r363952 - Store a pointer to the return value in a static alloca and let the debugger use that
Amy Huang via cfe-commits
cfe-commits at lists.llvm.org
Thu Jun 20 10:15:22 PDT 2019
Author: akhuang
Date: Thu Jun 20 10:15:21 2019
New Revision: 363952
URL: http://llvm.org/viewvc/llvm-project?rev=363952&view=rev
Log:
Store a pointer to the return value in a static alloca and let the debugger use that
as the variable address for NRVO variables.
Subscribers: hiraditya, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D63361
Added:
cfe/trunk/test/CodeGenCXX/debug-info-nrvo.cpp
Modified:
cfe/trunk/lib/CodeGen/CGDebugInfo.cpp
cfe/trunk/lib/CodeGen/CGDebugInfo.h
cfe/trunk/lib/CodeGen/CGDecl.cpp
cfe/trunk/lib/CodeGen/CodeGenFunction.cpp
cfe/trunk/lib/CodeGen/CodeGenFunction.h
cfe/trunk/test/CodeGen/arm64-microsoft-arguments.cpp
cfe/trunk/test/CodeGenCXX/conditional-gnu-ext.cpp
cfe/trunk/test/CodeGenCXX/lambda-expressions.cpp
cfe/trunk/test/CodeGenObjC/objc-non-trivial-struct-nrvo.m
Modified: cfe/trunk/lib/CodeGen/CGDebugInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGDebugInfo.cpp?rev=363952&r1=363951&r2=363952&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGDebugInfo.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGDebugInfo.cpp Thu Jun 20 10:15:21 2019
@@ -3835,7 +3835,8 @@ CGDebugInfo::EmitTypeForVarWithBlocksAtt
llvm::DILocalVariable *CGDebugInfo::EmitDeclare(const VarDecl *VD,
llvm::Value *Storage,
llvm::Optional<unsigned> ArgNo,
- CGBuilderTy &Builder) {
+ CGBuilderTy &Builder,
+ const bool UsePointerValue) {
assert(DebugKind >= codegenoptions::LimitedDebugInfo);
assert(!LexicalBlockStack.empty() && "Region stack mismatch, stack empty!");
if (VD->hasAttr<NoDebugAttr>())
@@ -3940,6 +3941,16 @@ llvm::DILocalVariable *CGDebugInfo::Emit
}
}
+ // Clang stores the sret pointer provided by the caller in a static alloca.
+ // Use DW_OP_deref to tell the debugger to load the pointer and treat it as
+ // the address of the variable.
+ if (UsePointerValue) {
+ assert(std::find(Expr.begin(), Expr.end(), llvm::dwarf::DW_OP_deref) ==
+ Expr.end() &&
+ "Debug info already contains DW_OP_deref.");
+ Expr.push_back(llvm::dwarf::DW_OP_deref);
+ }
+
// Create the descriptor for the variable.
auto *D = ArgNo ? DBuilder.createParameterVariable(
Scope, Name, *ArgNo, Unit, Line, Ty,
@@ -3958,9 +3969,10 @@ llvm::DILocalVariable *CGDebugInfo::Emit
llvm::DILocalVariable *
CGDebugInfo::EmitDeclareOfAutoVariable(const VarDecl *VD, llvm::Value *Storage,
- CGBuilderTy &Builder) {
+ CGBuilderTy &Builder,
+ const bool UsePointerValue) {
assert(DebugKind >= codegenoptions::LimitedDebugInfo);
- return EmitDeclare(VD, Storage, llvm::None, Builder);
+ return EmitDeclare(VD, Storage, llvm::None, Builder, UsePointerValue);
}
void CGDebugInfo::EmitLabel(const LabelDecl *D, CGBuilderTy &Builder) {
Modified: cfe/trunk/lib/CodeGen/CGDebugInfo.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGDebugInfo.h?rev=363952&r1=363951&r2=363952&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGDebugInfo.h (original)
+++ cfe/trunk/lib/CodeGen/CGDebugInfo.h Thu Jun 20 10:15:21 2019
@@ -422,9 +422,10 @@ public:
/// declaration.
/// Returns a pointer to the DILocalVariable associated with the
/// llvm.dbg.declare, or nullptr otherwise.
