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[NewPM][Inliner] Check if deleted function is in current SCC

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In weird cases, the inliner will inline internal recursive functions,
sometimes causing them to have no more uses, in which case the
inliner will mark the function to be deleted. The function is
actually deleted after the call to
updateCGAndAnalysisManagerForCGSCCPass(). In
updateCGAndAnalysisManagerForCGSCCPass(), UR.UpdatedC may be set to
the SCC containing the function to be deleted. Then the inliner calls
CG.removeDeadFunction() which can cause that SCC to be deleted, even
though it's still stored in UR.UpdatedC.

We could potentially check in the wrappers/pass managers if UR.UpdatedC
is in UR.InvalidatedSCCs before doing anything with it, but it's safer
to do this as close to possible to the call to CG.removeDeadFunction()
to avoid issues with allocating a new SCC in the same address as
the deleted one.

It's hard to find a small test case since we need to have recursive
internal functions be reachable from non-internal functions, yet they
need to become non-recursive and not referenced by other functions when
inlined.

Similar to https://reviews.llvm.org/D106306.

Fixes PR50788.

Reviewed By: asbirlea

Differential Revision: https://reviews.llvm.org/D106405
This commit is contained in:
Arthur Eubanks 2021-07-20 14:51:12 -07:00
parent 48d5dbf972
commit f3b675c071
2 changed files with 58 additions and 0 deletions
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4
lib/Transforms/IPO/Inliner.cpp
View File

@ -1127,6 +1127,10 @@ PreservedAnalyses InlinerPass::run(LazyCallGraph::SCC &InitialC,
UR.InvalidatedSCCs.insert(&DeadC);
UR.InvalidatedRefSCCs.insert(&DeadRC);
// If the updated SCC was the one containing the deleted function, clear it.
if (&DeadC == UR.UpdatedC)
UR.UpdatedC = nullptr;
// And delete the actual function from the module.
// The Advisor may use Function pointers to efficiently index various
// internal maps, e.g. for memoization. Function cleanup passes like

54
test/Transforms/Inline/deleted-scc.ll Normal file
View File

@ -0,0 +1,54 @@
; RUN: opt -passes=inline < %s -S | FileCheck %s
; CHECK-NOT: define
; CHECK: define void @e()
; CHECK-NOT: define
@b = external local_unnamed_addr global i32, align 4
define void @e() local_unnamed_addr {
entry:
call fastcc void @d()
ret void
}
define internal fastcc void @f() unnamed_addr {
entry:
call fastcc void @d()
ret void
}
define internal fastcc void @d() unnamed_addr {
entry:
br label %L
L: ; preds = %cleanup9, %entry
%cleanup.dest.slot.0 = phi i32 [ undef, %entry ], [ %cleanup.dest.slot.3, %cleanup9 ]
store i32 0, i32* @b, align 4
%tobool.not = icmp eq i32 0, 0
br i1 %tobool.not, label %if.then, label %while.cond
while.cond: ; preds = %cleanup9, %L
%cleanup.dest.slot.2 = phi i32 [ %cleanup.dest.slot.0, %L ], [ 0, %cleanup9 ]
%0 = load i32, i32* @b, align 4
%tobool3.not = icmp eq i32 %0, 0
br i1 %tobool3.not, label %cleanup9, label %while.body4
while.body4: ; preds = %while.cond
call fastcc void @f()
br label %cleanup9
cleanup9: ; preds = %while.cond, %while.body4
%cleanup.dest.slot.3 = phi i32 [ %cleanup.dest.slot.2, %while.body4 ], [ 0, %while.cond ]
switch i32 %cleanup.dest.slot.3, label %common.ret [
i32 0, label %while.cond
i32 2, label %L
]
common.ret: ; preds = %cleanup9, %if.then
ret void
if.then: ; preds = %L
call void @e()
br label %common.ret
}