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[LLD] [COFF] Fix implicit DLL entry point for MinGW (#171680)

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Previously, LLD would always set the implicit entry point for DLLs to
the symbol that is prefixed with an underscore. However, mingw-w64
defines it without that underscore.

This change fixes that by adding a special branch for MinGW. Also, it
simplifies tests that use MinGW style DLL entry symbol by skipping the
entry point argument.

Note, tests that use MSVC style DLL entry symbol and LLD in MinGW mode,
will now require using explicit entry point. I believe this is sensible.
When an explicit entry point is passed, i.e. LLD is called by Clang or
GCC, there will be no observable difference.

Fixes https://github.com/llvm/llvm-project/issues/171441
This commit is contained in:
Mateusz Mikuła 2025-12-17 22:22:01 +01:00 committed by GitHub
parent 21fd8cc2a5
commit 2824225d27
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
12 changed files with 24 additions and 17 deletions
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11
lld/COFF/Driver.cpp
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@ -1489,6 +1489,14 @@ getVFS(COFFLinkerContext &ctx, const opt::InputArgList &args) {
return nullptr;
}
static StringRef DllDefaultEntryPoint(MachineTypes machine, bool mingw) {
if (mingw) {
return (machine == I386) ? "_DllMainCRTStartup@12" : "DllMainCRTStartup";
} else {
return (machine == I386) ? "__DllMainCRTStartup@12" : "_DllMainCRTStartup";
}
}
constexpr const char *lldsaveTempsValues[] = {
"resolution", "preopt", "promote", "internalize", "import",
"opt", "precodegen", "prelink", "combinedindex"};
@ -2408,8 +2416,7 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
symtab.entry = symtab.addGCRoot(symtab.mangle(arg->getValue()), true);
} else if (!symtab.entry && !config->noEntry) {
if (args.hasArg(OPT_dll)) {
StringRef s = (config->machine == I386) ? "__DllMainCRTStartup@12"
: "_DllMainCRTStartup";
StringRef s = DllDefaultEntryPoint(config->machine, config->mingw);
symtab.entry = symtab.addGCRoot(s, true);
} else if (config->driverWdm) {
// /driver:wdm implies /entry:_NtProcessStartup

2
lld/test/COFF/autoimport-arm-code.s
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@ -2,7 +2,7 @@
# RUN: echo -e ".global variable\n.global DllMainCRTStartup\n.thumb\n.text\nDllMainCRTStartup:\nbx lr\n.data\nvariable:\n.long 42" > %t-lib.s
# RUN: llvm-mc -triple=armv7-windows-gnu %t-lib.s -filetype=obj -o %t-lib.obj
# RUN: lld-link -out:%t-lib.dll -dll -entry:DllMainCRTStartup %t-lib.obj -lldmingw -implib:%t-lib.lib
# RUN: lld-link -out:%t-lib.dll -dll %t-lib.obj -lldmingw -implib:%t-lib.lib
# RUN: llvm-mc -triple=armv7-windows-gnu %s -filetype=obj -o %t.obj
# RUN: not lld-link -lldmingw -out:%t.exe -entry:main %t.obj %t-lib.lib 2>&1 | FileCheck %s

2
lld/test/COFF/autoimport-arm-data.s
View File

@ -2,7 +2,7 @@
# RUN: echo -e ".global variable\n.global DllMainCRTStartup\n.thumb\n.text\nDllMainCRTStartup:\nbx lr\n.data\nvariable:\n.long 42" > %t-lib.s
# RUN: llvm-mc -triple=armv7-windows-gnu %t-lib.s -filetype=obj -o %t-lib.obj
# RUN: lld-link -out:%t-lib.dll -dll -entry:DllMainCRTStartup %t-lib.obj -lldmingw -implib:%t-lib.lib
# RUN: lld-link -out:%t-lib.dll -dll %t-lib.obj -lldmingw -implib:%t-lib.lib
# RUN: llvm-mc -triple=armv7-windows-gnu %s -filetype=obj -o %t.obj
# RUN: lld-link -lldmingw -out:%t.exe -entry:main %t.obj %t-lib.lib -verbose

2
lld/test/COFF/autoimport-arm64-code.s
View File

@ -2,7 +2,7 @@
# RUN: echo -e ".global variable\n.global DllMainCRTStartup\n.text\nDllMainCRTStartup:\nret\n.data\nvariable:\n.long 42" > %t-lib.s
# RUN: llvm-mc -triple=aarch64-windows-gnu %t-lib.s -filetype=obj -o %t-lib.obj
# RUN: lld-link -out:%t-lib.dll -dll -entry:DllMainCRTStartup %t-lib.obj -lldmingw -implib:%t-lib.lib
# RUN: lld-link -out:%t-lib.dll -dll %t-lib.obj -lldmingw -implib:%t-lib.lib
# RUN: llvm-mc -triple=aarch64-windows-gnu %s -filetype=obj -o %t.obj
# RUN: not lld-link -lldmingw -out:%t.exe -entry:main %t.obj %t-lib.lib 2>&1 | FileCheck %s

