ahatanak updated this revision to Diff 82142.
ahatanak added a comment.
Rebase and improve test cases.
- Add "-mllvm -disable-llvm-optzns" to the RUN line.
- Add a test case that shows lifetime.start of a variable isn't moved to the
beginning of its scope when the goto leaves the scope.
https://reviews.llvm.org/D27680
Files:
lib/CodeGen/CGDecl.cpp
lib/CodeGen/CGExpr.cpp
lib/CodeGen/CGStmt.cpp
lib/CodeGen/CodeGenFunction.h
test/CodeGen/lifetime2.c
Index: test/CodeGen/lifetime2.c
===================================================================
--- test/CodeGen/lifetime2.c
+++ test/CodeGen/lifetime2.c
@@ -1,4 +1,4 @@
-// RUN: %clang -S -emit-llvm -o - -O2 %s | FileCheck %s -check-prefixes=CHECK,O2
+// RUN: %clang -S -emit-llvm -o - -O2 -mllvm -disable-llvm-optzns %s | FileCheck %s -check-prefixes=CHECK,O2
// RUN: %clang -S -emit-llvm -o - -O0 %s | FileCheck %s -check-prefixes=CHECK,O0
extern int bar(char *A, int n);
@@ -19,11 +19,11 @@
// CHECK-LABEL: @no_goto_bypass
void no_goto_bypass() {
+ // O2: @llvm.lifetime.start(i64 5
// O2: @llvm.lifetime.start(i64 1
char x;
l1:
bar(&x, 1);
- // O2: @llvm.lifetime.start(i64 5
// O2: @llvm.lifetime.end(i64 5
char y[5];
bar(y, 5);
@@ -89,3 +89,58 @@
L:
bar(&x, 1);
}
+
+// O2-LABEL: define i32 @move_lifetime_start
+// O2: %i = alloca i32, align 4
+// O2: %[[BITCAST:[0-9]+]] = bitcast i32* %i to i8*
+// O2: call void @llvm.lifetime.start(i64 4, i8* %[[BITCAST]])
+// O2: br label %[[DESTLABEL:[a-z0-9]+]]
+// O2: [[DESTLABEL]]:
+// O2: switch i32 %{{.*}}, label %{{.*}} [
+// O2-NEXT: i32 2, label %[[DESTLABEL]]
+
+extern void foo2(int p);
+
+int move_lifetime_start(int a) {
+ int *p = 0;
+label1:
+ if (p) {
+ foo2(*p);
+ return 0;
+ }
+
+ int i = 999;
+ if (a != 2) {
+ p = &i;
+ goto label1;
+ }
+ return -1;
+}
+
+// O2-LABEL: define i32 @dont_move_lifetime_start
+// O2: %i = alloca i32, align 4
+// O2: br label %[[DESTLABEL:[a-z0-9]+]]
+// O2: [[DESTLABEL]]:
+// O2: %[[BITCAST:[0-9]+]] = bitcast i32* %i to i8*
+// O2: call void @llvm.lifetime.start(i64 4, i8* %[[BITCAST]])
+// O2: switch i32 %{{.*}}, label %{{.*}} [
+// O2-NEXT: i32 0, label %{{.*}}
+// O2-NEXT: i32 2, label %[[DESTLABEL]]
+
+int dont_move_lifetime_start(int a) {
+ int *p = 0;
+label1:
+ {
+ if (p) {
+ foo2(*p);
+ return 0;
+ }
+
+ int i = 999;
+ if (a != 2) {
+ p = &i;
+ goto label1;
+ }
+ }
+ return -1;
+}
Index: lib/CodeGen/CodeGenFunction.h
===================================================================
--- lib/CodeGen/CodeGenFunction.h
+++ lib/CodeGen/CodeGenFunction.h
@@ -348,14 +348,20 @@
class CallLifetimeEnd final : public EHScopeStack::Cleanup {
llvm::Value *Addr;
llvm::Value *Size;
+ llvm::CallInst *LifetimeStart;
public:
- CallLifetimeEnd(Address addr, llvm::Value *size)
- : Addr(addr.getPointer()), Size(size) {}
+ CallLifetimeEnd(Address addr, llvm::Value *size,
+ llvm::CallInst *lifetimeStart = nullptr)
+ : Addr(addr.getPointer()), Size(size), LifetimeStart(lifetimeStart) {}
void Emit(CodeGenFunction &CGF, Flags flags) override {
CGF.EmitLifetimeEnd(Size, Addr);
}
+
+ llvm::CallInst *&getLifetimeStart() {
+ return LifetimeStart;
+ }
};
/// Header for data within LifetimeExtendedCleanupStack.
