ping.
Can I pull the trigger to always run the pass? Here is a patch with some tweaks
from the previous one because we don’t actually want to run the pass with -O0.
diff --git a/lib/CodeGen/BackendUtil.cpp b/lib/CodeGen/BackendUtil.cpp
index 7bc351a..177deb1 100644
--- a/lib/CodeGen/BackendUtil.cpp
+++ b/lib/CodeGen/BackendUtil.cpp
@@ -570,8 +570,7 @@ bool EmitAssemblyHelper::AddEmitPasses(BackendAction Action,
// Add ObjC ARC final-cleanup optimizations. This is done as part of the
// "codegen" passes so that it isn't run multiple times when there is
// inlining happening.
- if (LangOpts.ObjCAutoRefCount &&
- CodeGenOpts.OptimizationLevel > 0)
+ if (CodeGenOpts.OptimizationLevel > 0)
PM->add(createObjCARCContractPass());
if (TM->addPassesToEmitFile(*PM, OS, CGFT,
Thanks
Steven
> On Mar 16, 2015, at 2:19 PM, Steven Wu <[email protected]> wrote:
>
> No patch for the previous email. I really wanted to move the ObjCConstract
> pass to libLLVMCodeGen but the pass is very tightly coupled with other parts
> of ObjC-ARC. I will leave that as future work.
> I will just fix clang to run the pass before they can be decoupled. Here is
> the patch:
>
> From fca14e93b929b6aa5e22ad64040ad8b9e3965364 Mon Sep 17 00:00:00 2001
> From: Steven Wu <[email protected]>
> Date: Mon, 16 Mar 2015 14:08:42 -0700
> Subject: [PATCH] Always run ObjCARCContract in clang to match LTO
>
> ObjCARCContract is mandatory for ObjC code with ARC. It only runs when
> -fobj-arc flag is specified. Since -fobj-arc is a frontend flag, there are
> no way to run the ObjCARCContract pass from bitcode input in clang.
> Since ObjCARCContract checks the presence of ARC function in the module
> level, it has little overhead for code not using ObjCARC (not observable
> under -O0), it is now enable all the time to match the behavior in LTO.
> ---
> lib/CodeGen/BackendUtil.cpp | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/lib/CodeGen/BackendUtil.cpp b/lib/CodeGen/BackendUtil.cpp
> index d3d5bcf..09f1e2a 100644
> --- a/lib/CodeGen/BackendUtil.cpp
> +++ b/lib/CodeGen/BackendUtil.cpp
> @@ -566,9 +566,7 @@ bool EmitAssemblyHelper::AddEmitPasses(BackendAction
> Action,
> // Add ObjC ARC final-cleanup optimizations. This is done as part of the
> // "codegen" passes so that it isn't run multiple times when there is
> // inlining happening.
> - if (LangOpts.ObjCAutoRefCount &&
> - CodeGenOpts.OptimizationLevel > 0)
> - PM->add(createObjCARCContractPass());
> + PM->add(createObjCARCContractPass());
>
> if (TM->addPassesToEmitFile(*PM, OS, CGFT,
> /*DisableVerify=*/!CodeGenOpts.VerifyModule)) {
> --
> 2.3.0 (Apple Git-54)
>
> Steven
>
>
>> On Mar 16, 2015, at 11:12 AM, Duncan P. N. Exon Smith <[email protected]>
>> wrote:
>>
>>
>>> On 2015 Mar 16, at 10:34, Steven Wu <[email protected]> wrote:
>>>
>>> After a detailed looked at ObjCContract pass, it already has a module level
>>> check to decide whether the pass should be run or not. It checks the
>>> presence of ARC function at module level. The overhead of this check is
>>> very low and it doesn’t hurt to run it all the time. So there are three
>>> options now:
>>> 1. Function attribute: the advantage is that we can run ObjCContract pass
>>> only on function instead of the entire module. The disadvantage is that it
>>> introduces complication in the bicode and we have to run upgrade pass for
>>> old bitcode by checking all the presence of ARC function.
>>> 2. Module flag: it is really not helpful to create a module flag after I
>>> find there is almost no overhead to run ObjCARCContract pass on a module
>>> without Objc-ARC. It is also tricky to get the consistence behavior after
>>> the upgrade of bitcode by only checking the module flag.
>>> 3. Always run the pass to match the behavior in LTO: this seems the
>>> simplest solution. I also run full LNT test-suite to prove that there are
>>> no overhead to run the pass on the code without ObjC-ARC. I force
>>> ObjCARCContract pass to run at -O0 on the code and there are no observable
>>> overhead even at -O0. Results attached.