2
lld/test/COFF/autoimport-arm64-data.s
View File

@ -2,7 +2,7 @@
# RUN: echo -e ".global variable\n.global DllMainCRTStartup\n.text\nDllMainCRTStartup:\nret\n.data\nvariable:\n.long 42" > %t-lib.s
# RUN: llvm-mc -triple=aarch64-windows-gnu %t-lib.s -filetype=obj -o %t-lib.obj
# RUN: lld-link -out:%t-lib.dll -dll -entry:DllMainCRTStartup %t-lib.obj -lldmingw -implib:%t-lib.lib
# RUN: lld-link -out:%t-lib.dll -dll %t-lib.obj -lldmingw -implib:%t-lib.lib
# RUN: llvm-mc -triple=aarch64-windows-gnu %s -filetype=obj -o %t.obj
# RUN: lld-link -lldmingw -out:%t.exe -entry:main %t.obj %t-lib.lib -verbose

2
lld/test/COFF/autoimport-debug.s
View File

@ -10,7 +10,7 @@
## debug info.
# RUN: llvm-mc -triple=x86_64-windows-gnu %t.dir/lib.s -filetype=obj -o %t.dir/lib.obj
# RUN: lld-link -out:%t.dir/lib.dll -dll -entry:DllMainCRTStartup %t.dir/lib.obj -lldmingw -implib:%t.dir/lib.lib
# RUN: lld-link -out:%t.dir/lib.dll -dll %t.dir/lib.obj -lldmingw -implib:%t.dir/lib.lib
# RUN: llvm-mc -triple=x86_64-windows-gnu %t.dir/main.s -filetype=obj -o %t.dir/main.obj
# RUN: lld-link -lldmingw -out:%t.dir/main.exe -entry:main %t.dir/main.obj %t.dir/lib.lib -opt:noref -debug:dwarf -runtime-pseudo-reloc:no

2
lld/test/COFF/autoimport-gc.s
View File

@ -2,7 +2,7 @@
# RUN: split-file %s %t.dir
# RUN: llvm-mc -triple=x86_64-windows-gnu %t.dir/lib.s -filetype=obj -o %t.dir/lib.obj
# RUN: lld-link -out:%t.dir/lib.dll -dll -entry:DllMainCRTStartup %t.dir/lib.obj -lldmingw -implib:%t.dir/lib.lib
# RUN: lld-link -out:%t.dir/lib.dll -dll %t.dir/lib.obj -lldmingw -implib:%t.dir/lib.lib
# RUN: llvm-mc -triple=x86_64-windows-gnu %t.dir/main.s -filetype=obj -o %t.dir/main.obj
# RUN: lld-link -lldmingw -out:%t.dir/main.exe -entry:main %t.dir/main.obj %t.dir/lib.lib -opt:ref -debug:dwarf

2
lld/test/COFF/autoimport-lto.ll
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@ -2,7 +2,7 @@
; RUN: echo -e ".global variable\n.global DllMainCRTStartup\n.text\nDllMainCRTStartup:\nret\n.data\nvariable:\n.long 42" > %t-lib.s
; RUN: llvm-mc -triple=x86_64-windows-gnu %t-lib.s -filetype=obj -o %t-lib.obj
; RUN: lld-link -out:%t-lib.dll -dll -entry:DllMainCRTStartup %t-lib.obj -lldmingw -implib:%t-lib.lib
; RUN: lld-link -out:%t-lib.dll -dll %t-lib.obj -lldmingw -implib:%t-lib.lib
; RUN: llvm-as -o %t.obj %s
; RUN: lld-link -lldmingw -out:%t.exe -entry:entry %t.obj %t-lib.lib

2
lld/test/COFF/autoimport-refptr.s
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@ -2,7 +2,7 @@
# RUN: echo -e ".global variable\n.global DllMainCRTStartup\n.text\nDllMainCRTStartup:\nret\n.data\nvariable:\n.long 42" > %t-lib.s
# RUN: llvm-mc -triple=x86_64-windows-gnu %t-lib.s -filetype=obj -o %t-lib.obj
# RUN: lld-link -out:%t-lib.dll -dll -entry:DllMainCRTStartup %t-lib.obj -lldmingw -implib:%t-lib.lib
# RUN: lld-link -out:%t-lib.dll -dll %t-lib.obj -lldmingw -implib:%t-lib.lib
# RUN: llvm-mc -triple=x86_64-windows-gnu %s -defsym listptrs=1 -filetype=obj -o %t.obj
# RUN: lld-link -lldmingw -out:%t.exe -entry:main %t.obj %t-lib.lib -verbose

