IRGen: swift_taskAlloc wants its size input to be multiple of MaximumAlignment

Author: aschwaighofer

lib/IRGen/GenOpaque.cpp

@@ -545,6 +545,9 @@ StackAddress IRGenFunction::emitDynamicAlloca(llvm::Type *eltTy,
     } else {
       byteCount = Builder.CreateMul(arraySize, IGM.getSize(Size(eltSize)));
     }
+    // The task allocator wants size increments in the mulitple of
+    // MaximumAlignment.
+    byteCount = alignUpToMaximumAlignment(IGM.SizeTy, byteCount);
     auto address = emitTaskAlloc(byteCount, align);
     return {address, address.getAddress()};
   // In coroutines, call llvm.coro.alloca.alloc.

lib/IRGen/IRGenFunction.cpp

@@ -14,7 +14,7 @@
 //  performs IR generation for function bodies.
 //
 //===----------------------------------------------------------------------===//
-
+#include "swift/ABI/MetadataValues.h"
 #include "swift/AST/IRGenOptions.h"
 #include "swift/Basic/SourceLoc.h"
 #include "swift/IRGen/Linking.h"
@@ -507,3 +507,9 @@ void IRGenFunction::emitTaskDealloc(Address address) {
   call->setDoesNotThrow();
   call->setCallingConv(IGM.SwiftCC);
 }
+
+llvm::Value *IRGenFunction::alignUpToMaximumAlignment(llvm::Type *sizeTy, llvm::Value *val) {
+  auto *alignMask = llvm::ConstantInt::get(sizeTy, MaximumAlignment - 1);
+  auto *invertedMask = Builder.CreateNot(alignMask);
+  return Builder.CreateAnd(Builder.CreateAdd(val, alignMask), invertedMask);
+}

lib/IRGen/IRGenFunction.h

@@ -460,6 +460,8 @@ class IRGenFunction {
                         Alignment alignment);
   void emitTaskDealloc(Address address);
 
+  llvm::Value *alignUpToMaximumAlignment(llvm::Type *sizeTy, llvm::Value *val);
+
   //--- Expression emission
   //------------------------------------------------------
 public: