r326530 - Add an option to disable tail-call optimization for escaping blocks.
Akira Hatanaka via cfe-commits
cfe-commits at lists.llvm.org
Thu Mar 1 17:53:15 PST 2018
Author: ahatanak
Date: Thu Mar 1 17:53:15 2018
New Revision: 326530
URL: http://llvm.org/viewvc/llvm-project?rev=326530&view=rev
Log:
Add an option to disable tail-call optimization for escaping blocks.
This makes it easier to debug crashes and hangs in block functions since
users can easily find out where the block is called from. The option
doesn't disable tail-calls from non-escaping blocks since non-escaping
blocks are not as hard to debug as escaping blocks.
rdar://problem/35758207
Differential Revision: https://reviews.llvm.org/D43841
Added:
cfe/trunk/test/CodeGenObjC/disable-tail-call-escaping-block.m
cfe/trunk/test/Driver/fno-escaping-block-tail-calls.c
Modified:
cfe/trunk/include/clang/AST/Decl.h
cfe/trunk/include/clang/Driver/Options.td
cfe/trunk/include/clang/Frontend/CodeGenOptions.def
cfe/trunk/lib/CodeGen/CGCall.cpp
cfe/trunk/lib/Driver/ToolChains/Clang.cpp
cfe/trunk/lib/Frontend/CompilerInvocation.cpp
cfe/trunk/lib/Sema/SemaExpr.cpp
cfe/trunk/lib/Sema/SemaExprObjC.cpp
cfe/trunk/lib/Sema/SemaPseudoObject.cpp
Modified: cfe/trunk/include/clang/AST/Decl.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/AST/Decl.h?rev=326530&r1=326529&r2=326530&view=diff
==============================================================================
--- cfe/trunk/include/clang/AST/Decl.h (original)
+++ cfe/trunk/include/clang/AST/Decl.h Thu Mar 1 17:53:15 2018
@@ -3802,6 +3802,10 @@ private:
bool BlockMissingReturnType : 1;
bool IsConversionFromLambda : 1;
+ /// A bit that indicates this block is passed directly to a function as a
+ /// non-escaping parameter.
+ bool DoesNotEscape : 1;
+
/// A new[]'d array of pointers to ParmVarDecls for the formal
/// parameters of this function. This is null if a prototype or if there are
/// no formals.
@@ -3821,7 +3825,7 @@ protected:
BlockDecl(DeclContext *DC, SourceLocation CaretLoc)
: Decl(Block, DC, CaretLoc), DeclContext(Block), IsVariadic(false),
CapturesCXXThis(false), BlockMissingReturnType(true),
- IsConversionFromLambda(false) {}
+ IsConversionFromLambda(false), DoesNotEscape(false) {}
public:
static BlockDecl *Create(ASTContext &C, DeclContext *DC, SourceLocation L);
@@ -3893,6 +3897,9 @@ public:
bool isConversionFromLambda() const { return IsConversionFromLambda; }
void setIsConversionFromLambda(bool val) { IsConversionFromLambda = val; }
+ bool doesNotEscape() const { return DoesNotEscape; }
+ void setDoesNotEscape() { DoesNotEscape = true; }
+
bool capturesVariable(const VarDecl *var) const;
void setCaptures(ASTContext &Context, ArrayRef<Capture> Captures,
Modified: cfe/trunk/include/clang/Driver/Options.td
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Driver/Options.td?rev=326530&r1=326529&r2=326530&view=diff
==============================================================================
--- cfe/trunk/include/clang/Driver/Options.td (original)
+++ cfe/trunk/include/clang/Driver/Options.td Thu Mar 1 17:53:15 2018
@@ -1430,6 +1430,8 @@ def fopenmp_cuda_mode : Flag<["-"], "fop
def fno_openmp_cuda_mode : Flag<["-"], "fno-openmp-cuda-mode">, Group<f_Group>, Flags<[CC1Option, NoArgumentUnused]>;
def fno_optimize_sibling_calls : Flag<["-"], "fno-optimize-sibling-calls">, Group<f_Group>;
def foptimize_sibling_calls : Flag<["-"], "foptimize-sibling-calls">, Group<f_Group>;
+def fno_escaping_block_tail_calls : Flag<["-"], "fno-escaping-block-tail-calls">, Group<f_Group>, Flags<[CC1Option]>;
+def fescaping_block_tail_calls : Flag<["-"], "fescaping-block-tail-calls">, Group<f_Group>;
def force__cpusubtype__ALL : Flag<["-"], "force_cpusubtype_ALL">;
def force__flat__namespace : Flag<["-"], "force_flat_namespace">;
def force__load : Separate<["-"], "force_load">;
Modified: cfe/trunk/include/clang/Frontend/CodeGenOptions.def
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Frontend/CodeGenOptions.def?rev=326530&r1=326529&r2=326530&view=diff
==============================================================================
--- cfe/trunk/include/clang/Frontend/CodeGenOptions.def (original)
+++ cfe/trunk/include/clang/Frontend/CodeGenOptions.def Thu Mar 1 17:53:15 2018
@@ -62,6 +62,8 @@ CODEGENOPT(DebugPassManager, 1, 0) ///<
///< pass manager.
