[lld] 343ffa7 - [LLD] [COFF] Fix mingw comdat associativity for leader symbols with a different name
Martin Storsjö via llvm-commits
llvm-commits at lists.llvm.org
Mon Jul 27 07:32:18 PDT 2020
Author: Martin Storsjö
Date: 2020-07-27T17:32:08+03:00
New Revision: 343ffa70fc4c55f4dc0d717cf8c168865beaa9c4
URL: https://github.com/llvm/llvm-project/commit/343ffa70fc4c55f4dc0d717cf8c168865beaa9c4
DIFF: https://github.com/llvm/llvm-project/commit/343ffa70fc4c55f4dc0d717cf8c168865beaa9c4.diff
LOG: [LLD] [COFF] Fix mingw comdat associativity for leader symbols with a different name
For a weak symbol func in a comdat, the actual leader symbol ends up
named like .weak.func.default*. Likewise, for stdcall on i386, the symbol
may be named _func at 4, while the section suffix only is "func", which the
previous implementation didn't handle.
This fixes unwinding through weak functions when using
-ffunction-sections in mingw environments.
Differential Revision: https://reviews.llvm.org/D84607
Added:
lld/test/COFF/associative-comdat-mingw-weak.s
Modified:
lld/COFF/InputFiles.cpp
lld/test/COFF/associative-comdat-mingw-i386.s
Removed:
################################################################################
diff --git a/lld/COFF/InputFiles.cpp b/lld/COFF/InputFiles.cpp
index 0adc2b91bd999..4346b3a2ffa7b 100644
--- a/lld/COFF/InputFiles.cpp
+++ b/lld/COFF/InputFiles.cpp
@@ -348,13 +348,13 @@ void ObjFile::recordPrevailingSymbolForMingw(
// of the section chunk we actually include instead of discarding it,
// add the symbol to a map to allow using it for implicitly
// associating .[px]data$<func> sections to it.
+ // Use the suffix from the .text$<func> instead of the leader symbol
+ // name, for cases where the names
diff er (i386 mangling/decorations,
+ // cases where the leader is a weak symbol named .weak.func.default*).
int32_t sectionNumber = sym.getSectionNumber();
SectionChunk *sc = sparseChunks[sectionNumber];
if (sc && sc->getOutputCharacteristics() & IMAGE_SCN_MEM_EXECUTE) {
- StringRef name;
- name = check(coffObj->getSymbolName(sym));
- if (getMachineType() == I386)
- name.consume_front("_");
+ StringRef name = sc->getSectionName().split('$').second;
prevailingSectionMap[name] = sectionNumber;
}
}
diff --git a/lld/test/COFF/associative-comdat-mingw-i386.s b/lld/test/COFF/associative-comdat-mingw-i386.s
index 8d89478d4eb03..3ba8c1cd9a75b 100644
--- a/lld/test/COFF/associative-comdat-mingw-i386.s
+++ b/lld/test/COFF/associative-comdat-mingw-i386.s
@@ -1,10 +1,14 @@
# REQUIRES: x86
-# RUN: llvm-mc -triple=i686-windows-gnu %s -filetype=obj -o %t.obj
+# RUN: llvm-mc -triple=i686-windows-gnu %s -defsym stdcall=0 -filetype=obj -o %t.obj
# RUN: lld-link -lldmingw -entry:main %t.obj -out:%t.exe
# RUN: llvm-objdump -s %t.exe | FileCheck %s
+# RUN: llvm-mc -triple=i686-windows-gnu %s -defsym stdcall=1 -filetype=obj -o %t.stdcall.obj
+# RUN: lld-link -lldmingw -entry:main %t.stdcall.obj -out:%t.stdcall.exe
+# RUN: llvm-objdump -s %t.stdcall.exe | FileCheck %s
+
# Check that the .eh_frame comdat was included, even if it had no symbols,
# due to associativity with the symbol _foo.
@@ -19,19 +23,34 @@
.globl _main
.p2align 4, 0x90
_main:
+.if stdcall==0
call _foo
+.else
+ call _foo at 0
+.endif
ret
.section .eh_frame$foo,"dr"
.linkonce discard
.byte 0x42
+.if stdcall==0
.def _foo;
+.else
+ .def _foo at 0;
+.endif
.scl 2;
.type 32;
.endef
+.if stdcall==0
.section .text$foo,"xr",discard,_foo
.globl _foo
.p2align 4
_foo:
+.else
+ .section .text$foo,"xr",discard,_foo at 0
+ .globl _foo at 0
+ .p2align 4
+_foo at 0:
+.endif
ret
diff --git a/lld/test/COFF/associative-comdat-mingw-weak.s b/lld/test/COFF/associative-comdat-mingw-weak.s
new file mode 100644
index 0000000000000..80c738b436be4
--- /dev/null
+++ b/lld/test/COFF/associative-comdat-mingw-weak.s
@@ -0,0 +1,63 @@
+# REQUIRES: x86
+
+# RUN: llvm-mc -triple=x86_64-windows-gnu %s -filetype=obj -o %t.obj
+# RUN: llvm-readobj --symbols %t.obj | FileCheck %s --check-prefix=SYMBOL
+
+# RUN: lld-link -lldmingw -entry:main %t.obj -out:%t.exe -lldmap:%t.map -verbose
+# RUN: llvm-readobj --sections %t.exe | FileCheck %s
+
+# CHECK: Sections [
+# CHECK: Section {
+# CHECK: Number: 2
+# CHECK-LABEL: Name: .rdata (2E 72 64 61 74 61 00 00)
+# This is the critical check to show that .xdata$foo was
+# retained, while .xdata$bar wasn't. This *must* be 0x24
+# (0x4 for the .xdata section and 0x20 for the
+# .ctors/.dtors headers/ends).
+# CHECK-NEXT: VirtualSize: 0x24
+
+# Check that the weak symbols still are emitted as it was when the test was
+# written, to make sure the test still actually tests what was intended.
+
+# SYMBOL: Symbol {
+# SYMBOL: Name: foo
+# SYMBOL-NEXT: Value: 0
+# SYMBOL-NEXT: Section: IMAGE_SYM_UNDEFINED (0)
+# SYMBOL-NEXT: BaseType: Null (0x0)
+# SYMBOL-NEXT: ComplexType: Null (0x0)
+# SYMBOL-NEXT: StorageClass: WeakExternal (0x69)
+# SYMBOL-NEXT: AuxSymbolCount: 1
+# SYMBOL-NEXT: AuxWeakExternal {
+# SYMBOL-NEXT: Linked: .weak.foo.default.main (19)
+# SYMBOL-NEXT: Search: Alias (0x3)
+# SYMBOL-NEXT: }
+# SYMBOL-NEXT: }
+
+ .text
+ .globl main
+main:
+ call foo
+ retq
+
+# See associative-comdat-mingw.s for the general setup. Here, the leader
+# symbols are weak, which causes the functions foo and bar to be undefined
+# weak externals, while the actual leader symbols are named like
+# .weak.foo.default.main.
+
+ .section .xdata$foo,"dr"
+ .linkonce discard
+ .long 42
+
+ .section .xdata$bar,"dr"
+ .linkonce discard
+ .long 43
+
+ .section .text$foo,"xr",discard,foo
+ .weak foo
+foo:
+ ret
+
+ .section .text$bar,"xr",discard,bar
+ .weak bar
+bar:
+ ret
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