forked from OSchip/llvm-project
[CodeGen] Emit lifetime.ends in both EH and non-EH blocks
Before this, we'd only emit lifetime.ends for these temps in
non-exceptional paths. This potentially made our stack larger than it
needed to be for any code that follows an EH cleanup. e.g. in
```
struct Foo { char cs[32]; };
void escape(void *);
struct Bar { ~Bar() { char cs[64]; escape(cs); } };
Foo getFoo();
void baz() {
Bar b;
getFoo();
}
```
baz() would require 96 bytes of stack, since the temporary from getFoo()
only had a lifetime.end on the non-exceptional path.
This also makes us keep hold of the Value* returned by
EmitLifetimeStart, so we don't have to remake it later.
llvm-svn: 326988
This commit is contained in:
George Burgess IV
parent
e465a84f85
commit
003be7cbf4
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@ -3790,7 +3790,7 @@ RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
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// If the call returns a temporary with struct return, create a temporary
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// alloca to hold the result, unless one is given to us.
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Address SRetPtr = Address::invalid();
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size_t UnusedReturnSize = 0;
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llvm::Value *UnusedReturnSizePtr = nullptr;
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if (RetAI.isIndirect() || RetAI.isInAlloca() || RetAI.isCoerceAndExpand()) {
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if (!ReturnValue.isNull()) {
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SRetPtr = ReturnValue.getValue();
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@ -3799,8 +3799,7 @@ RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
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if (HaveInsertPoint() && ReturnValue.isUnused()) {
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uint64_t size =
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CGM.getDataLayout().getTypeAllocSize(ConvertTypeForMem(RetTy));
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if (EmitLifetimeStart(size, SRetPtr.getPointer()))
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UnusedReturnSize = size;
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UnusedReturnSizePtr = EmitLifetimeStart(size, SRetPtr.getPointer());
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}
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}
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if (IRFunctionArgs.hasSRetArg()) {
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@ -4231,6 +4230,15 @@ RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
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CannotThrow = Attrs.hasAttribute(llvm::AttributeList::FunctionIndex,
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llvm::Attribute::NoUnwind);
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}
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// If we made a temporary, be sure to clean up after ourselves. Note that we
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// can't depend on being inside of an ExprWithCleanups, so we need to manually
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// pop this cleanup later on. Being eager about this is OK, since this
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// temporary is 'invisible' outside of the callee.
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if (UnusedReturnSizePtr)
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pushFullExprCleanup<CallLifetimeEnd>(NormalEHLifetimeMarker, SRetPtr,
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UnusedReturnSizePtr);
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llvm::BasicBlock *InvokeDest = CannotThrow ? nullptr : getInvokeDest();
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SmallVector<llvm::OperandBundleDef, 1> BundleList =
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@ -4284,9 +4292,8 @@ RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
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// insertion point; this allows the rest of IRGen to discard
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// unreachable code.
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if (CS.doesNotReturn()) {
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if (UnusedReturnSize)
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EmitLifetimeEnd(llvm::ConstantInt::get(Int64Ty, UnusedReturnSize),
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SRetPtr.getPointer());
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if (UnusedReturnSizePtr)
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PopCleanupBlock();
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// Strip away the noreturn attribute to better diagnose unreachable UB.
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if (SanOpts.has(SanitizerKind::Unreachable)) {
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@ -4355,9 +4362,8 @@ RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
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case ABIArgInfo::InAlloca:
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case ABIArgInfo::Indirect: {
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RValue ret = convertTempToRValue(SRetPtr, RetTy, SourceLocation());
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if (UnusedReturnSize)
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EmitLifetimeEnd(llvm::ConstantInt::get(Int64Ty, UnusedReturnSize),
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SRetPtr.getPointer());
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if (UnusedReturnSizePtr)
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PopCleanupBlock();
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return ret;
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}
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@ -0,0 +1,189 @@
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// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu %s -o - -emit-llvm -O1 \
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// RUN: -fexceptions -fcxx-exceptions | FileCheck %s
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//
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// We should emit lifetime.ends for these temporaries in both the 'exception'
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// and 'normal' paths in functions.
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//
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// -O1 is necessary to make lifetime markers appear.
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struct Large {
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int cs[32];
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};
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Large getLarge();
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// Used to ensure we emit invokes.