- llvm::DILocalVariable *EmitDeclareOfAutoVariable(const VarDecl *Decl,
- llvm::Value *AI,
- CGBuilderTy &Builder);
+ llvm::DILocalVariable *
+ EmitDeclareOfAutoVariable(const VarDecl *Decl, llvm::Value *AI,
+ CGBuilderTy &Builder,
+ const bool UsePointerValue = false);
/// Emit call to \c llvm.dbg.label for an label.
void EmitLabel(const LabelDecl *D, CGBuilderTy &Builder);
@@ -507,7 +508,8 @@ private:
/// llvm.dbg.declare, or nullptr otherwise.
llvm::DILocalVariable *EmitDeclare(const VarDecl *decl, llvm::Value *AI,
llvm::Optional<unsigned> ArgNo,
- CGBuilderTy &Builder);
+ CGBuilderTy &Builder,
+ const bool UsePointerValue = false);
struct BlockByRefType {
/// The wrapper struct used inside the __block_literal struct.
Modified: cfe/trunk/lib/CodeGen/CGDecl.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGDecl.cpp?rev=363952&r1=363951&r2=363952&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGDecl.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGDecl.cpp Thu Jun 20 10:15:21 2019
@@ -1403,12 +1403,11 @@ CodeGenFunction::EmitAutoVarAlloca(const
getLangOpts().OpenMP
? CGM.getOpenMPRuntime().getAddressOfLocalVariable(*this, &D)
: Address::invalid();
+ bool NRVO = getLangOpts().ElideConstructors && D.isNRVOVariable();
+
if (getLangOpts().OpenMP && OpenMPLocalAddr.isValid()) {
address = OpenMPLocalAddr;
} else if (Ty->isConstantSizeType()) {
- bool NRVO = getLangOpts().ElideConstructors &&
- D.isNRVOVariable();
-
// If this value is an array or struct with a statically determinable
// constant initializer, there are optimizations we can do.
//
@@ -1561,8 +1560,16 @@ CodeGenFunction::EmitAutoVarAlloca(const
// Emit debug info for local var declaration.
if (EmitDebugInfo && HaveInsertPoint()) {
+ Address DebugAddr = address;
+ bool UsePointerValue = NRVO && ReturnValuePointer.isValid();
DI->setLocation(D.getLocation());
- (void)DI->EmitDeclareOfAutoVariable(&D, address.getPointer(), Builder);
+
+ // If NRVO, use a pointer to the return address.
+ if (UsePointerValue)
+ DebugAddr = ReturnValuePointer;
+
+ (void)DI->EmitDeclareOfAutoVariable(&D, DebugAddr.getPointer(), Builder,
+ UsePointerValue);
}
if (D.hasAttr<AnnotateAttr>() && HaveInsertPoint())
Modified: cfe/trunk/lib/CodeGen/CodeGenFunction.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenFunction.cpp?rev=363952&r1=363951&r2=363952&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CodeGenFunction.cpp (original)
+++ cfe/trunk/lib/CodeGen/CodeGenFunction.cpp Thu Jun 20 10:15:21 2019
@@ -895,6 +895,13 @@ void CodeGenFunction::StartFunction(Glob
if (CurFnInfo->getReturnInfo().isSRetAfterThis())
++AI;
ReturnValue = Address(&*AI, CurFnInfo->getReturnInfo().getIndirectAlign());
+ if (!CurFnInfo->getReturnInfo().getIndirectByVal()) {
+ ReturnValuePointer =
+ CreateDefaultAlignTempAlloca(Int8PtrTy, "result.ptr");
+ Builder.CreateStore(Builder.CreatePointerBitCastOrAddrSpaceCast(
+ ReturnValue.getPointer(), Int8PtrTy),
+ ReturnValuePointer);
+ }
} else if (CurFnInfo->getReturnInfo().getKind() == ABIArgInfo::InAlloca &&
!hasScalarEvaluationKind(CurFnInfo->getReturnType())) {
// Load the sret pointer from the argument struct and return into that.
@@ -902,6 +909,7 @@ void CodeGenFunction::StartFunction(Glob
llvm::Function::arg_iterator EI = CurFn->arg_end();
--EI;
llvm::Value *Addr = Builder.CreateStructGEP(nullptr, &*EI, Idx);
+ ReturnValuePointer = Address(Addr, getPointerAlign());
Addr = Builder.CreateAlignedLoad(Addr, getPointerAlign(), "agg.result");
ReturnValue = Address(Addr, getNaturalTypeAlignment(RetTy));
} else {
Modified: cfe/trunk/lib/CodeGen/CodeGenFunction.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenFunction.h?rev=363952&r1=363951&r2=363952&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CodeGenFunction.h (original)
+++ cfe/trunk/lib/CodeGen/CodeGenFunction.h Thu Jun 20 10:15:21 2019
@@ -327,6 +327,10 @@ public:
/// value. This is invalid iff the function has no return value.
