GorNishanov created this revision.
Wrap deallocation code with:
if (auto *mem = coro.free()) Deallocate
When backend decides to elide allocations it will replace coro.free with
nullptr to suppress deallocation code.
https://reviews.llvm.org/D31590
Files:
lib/CodeGen/CGCoroutine.cpp
test/CodeGenCoroutines/coro-alloc.cpp
Index: test/CodeGenCoroutines/coro-alloc.cpp
===================================================================
--- test/CodeGenCoroutines/coro-alloc.cpp
+++ test/CodeGenCoroutines/coro-alloc.cpp
@@ -56,7 +56,15 @@
// CHECK: %[[FRAME:.+]] = call i8* @llvm.coro.begin(token %[[ID]], i8* %[[PHI]])
// CHECK: %[[MEM:.+]] = call i8* @llvm.coro.free(token %[[ID]], i8* %[[FRAME]])
+ // CHECK: %[[NeedDealloc:.+]] = icmp ne i8* %[[MEM]], null
+ // CHECK: br i1 %[[NeedDealloc]], label %[[FreeBB:.+]], label %[[Afterwards:.+]]
+
+ // CHECK: [[FreeBB]]:
// CHECK: call void @_ZdlPv(i8* %[[MEM]])
+ // CHECK: br label %[[Afterwards]]
+
+ // CHECK: [[Afterwards]]:
+ // CHECK: ret void
co_return;
}
Index: lib/CodeGen/CGCoroutine.cpp
===================================================================
--- lib/CodeGen/CGCoroutine.cpp
+++ lib/CodeGen/CGCoroutine.cpp
@@ -62,6 +62,10 @@
// the address of the coroutine frame of the current coroutine.
llvm::CallInst *CoroBegin = nullptr;
+ // Stores the last emitted coro.free for the deallocate expressions, we use it
+ // to wrap dealloc code with if(auto mem = coro.free) dealloc(mem).
+ llvm::CallInst *LastCoroFree = nullptr;
+
// If coro.id came from the builtin, remember the expression to give better
// diagnostic. If CoroIdExpr is nullptr, the coro.id was created by
// EmitCoroutineBody.
@@ -225,14 +229,47 @@
struct CallCoroDelete final : public EHScopeStack::Cleanup {
Stmt *Deallocate;
- // TODO: Wrap deallocate in if(coro.free(...)) Deallocate.
+ // Emit "if (coro.free(CoroId, CoroBegin)) Deallocate;"
+
+ // Note: That deallocation will be emitted twice: once for a normal exit and
+ // once for exceptional exit. This usage is safe because Deallocate does not
+ // contain any declarations. The SubStmtBuilder::makeNewAndDeleteExpr()
+ // builds a single call to a deallocation function which is safe to emit
+ // multiple times.
void Emit(CodeGenFunction &CGF, Flags) override {
- // Note: That deallocation will be emitted twice: once for a normal exit and
- // once for exceptional exit. This usage is safe because Deallocate does not
- // contain any declarations. The SubStmtBuilder::makeNewAndDeleteExpr()
- // builds a single call to a deallocation function which is safe to emit
- // multiple times.
+ // Remember the current point, as we are going to emit deallocation code
+ // first to get to coro.free instruction that is an argument to a delete
+ // call.
+ BasicBlock *SaveInsertBlock = CGF.Builder.GetInsertBlock();
+
+ auto *FreeBB = CGF.createBasicBlock("coro.free");
+ CGF.EmitBlock(FreeBB);
CGF.EmitStmt(Deallocate);
+
+ auto *AfterFreeBB = CGF.createBasicBlock("after.coro.free");
+ CGF.EmitBlock(AfterFreeBB);
+
+ // We should have captured coro.free from the emission of deallocate.
+ auto *CoroFree = CGF.CurCoro.Data->LastCoroFree;
+ if (!CoroFree) {
+ CGF.CGM.Error(Deallocate->getLocStart(),
+ "Deallocation expressoin does not refer to coro.free");
+ return;
+ }
+
+ // Get back to the block we were originally and move coro.free there.
+ auto *InsertPt = SaveInsertBlock->getTerminator();
+ CoroFree->moveBefore(InsertPt);
+ CGF.Builder.SetInsertPoint(InsertPt);
+
+ // Add if (auto *mem = coro.free) Deallocate;
+ auto *NullPtr = llvm::ConstantPointerNull::get(CGF.Int8PtrTy);
+ auto *Cond = CGF.Builder.CreateICmpNE(CoroFree, NullPtr);
+ CGF.Builder.CreateCondBr(Cond, FreeBB, AfterFreeBB);
+
+ // No longer need old terminator.
+ InsertPt->eraseFromParent();
+ CGF.Builder.SetInsertPoint(AfterFreeBB);
}
explicit CallCoroDelete(Stmt *DeallocStmt) : Deallocate(DeallocStmt) {}
};
@@ -365,7 +402,7 @@
llvm::Value *F = CGM.getIntrinsic(IID);
llvm::CallInst *Call = Builder.CreateCall(F, Args);
- // Note: The following code is to enable to emit coroutine intrinsics by
+ // Note: The following code is to enable to emit coro.id and coro.begin by
// hand to experiment with coroutines in C.
// If we see @llvm.coro.id remember it in the CoroData. We will update
// coro.alloc, coro.begin and coro.free intrinsics to refer to it.
@@ -376,5 +413,10 @@
if (CurCoro.Data)
CurCoro.Data->CoroBegin = Call;
}
- return RValue::get(Call);
+ else if (IID == llvm::Intrinsic::coro_free) {
+ // Remember the last coro_free as we need it to build the conditional
+ // deletion of the coroutine frame.
+ if (CurCoro.Data)
+ CurCoro.Data->LastCoroFree = Call;
+ } return RValue::get(Call);
}
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