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struct NontrivialDtor {
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int i;
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~NontrivialDtor();
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};
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// CHECK-LABEL: define void @_Z33cleanupsAreEmittedWithoutTryCatchv
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void cleanupsAreEmittedWithoutTryCatch() {
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// CHECK: %[[CLEAN:[^ ]+]] = bitcast %struct.NontrivialDtor* %{{[^ ]+}} to i8*
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// CHECK: call void @llvm.lifetime.start.p0i8({{[^,]+}}, i8* nonnull %[[CLEAN]])
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// CHECK: %[[T1:[^ ]+]] = bitcast %struct.Large* %{{[^ ]+}} to i8*
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// CHECK: call void @llvm.lifetime.start.p0i8({{[^,]+}}, i8* nonnull %[[T1]])
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// CHECK-NEXT: invoke void @_Z8getLargev
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// CHECK-NEXT: to label %[[CONT:[^ ]+]] unwind label %[[LPAD:[^ ]+]]
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//
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// CHECK: [[CONT]]:
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// CHECK: call void @llvm.lifetime.end.p0i8({{[^,]+}}, i8* nonnull %[[T1]])
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// CHECK: %[[T2:[^ ]+]] = bitcast %struct.Large* %{{[^ ]+}} to i8*
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// CHECK: call void @llvm.lifetime.start.p0i8({{[^,]+}}, i8* nonnull %[[T2]])
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// CHECK-NEXT: invoke void @_Z8getLargev
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// CHECK-NEXT: to label %[[CONT2:[^ ]+]] unwind label %[[LPAD2:.+]]
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//
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// CHECK: [[CONT2]]:
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// CHECK: call void @llvm.lifetime.end.p0i8({{[^,]+}}, i8* nonnull %[[T2]])
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// CHECK: call void @llvm.lifetime.end.p0i8({{[^,]+}}, i8* nonnull %[[CLEAN]])
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// CHECK: ret void
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//
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// CHECK: [[LPAD]]:
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// CHECK: call void @llvm.lifetime.end.p0i8({{[^,]+}}, i8* nonnull %[[T1]])
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// CHECK: br label %[[EHCLEANUP:.+]]
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//
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// CHECK: [[LPAD2]]:
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// CHECK: call void @llvm.lifetime.end.p0i8({{[^,]+}}, i8* nonnull %[[T2]])
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// CHECK: br label %[[EHCLEANUP]]
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//
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// CHECK: [[EHCLEANUP]]:
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// CHECK: call void @llvm.lifetime.end.p0i8({{[^,]+}}, i8* nonnull %[[CLEAN]])
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NontrivialDtor clean;
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getLarge();
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getLarge();
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}
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// CHECK-LABEL: define void @_Z30cleanupsAreEmittedWithTryCatchv
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void cleanupsAreEmittedWithTryCatch() {
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// CHECK: %[[CLEAN:[^ ]+]] = bitcast %struct.NontrivialDtor* %{{[^ ]+}} to i8*
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// CHECK: call void @llvm.lifetime.start.p0i8({{[^,]+}}, i8* nonnull %[[CLEAN]])
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// CHECK: %[[T1:[^ ]+]] = bitcast %struct.Large* %{{[^ ]+}} to i8*
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// CHECK: call void @llvm.lifetime.start.p0i8({{[^,]+}}, i8* nonnull %[[T1]])
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// CHECK-NEXT: invoke void @_Z8getLargev
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// CHECK-NEXT: to label %[[CONT:[^ ]+]] unwind label %[[LPAD:[^ ]+]]
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//
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// CHECK: [[CONT]]:
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// CHECK: call void @llvm.lifetime.end.p0i8({{[^,]+}}, i8* nonnull %[[T1]])
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// CHECK: %[[T2:[^ ]+]] = bitcast %struct.Large* %{{[^ ]+}} to i8*
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// CHECK: call void @llvm.lifetime.start.p0i8({{[^,]+}}, i8* nonnull %[[T2]])
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// CHECK-NEXT: invoke void @_Z8getLargev
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// CHECK-NEXT: to label %[[CONT2:[^ ]+]] unwind label %[[LPAD2:.+]]
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//
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// CHECK: [[CONT2]]:
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// CHECK: call void @llvm.lifetime.end.p0i8({{[^,]+}}, i8* nonnull %[[T2]])
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// CHECK: br label %[[TRY_CONT:.+]]
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//
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// CHECK: [[LPAD]]:
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// CHECK: call void @llvm.lifetime.end.p0i8({{[^,]+}}, i8* nonnull %[[T1]])
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// CHECK: br label %[[CATCH:.+]]
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//
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// CHECK: [[LPAD2]]:
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// CHECK: call void @llvm.lifetime.end.p0i8({{[^,]+}}, i8* nonnull %[[T2]])
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// CHECK: br label %[[CATCH]]
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//
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// CHECK: [[CATCH]]:
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// CHECK-NOT: call void @llvm.lifetime
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// CHECK: invoke void
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// CHECK-NEXT: to label %[[TRY_CONT]] unwind label %[[OUTER_LPAD:.+]]
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//
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// CHECK: [[TRY_CONT]]:
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// CHECK: %[[T_OUTER:[^ ]+]] = bitcast %struct.Large* %{{[^ ]+}} to i8*
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// CHECK: call void @llvm.lifetime.start.p0i8({{[^,]+}}, i8* nonnull %[[T_OUTER]])
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// CHECK-NEXT: invoke void @_Z8getLargev
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// CHECK-NEXT: to label %[[OUTER_CONT:[^ ]+]] unwind label %[[OUTER_LPAD2:.+]]
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//
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// CHECK: [[OUTER_CONT]]:
