCheck %s --check-prefix=BACKEND4
+
+; RUN: rm -f 1.o.thinlto.bc d/2.o.thinlto.bc 3.o.thinlto.bc 4.o.thinlto.bc
+; RUN: wasm-ld --thinlto-index-only=4.txt --thinlto-emit-imports-files -shared 1.o --start-lib d/2.o 3.o --end-lib 4.o -o 4
+; RUN: not test -e 4
+; RUN: FileCheck %s --check-prefix=RSP --implicit-check-not={{.}} < 4.txt
+; RUN: llvm-bcanalyzer -dump 1.o.thinlto.bc | FileCheck %s --check-prefix=BACKEND1
+; RUN: llvm-bcanalyzer -dump d/2.o.thinlto.bc | FileCheck %s --check-prefix=BACKEND2
+; RUN: llvm-dis < 3.o.thinlto.bc | FileCheck %s --check-prefix=BACKEND3
+; RUN: llvm-dis < 4.o.thinlto.bc | FileCheck %s --check-prefix=BACKEND4
+; RUN: FileCheck %s --check-prefix=IMPORTS1 --implicit-check-not={{.}} < 1.o.imports
+; RUN: count 0 < d/2.o.imports
+;; Test that LLD generates an empty index even for lazy object file that is not added to link.
+; RUN: count 0 < 3.o.imports
+; RUN: count 0 < 4.o.imports
+
+;; Test interaction with --save-temps.
+; RUN: rm -f 4.txt 1.o.thinlto.bc d/2.o.thinlto.bc 3.o.thinlto.bc 4.o.thinlto.bc
+; RUN: wasm-ld --thinlto-index-only=4.txt --thinlto-emit-imports-files --save-temps -shared 0.o 1.o --start-lib d/2.o 3.o --end-lib 4.o -o t
+; RUN: not test -e 4
+; RUN: FileCheck %s --check-prefix=RSP --implicit-check-not={{.}} < 4.txt
+; RUN: llvm-bcanalyzer -dump 1.o.thinlto.bc | FileCheck %s --check-prefix=BACKEND1
+; RUN: FileCheck %s --check-prefix=IMPORTS1 --implicit-check-not={{.}} < 1.o.imports
+; RUN: FileCheck %s --check-prefix=RESOLUTION < t.resolution.txt
+; RUN: llvm-dis < t.index.bc | FileCheck %s --check-prefix=INDEX-BC
+
+; RSP:      1.o
+; RSP-NEXT: d/2.o
+; RSP-NEXT: 4.o
+
+; IMPORTS1: d/2.o
+
+; RESOLUTION:      0.o
+; RESOLUTION-NEXT: -r=0.o,foo,px
+; RESOLUTION-NEXT: 1.o
+
+; INDEX-BC:      ^0 = module: (path: "1.o", hash: (0, 0, 0, 0, 0))
+; INDEX-BC-NEXT: ^1 = module: (path: "4.o", hash: (0, 0, 0, 0, 0))
+; INDEX-BC-NEXT: ^2 = module: (path: "d/2.o", hash: (0, 0, 0, 0, 0))
+
+;; Ensure LLD generates an empty index for each bitcode file even if all bitcode files are lazy.
+; RUN: rm -f 1.o.thinlto.bc
+; RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown /dev/null -o dummy.o
+; RUN: wasm-ld --thinlto-index-only -shared dummy.o --start-lib 1.o --end-lib -o /dev/null
+; RUN: ls 1.o.thinlto.bc
+
+;; Ensure when the same bitcode object is given as both lazy and non-lazy,
+;; LLD does not generate an empty index for the lazy object.