Address ReturnValue = Address::invalid();
+ /// ReturnValuePointer - The temporary alloca to hold a pointer to sret.
+ /// This is invalid if sret is not in use.
+ Address ReturnValuePointer = Address::invalid();
+
/// Return true if a label was seen in the current scope.
bool hasLabelBeenSeenInCurrentScope() const {
if (CurLexicalScope)
Modified: cfe/trunk/test/CodeGen/arm64-microsoft-arguments.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/arm64-microsoft-arguments.cpp?rev=363952&r1=363951&r2=363952&view=diff
==============================================================================
--- cfe/trunk/test/CodeGen/arm64-microsoft-arguments.cpp (original)
+++ cfe/trunk/test/CodeGen/arm64-microsoft-arguments.cpp Thu Jun 20 10:15:21 2019
@@ -43,7 +43,7 @@ S3 f3() {
// Pass and return aggregate (of size < 16 bytes) with non-trivial destructor.
// Passed directly but returned indirectly.
// CHECK: define {{.*}} void {{.*}}f4{{.*}}(%struct.S4* inreg noalias sret %agg.result)
-// CHECK: call void {{.*}}func4{{.*}}(%struct.S4* inreg sret %agg.result, [2 x i64] %4)
+// CHECK: call void {{.*}}func4{{.*}}(%struct.S4* inreg sret %agg.result, [2 x i64] %5)
struct S4 {
int a[3];
~S4();
@@ -57,7 +57,7 @@ S4 f4() {
// Pass and return from instance method called from instance method.
// CHECK: define {{.*}} void @{{.*}}bar at Q1{{.*}}(%class.Q1* %this, %class.P1* inreg noalias sret %agg.result)
-// CHECK: call void {{.*}}foo at P1{{.*}}(%class.P1* %ref.tmp, %class.P1* inreg sret %agg.result, i8 %0)
+// CHECK: call void {{.*}}foo at P1{{.*}}(%class.P1* %ref.tmp, %class.P1* inreg sret %agg.result, i8 %1)
class P1 {
public:
Modified: cfe/trunk/test/CodeGenCXX/conditional-gnu-ext.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/conditional-gnu-ext.cpp?rev=363952&r1=363951&r2=363952&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenCXX/conditional-gnu-ext.cpp (original)
+++ cfe/trunk/test/CodeGenCXX/conditional-gnu-ext.cpp Thu Jun 20 10:15:21 2019
@@ -79,7 +79,7 @@ namespace test3 {
B test0(B &x) {
// CHECK-LABEL: define void @_ZN5test35test0ERNS_1BE(
// CHECK: [[X:%.*]] = alloca [[B:%.*]]*,
- // CHECK-NEXT: store [[B]]* {{%.*}}, [[B]]** [[X]]
+ // CHECK: store [[B]]* {{%.*}}, [[B]]** [[X]]
// CHECK-NEXT: [[T0:%.*]] = load [[B]]*, [[B]]** [[X]]
// CHECK-NEXT: [[BOOL:%.*]] = call zeroext i1 @_ZN5test31BcvbEv([[B]]* [[T0]])
// CHECK-NEXT: br i1 [[BOOL]]
@@ -94,7 +94,7 @@ namespace test3 {
B test1() {
// CHECK-LABEL: define void @_ZN5test35test1Ev(
// CHECK: [[TEMP:%.*]] = alloca [[B]],
- // CHECK-NEXT: call void @_ZN5test312test1_helperEv([[B]]* sret [[TEMP]])
+ // CHECK: call void @_ZN5test312test1_helperEv([[B]]* sret [[TEMP]])
// CHECK-NEXT: [[BOOL:%.*]] = call zeroext i1 @_ZN5test31BcvbEv([[B]]* [[TEMP]])
// CHECK-NEXT: br i1 [[BOOL]]
// CHECK: call void @_ZN5test31BC1ERKS0_([[B]]* [[RESULT:%.*]], [[B]]* dereferenceable({{[0-9]+}}) [[TEMP]])
@@ -111,7 +111,7 @@ namespace test3 {
A test2(B &x) {
// CHECK-LABEL: define void @_ZN5test35test2ERNS_1BE(
// CHECK: [[X:%.*]] = alloca [[B]]*,
- // CHECK-NEXT: store [[B]]* {{%.*}}, [[B]]** [[X]]
+ // CHECK: store [[B]]* {{%.*}}, [[B]]** [[X]]
// CHECK-NEXT: [[T0:%.*]] = load [[B]]*, [[B]]** [[X]]
