[llvm-dev] LLVM v6.0 Internalize and GlobalDCE PASS can not work together?
Hal Finkel via llvm-dev
llvm-dev at lists.llvm.org
Wed Oct 25 19:20:15 PDT 2017
On 10/25/2017 09:07 PM, Leslie Zhai wrote:
> Hi Hal,
>
> Thanks for your hint!
>
> $ /opt/llvm-svn/bin/opt -S -internalize
> -internalize-public-api-list=main -globaldce hello3.ll -o
> hello3.dce.ll it works :)
>
> But I argue that `main` Function should be inserted into ExternalNames
> by default:
But "main" is neither necessary nor sufficient depending on the
target/configuration. Internalize is really intended to be used by a
linker plugin (or in some other context where a callback can be provided
that has the right information). Using the pass as you're doing is
really a development aid - it's not a user-facing tool by itself.
-Hal
>
> Index: lib/Transforms/IPO/Internalize.cpp
> ===================================================================
> --- lib/Transforms/IPO/Internalize.cpp (revision 316540)
> +++ lib/Transforms/IPO/Internalize.cpp (working copy)
> @@ -61,6 +61,7 @@
> if (!APIFile.empty())
> LoadFile(APIFile);
> ExternalNames.insert(APIList.begin(), APIList.end());
> + ExternalNames.insert("main");
> }
>
> bool operator()(const GlobalValue &GV) {
>
>
> 在 2017年10月25日 21:20, Hal Finkel 写道:
>> Hi, Leslie,
>>
>> When you use internalize, you need to provide it with a list of
>> symbols to preserve as external (otherwise everything will be
>> internalized, including main, and then DCE will remove everything).
>> You can use -internalize-public-api-list=main (a comma-separated
>> list) or -internalize-public-api-file=some_file_name where
>> some_file_name has the list of symbols. See the comments in
>> lib/Transforms/IPO/Internalize.cpp.
>>
>> -Hal
>>
>> On 10/24/2017 11:22 PM, Leslie Zhai via llvm-dev wrote:
>>> Hi LLVM developers,
>>>
>>> $ cat hello.c
>>> #include <stdio.h>
>>>
>>> void foo() {
>>> }
>>>
>>> int main(int argc, char *argv[]) {
>>> for (int i = 0; i < 10; i++) {
>>> printf("%d\n", i);
>>> }
>>> return 0;
>>> }
>>>
>>> $ /opt/llvm-svn/bin/clang --version
>>> Fedora clang version 6.0.0 (trunk 316308) (based on LLVM 6.0.0svn)
>>> Target: x86_64-redhat-linux
>>> Thread model: posix
>>> InstalledDir: /opt/llvm-svn/bin
>>>
>>> $ /opt/llvm-svn/bin/clang -Xclang -disable-O0-optnone -S -emit-llvm
>>> hello.c -o hello2.ll
>>>
>>> $ cat hello2.ll
>>> ; ModuleID = 'hello.c'
>>> source_filename = "hello.c"
>>> target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
>>> target triple = "x86_64-unknown-linux-gnu"
>>>
>>> @.str = private unnamed_addr constant [4 x i8] c"%d\0A\00", align 1
>>>
>>> ; Function Attrs: noinline nounwind uwtable
>>> define void @foo() #0 {
>>> entry:
>>> ret void
>>> }
>>>
>>> ; Function Attrs: noinline nounwind uwtable
>>> define i32 @main(i32 %argc, i8** %argv) #0 {
>>> entry:
>>> %retval = alloca i32, align 4
>>> %argc.addr = alloca i32, align 4
>>> %argv.addr = alloca i8**, align 8
>>> %i = alloca i32, align 4
>>> store i32 0, i32* %retval, align 4
>>> store i32 %argc, i32* %argc.addr, align 4
>>> store i8** %argv, i8*** %argv.addr, align 8