CODEGENOPT(DisableRedZone , 1, 0) ///< Set when -mno-red-zone is enabled.
CODEGENOPT(DisableTailCalls , 1, 0) ///< Do not emit tail calls.
+CODEGENOPT(NoEscapingBlockTailCalls, 1, 0) ///< Do not emit tail calls from
+ ///< escaping blocks.
CODEGENOPT(EmitDeclMetadata , 1, 0) ///< Emit special metadata indicating what
///< Decl* various IR entities came from.
///< Only useful when running CodeGen as a
Modified: cfe/trunk/lib/CodeGen/CGCall.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGCall.cpp?rev=326530&r1=326529&r2=326530&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGCall.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGCall.cpp Thu Mar 1 17:53:15 2018
@@ -1887,10 +1887,21 @@ void CodeGenModule::ConstructAttributeLi
}
if (!AttrOnCallSite) {
- bool DisableTailCalls =
- CodeGenOpts.DisableTailCalls ||
- (TargetDecl && (TargetDecl->hasAttr<DisableTailCallsAttr>() ||
- TargetDecl->hasAttr<AnyX86InterruptAttr>()));
+ bool DisableTailCalls = false;
+
+ if (CodeGenOpts.DisableTailCalls)
+ DisableTailCalls = true;
+ else if (TargetDecl) {
+ if (TargetDecl->hasAttr<DisableTailCallsAttr>() ||
+ TargetDecl->hasAttr<AnyX86InterruptAttr>())
+ DisableTailCalls = true;
+ else if (CodeGenOpts.NoEscapingBlockTailCalls) {
+ if (const auto *BD = dyn_cast<BlockDecl>(TargetDecl))
+ if (!BD->doesNotEscape())
+ DisableTailCalls = true;
+ }
+ }
+
FuncAttrs.addAttribute("disable-tail-calls",
llvm::toStringRef(DisableTailCalls));
GetCPUAndFeaturesAttributes(TargetDecl, FuncAttrs);
Modified: cfe/trunk/lib/Driver/ToolChains/Clang.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Driver/ToolChains/Clang.cpp?rev=326530&r1=326529&r2=326530&view=diff
==============================================================================
--- cfe/trunk/lib/Driver/ToolChains/Clang.cpp (original)
+++ cfe/trunk/lib/Driver/ToolChains/Clang.cpp Thu Mar 1 17:53:15 2018
@@ -3454,6 +3454,9 @@ void Clang::ConstructJob(Compilation &C,
if (!Args.hasFlag(options::OPT_foptimize_sibling_calls,
options::OPT_fno_optimize_sibling_calls))
CmdArgs.push_back("-mdisable-tail-calls");
+ if (Args.hasFlag(options::OPT_fno_escaping_block_tail_calls,
+ options::OPT_fescaping_block_tail_calls))
+ CmdArgs.push_back("-fno-escaping-block-tail-calls");
Args.AddLastArg(CmdArgs, options::OPT_ffine_grained_bitfield_accesses,
options::OPT_fno_fine_grained_bitfield_accesses);
Modified: cfe/trunk/lib/Frontend/CompilerInvocation.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Frontend/CompilerInvocation.cpp?rev=326530&r1=326529&r2=326530&view=diff
==============================================================================
