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[Attributor] Provide a command line option that limits recursion depth

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In `MultiSource/Benchmarks/tramp3d-v4/tramp3d-v4.cpp` we initialized
attributes until stack frame ~35k caused space to run out. The initial
size 1024 is pretty much random.
This commit is contained in:
Johannes Doerfert 2020-08-18 15:27:41 -05:00
parent e249eaa2a3
commit 8c1b461de9
3 changed files with 51 additions and 2 deletions
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14
include/llvm/Transforms/IPO/Attributor.h
View File

@ -133,8 +133,10 @@ struct AAIsDead;
class Function;
/// Simple enum classes that forces properties to be spelled out explicitly.
///
/// The value passed to the line option that defines the maximal initialization
/// chain length.
extern unsigned MaxInitializationChainLength;
///{
enum class ChangeStatus {
CHANGED,
@ -1071,6 +1073,9 @@ struct Attributor {
Invalidate |= FnScope->hasFnAttribute(Attribute::Naked) ||
FnScope->hasFnAttribute(Attribute::OptimizeNone);
// Avoid too many nested initializations to prevent a stack overflow.
Invalidate |= InitializationChainLength > MaxInitializationChainLength;
// Bootstrap the new attribute with an initial update to propagate
// information, e.g., function -> call site. If it is not on a given
// Allowed we will not perform updates at all.
@ -1081,7 +1086,9 @@ struct Attributor {
{
TimeTraceScope TimeScope(AA.getName() + "::initialize");
++InitializationChainLength;
AA.initialize(*this);
--InitializationChainLength;
}
// Initialize and update is allowed for code outside of the current function
@ -1615,6 +1622,9 @@ private:
CLEANUP,
} Phase = AttributorPhase::SEEDING;
/// The current initialization chain length. Tracked to avoid stack overflows.
unsigned InitializationChainLength = 0;
/// Functions, blocks, and instructions we delete after manifest is done.
///
///{

8
lib/Transforms/IPO/Attributor.cpp
View File

@ -73,6 +73,14 @@ static cl::opt<unsigned>
MaxFixpointIterations("attributor-max-iterations", cl::Hidden,
cl::desc("Maximal number of fixpoint iterations."),
cl::init(32));
static cl::opt<unsigned, true> MaxInitializationChainLengthX(
"attributor-max-initialization-chain-length", cl::Hidden,
cl::desc(
"Maximal number of chained initializations (to avoid stack overflows)"),
cl::location(MaxInitializationChainLength), cl::init(1024));
unsigned llvm::MaxInitializationChainLength;
static cl::opt<bool> VerifyMaxFixpointIterations(
"attributor-max-iterations-verify", cl::Hidden,
cl::desc("Verify that max-iterations is a tight bound for a fixpoint"),

31
test/Transforms/Attributor/chain.ll Normal file
View File

@ -0,0 +1,31 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --function-signature --scrub-attributes --check-attributes
; RUN: opt -attributor -enable-new-pm=0 -attributor-manifest-internal -attributor-annotate-decl-cs -attributor-max-initialization-chain-length=1 -S < %s | FileCheck %s --check-prefixes=CHECK,CHECK_1
; RUN: opt -aa-pipeline=basic-aa -passes=attributor -attributor-manifest-internal -attributor-annotate-decl-cs -attributor-max-initialization-chain-length=1 -S < %s | FileCheck %s --check-prefixes=CHECK,CHECK_1
; RUN: opt -attributor -enable-new-pm=0 -attributor-manifest-internal -attributor-annotate-decl-cs -attributor-max-initialization-chain-length=1024 -S < %s | FileCheck %s --check-prefixes=CHECK,CHECK_5
; RUN: opt -aa-pipeline=basic-aa -passes=attributor -attributor-manifest-internal -attributor-annotate-decl-cs -attributor-max-initialization-chain-length=1024 -S < %s | FileCheck %s --check-prefixes=CHECK,CHECK_5
declare void @foo(i8* dereferenceable(8) %arg)
define dso_local i32 @bar(i32* %arg) {
; CHECK_1-LABEL: define {{[^@]+}}@bar
; CHECK_1-SAME: (i32* dereferenceable_or_null(8) [[ARG:%.*]]) {
; CHECK_1-NEXT: entry:
; CHECK_1-NEXT: [[BC1:%.*]] = bitcast i32* [[ARG]] to i8*
; CHECK_1-NEXT: call void @foo(i8* dereferenceable_or_null(8) [[BC1]])
; CHECK_1-NEXT: [[LD:%.*]] = load i32, i32* [[ARG]], align 4
; CHECK_1-NEXT: ret i32 [[LD]]
;
; CHECK_5-LABEL: define {{[^@]+}}@bar
; CHECK_5-SAME: (i32* nonnull dereferenceable(8) [[ARG:%.*]]) {
; CHECK_5-NEXT: entry:
; CHECK_5-NEXT: [[BC1:%.*]] = bitcast i32* [[ARG]] to i8*
; CHECK_5-NEXT: call void @foo(i8* nonnull dereferenceable(8) [[BC1]])
; CHECK_5-NEXT: [[LD:%.*]] = load i32, i32* [[ARG]], align 4
; CHECK_5-NEXT: ret i32 [[LD]]
;
entry:
%bc1 = bitcast i32* %arg to i8*
call void @foo(i8* %bc1)
%ld = load i32, i32* %arg
ret i32 %ld
}