>>> store i32 0, i32* %i, align 4
>>> br label %for.cond
>>>
>>> for.cond: ; preds =
>>> %for.inc, %entry
>>> %0 = load i32, i32* %i, align 4
>>> %cmp = icmp slt i32 %0, 10
>>> br i1 %cmp, label %for.body, label %for.end
>>>
>>> for.body: ; preds = %for.cond
>>> %1 = load i32, i32* %i, align 4
>>> %call = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([4
>>> x i8], [4 x i8]* @.str, i32 0, i32 0), i32 %1)
>>> br label %for.inc
>>>
>>> for.inc: ; preds = %for.body
>>> %2 = load i32, i32* %i, align 4
>>> %inc = add nsw i32 %2, 1
>>> store i32 %inc, i32* %i, align 4
>>> br label %for.cond
>>>
>>> for.end: ; preds = %for.cond
>>> ret i32 0
>>> }
>>>
>>> declare i32 @printf(i8*, ...) #1
>>>
>>> attributes #0 = { noinline nounwind uwtable
>>> "correctly-rounded-divide-sqrt-fp-math"="false"
>>> "disable-tail-calls"="false" "less-precise-fpmad"="false"
>>> "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf"
>>> "no-infs-fp-math"="false" "no-jump-tables"="false"
>>> "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false"
>>> "no-trapping-math"="false" "stack-protector-buffer-size"="8"
>>> "target-cpu"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2,+x87"
>>> "unsafe-fp-math"="false" "use-soft-float"="false" }
>>> attributes #1 = { "correctly-rounded-divide-sqrt-fp-math"="false"
>>> "disable-tail-calls"="false" "less-precise-fpmad"="false"
>>> "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf"
>>> "no-infs-fp-math"="false" "no-nans-fp-math"="false"
>>> "no-signed-zeros-fp-math"="false" "no-trapping-math"="false"
>>> "stack-protector-buffer-size"="8" "target-cpu"="x86-64"
>>> "target-features"="+fxsr,+mmx,+sse,+sse2,+x87"
>>> "unsafe-fp-math"="false" "use-soft-float"="false" }
>>>
>>> !llvm.module.flags = !{!0}
>>> !llvm.ident = !{!1}
>>>
>>> !0 = !{i32 1, !"wchar_size", i32 4}
>>> !1 = !{!"clang version 6.0.0 (git at github.com:llvm-mirror/clang.git
>>> 0aed123216ad4a38a9c2b16f1783895fd5cb1a04)
>>> (git at github.com:llvm-mirror/llvm.git
>>> d209b37aec1e392dabbf9b5324ea4a60c36fbc55)"}
>>>
>>> $ /opt/llvm-svn/bin/opt -S -internalize -globaldce hello2.ll -o
>>> hello2.dce.ll
>>>
>>> $ cat hello2.dce.ll
>>> ; ModuleID = 'hello2.ll'
>>> source_filename = "hello.c"
>>> target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
>>> target triple = "x86_64-unknown-linux-gnu"
>>>
>>> !llvm.module.flags = !{!0}
>>> !llvm.ident = !{!1}
>>>
>>> !0 = !{i32 1, !"wchar_size", i32 4}
>>> !1 = !{!"clang version 6.0.0 (git at github.com:llvm-mirror/clang.git
>>> 0aed123216ad4a38a9c2b16f1783895fd5cb1a04)
>>> (git at github.com:llvm-mirror/llvm.git
>>> d209b37aec1e392dabbf9b5324ea4a60c36fbc55)"}
>>>
>>> $ /opt/llvm-svn/bin/lli hello2.dce.ll
>>> 'main' function not found in module.
>>>
>>>
>>> *No* more Alive Functions, so LLVM v6.0 Internalize and GlobalDCE
>>> PASS failed to MarkLive Function together?
>>>
>>>
>>> But LLVM 3.1 is able to work together:
>>>
>>> $ ./build/Release+Asserts/bin/opt --version
>>> LLVM (http://llvm.org/):
>>> LLVM version 3.1
>>> Optimized build with assertions.
>>> Built Oct 23 2017 (16:22:51).