--- cfe/trunk/lib/Frontend/CompilerInvocation.cpp (original)
+++ cfe/trunk/lib/Frontend/CompilerInvocation.cpp Thu Mar 1 17:53:15 2018
@@ -640,6 +640,8 @@ static bool ParseCodeGenArgs(CodeGenOpti
Opts.DisableFree = Args.hasArg(OPT_disable_free);
Opts.DiscardValueNames = Args.hasArg(OPT_discard_value_names);
Opts.DisableTailCalls = Args.hasArg(OPT_mdisable_tail_calls);
+ Opts.NoEscapingBlockTailCalls =
+ Args.hasArg(OPT_fno_escaping_block_tail_calls);
Opts.FloatABI = Args.getLastArgValue(OPT_mfloat_abi);
Opts.LessPreciseFPMAD = Args.hasArg(OPT_cl_mad_enable) ||
Args.hasArg(OPT_cl_unsafe_math_optimizations) ||
Modified: cfe/trunk/lib/Sema/SemaExpr.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExpr.cpp?rev=326530&r1=326529&r2=326530&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaExpr.cpp (original)
+++ cfe/trunk/lib/Sema/SemaExpr.cpp Thu Mar 1 17:53:15 2018
@@ -4841,6 +4841,10 @@ bool Sema::GatherArgumentsForCall(Source
(!Param || !Param->hasAttr<CFConsumedAttr>()))
CFAudited = true;
+ if (Proto->getExtParameterInfo(i).isNoEscape())
+ if (auto *BE = dyn_cast<BlockExpr>(Arg->IgnoreParenNoopCasts(Context)))
+ BE->getBlockDecl()->setDoesNotEscape();
+
InitializedEntity Entity =
Param ? InitializedEntity::InitializeParameter(Context, Param,
ProtoArgType)
Modified: cfe/trunk/lib/Sema/SemaExprObjC.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExprObjC.cpp?rev=326530&r1=326529&r2=326530&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaExprObjC.cpp (original)
+++ cfe/trunk/lib/Sema/SemaExprObjC.cpp Thu Mar 1 17:53:15 2018
@@ -1613,6 +1613,11 @@ bool Sema::CheckMessageArgumentTypes(Qua
ParmVarDecl *param = Method->parameters()[i];
assert(argExpr && "CheckMessageArgumentTypes(): missing expression");
+ if (param->hasAttr<NoEscapeAttr>())
+ if (auto *BE = dyn_cast<BlockExpr>(
+ argExpr->IgnoreParenNoopCasts(Context)))
+ BE->getBlockDecl()->setDoesNotEscape();
+
// Strip the unbridged-cast placeholder expression off unless it's
// a consumed argument.
if (argExpr->hasPlaceholderType(BuiltinType::ARCUnbridgedCast) &&
Modified: cfe/trunk/lib/Sema/SemaPseudoObject.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaPseudoObject.cpp?rev=326530&r1=326529&r2=326530&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaPseudoObject.cpp (original)
+++ cfe/trunk/lib/Sema/SemaPseudoObject.cpp Thu Mar 1 17:53:15 2018
@@ -993,6 +993,7 @@ ObjCSubscriptOpBuilder::buildAssignmentO
SourceLocation opcLoc,
BinaryOperatorKind opcode,
Expr *LHS, Expr *RHS) {
+ assert(false);
assert(BinaryOperator::isAssignmentOp(opcode));
// There must be a method to do the Index'ed assignment.
