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[PECOFF] Resolve __delayLoadHelper2 if /delayload is given 

DLL delay importing is a feature to load a DLL lazily, instead of
at program start-up time.

If the feature is turned on with the /delayload flag, the linker
resolves the delay-load helper function. All function pointer table
entries for the DLL are initially pointing to the helper function.
When called, the function loads and resolves the DLL symbols using
dlopen-ish Windows system calls and then write the reuslts to the
function pointer table. The helper function is in "delayimp.lib".

Note that this feature is not completely implemented yet. LLD
also needs to emit the table that's consumed by the delay-load
helper function. That'll be done in another patch.

llvm-svn: 218943
This commit is contained in:
Rui Ueyama 2014-10-03 01:14:50 +00:00
parent 4075f6ce21
commit 711471ea1e
3 changed files with 18 additions and 1 deletions
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5
lld/lib/Driver/WinLinkDriver.cpp
View File

@ -1189,6 +1189,11 @@ bool WinLinkDriver::parse(int argc, const char *argv[],
ctx.setOutputImportLibraryPath(inputArg->getValue());
break;
case OPT_delayload:
ctx.addInitialUndefinedSymbol(
ctx.is64Bit() ? "__delayLoadHelper2" : "___delayLoadHelper2@8");
break;
case OPT_stub: {
ArrayRef<uint8_t> contents;
if (!readFile(ctx, inputArg->getValue(), contents)) {

2
lld/lib/Driver/WinLinkOptions.td
View File

@ -38,6 +38,7 @@ def subsystem : P<"subsystem", "Specify subsystem">;
def stub : P<"stub", "Specify DOS stub file">;
def opt : P<"opt", "Control optimizations">;
def implib : P<"implib", "Import library name">;
def delayload : P<"delayload", "Delay loaded DLL name">;
def manifest : F<"manifest">;
def manifest_colon : P<"manifest", "Create manifest file">;
@ -106,7 +107,6 @@ def no_incremental : F<"incremental:no">;
def nologo : F<"nologo">;
def delay : QF<"delay">;
def delayload : QF<"delayload">;
def errorreport : QF<"errorreport">;
def idlout : QF<"idlout">;
def ignore : QF<"ignore">;

12
lld/test/pecoff/delayimport.test Normal file
View File

@ -0,0 +1,12 @@
# RUN: yaml2obj %p/Inputs/vars-main.obj.yaml > %t.obj
#
# RUN: not lld -flavor link /out:%t1.exe /subsystem:console /entry:main \
# RUN: /delayload:vars.dll -- %t.obj %p/Inputs/vars.lib >& %t.log
# RUN: FileCheck -check-prefix=X86 %s < %t.log
#
# RUN: not lld -flavor link /out:%t1.exe /subsystem:console /entry:main \
# RUN: /machine:x64 /delayload:vars.dll -- %t.obj %p/Inputs/vars.lib >& %t.log
# RUN: FileCheck -check-prefix=X64 %s < %t.log
X86: Undefined symbol: {{.*}} ___delayLoadHelper2@8
X64: Undefined symbol: {{.*}} __delayLoadHelper2