2
lld/test/COFF/autoimport-x86.s
View File

@ -2,7 +2,7 @@
# RUN: echo -e ".global variable\n.global DllMainCRTStartup\n.text\nDllMainCRTStartup:\nret\n.data\nvariable:\n.long 42" > %t-lib.s
# RUN: llvm-mc -triple=x86_64-windows-gnu %t-lib.s -filetype=obj -o %t-lib.obj
# RUN: lld-link -out:%t-lib.dll -dll -entry:DllMainCRTStartup %t-lib.obj -lldmingw -implib:%t-lib.lib
# RUN: lld-link -out:%t-lib.dll -dll %t-lib.obj -lldmingw -implib:%t-lib.lib
# RUN: llvm-mc -triple=x86_64-windows-gnu -defsym listptrs=1 %s -filetype=obj -o %t.obj
# RUN: lld-link -lldmingw -debug:symtab -out:%t.exe -entry:main %t.obj %t-lib.lib -verbose

4
lld/test/COFF/exclude-all.s
View File

@ -2,7 +2,7 @@
# RUN: llvm-mc -triple=i686-windows-gnu %s -filetype=obj -o %t.obj
# RUN: lld-link -lldmingw -exclude-all-symbols -dll -out:%t.dll -entry:DllMainCRTStartup@12 %t.obj
# RUN: lld-link -lldmingw -exclude-all-symbols -dll -out:%t.dll %t.obj
# RUN: llvm-readobj --coff-exports %t.dll | FileCheck %s -check-prefix=NO-EXPORTS
# NO-EXPORTS-NOT: Name:
@ -25,7 +25,7 @@ _dataSym:
# RUN: yaml2obj %p/Inputs/export.yaml -o %t.obj
#
# RUN: lld-link -safeseh:no -out:%t.dll -dll %t.obj -lldmingw -exclude-all-symbols -output-def:%t.def
# RUN: lld-link -safeseh:no -out:%t.dll -dll %t.obj -lldmingw -exclude-all-symbols -entry:_DllMainCRTStartup -output-def:%t.def
# RUN: llvm-readobj --coff-exports %t.dll | FileCheck -check-prefix=DLLEXPORT %s
# DLLEXPORT: Name: exportfn3

8
lld/test/COFF/export-all.s
View File

@ -2,7 +2,7 @@
# RUN: llvm-mc -triple=i686-windows-gnu %s -filetype=obj -o %t.obj
# RUN: lld-link -lldmingw -dll -out:%t.dll -entry:DllMainCRTStartup@12 %t.obj -implib:%t.lib
# RUN: lld-link -lldmingw -dll -out:%t.dll %t.obj -implib:%t.lib
# RUN: llvm-readobj --coff-exports %t.dll | grep Name: | FileCheck %s
# RUN: llvm-readobj --coff-exports %t.dll | FileCheck %s --check-prefix=CHECK-RVA
# RUN: llvm-readobj %t.lib | FileCheck -check-prefix=IMPLIB %s
@ -57,7 +57,7 @@ __imp__unexported:
# RUN: yaml2obj %p/Inputs/export.yaml -o %t.obj
#
# RUN: lld-link -safeseh:no -out:%t.dll -dll %t.obj -lldmingw -export-all-symbols -output-def:%t.def
# RUN: lld-link -safeseh:no -out:%t.dll -dll %t.obj -lldmingw -export-all-symbols -entry:_DllMainCRTStartup -output-def:%t.def
# RUN: llvm-readobj --coff-exports %t.dll | FileCheck -check-prefix=CHECK2 %s
# RUN: cat %t.def | FileCheck -check-prefix=CHECK2-DEF %s
@ -88,7 +88,7 @@ __imp__unexported:
# RUN: llvm-ar rcs %t.dir/libs/libmingwex.a %t.dir/libs/mingwfunc.o
# RUN: echo -e ".global crtfunc\n.text\ncrtfunc:\nret\n" > %t.dir/libs/crtfunc.s
# RUN: llvm-mc -triple=x86_64-windows-gnu %t.dir/libs/crtfunc.s -filetype=obj -o %t.dir/libs/crt2.o
# RUN: lld-link -safeseh:no -out:%t.dll -dll -entry:DllMainCRTStartup %t.main.obj -lldmingw %t.dir/libs/crt2.o %t.dir/libs/libmingwex.a -output-def:%t.def
# RUN: lld-link -safeseh:no -out:%t.dll -dll %t.main.obj -lldmingw %t.dir/libs/crt2.o %t.dir/libs/libmingwex.a -output-def:%t.def
# RUN: echo "EOF" >> %t.def
# RUN: cat %t.def | FileCheck -check-prefix=CHECK-EXCLUDE %s
@ -99,7 +99,7 @@ __imp__unexported:
# Test that libraries included with -wholearchive: are autoexported, even if
# they are in a library that otherwise normally would be excluded.
# RUN: lld-link -safeseh:no -out:%t.dll -dll -entry:DllMainCRTStartup %t.main.obj -lldmingw %t.dir/libs/crt2.o -wholearchive:%t.dir/libs/libmingwex.a -output-def:%t.def
# RUN: lld-link -safeseh:no -out:%t.dll -dll %t.main.obj -lldmingw %t.dir/libs/crt2.o -wholearchive:%t.dir/libs/libmingwex.a -output-def:%t.def
# RUN: echo "EOF" >> %t.def
# RUN: cat %t.def | FileCheck -check-prefix=CHECK-WHOLEARCHIVE %s