if (!findAtIndexSetter())
Added: cfe/trunk/test/CodeGenObjC/disable-tail-call-escaping-block.m
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenObjC/disable-tail-call-escaping-block.m?rev=326530&view=auto
==============================================================================
--- cfe/trunk/test/CodeGenObjC/disable-tail-call-escaping-block.m (added)
+++ cfe/trunk/test/CodeGenObjC/disable-tail-call-escaping-block.m Thu Mar 1 17:53:15 2018
@@ -0,0 +1,54 @@
+// RUN: %clang_cc1 -triple x86_64-apple-darwin -fblocks -fno-escaping-block-tail-calls -emit-llvm -o - %s | FileCheck %s
+
+// CHECK-LABEL: define void @test(
+// CHECK: store i8* bitcast (void (i8*)* @[[TEST_BLOCK_INVOKE0:.*]] to i8*)
+// CHECK: store i8* bitcast (void (i8*)* @[[TEST_BLOCK_INVOKE1:.*]] to i8*)
+// CHECK: store i8* bitcast (void (i8*)* @[[TEST_BLOCK_INVOKE2:.*]] to i8*)
+// CHECK: store i8* bitcast (void (i8*)* @[[TEST_BLOCK_INVOKE3:.*]] to i8*)
+// CHECK: store i8* bitcast (void (i8*)* @[[TEST_BLOCK_INVOKE4:.*]] to i8*)
+// CHECK: store i8* bitcast (void (i8*)* @[[TEST_BLOCK_INVOKE5:.*]] to i8*)
+// CHECK: store i8* bitcast (void (i8*)* @[[TEST_BLOCK_INVOKE6:.*]] to i8*)
+
+// CHECK: define internal void @[[TEST_BLOCK_INVOKE0]]({{.*}}) #[[DISABLEATTR:.*]] {
+// CHECK: define internal void @[[TEST_BLOCK_INVOKE1]]({{.*}}) #[[ENABLEATTR:.*]] {
+// CHECK: define internal void @[[TEST_BLOCK_INVOKE2]]({{.*}}) #[[DISABLEATTR]] {
+// CHECK: define internal void @[[TEST_BLOCK_INVOKE3]]({{.*}}) #[[DISABLEATTR]] {
+// CHECK: define internal void @[[TEST_BLOCK_INVOKE4]]({{.*}}) #[[ENABLEATTR]] {
+// CHECK: define internal void @[[TEST_BLOCK_INVOKE5]]({{.*}}) #[[DISABLEATTR]] {
+// CHECK: define internal void @[[TEST_BLOCK_INVOKE6]]({{.*}}) #[[ENABLEATTR]] {
+
+// CHECK: attributes #[[ENABLEATTR]] = {{{.*}}"disable-tail-calls"="false"{{.*}}}
+// CHECK: attributes #[[DISABLEATTR]] = {{{.*}}"disable-tail-calls"="true"{{.*}}}
+
+typedef void (^BlockTy)(void);
+typedef void (*NoEscapeFnTy)(__attribute__((noescape)) BlockTy);
+
+void callee0(__attribute__((noescape)) BlockTy);
+void callee1(BlockTy);
+
+__attribute__((objc_root_class))
+ at interface C0
+-(void)m0:(__attribute__((noescape)) BlockTy)p;
+-(void)m1:(BlockTy)p;
+ at end
+
+ at implementation C0
+-(void)m0:(__attribute__((noescape)) BlockTy)p {}
+-(void)m1:(BlockTy)p {}
+ at end
+
+NoEscapeFnTy noescapefunc;
+
+void test(id a, C0 *c0) {
+ BlockTy b0 = ^{ (void)a; }; // disable tail-call optimization.
+ callee0(b0);
+ callee0(^{ (void)a; }); // enable tail-call optimization.
+ callee1(^{ (void)a; }); // disable tail-call optimization.
+
+ BlockTy b1 = ^{ (void)a; }; // disable tail-call optimization.
+ [c0 m0:b1];
+ [c0 m0:^{ (void)a; }]; // enable tail-call optimization.
+ [c0 m1:^{ (void)a; }]; // disable tail-call optimization.
+
+ noescapefunc(^{ (void)a; }); // enable tail-call optimization.
+}
Added: cfe/trunk/test/Driver/fno-escaping-block-tail-calls.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Driver/fno-escaping-block-tail-calls.c?rev=326530&view=auto
==============================================================================
--- cfe/trunk/test/Driver/fno-escaping-block-tail-calls.c (added)
+++ cfe/trunk/test/Driver/fno-escaping-block-tail-calls.c Thu Mar 1 17:53:15 2018
@@ -0,0 +1,7 @@
+// RUN: %clang -### %s -fescaping-block-tail-calls -fno-escaping-block-tail-calls 2> %t
+// RUN: FileCheck --check-prefix=CHECK-DISABLE < %t %s
+// CHECK-DISABLE: "-fno-escaping-block-tail-calls"
+
+// RUN: %clang -### %s -fno-escaping-block-tail-calls -fescaping-block-tail-calls 2> %t
+// RUN: FileCheck --check-prefix=CHECK-NO-DISABLE < %t %s
+// CHECK-NO-DISABLE-NOT: "-fno-escaping-block-tail-calls"
More information about the cfe-commits
mailing list