[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 06:20:42 PDT 2017
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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