+; RUN: rm -f d/2.o.thinlto.bc
+; RUN: wasm-ld --thinlto-index-only -shared 1.o d/2.o --start-lib d/2.o --end-lib -o /dev/null
+; RUN: llvm-dis < d/2.o.thinlto.bc | grep -q '\^0 = module:'
+; RUN: rm -f d/2.o.thinlto.bc
+; RUN: wasm-ld --thinlto-index-only -shared --start-lib d/2.o --end-lib d/2.o 1.o -o /dev/null
+; RUN: llvm-dis < d/2.o.thinlto.bc | grep -q '\^0 = module:'
+
+;; Ensure when the same lazy bitcode object is given multiple times,
+;; no empty index file is generated if one of the copies is linked.
+; RUN: rm -f d/2.o.thinlto.bc
+; RUN: wasm-ld --thinlto-index-only -shared 1.o --start-lib d/2.o --end-lib --start-lib d/2.o --end-lib -o /dev/null
+; RUN: llvm-dis < d/2.o.thinlto.bc | grep -q '\^0 = module:'
+
+; NM: T f
+
+;; The backend index for this module contains summaries from itself and
+;; Inputs/thinlto.ll, as it imports from the latter.
+; BACKEND1: <MODULE_STRTAB_BLOCK
+; BACKEND1-NEXT: <ENTRY {{.*}} record string = '1.o'
+; BACKEND1-NEXT: <ENTRY {{.*}} record string = 'd/2.o'
+; BACKEND1-NEXT: </MODULE_STRTAB_BLOCK
+; BACKEND1: <GLOBALVAL_SUMMARY_BLOCK
+; BACKEND1: <VERSION
+; BACKEND1: <FLAGS
+; BACKEND1: <VALUE_GUID {{.*}} op0={{1|2}} {{op1=3060885059 op2=1207956914|op1=3432075125 op2=3712786831}}
+; BACKEND1: <VALUE_GUID {{.*}} op0={{1|2}} {{op1=3060885059 op2=1207956914|op1=3432075125 op2=3712786831}}
+; BACKEND1: <COMBINED
+; BACKEND1: <COMBINED
+; BACKEND1: </GLOBALVAL_SUMMARY_BLOCK
+
+;; The backend index for Input/thinlto.ll contains summaries from itself only,
+;; as it does not import anything.
+; BACKEND2: <MODULE_STRTAB_BLOCK
+; BACKEND2-NEXT: <ENTRY {{.*}} record string = 'd/2.o'
+; BACKEND2-NEXT: </MODULE_STRTAB_BLOCK
+; BACKEND2-NEXT: <GLOBALVAL_SUMMARY_BLOCK
+; BACKEND2-NEXT: <VERSION
+; BACKEND2-NEXT: <FLAGS
+; BACKEND2-NEXT: <VALUE_GUID {{.*}} op0=1 op1=3060885059 op2=1207956914
+; BACKEND2-NEXT: <COMBINED
+; BACKEND2-NEXT: </GLOBALVAL_SUMMARY_BLOCK
+
+; BACKEND3: ^0 = flags:
+
+; BACKEND4: ^0 = module: (path: "4.o", hash: (0, 0, 0, 0, 0))
+
+;--- 0.ll
+target datalayout = "e-m:e-p:32:32-p10:8:8-p20:8:8-i64:64-n32:64-S128-ni:1:10:20"
+target triple = "wasm32-unknown-unknown"
+
+define void @foo() {
+  ret void
+}
+
+;--- 1.ll
+target datalayout = "e-m:e-p:32:32-p10:8:8-p20:8:8-i64:64-n32:64-S128-ni:1:10:20"
+target triple = "wasm32-unknown-unknown"
+
+declare void @g(...)
+
+define void @f() {
+entry:
+  call void (...) @g()
+  ret void
+}

