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[Attributor][FIX] Carefully handle/ignore/forget argmemonly

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When we have an existing `argmemonly` or `inaccessiblememorargmemonly`
we used to "know" that information. However, interprocedural constant
propagation can invalidate these attributes. We now ignore and remove
these attributes for internal functions (which may be affected by IP
constant propagation), if we are deriving new attributes for the
function.
This commit is contained in:
Johannes Doerfert 2020-05-09 12:48:29 -05:00
parent 2251bdf0ea
commit 1e8b1544dc
3 changed files with 51 additions and 6 deletions
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5
include/llvm/Transforms/IPO/Attributor.h
View File

@ -903,6 +903,11 @@ struct Attributor {
Functions.size() == Functions.front()->getParent()->size();
}
/// Return true if we derive attributes for \p Fn
bool isRunOn(Function &Fn) const {
return Functions.empty() || Functions.count(&Fn);
}
/// Determine opportunities to derive 'default' attributes in \p F and create
/// abstract attribute objects for them.
///

27
lib/Transforms/IPO/AttributorAttributes.cpp
View File

@ -6017,14 +6017,25 @@ struct AAMemoryLocationImpl : public AAMemoryLocation {
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
intersectAssumedBits(BEST_STATE);
getKnownStateFromValue(getIRPosition(), getState());
getKnownStateFromValue(A, getIRPosition(), getState());
IRAttribute::initialize(A);
}
/// Return the memory behavior information encoded in the IR for \p IRP.
static void getKnownStateFromValue(const IRPosition &IRP,
static void getKnownStateFromValue(Attributor &A, const IRPosition &IRP,
BitIntegerState &State,
bool IgnoreSubsumingPositions = false) {
// For internal functions we ignore `argmemonly` and
// `inaccessiblememorargmemonly` as we might break it via interprocedural
// constant propagation. It is unclear if this is the best way but it is
// unlikely this will cause real performance problems. If we are deriving
// attributes for the anchor function we even remove the attribute in
// addition to ignoring it.
bool UseArgMemOnly = true;
Function *AnchorFn = IRP.getAnchorScope();
if (AnchorFn && A.isRunOn(*AnchorFn))
UseArgMemOnly = !AnchorFn->hasLocalLinkage();
SmallVector<Attribute, 2> Attrs;
IRP.getAttrs(AttrKinds, Attrs, IgnoreSubsumingPositions);
for (const Attribute &Attr : Attrs) {
@ -6036,11 +6047,17 @@ struct AAMemoryLocationImpl : public AAMemoryLocation {
State.addKnownBits(inverseLocation(NO_INACCESSIBLE_MEM, true, true));
break;
case Attribute::ArgMemOnly:
State.addKnownBits(inverseLocation(NO_ARGUMENT_MEM, true, true));
if (UseArgMemOnly)
State.addKnownBits(inverseLocation(NO_ARGUMENT_MEM, true, true));
else
IRP.removeAttrs({Attribute::ArgMemOnly});
break;
case Attribute::InaccessibleMemOrArgMemOnly:
State.addKnownBits(
inverseLocation(NO_INACCESSIBLE_MEM | NO_ARGUMENT_MEM, true, true));
if (UseArgMemOnly)
State.addKnownBits(inverseLocation(
NO_INACCESSIBLE_MEM | NO_ARGUMENT_MEM, true, true));
else
IRP.removeAttrs({Attribute::InaccessibleMemOrArgMemOnly});
break;
default:
llvm_unreachable("Unexpected attribute!");

25
test/Transforms/Attributor/memory_locations.ll
View File

@ -5,6 +5,8 @@
; RUN: opt -aa-pipeline=basic-aa -passes=attributor-cgscc -attributor-manifest-internal -attributor-annotate-decl-cs -S < %s | FileCheck %s --check-prefixes=CHECK,NOT_TUNIT_NPM,NOT_TUNIT_OPM,NOT_CGSCC_OPM,IS__CGSCC____,IS________NPM,IS__CGSCC_NPM
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
@G = external dso_local global i32, align 4
; CHECK: Function Attrs: inaccessiblememonly
declare noalias i8* @malloc(i64) inaccessiblememonly
@ -397,7 +399,6 @@ define void @callerE(i8* %arg) {
ret void
}
@G = external dso_local global i32, align 4
; CHECK: Function Attrs:
; CHECK-SAME: writeonly
@ -601,3 +602,25 @@ define i8 @readnone_caller2(i1 %c) {
%r = call i8 @recursive_not_readnone_internal2(i8* undef, i1 %c)
ret i8 %r
}
; CHECK: Function Attrs:
; CHECK-NOT: argmemonly
define internal void @argmemonly_before_ipconstprop(i32* %p) argmemonly {
; CHECK-LABEL: define {{[^@]+}}@argmemonly_before_ipconstprop()
; CHECK-NEXT: store i32 0, i32* @G, align 4
; CHECK-NEXT: ret void
;
store i32 0, i32* %p
ret void
}
; CHECK: Function Attrs:
; CHECK-NOT: argmemonly
define void @argmemonky_caller() {
; CHECK-LABEL: define {{[^@]+}}@argmemonky_caller()
; CHECK-NEXT: call void @argmemonly_before_ipconstprop()
; CHECK-NEXT: ret void
;
call void @argmemonly_before_ipconstprop(i32* @G)
ret void
}