>>> Default target: x86_64-unknown-linux-gnu
>>> Host CPU: corei7-avx
>>>
>>> $ ./build/Release+Asserts/bin/clang -S -emit-llvm hello.c -o hello0.ll
>>>
>>> $ cat hello0.ll
>>> ; ModuleID = 'hello.c'
>>> target datalayout =
>>> "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
>>> target triple = "x86_64-unknown-linux-gnu"
>>>
>>> @.str = private unnamed_addr constant [4 x i8] c"%d\0A\00", align 1
>>>
>>> define void @foo() nounwind uwtable {
>>> entry:
>>> ret void
>>> }
>>>
>>> define i32 @main(i32 %argc, i8** %argv) nounwind uwtable {
>>> entry:
>>> %retval = alloca i32, align 4
>>> %argc.addr = alloca i32, align 4
>>> %argv.addr = alloca i8**, align 8
>>> %i = alloca i32, align 4
>>> store i32 0, i32* %retval
>>> store i32 %argc, i32* %argc.addr, align 4
>>> store i8** %argv, i8*** %argv.addr, align 8
>>> store i32 0, i32* %i, align 4
>>> br label %for.cond
>>>
>>> for.cond: ; preds =
>>> %for.inc, %entry
>>> %0 = load i32* %i, align 4
>>> %cmp = icmp slt i32 %0, 10
>>> br i1 %cmp, label %for.body, label %for.end
>>>
>>> for.body: ; preds = %for.cond
>>> %1 = load i32* %i, align 4
>>> %call = call i32 (i8*, ...)* @printf(i8* getelementptr inbounds
>>> ([4 x i8]* @.str, i32 0, i32 0), i32 %1)
>>> br label %for.inc
>>>
>>> for.inc: ; preds = %for.body
>>> %2 = load i32* %i, align 4
>>> %inc = add nsw i32 %2, 1
>>> store i32 %inc, i32* %i, align 4
>>> br label %for.cond
>>>
>>> for.end: ; preds = %for.cond
>>> ret i32 0
>>> }
>>>
>>> declare i32 @printf(i8*, ...)
>>>
>>> $ ./build/Release+Asserts/bin/opt -S -internalize -globaldce
>>> hello0.ll -o hello0.dce.ll
>>>
>>> $ cat hello0.dce.ll
>>> ; ModuleID = 'hello0.ll'
>>> target datalayout =
>>> "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
>>> target triple = "x86_64-unknown-linux-gnu"
>>>
>>> @.str = private unnamed_addr constant [4 x i8] c"%d\0A\00", align 1
>>>
>>> define i32 @main(i32 %argc, i8** %argv) nounwind uwtable {
>>> entry:
>>> %retval = alloca i32, align 4
>>> %argc.addr = alloca i32, align 4
>>> %argv.addr = alloca i8**, align 8
>>> %i = alloca i32, align 4
>>> store i32 0, i32* %retval
>>> store i32 %argc, i32* %argc.addr, align 4
>>> store i8** %argv, i8*** %argv.addr, align 8
>>> store i32 0, i32* %i, align 4
>>> br label %for.cond
>>>
>>> for.cond: ; preds =
>>> %for.inc, %entry
>>> %0 = load i32* %i, align 4
>>> %cmp = icmp slt i32 %0, 10
>>> br i1 %cmp, label %for.body, label %for.end
>>>
>>> for.body: ; preds = %for.cond
>>> %1 = load i32* %i, align 4
>>> %call = call i32 (i8*, ...)* @printf(i8* getelementptr inbounds
>>> ([4 x i8]* @.str, i32 0, i32 0), i32 %1)
>>> br label %for.inc
>>>
>>> for.inc: ; preds = %for.body
>>> %2 = load i32* %i, align 4
>>> %inc = add nsw i32 %2, 1
>>> store i32 %inc, i32* %i, align 4
>>> br label %for.cond
>>>
>>> for.end: ; preds = %for.cond
>>> ret i32 0
>>> }
>>>
>>> declare i32 @printf(i8*, ...)
>>>
>>>
>>> Succeeded drop DeadFunction foo.
>>>
>>> Maybe I wrongly use the Internalize and GlobalDCE PASS together?