@@ -523,10 +529,10 @@
/// \brief Enters a new scope for capturing cleanups, all of which
/// will be executed once the scope is exited.
class RunCleanupsScope {
- EHScopeStack::stable_iterator CleanupStackDepth;
size_t LifetimeExtendedCleanupStackSize;
bool OldDidCallStackSave;
protected:
+ EHScopeStack::stable_iterator CleanupStackDepth;
bool PerformCleanup;
private:
@@ -578,6 +584,7 @@
SourceRange Range;
SmallVector<const LabelDecl*, 4> Labels;
LexicalScope *ParentScope;
+ llvm::BasicBlock *BB;
LexicalScope(const LexicalScope &) = delete;
void operator=(const LexicalScope &) = delete;
@@ -589,13 +596,27 @@
CGF.CurLexicalScope = this;
if (CGDebugInfo *DI = CGF.getDebugInfo())
DI->EmitLexicalBlockStart(CGF.Builder, Range.getBegin());
+ CGF.EnsureInsertPoint();
+ BB = CGF.Builder.GetInsertBlock();
}
void addLabel(const LabelDecl *label) {
assert(PerformCleanup && "adding label to dead scope?");
Labels.push_back(label);
}
+ EHScopeStack::stable_iterator getCleanupStackDepth() const {
+ return CleanupStackDepth;
+ }
+
+ llvm::BasicBlock *getBasicBlock() const {
+ return BB;
+ }
+
+ LexicalScope *getParentScope() const {
+ return ParentScope;
+ }
+
/// \brief Exit this cleanup scope, emitting any accumulated
/// cleanups.
~LexicalScope() {
@@ -620,6 +641,10 @@
rescopeLabels();
}
+ bool hasLabel(const LabelDecl *LD) const {
+ return llvm::is_contained(Labels, LD);
+ }
+
void rescopeLabels();
};
@@ -2184,7 +2209,7 @@
void EmitCXXTemporary(const CXXTemporary *Temporary, QualType TempType,
Address Ptr);
- llvm::Value *EmitLifetimeStart(uint64_t Size, llvm::Value *Addr);
+ llvm::CallInst *EmitLifetimeStart(uint64_t Size, llvm::Value *Addr);
void EmitLifetimeEnd(llvm::Value *Size, llvm::Value *Addr);
llvm::Value *EmitCXXNewExpr(const CXXNewExpr *E);
@@ -2313,27 +2338,30 @@
bool IsConstantAggregate;
/// Non-null if we should use lifetime annotations.
- llvm::Value *SizeForLifetimeMarkers;
+ llvm::CallInst *LifetimeStart;
struct Invalid {};
AutoVarEmission(Invalid) : Variable(nullptr), Addr(Address::invalid()) {}
AutoVarEmission(const VarDecl &variable)
: Variable(&variable), Addr(Address::invalid()), NRVOFlag(nullptr),
- IsByRef(false), IsConstantAggregate(false),
- SizeForLifetimeMarkers(nullptr) {}
+ IsByRef(false), IsConstantAggregate(false), LifetimeStart(nullptr) {}
bool wasEmittedAsGlobal() const { return !Addr.isValid(); }
public:
static AutoVarEmission invalid() { return AutoVarEmission(Invalid()); }
bool useLifetimeMarkers() const {
- return SizeForLifetimeMarkers != nullptr;
+ return LifetimeStart != nullptr;
}
llvm::Value *getSizeForLifetimeMarkers() const {
+ return LifetimeStart->getOperand(0);
+ }
+
+ llvm::CallInst *getLifetimeStartMarker() const {
assert(useLifetimeMarkers());
- return SizeForLifetimeMarkers;
+ return LifetimeStart;
}
/// Returns the raw, allocated address, which is not necessarily
Index: lib/CodeGen/CGStmt.cpp
===================================================================
--- lib/CodeGen/CGStmt.cpp
+++ lib/CodeGen/CGStmt.cpp
@@ -12,6 +12,7 @@
//===----------------------------------------------------------------------===//
#include "CodeGenFunction.h"
+#include "CGCleanup.h"
#include "CGDebugInfo.h"
#include "CodeGenModule.h"
#include "TargetInfo.h"
@@ -558,14 +559,80 @@
}
}
+/// Move LifetimeStart to the beginning of lexical scope LS.
+static void moveLifetimeStart(llvm::CallInst *&LifetimeStart,
+ CodeGenFunction::LexicalScope *LS,
+ CodeGenFunction *CGF) {
+ llvm::BasicBlock *EntryBlock = &CGF->CurFn->getEntryBlock();
+ llvm::BasicBlock *BB = LS ? LS->getBasicBlock() : EntryBlock;
+ auto I = BB->begin();
+
+ // If BB is the entry block, move the lifetime marker to after the alloca
+ // insertion point.
+ if (BB == EntryBlock)
+ I = CGF->AllocaInsertPt->getIterator();
+
+ // Move the lifetime marker.
+ LifetimeStart->removeFromParent();
+ BB->getInstList().insertAfter(I, LifetimeStart);
+
+ // Move the bitcast instruction too.