// CHECK-NEXT: [[BOOL:%.*]] = call zeroext i1 @_ZN5test31BcvbEv([[B]]* [[T0]])
// CHECK-NEXT: br i1 [[BOOL]]
@@ -126,7 +126,7 @@ namespace test3 {
A test3() {
// CHECK-LABEL: define void @_ZN5test35test3Ev(
// CHECK: [[TEMP:%.*]] = alloca [[B]],
- // CHECK-NEXT: call void @_ZN5test312test3_helperEv([[B]]* sret [[TEMP]])
+ // CHECK: call void @_ZN5test312test3_helperEv([[B]]* sret [[TEMP]])
// CHECK-NEXT: [[BOOL:%.*]] = call zeroext i1 @_ZN5test31BcvbEv([[B]]* [[TEMP]])
// CHECK-NEXT: br i1 [[BOOL]]
// CHECK: call void @_ZN5test31BcvNS_1AEEv([[A]]* sret [[RESULT:%.*]], [[B]]* [[TEMP]])
Added: cfe/trunk/test/CodeGenCXX/debug-info-nrvo.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/debug-info-nrvo.cpp?rev=363952&view=auto
==============================================================================
--- cfe/trunk/test/CodeGenCXX/debug-info-nrvo.cpp (added)
+++ cfe/trunk/test/CodeGenCXX/debug-info-nrvo.cpp Thu Jun 20 10:15:21 2019
@@ -0,0 +1,28 @@
+// RUN: %clangxx -target x86_64-unknown-unknown -g %s -emit-llvm -S -o - | FileCheck %s
+// RUN: %clangxx -target x86_64-unknown-unknown -g -fno-elide-constructors %s -emit-llvm -S -o - | FileCheck %s -check-prefix=NOELIDE
+struct Foo {
+ Foo() = default;
+ Foo(Foo &&other) { x = other.x; }
+ int x;
+};
+void some_function(int);
+Foo getFoo() {
+ Foo foo;
+ foo.x = 41;
+ some_function(foo.x);
+ return foo;
+}
+
+int main() {
+ Foo bar = getFoo();
+ return bar.x;
+}
+
+// Check that NRVO variables are stored as a pointer with deref if they are
+// stored in the return register.
+
+// CHECK: %result.ptr = alloca i8*, align 8
+// CHECK: call void @llvm.dbg.declare(metadata i8** %result.ptr,
+// CHECK-SAME: metadata !DIExpression(DW_OP_deref)
+// NOELIDE: call void @llvm.dbg.declare(metadata %struct.Foo* %foo,
+// NOELIDE-SAME: metadata !DIExpression()
Modified: cfe/trunk/test/CodeGenCXX/lambda-expressions.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/lambda-expressions.cpp?rev=363952&r1=363951&r2=363952&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenCXX/lambda-expressions.cpp (original)
+++ cfe/trunk/test/CodeGenCXX/lambda-expressions.cpp Thu Jun 20 10:15:21 2019
@@ -195,7 +195,6 @@ namespace pr28595 {
// CHECK-NEXT: ret i32
// CHECK-LABEL: define internal void @"_ZZ1hvEN4$_118__invokeEv"(%struct.A* noalias sret %agg.result) {{.*}} {
-// CHECK-NOT: =
// CHECK: call void @"_ZZ1hvENK4$_11clEv"(%struct.A* sret %agg.result,
// CHECK-NEXT: ret void
struct A { ~A(); };
Modified: cfe/trunk/test/CodeGenObjC/objc-non-trivial-struct-nrvo.m
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenObjC/objc-non-trivial-struct-nrvo.m?rev=363952&r1=363951&r2=363952&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenObjC/objc-non-trivial-struct-nrvo.m (original)
+++ cfe/trunk/test/CodeGenObjC/objc-non-trivial-struct-nrvo.m Thu Jun 20 10:15:21 2019
@@ -38,7 +38,6 @@ Trivial testTrivial(void) {
void func1(TrivialBig *);
// CHECK: define void @testTrivialBig(%[[STRUCT_TRIVIALBIG]]* noalias sret %[[AGG_RESULT:.*]])
-// CHECK-NOT: alloca
// CHECK: call void @func1(%[[STRUCT_TRIVIALBIG]]* %[[AGG_RESULT]])
// CHECK-NEXT: ret void
More information about the cfe-commits
mailing list