alloc entries in frametables + disable musttail in RS4GC

Author: usuyus

llvm/lib/CodeGen/AsmPrinter/OxCamlGCPrinter.cpp

@@ -140,6 +140,20 @@ static unsigned mapLLVMDwarfRegToOxCamlIndex(unsigned DwarfRegNum) {
   }
 }
 
+static uint64_t stackOffsetOfID(uint64_t ID) {
+  return ID & ((1ull << 16) - 1) & ~(1ull);
+}
+
+static uint64_t allocSizeOfID(uint64_t ID) {
+  return ID >> 16;
+}
+
+static bool IDHasAlloc(uint64_t ID) {
+  return ID & 1ull;
+}
+
+static const int allocMask = 2;
+
 bool OxCamlGCMetadataPrinter::emitStackMaps(Module &M, StackMaps &SM, AsmPrinter &AP) {
   MCStreamer &OS = *AP.OutStreamer;
   unsigned PtrSize = M.getDataLayout().getPointerSize(); // Can only be 8 for now
@@ -173,10 +187,16 @@ bool OxCamlGCMetadataPrinter::emitStackMaps(Module &M, StackMaps &SM, AsmPrinter
 
     // frame_data
     uint64_t FrameSize = CSI.CSFunctionInfo.StaticStackSize;
-    if (CSI.ID != StatepointDirectives::DefaultStatepointID)
-      FrameSize += CSI.ID; // Stack offset from OxCaml
     FrameSize += PtrSize; // Return address
 
+    if (CSI.ID != StatepointDirectives::DefaultStatepointID) {
+      // Alloc bit
+      if (IDHasAlloc(CSI.ID)) FrameSize |= allocMask;
+      
+      // Stack offset from OxCaml
+      FrameSize += stackOffsetOfID(CSI.ID);
+    }
+
     if (FrameSize >= 1 << 16)
       report_fatal_error("Long frames not supported for OxCaml GC: FrameSize = "
         + Twine(FrameSize));
@@ -238,6 +258,11 @@ bool OxCamlGCMetadataPrinter::emitStackMaps(Module &M, StackMaps &SM, AsmPrinter
       OS.emitInt16(EncodedReg);
     }
 
+    if (IDHasAlloc(CSI.ID)) {
+      OS.emitInt8(1);
+      OS.emitInt8(allocSizeOfID(CSI.ID));
+    }
+
     OS.emitValueToAlignment(Align(PtrSize));
   }
 

llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp

@@ -3087,6 +3087,11 @@ bool RewriteStatepointsForGC::runOnFunction(Function &F, DominatorTree &DT,
                "Don't expect any other calls here!");
         return false;
       }
+
+      // `musttail` calls wrapped in statepoints fail to verify due to
+      // the intrinsic using variadic arguments.
+      if (Call->isMustTailCall()) return false;
+      
       return true;
     }
     return false;