[lld] [lld][WebAssembly] Fix stub library deps causing LTO archive members to be required post-LTO (PR #101894)
Sam Clegg via llvm-commits
llvm-commits at lists.llvm.org
Tue Aug 6 15:03:27 PDT 2024
https://github.com/sbc100 updated https://github.com/llvm/llvm-project/pull/101894
>From d7dfe2b0e70aff2ee4db9676281640056120ec4f Mon Sep 17 00:00:00 2001
From: Sam Clegg <sbc at chromium.org>
Date: Sun, 4 Aug 2024 07:17:55 -0700
Subject: [PATCH 1/3] [lld][WebAssembly] Fix stub library deps causing LTO
archive members to be required post-LTO
Fixes: https://github.com/emscripten-core/emscripten/issues/16836
Fixes: https://github.com/emscripten-core/emscripten/issues/20275
---
lld/test/wasm/lto/stub-library.s | 15 +++++++++------
lld/wasm/Driver.cpp | 11 +++++++++++
lld/wasm/InputFiles.cpp | 4 ++--
3 files changed, 22 insertions(+), 8 deletions(-)
diff --git a/lld/test/wasm/lto/stub-library.s b/lld/test/wasm/lto/stub-library.s
index 20e2a62211413..a5c724012faec 100644
--- a/lld/test/wasm/lto/stub-library.s
+++ b/lld/test/wasm/lto/stub-library.s
@@ -1,12 +1,15 @@
# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown -o %t.o %s
-# RUN: llvm-as %S/Inputs/foo.ll -o %t1.o
-# RUN: wasm-ld %t.o %t1.o %p/Inputs/stub.so -o %t.wasm
+# RUN: mkdir -p %t
+# RUN: llvm-as %S/Inputs/foo.ll -o %t/foo.o
+# RUN: rm -f %t/libfoo.a
+# RUN: llvm-ar rcs %t/libfoo.a %t/foo.o
+# RUN: wasm-ld %t.o %t/libfoo.a %p/Inputs/stub.so -o %t.wasm
# RUN: obj2yaml %t.wasm | FileCheck %s
-# The function `bar` is declared in stub.so and depends on `foo`, which happens
-# be in an LTO object.
-# This verifies that stub library dependencies (required exports) can be defined
-# in LTO objects.
+## The function `bar` is declared in stub.so and depends on `foo`, which happens
+## be in an LTO object, in an archive file.
+## This verifies that stub library dependencies (required exports) can be defined
+## in LTO objects.
.functype bar () -> ()
.globl _start
diff --git a/lld/wasm/Driver.cpp b/lld/wasm/Driver.cpp
index 8c83d17db02f5..44f35eb82aaa2 100644
--- a/lld/wasm/Driver.cpp
+++ b/lld/wasm/Driver.cpp
@@ -949,6 +949,17 @@ static void processStubLibrariesPreLTO() {
auto* needed = symtab->find(dep);
if (needed ) {
needed->isUsedInRegularObj = true;
+ // Like with handleLibcall we have extract any LTO archive members
+ // that might need to be exported due to stub library symbol being
+ // used. Without this the LTO object could be extracted during
+ // processStubLibraries, which is too late since LTO has already
+ // beeing performed at that point.
+ if (needed->isLazy() && isa<BitcodeFile>(needed->getFile())) {
+ if (!config->whyExtract.empty())
+ ctx.whyExtractRecords.emplace_back(toString(stub_file),
+ needed->getFile(), *needed);
+ cast<LazySymbol>(needed)->extract();
+ }
}
}
}
diff --git a/lld/wasm/InputFiles.cpp b/lld/wasm/InputFiles.cpp
index f3f0ef9a99497..706ee25d5aae2 100644
--- a/lld/wasm/InputFiles.cpp
+++ b/lld/wasm/InputFiles.cpp
@@ -744,7 +744,7 @@ Symbol *ObjFile::createUndefined(const WasmSymbol &sym, bool isCalledDirectly) {
llvm_unreachable("unknown symbol kind");
}
-StringRef strip(StringRef s) { return s.trim(' '); }
+static StringRef strip(StringRef s) { return s.trim(' '); }
void StubFile::parse() {
bool first = true;
@@ -761,7 +761,7 @@ void StubFile::parse() {
}
// Lines starting with # are considered comments
- if (line.starts_with("#"))
+ if (line.starts_with("#") || !line.size())
continue;
StringRef sym;
>From 7c29cef8fae1c8774cf97765f921dd9cfbb0e347 Mon Sep 17 00:00:00 2001
From: Sam Clegg <sbc at chromium.org>
Date: Tue, 6 Aug 2024 14:56:43 -0700
Subject: [PATCH 2/3] feedback
---
lld/test/wasm/lto/stub-library.s | 8 ++++----
lld/wasm/Driver.cpp | 10 +++++-----
2 files changed, 9 insertions(+), 9 deletions(-)
diff --git a/lld/test/wasm/lto/stub-library.s b/lld/test/wasm/lto/stub-library.s
index a5c724012faec..aa892b62b714c 100644
--- a/lld/test/wasm/lto/stub-library.s
+++ b/lld/test/wasm/lto/stub-library.s
@@ -6,10 +6,10 @@
# RUN: wasm-ld %t.o %t/libfoo.a %p/Inputs/stub.so -o %t.wasm
# RUN: obj2yaml %t.wasm | FileCheck %s
-## The function `bar` is declared in stub.so and depends on `foo`, which happens
-## be in an LTO object, in an archive file.
