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MemoryBuiltins: accept non-TLI funcs with attribs as allocator funcs 

This allows us to accept annotations from out-of-tree languages (the
example test is derived from Rust) so they can enjoy the benefits of
LLVM's optimizations without requiring LLVM to have language-specific
knowledge.

Differential Revision: https://reviews.llvm.org/D123091
This commit is contained in:
Augie Fackler 2022-03-31 22:33:13 -04:00
parent 5a3e3675f6
commit 62f48cadfd
2 changed files with 29 additions and 8 deletions
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19
llvm/lib/Analysis/MemoryBuiltins.cpp
View File

@ -540,14 +540,17 @@ Optional<StringRef> llvm::getAllocationFamily(const Value *I,
if (Callee == nullptr || IsNoBuiltin)
return None;
LibFunc TLIFn;
if (!TLI || !TLI->getLibFunc(*Callee, TLIFn) || !TLI->has(TLIFn))
return None;
const auto AllocData = getAllocationDataForFunction(Callee, AnyAlloc, TLI);
if (AllocData)
return mangledNameForMallocFamily(AllocData.value().Family);
const auto FreeData = getFreeFunctionDataForFunction(Callee, TLIFn);
if (FreeData)
return mangledNameForMallocFamily(FreeData.value().Family);
if (TLI && TLI->getLibFunc(*Callee, TLIFn) && TLI->has(TLIFn)) {
// Callee is some known library function.
const auto AllocData = getAllocationDataForFunction(Callee, AnyAlloc, TLI);
if (AllocData)
return mangledNameForMallocFamily(AllocData.value().Family);
const auto FreeData = getFreeFunctionDataForFunction(Callee, TLIFn);
if (FreeData)
return mangledNameForMallocFamily(FreeData.value().Family);
}
// Callee isn't a known library function, still check attributes.
if (checkFnAllocKind(I, AllocFnKind::Free | AllocFnKind::Alloc |
AllocFnKind::Realloc)) {
Attribute Attr = cast<CallBase>(I)->getFnAttr("alloc-family");

18
llvm/test/Transforms/InstCombine/out-of-tree-allocator-optimizes-away.ll Normal file
View File

@ -0,0 +1,18 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -S -passes=instcombine %s | FileCheck %s
; Function Attrs: nonlazybind uwtable
define void @alloc_elides_test(i32 %data){
; CHECK-LABEL: @alloc_elides_test(
; CHECK-NEXT: start:
; CHECK-NEXT: ret void
;
start:
%0 = tail call i8* @__rust_alloc(i64 4, i64 32)
tail call void @__rust_dealloc(i8* nonnull %0, i64 4, i64 32)
ret void
}
declare noalias i8* @__rust_alloc(i64, i64 allocalign) unnamed_addr nounwind nonlazybind allocsize(0) uwtable allockind("alloc,uninitialized,aligned") "alloc-family"="__rust_alloc"
declare void @__rust_dealloc(i8* allocptr, i64, i64) unnamed_addr nounwind nonlazybind uwtable allockind("free") "alloc-family"="__rust_alloc"