lld/test/wasm/lto/thinlto.ll

@@ -1,53 +1,56 @@
 ; Basic ThinLTO tests.
-; RUN: opt -module-summary %s -o %t1.o
-; RUN: opt -module-summary %p/Inputs/thinlto.ll -o %t2.o
+; RUN: rm -rf %t && mkdir %t && cd %t
+; RUN: mkdir d e
+
+; RUN: opt -module-summary %s -o a.o
+; RUN: opt -module-summary %p/Inputs/thinlto.ll -o d/b.o
 
 ; First force single-threaded mode
-; RUN: rm -f %t31.lto.o %t32.lto.o
-; RUN: wasm-ld -r -save-temps --thinlto-jobs=1 %t1.o %t2.o -o %t3
-; RUN: llvm-nm %t31.lto.o | FileCheck %s --check-prefix=NM1
-; RUN: llvm-nm %t32.lto.o | FileCheck %s --check-prefix=NM2
+; RUN: rm -f out.lto.a.o d/out.lto.b.o
+; RUN: wasm-ld -r -save-temps --thinlto-jobs=1 a.o d/b.o -o e/out
+; RUN: llvm-nm out.lto.a.o | FileCheck %s --check-prefix=NM1
+; RUN: llvm-nm d/out.lto.b.o | FileCheck %s --check-prefix=NM2
 
 ; Next force multi-threaded mode
-; RUN: rm -f %t31.lto.o %t32.lto.o
-; RUN: wasm-ld -r -save-temps --thinlto-jobs=2 %t1.o %t2.o -o %t3
-; RUN: llvm-nm %t31.lto.o | FileCheck %s --check-prefix=NM1
-; RUN: llvm-nm %t32.lto.o | FileCheck %s --check-prefix=NM2
+; RUN: rm -f out.lto.a.o d/out.lto.b.o
+; RUN: wasm-ld -r -save-temps --thinlto-jobs=2 a.o d/b.o -o e/out
+; RUN: llvm-nm out.lto.a.o | FileCheck %s --check-prefix=NM1
+; RUN: llvm-nm d/out.lto.b.o | FileCheck %s --check-prefix=NM2
 
 ;; --thinlto-jobs= defaults to --threads=.
-; RUN: rm -f %t31.lto.o %t32.lto.o
-; RUN: wasm-ld -r -save-temps --threads=2 %t1.o %t2.o -o %t3
-; RUN: llvm-nm %t31.lto.o | FileCheck %s --check-prefix=NM1
-; RUN: llvm-nm %t32.lto.o | FileCheck %s --check-prefix=NM2
+; RUN: rm -f out.lto.a.o d/out.lto.b.o
+; RUN: wasm-ld -r -save-temps --threads=2 a.o d/b.o -o e/out
+; RUN: llvm-nm out.lto.a.o | FileCheck %s --check-prefix=NM1
+; RUN: llvm-nm d/out.lto.b.o | FileCheck %s --check-prefix=NM2
 
 ;; --thinlto-jobs= overrides --threads=.
-; RUN: rm -f %t31.lto.o %t32.lto.o
-; RUN: wasm-ld -r -save-temps --threads=1 --thinlto-jobs=2 %t1.o %t2.o -o %t3
-; RUN: llvm-nm %t31.lto.o | FileCheck %s --check-prefix=NM1
-; RUN: llvm-nm %t32.lto.o | FileCheck %s --check-prefix=NM2
+; RUN: rm -f out.lto.a.o d/out.lto.b.o
+; RUN: wasm-ld -r -save-temps --threads=1 --thinlto-jobs=2 a.o d/b.o -o e/out
+; RUN: llvm-nm out.lto.a.o | FileCheck %s --check-prefix=NM1
+; RUN: llvm-nm d/out.lto.b.o | FileCheck %s --check-prefix=NM2
 
 ; Test with all threads, on all cores, on all CPU sockets
-; RUN: rm -f %t31.lto.o %t32.lto.o
-; RUN: wasm-ld -r -save-temps --thinlto-jobs=all %t1.o %t2.o -o %t3
-; RUN: llvm-nm %t31.lto.o | FileCheck %s --check-prefix=NM1
-; RUN: llvm-nm %t32.lto.o | FileCheck %s --check-prefix=NM2
+; RUN: rm -f out.lto.a.o d/out.lto.b.o
+; RUN: wasm-ld -r -save-temps --thinlto-jobs=all a.o d/b.o -o e/out
+; RUN: llvm-nm out.lto.a.o | FileCheck %s --check-prefix=NM1
+; RUN: llvm-nm d/out.lto.b.o | FileCheck %s --check-prefix=NM2
 