>>> please give me some hints, thanks a lot!
>>>
>>>
>>> PS: LLVM 6.0 Internalize PASS is able to work, internal foo:
>>>
>>> $ /opt/llvm-svn/bin/opt -S -internalize hello2.ll -o hello2.internal.ll
>>>
>>> $ cat hello2.internal.ll
>>> ; ModuleID = 'hello2.ll'
>>> source_filename = "hello.c"
>>> target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
>>> target triple = "x86_64-unknown-linux-gnu"
>>>
>>> @.str = private unnamed_addr constant [4 x i8] c"%d\0A\00", align 1
>>>
>>> ; Function Attrs: noinline nounwind uwtable
>>> define internal void @foo() #0 {
>>> entry:
>>> ret void
>>> }
>>>
>>> ; Function Attrs: noinline nounwind uwtable
>>> define internal i32 @main(i32 %argc, i8** %argv) #0 {
>>> entry:
>>> %retval = alloca i32, align 4
>>> %argc.addr = alloca i32, align 4
>>> %argv.addr = alloca i8**, align 8
>>> %i = alloca i32, align 4
>>> store i32 0, i32* %retval, align 4
>>> store i32 %argc, i32* %argc.addr, align 4
>>> store i8** %argv, i8*** %argv.addr, align 8
>>> store i32 0, i32* %i, align 4
>>> br label %for.cond
>>>
>>> for.cond: ; preds =
>>> %for.inc, %entry
>>> %0 = load i32, i32* %i, align 4
>>> %cmp = icmp slt i32 %0, 10
>>> br i1 %cmp, label %for.body, label %for.end
>>>
>>> for.body: ; preds = %for.cond
>>> %1 = load i32, i32* %i, align 4
>>> %call = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([4
>>> x i8], [4 x i8]* @.str, i32 0, i32 0), i32 %1)
>>> br label %for.inc
>>>
>>> for.inc: ; preds = %for.body
>>> %2 = load i32, i32* %i, align 4
>>> %inc = add nsw i32 %2, 1
>>> store i32 %inc, i32* %i, align 4
>>> br label %for.cond
>>>
>>> for.end: ; preds = %for.cond
>>> ret i32 0
>>> }
>>>
>>> declare i32 @printf(i8*, ...) #1
>>>
>>> attributes #0 = { noinline nounwind uwtable
>>> "correctly-rounded-divide-sqrt-fp-math"="false"
>>> "disable-tail-calls"="false" "less-precise-fpmad"="false"
>>> "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf"
>>> "no-infs-fp-math"="false" "no-jump-tables"="false"
>>> "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false"
>>> "no-trapping-math"="false" "stack-protector-buffer-size"="8"
>>> "target-cpu"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2,+x87"
>>> "unsafe-fp-math"="false" "use-soft-float"="false" }
>>> attributes #1 = { "correctly-rounded-divide-sqrt-fp-math"="false"
>>> "disable-tail-calls"="false" "less-precise-fpmad"="false"
>>> "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf"
>>> "no-infs-fp-math"="false" "no-nans-fp-math"="false"
>>> "no-signed-zeros-fp-math"="false" "no-trapping-math"="false"
>>> "stack-protector-buffer-size"="8" "target-cpu"="x86-64"
>>> "target-features"="+fxsr,+mmx,+sse,+sse2,+x87"
>>> "unsafe-fp-math"="false" "use-soft-float"="false" }
>>>
>>> !llvm.module.flags = !{!0}
>>> !llvm.ident = !{!1}
>>>
>>> !0 = !{i32 1, !"wchar_size", i32 4}
>>> !1 = !{!"clang version 6.0.0 (git at github.com:llvm-mirror/clang.git
>>> 0aed123216ad4a38a9c2b16f1783895fd5cb1a04)
>>> (git at github.com:llvm-mirror/llvm.git
>>> d209b37aec1e392dabbf9b5324ea4a60c36fbc55)"}
>>>
>>
>
--
Hal Finkel
Lead, Compiler Technology and Programming Languages
Leadership Computing Facility
Argonne National Laboratory
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