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// CHECK: call void @llvm.lifetime.end.p0i8({{[^,]+}}, i8* nonnull %[[T_OUTER]])
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// CHECK: call void @llvm.lifetime.end.p0i8({{[^,]+}}, i8* nonnull %[[CLEAN]])
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// CHECK: ret void
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//
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// CHECK: [[OUTER_LPAD]]:
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// CHECK-NOT: call void @llvm.lifetime
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// CHECK: br label %[[EHCLEANUP:.+]]
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//
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// CHECK: [[OUTER_LPAD2]]:
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// CHECK: call void @llvm.lifetime.end.p0i8({{[^,]+}}, i8* nonnull %[[T_OUTER]])
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// CHECK: br label %[[EHCLEANUP]]
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//
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// CHECK: [[EHCLEANUP]]:
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// CHECK: call void @llvm.lifetime.end.p0i8({{[^,]+}}, i8* nonnull %[[CLEAN]])
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NontrivialDtor clean;
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try {
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getLarge();
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getLarge();
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} catch (...) {}
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getLarge();
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}
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// CHECK-LABEL: define void @_Z39cleanupInTryHappensBeforeCleanupInCatchv
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void cleanupInTryHappensBeforeCleanupInCatch() {
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// CHECK: %[[T1:[^ ]+]] = bitcast %struct.Large* %{{[^ ]+}} to i8*
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// CHECK: call void @llvm.lifetime.start.p0i8({{[^,]+}}, i8* nonnull %[[T1]])
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// CHECK-NEXT: invoke void @_Z8getLargev
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// CHECK-NEXT: to label %[[CONT:[^ ]+]] unwind label %[[LPAD:[^ ]+]]
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//
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// CHECK: [[CONT]]:
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// CHECK: call void @llvm.lifetime.end.p0i8({{[^,]+}}, i8* nonnull %[[T1]])
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// CHECK: br label %[[TRY_CONT]]
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//
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// CHECK: [[LPAD]]:
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// CHECK: call void @llvm.lifetime.end.p0i8({{[^,]+}}, i8* nonnull %[[T1]])
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// CHECK: br i1 {{[^,]+}}, label %[[CATCH_INT_MATCH:[^,]+]], label %[[CATCH_ALL:.+]]
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//
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// CHECK: [[CATCH_INT_MATCH]]:
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// CHECK: %[[T2:[^ ]+]] = bitcast %struct.Large* %{{[^ ]+}} to i8*
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// CHECK: call void @llvm.lifetime.start.p0i8({{[^,]+}}, i8* nonnull %[[T2]])
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// CHECK-NEXT: invoke void @_Z8getLargev
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// CHECK-NEXT: to label %[[CATCH_INT_CONT:[^ ]+]] unwind label %[[CATCH_INT_LPAD:[^ ]+]]
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//
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// CHECK: [[CATCH_INT_CONT]]:
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// CHECK: call void @llvm.lifetime.end.p0i8({{[^,]+}}, i8* nonnull %[[T2]])
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// CHECK: br label %[[TRY_CONT]]
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//
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// CHECK: [[TRY_CONT]]:
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// CHECK: ret void
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//
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// CHECK: [[CATCH_ALL]]:
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// CHECK: %[[T3:[^ ]+]] = bitcast %struct.Large* %{{[^ ]+}} to i8*
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// CHECK: call void @llvm.lifetime.start.p0i8({{[^,]+}}, i8* nonnull %[[T3]])
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// CHECK-NEXT: invoke void @_Z8getLargev
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// CHECK-NEXT: to label %[[CATCH_ALL_CONT:[^ ]+]] unwind label %[[CATCH_ALL_LPAD:[^ ]+]]
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//
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// CHECK: [[CATCH_ALL_CONT]]:
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// CHECK: call void @llvm.lifetime.end.p0i8({{[^,]+}}, i8* nonnull %[[T3]])
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// CHECK: br label %[[TRY_CONT]]
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//
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// CHECK: [[CATCH_ALL_LPAD]]:
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// CHECK: call void @llvm.lifetime.end.p0i8({{[^,]+}}, i8* nonnull %[[T3]])
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//
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// CHECK: [[CATCH_INT_LPAD]]:
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// CHECK: call void @llvm.lifetime.end.p0i8({{[^,]+}}, i8* nonnull %[[T2]])
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// CHECK-NOT: call void @llvm.lifetime
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try {
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getLarge();
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} catch (const int &) {
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getLarge();
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} catch (...) {
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getLarge();
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}
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}
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// FIXME: We don't currently emit lifetime markers for aggregate by-value
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// temporaries (e.g. given a function `Large combine(Large, Large);`
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// combine(getLarge(), getLarge()) "leaks" two `Large`s). We probably should. We
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// also don't emit markers for things like:
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//
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// {
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// Large L = getLarge();
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// combine(L, L);
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// }
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//
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// Though this arguably isn't as bad, since we pass a pointer to `L` as one of
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// the two args.
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