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[LCG] Add aliased functions as LCG roots

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Current LCG doesn't check aliased functions. So if an internal function has a public alias it will not be added to CG SCC, but it is still reachable from outside through the alias.
So this patch adds aliased functions to SCC.

Differential Revision: https://reviews.llvm.org/D59898

llvm-svn: 357795
This commit is contained in:
Guozhi Wei 2019-04-05 18:51:08 +00:00
parent 19c44c5a00
commit 36fc9c3107
2 changed files with 51 additions and 0 deletions
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13
llvm/lib/Analysis/LazyCallGraph.cpp
View File

@ -172,6 +172,19 @@ LazyCallGraph::LazyCallGraph(Module &M, TargetLibraryInfo &TLI) {
addEdge(EntryEdges.Edges, EntryEdges.EdgeIndexMap, get(F), Edge::Ref);
}
// Externally visible aliases of internal functions are also viable entry
// edges to the module.
for (auto &A : M.aliases()) {
if (A.hasLocalLinkage())
continue;
if (Function* F = dyn_cast<Function>(A.getAliasee())) {
LLVM_DEBUG(dbgs() << " Adding '" << F->getName()
<< "' with alias '" << A.getName()
<< "' to entry set of the graph.\n");
addEdge(EntryEdges.Edges, EntryEdges.EdgeIndexMap, get(*F), Edge::Ref);
}
}
// Now add entry nodes for functions reachable via initializers to globals.
SmallVector<Constant *, 16> Worklist;
SmallPtrSet<Constant *, 16> Visited;

38
llvm/test/Analysis/LazyCallGraph/alias.ll Normal file
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@ -0,0 +1,38 @@
; RUN: opt -disable-output -passes=print-lcg %s 2>&1 | FileCheck %s
;
; Aliased function should be reachable in CGSCC.
target triple = "x86_64-grtev4-linux-gnu"
; CHECK: Edges in function: foo
; CHECK: Edges in function: bar
; CHECK: Edges in function: baz
; CHECK: RefSCC with 1 call SCCs:
; CHECK-NEXT: SCC with 1 functions:
; CHECK-NEXT: bar
; CHECK: RefSCC with 1 call SCCs:
; CHECK-NEXT: SCC with 1 functions:
; CHECK-NEXT: foo
; CHECK-NOT: baz
@alias1 = weak dso_local alias i8* (i8*), i8* (i8*)* @foo
define dso_local i8* @foo(i8* %returned) {
ret i8* %returned
}
@alias2 = weak dso_local alias i8* (i8*), i8* (i8*)* @bar
define internal i8* @bar(i8* %returned) {
ret i8* %returned
}
; Internal alias is not reachable.
@alias3 = internal alias i8* (i8*), i8* (i8*)* @baz
define internal i8* @baz(i8* %returned) {
ret i8* %returned
}