[PATCH] D73139: [LLD][COFF] Enable linking of __declspec(selectany) symbols from Clang and GCC
Markus Böck via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Wed Jan 22 08:41:06 PST 2020
zero9178 updated this revision to Diff 239611.
zero9178 added a comment.
Removed /:nodefaultlib. Applied formatting
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D73139/new/
https://reviews.llvm.org/D73139
Files:
lld/COFF/InputFiles.cpp
lld/test/COFF/comdat-gcc-compatibility.s
Index: lld/test/COFF/comdat-gcc-compatibility.s
===================================================================
--- lld/test/COFF/comdat-gcc-compatibility.s
+++ lld/test/COFF/comdat-gcc-compatibility.s
@@ -0,0 +1,12 @@
+# RUN: llvm-mc %s -triple x86_64-pc-win32 -defsym obj=0 -filetype=obj -o %t1.obj
+# RUN: llvm-mc %s -triple x86_64-pc-win32 -defsym obj=1 -filetype=obj -o %t2.obj
+# RUN: lld-link /lldmingw /noentry /dll %t1.obj %t2.obj /out:%t3.dll
+# RUN: not lld-link /noentry /dll %t1.obj %t2.obj /out:%t3.dll
+.if obj==0
+ .section .text$nm, "", discard, symbol
+.else
+ .section .text$nm, "", same_size, symbol
+.endif
+ .globl symbol
+symbol:
+ .long 1
Index: lld/COFF/InputFiles.cpp
===================================================================
--- lld/COFF/InputFiles.cpp
+++ lld/COFF/InputFiles.cpp
@@ -500,6 +500,17 @@
leaderSelection = selection = IMAGE_COMDAT_SELECT_LARGEST;
}
+ // GCCs __declspec(selectany) doesn't actually pick "any" but "same size as".
+ // Clang on the other hand picks "any". To be able to link two object files
+ // with a __declspec(selectany) declaration, one compiled with gcc and the
+ // other with clang, we merge them as proper "same size as"
+ if (config->mingw && ((selection == IMAGE_COMDAT_SELECT_ANY &&
+ leaderSelection == IMAGE_COMDAT_SELECT_SAME_SIZE) ||
+ (selection == IMAGE_COMDAT_SELECT_SAME_SIZE &&
+ leaderSelection == IMAGE_COMDAT_SELECT_ANY))) {
+ leaderSelection = selection = IMAGE_COMDAT_SELECT_SAME_SIZE;
+ }
+
// Other than that, comdat selections must match. This is a bit more
// strict than link.exe which allows merging "any" and "largest" if "any"
// is the first symbol the linker sees, and it allows merging "largest"
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