>>>
>>> Steven
>>> <no-objc-arc-O0.json><objc-arc-O0.json>
>>
>> (Did you mean to attach a patch to this email?)
>>
>> #3 makes sense to me given how cheap the checks are. I hadn't
>> realized they were on the module.
>>
>>>
>>>
>>>> On Mar 3, 2015, at 1:20 PM, Duncan P. N. Exon Smith <[email protected]>
>>>> wrote:
>>>>
>>>>
>>>>> On 2015-Mar-02, at 14:56, Steven Wu <[email protected]> wrote:
>>>>>
>>>>> Fix the code according to Duncan's feedback. Attempt to add a testcase.
>>>>> Not sure if there is better to check if the pass is run other than using
>>>>> -debug-pass=Arguments.
>>>>
>>>> Steven and I talked offline. All the passes that depend on this flag
>>>> are function passes. Since it's possible to switch on a per-function
>>>> basis, this should be a function attribute (not a module flag).
>>>>
>>>>> http://reviews.llvm.org/D7799
>>>>>
>>>>> Files:
>>>>> lib/CodeGen/BackendUtil.cpp
>>>>> lib/CodeGen/CGObjCMac.cpp
>>>>> test/CodeGen/arc-passes.m
>>>>>
>>>>> Index: lib/CodeGen/BackendUtil.cpp
>>>>> ===================================================================
>>>>> --- lib/CodeGen/BackendUtil.cpp
>>>>> +++ lib/CodeGen/BackendUtil.cpp
>>>>> @@ -569,7 +569,7 @@
>>>>> // Add ObjC ARC final-cleanup optimizations. This is done as part of the
>>>>> // "codegen" passes so that it isn't run multiple times when there is
>>>>> // inlining happening.
>>>>> - if (LangOpts.ObjCAutoRefCount &&
>>>>> + if (TheModule->getModuleFlag("Objective-C ARC") &&
>>>>> CodeGenOpts.OptimizationLevel > 0)
>>>>> PM->add(createObjCARCContractPass());
>>>>>
>>>>> Index: lib/CodeGen/CGObjCMac.cpp
>>>>> ===================================================================
>>>>> --- lib/CodeGen/CGObjCMac.cpp
>>>>> +++ lib/CodeGen/CGObjCMac.cpp
>>>>> @@ -4284,6 +4284,12 @@
>>>>> }
>>>>> }
>>>>>
>>>>> + // Add ObjCAutoRefCount as a module flag
>>>>> + if (CGM.getLangOpts().ObjCAutoRefCount) {
>>>>> + Mod.addModuleFlag(llvm::Module::Error,
>>>>> + "Objective-C ARC", 1u);
>>>>> + }
>>>>> +
>>>>> // Indicate whether we're compiling this to run on a simulator.
>>>>> const llvm::Triple &Triple = CGM.getTarget().getTriple();
>>>>> if (Triple.isiOS() &&
>>>>> Index: test/CodeGen/arc-passes.m
>>>>> ===================================================================
>>>>> --- /dev/null
>>>>> +++ test/CodeGen/arc-passes.m
>>>>> @@ -0,0 +1,12 @@
>>>>> +// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -fobjc-arc -emit-llvm
>>>>> %s -o - | FileCheck %s
>>>>> +// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -emit-llvm %s -o - |
>>>>> FileCheck %s -check-prefix=NO-ARC
>>>>> +// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -fobjc-arc -emit-obj
>>>>> -O3 %s -o /dev/null -mllvm -debug-pass=Arguments 2>&1 | FileCheck %s
>>>>> -check-prefix=ARC-PASS
>>>>> +// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -emit-obj -O3 %s -o
>>>>> /dev/null -mllvm -debug-pass=Arguments 2>&1 | FileCheck %s
>>>>> -check-prefix=NO-ARC-PASS
>>>>> +
>>>>> +// CHECK: !{i32 1, !"Objective-C ARC", i32 1}
>>>>> +// NO-ARC-NOT: !{i32 1, !"Objective-C ARC", i32 1}
>>>>> +// ARC-PASS: -objc-arc-contract
>>>>> +// NO-ARC-PASS-NOT: -objc-arc-contract
>>>>> +
>>>>> +void test() {
>>>>> +}
>>>>>
>>>>> EMAIL PREFERENCES
>>>>> http://reviews.llvm.org/settings/panel/emailpreferences/
>>>>> <D7799.21048.patch>
>>>>
>>>
>>
>
>
> _______________________________________________
> cfe-commits mailing list
> [email protected]
> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
_______________________________________________
cfe-commits mailing list
[email protected]
http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