+ auto *Ptr = cast<llvm::Instruction>(LifetimeStart->getOperand(1));
+ if (isa<llvm::BitCastInst>(Ptr)) {
+ assert(isa<llvm::AllocaInst>(cast<llvm::BitCastInst>(Ptr)->getOperand(0)) &&
+ "this should be a bitcast of an alloca");
+ Ptr->removeFromParent();
+ BB->getInstList().insertAfter(I, Ptr);
+ }
+
+ LifetimeStart = nullptr;
+}
+
void CodeGenFunction::EmitGotoStmt(const GotoStmt &S) {
// If this code is reachable then emit a stop point (if generating
// debug info). We have to do this ourselves because we are on the
// "simple" statement path.
if (HaveInsertPoint())
EmitStopPoint(&S);
- EmitBranchThroughCleanup(getJumpDestForLabel(S.getLabel()));
+ auto Dest = getJumpDestForLabel(S.getLabel());
+ auto JumpDestIdx = Dest.getScopeDepth();
+
+ // If we are compiling for C and the goto's destination label has been seen,
+ // move the lifetime.start markers.
+ if (!getLangOpts().CPlusPlus && JumpDestIdx.isValid()) {
+ LexicalScope *LS = CurLexicalScope;
+ auto SI = EHStack.getInnermostNormalCleanup();
+
+ // Search for the lexical scope enclosing the destination label. Note that
+ // LS will be null if the function body is the enclosing lexical scope.
+ while (LS) {
+ if (LS->hasLabel(S.getLabel()))
+ break;
+ SI = LS->getCleanupStackDepth();
+ LS = LS->getParentScope();
+ }
+
+ // Move all the lifetime.start markers of the scopes in range
+ // [SI, JumpDestIdx) to the beginning of the enclosing lexical scope.
+ while (SI != JumpDestIdx) {
+ auto *Scope = &cast<EHCleanupScope>(*EHStack.find(SI));
+ SI = Scope->getEnclosingNormalCleanup();
+
+ if (!Scope->isLifetimeMarker())
+ continue;
+
+ auto *C = static_cast<CallLifetimeEnd *>(Scope->getCleanup());
+ llvm::CallInst *&LifetimeStart = C->getLifetimeStart();
+
+ if (!LifetimeStart)
+ continue;
+
+ moveLifetimeStart(LifetimeStart, LS, this);
+ }
+ }
+
+ EmitBranchThroughCleanup(Dest);
}
Index: lib/CodeGen/CGExpr.cpp
===================================================================
--- lib/CodeGen/CGExpr.cpp
+++ lib/CodeGen/CGExpr.cpp
@@ -430,9 +430,10 @@
switch (M->getStorageDuration()) {
case SD_Automatic:
case SD_FullExpression:
- if (auto *Size = EmitLifetimeStart(
+ if (auto *LifetimeStart = EmitLifetimeStart(
CGM.getDataLayout().getTypeAllocSize(Object.getElementType()),
Object.getPointer())) {
+ auto *Size = LifetimeStart->getOperand(0);
if (M->getStorageDuration() == SD_Automatic)
pushCleanupAfterFullExpr<CallLifetimeEnd>(NormalEHLifetimeMarker,
Object, Size);
Index: lib/CodeGen/CGDecl.cpp
===================================================================
--- lib/CodeGen/CGDecl.cpp
+++ lib/CodeGen/CGDecl.cpp
@@ -889,7 +889,7 @@
/// Emit a lifetime.begin marker if some criteria are satisfied.
/// \return a pointer to the temporary size Value if a marker was emitted, null
/// otherwise
-llvm::Value *CodeGenFunction::EmitLifetimeStart(uint64_t Size,
+llvm::CallInst *CodeGenFunction::EmitLifetimeStart(uint64_t Size,
llvm::Value *Addr) {
if (!ShouldEmitLifetimeMarkers)
return nullptr;
@@ -899,7 +899,7 @@
llvm::CallInst *C =
Builder.CreateCall(CGM.getLLVMLifetimeStartFn(), {SizeV, Addr});
C->setDoesNotThrow();
- return SizeV;
+ return C;
}
void CodeGenFunction::EmitLifetimeEnd(llvm::Value *Size, llvm::Value *Addr) {
@@ -1024,7 +1024,7 @@
// them incorrectly placed.
if (!Bypasses.IsBypassed(&D)) {
uint64_t size = CGM.getDataLayout().getTypeAllocSize(allocaTy);
- emission.SizeForLifetimeMarkers =
+ emission.LifetimeStart =
EmitLifetimeStart(size, address.getPointer());
}
} else {
@@ -1374,7 +1374,8 @@
if (emission.useLifetimeMarkers())
EHStack.pushCleanup<CallLifetimeEnd>(NormalEHLifetimeMarker,
emission.getAllocatedAddress(),
- emission.getSizeForLifetimeMarkers());
+ emission.getSizeForLifetimeMarkers(),
+ emission.getLifetimeStartMarker());
// Check the type for a cleanup.
if (QualType::DestructionKind dtorKind = D.getType().isDestructedType())
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