 ; Test with many more threads than the system has
-; RUN: rm -f %t31.lto.o %t32.lto.o
-; RUN: wasm-ld -r -save-temps --thinlto-jobs=100 %t1.o %t2.o -o %t3
-; RUN: llvm-nm %t31.lto.o | FileCheck %s --check-prefix=NM1
-; RUN: llvm-nm %t32.lto.o | FileCheck %s --check-prefix=NM2
+; RUN: rm -f out.lto.a.o d/out.lto.b.o
+; RUN: wasm-ld -r -save-temps --thinlto-jobs=100 a.o d/b.o -o e/out
+; RUN: llvm-nm out.lto.a.o | FileCheck %s --check-prefix=NM1
+; RUN: llvm-nm d/out.lto.b.o | FileCheck %s --check-prefix=NM2
 
 ; Test with a bad value
-; RUN: rm -f %t31.lto.o %t32.lto.o
-; RUN: not wasm-ld -r -save-temps --thinlto-jobs=foo %t1.o %t2.o -o %t3 2>&1 | FileCheck %s --check-prefix=BAD-JOBS
+; RUN: rm -f out.lto.a.o d/out.lto.b.o
+; RUN: not wasm-ld -r -save-temps --thinlto-jobs=foo a.o d/b.o -o e/out 2>&1 | FileCheck %s --check-prefix=BAD-JOBS
 ; BAD-JOBS: error: --thinlto-jobs: invalid job count: foo
 
 ; Check without --thinlto-jobs (which currently defaults to heavyweight_hardware_concurrency, meanning one thread per hardware core -- not SMT)
-; RUN: rm -f %t31.lto.o %t32.lto.o
-; RUN: wasm-ld -r -save-temps %t1.o %t2.o -o %t3
-; RUN: llvm-nm %t31.lto.o | FileCheck %s --check-prefix=NM1
-; RUN: llvm-nm %t32.lto.o | FileCheck %s --check-prefix=NM2
+; RUN: rm -f out.lto.a.o d/out.lto.b.o
+; RUN: wasm-ld -r -save-temps a.o d/b.o -o e/out
+; RUN: llvm-nm out.lto.a.o | FileCheck %s --check-prefix=NM1
+; RUN: llvm-nm d/out.lto.b.o | FileCheck %s --check-prefix=NM2
 
 ; NM1: T f
 ; NM2: T g

lld/wasm/CMakeLists.txt

@@ -21,6 +21,7 @@ add_lld_library(lldWasm
   LINK_COMPONENTS
   ${LLVM_TARGETS_TO_BUILD}
   BinaryFormat
+  BitWriter
   Core
   Demangle
   LTO

lld/wasm/Config.h

@@ -79,6 +79,9 @@ struct Configuration {
   // Because dyamanic linking under Wasm is still experimental we default to
   // static linking
   bool isStatic = true;
+  bool thinLTOEmitImportsFiles;
+  bool thinLTOEmitIndexFiles;
+  bool thinLTOIndexOnly;
   bool trace;
   uint64_t globalBase;
   uint64_t initialHeap;
@@ -95,16 +98,18 @@ struct Configuration {
   unsigned ltoo;
   llvm::CodeGenOptLevel ltoCgo;
   unsigned optimize;
-  llvm::StringRef thinLTOJobs;
   bool ltoDebugPassManager;
   UnresolvedPolicy unresolvedSymbols;
   BuildIdKind buildId = BuildIdKind::None;
 
   llvm::StringRef entry;
+  llvm::StringRef ltoObjPath;
   llvm::StringRef mapFile;
   llvm::StringRef outputFile;
   llvm::StringRef soName;
   llvm::StringRef thinLTOCacheDir;
+  llvm::StringRef thinLTOJobs;
+  llvm::StringRef thinLTOIndexOnlyArg;
   llvm::StringRef whyExtract;
 
   llvm::StringSet<> allowUndefinedSymbols;
@@ -126,6 +131,7 @@ struct Ctx {
   llvm::SmallVector<StubFile *, 0> stubFiles;
   llvm::SmallVector<SharedFile *, 0> sharedFiles;
   llvm::SmallVector<BitcodeFile *, 0> bitcodeFiles;
+  llvm::SmallVector<BitcodeFile *, 0> lazyBitcodeFiles;
   llvm::SmallVector<InputFunction *, 0> syntheticFunctions;
   llvm::SmallVector<InputGlobal *, 0> syntheticGlobals;
   llvm::SmallVector<InputTable *, 0> syntheticTables;