-## This verifies that stub library dependencies (required exports) can be defined
-## in LTO objects.
+## The function `bar` is declared in stub.so and depends on `foo`, which in this
+## case is defined in an LTO object, inside an archive file.
+## This verifies that stub library dependencies (required exports) can be
+## defined in LTO objects.
.functype bar () -> ()
.globl _start
diff --git a/lld/wasm/Driver.cpp b/lld/wasm/Driver.cpp
index 44f35eb82aaa2..5368fe79b7eb8 100644
--- a/lld/wasm/Driver.cpp
+++ b/lld/wasm/Driver.cpp
@@ -949,11 +949,11 @@ static void processStubLibrariesPreLTO() {
auto* needed = symtab->find(dep);
if (needed ) {
needed->isUsedInRegularObj = true;
- // Like with handleLibcall we have extract any LTO archive members
- // that might need to be exported due to stub library symbol being
- // used. Without this the LTO object could be extracted during
- // processStubLibraries, which is too late since LTO has already
- // beeing performed at that point.
+ // Like with handleLibcall we have to extract any LTO archive
+ // members that might need to be exported due to stub library
+ // symbols being referenced. Without this the LTO object could be
+ // extracted during processStubLibraries, which is too late since
+ // LTO has already being performed at that point.
if (needed->isLazy() && isa<BitcodeFile>(needed->getFile())) {
if (!config->whyExtract.empty())
ctx.whyExtractRecords.emplace_back(toString(stub_file),
>From 0a2c7317018b33c9784ce0ae70a658b42942a613 Mon Sep 17 00:00:00 2001
From: Sam Clegg <sbc at chromium.org>
Date: Tue, 6 Aug 2024 15:03:11 -0700
Subject: [PATCH 3/3] feedback
---
lld/test/wasm/lto/stub-library.s | 18 ++++++++++++------
1 file changed, 12 insertions(+), 6 deletions(-)
diff --git a/lld/test/wasm/lto/stub-library.s b/lld/test/wasm/lto/stub-library.s
index aa892b62b714c..36d6b7b3f38aa 100644
--- a/lld/test/wasm/lto/stub-library.s
+++ b/lld/test/wasm/lto/stub-library.s
@@ -1,15 +1,21 @@
+## The function `bar` is declared in stub.so and depends on `foo` which is
+## defined in an LTO object. We also test the case where the LTO object is
+## with an archive file.
+## This verifies that stub library dependencies (which are required exports) can
+## be defined in LTO objects, even when they are within archive files.
+
# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown -o %t.o %s
# RUN: mkdir -p %t
# RUN: llvm-as %S/Inputs/foo.ll -o %t/foo.o
+# RUN: wasm-ld %t.o %t/foo.o %p/Inputs/stub.so -o %t.wasm
+# RUN: obj2yaml %t.wasm | FileCheck %s
+
+## Run the same test but with foo.o inside of an archive file.
# RUN: rm -f %t/libfoo.a
# RUN: llvm-ar rcs %t/libfoo.a %t/foo.o
-# RUN: wasm-ld %t.o %t/libfoo.a %p/Inputs/stub.so -o %t.wasm
-# RUN: obj2yaml %t.wasm | FileCheck %s
+# RUN: wasm-ld %t.o %t/libfoo.a %p/Inputs/stub.so -o %t2.wasm
+# RUN: obj2yaml %t2.wasm | FileCheck %s
-## The function `bar` is declared in stub.so and depends on `foo`, which in this
-## case is defined in an LTO object, inside an archive file.
-## This verifies that stub library dependencies (required exports) can be
-## defined in LTO objects.
.functype bar () -> ()
.globl _start
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