Support GC closures with alignment > 16

Tested by tests/dmd/runnable/test16098.d.

Author: kinke

gen/llvmhelpers.cpp

@@ -207,17 +207,6 @@ llvm::AllocaInst *DtoRawAlloca(LLType *lltype, size_t alignment,
   return ai;
 }
 
-LLValue *DtoGcMalloc(const Loc &loc, LLType *lltype, const char *name) {
-  // get runtime function
-  llvm::Function *fn = getRuntimeFunction(loc, gIR->module, "_d_allocmemory");
-  // parameters
-  LLValue *size = DtoConstSize_t(getTypeAllocSize(lltype));
-  // call runtime allocator
-  LLValue *mem = gIR->CreateCallOrInvoke(fn, size, name);
-  // cast
-  return DtoBitCast(mem, getPtrToType(lltype), name);
-}
-
 LLValue *DtoAllocaDump(DValue *val, const char *name) {
   return DtoAllocaDump(val, val->type, name);
 }

gen/llvmhelpers.h

@@ -47,7 +47,6 @@ llvm::AllocaInst *DtoArrayAlloca(Type *type, unsigned arraysize,
                                  const char *name = "");
 llvm::AllocaInst *DtoRawAlloca(LLType *lltype, size_t alignment,
                                const char *name = "");
-LLValue *DtoGcMalloc(const Loc &loc, LLType *lltype, const char *name = "");
 
 LLValue *DtoAllocaDump(DValue *val, const char *name = "");
 LLValue *DtoAllocaDump(DValue *val, int alignment, const char *name = "");

gen/nested.cpp

@@ -17,6 +17,7 @@
 #include "gen/irstate.h"
 #include "gen/llvmhelpers.h"
 #include "gen/logger.h"
+#include "gen/runtime.h"
 #include "gen/tollvm.h"
 #include "ir/irfunction.h"
 #include "ir/irtypeaggr.h"
@@ -488,17 +489,33 @@ void DtoCreateNestedContext(FuncGenState &funcGen) {
     auto &irFunc = funcGen.irFunc;
     unsigned depth = irFunc.depth;
     LLStructType *frameType = irFunc.frameType;
+    const unsigned frameAlignment =
+        std::max(getABITypeAlign(frameType), irFunc.frameTypeAlignment);
+
     // Create frame for current function and append to frames list
     LLValue *frame = nullptr;
     bool needsClosure = fd->needsClosure();
     IF_LOG Logger::println("Needs closure (GC) flag: %d", (int)needsClosure);
     if (needsClosure) {
-      // FIXME: alignment ?
-      frame = DtoGcMalloc(fd->loc, frameType, ".frame");
+      LLFunction *fn =
+          getRuntimeFunction(fd->loc, gIR->module, "_d_allocmemory");
+      auto size = getTypeAllocSize(frameType);
+      if (frameAlignment > 16) // GC guarantees an alignment of 16
+        size += frameAlignment - 16;
+      LLValue *mem =
+          gIR->CreateCallOrInvoke(fn, DtoConstSize_t(size), ".gc_frame");
+      if (frameAlignment <= 16) {
+        frame = DtoBitCast(mem, frameType->getPointerTo(), ".frame");
+      } else {
+        const uint64_t mask = frameAlignment - 1;
+        mem = gIR->ir->CreatePtrToInt(mem, DtoSize_t());
+        mem = gIR->ir->CreateAdd(mem, DtoConstSize_t(mask));
+        mem = gIR->ir->CreateAnd(mem, DtoConstSize_t(~mask));
+        frame =
+            gIR->ir->CreateIntToPtr(mem, frameType->getPointerTo(), ".frame");
+      }
     } else {
-      unsigned alignment =
-          std::max(getABITypeAlign(frameType), irFunc.frameTypeAlignment);
-      frame = DtoRawAlloca(frameType, alignment, ".frame");
+      frame = DtoRawAlloca(frameType, frameAlignment, ".frame");
     }
 
     // copy parent frames into beginning