https://bugs.llvm.org/show_bug.cgi?id=50099
Bug ID: 50099
Summary: [NewPM] Inliner: Certain destructor calls are no
longer inlined, preventing SROA, causing +10% runtime
perf regression
Product: libraries
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: Interprocedural Analyses
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Created attachment 24799
--> https://bugs.llvm.org/attachment.cgi?id=24799&action=edit
unoptimized IR for reproduction
I'm seeing a rather big +10% runtime perf regression
from new-pm switch on a certain codepath.
I don't really have a small workable testcase yet,
but there's a full self-contained reproducer attached.
Here's how we can see that the problem is there:
$ clang -O3 -o old.ll -S -emit-llvm orig.ll -flegacy-pass-manager
$ clang -O3 -o new.ll -S -emit-llvm orig.ll
$ llvm-diff old.ll new.ll
<...>
function @_ZN8rawspeed6BufferD2Ev exists only in right module
<...>
in function _ZN8rawspeed23PanasonicDecompressorV511ProxyStream10parseBlockEv:
in block %entry:
> %FirstSection = alloca %"class.rawspeed::Buffer", align 8
> %SecondSection = alloca %"class.rawspeed::Buffer", align 8
> %0 = bitcast %"class.rawspeed::Buffer"* %FirstSection to i8*
> call void @llvm.lifetime.start.p0i8(i64 16, i8* nonnull %0) #17
> tail call void @llvm.experimental.noalias.scope.decl(metadata !135)
%pos.i = getelementptr inbounds
%"class.rawspeed::PanasonicDecompressorV5::ProxyStream",
%"class.rawspeed::PanasonicDecompressorV5::ProxyStream"* %this, i64 0, i32 0,
i32 1
%0 = load i32, i32* %pos.i, align 4, !tbaa !4, !noalias !9
> tail call void @llvm.experimental.noalias.scope.decl(metadata !138)
<...>
Inliner/inline cost model isn't something i'm familiar with,
so i'm posting this as is. Any suggestions how this can be approached from the
LLVM side?
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