Implement support for the abs intrinsic.

Note only floating point cases make it through as intrinsics. Also make sure we honor the alignment requests of the read-only data sections. Abs uses a 16-byte aligned constant mask.

Closes #329.

include/Reader/readerir.h

@@ -274,9 +274,7 @@ public:
   // Used for testing, client can force verification.
   bool verForceVerification(void) override { return false; };
 
-  bool abs(IRNode *Arg1, IRNode **RetVal) override {
-    throw NotYetImplementedException("abs");
-  };
+  bool abs(IRNode *Arg1, IRNode **RetVal) override;
 
   IRNode *argList() override;
   IRNode *instParam() override;

lib/Jit/EEMemoryManager.cpp

@@ -50,11 +50,22 @@ uint8_t *EEMemoryManager::allocateDataSection(uintptr_t Size,
   // We don't expect to see RW data requests.
   assert(IsReadOnly);
 
+  // Pad for alignment needs.
+  unsigned int Offset = ((uint64_t)ReadOnlyDataUnallocated) % Alignment;
+  if (Offset > 0) {
+    ReadOnlyDataUnallocated += Alignment - Offset;
+  }
+  assert((((uint64_t)ReadOnlyDataUnallocated) % Alignment) == 0);
+
   // There are multiple read-only sections, so we need to keep
   // track of the current allocation point in the read-only memory region.
   uint8_t *Result = ReadOnlyDataUnallocated;
   ReadOnlyDataUnallocated += Size;
 
+  // Make sure we are not allocating more than we expected to.
+  assert(ReadOnlyDataUnallocated <=
+         (ReadOnlyDataBlock + this->Context->ReadOnlyDataSize));
+
   return Result;
 }
 

lib/Reader/readerir.cpp

@@ -4518,6 +4518,28 @@ bool GenIR::disableCastClassOptimization() {
   return true;
 }
 
+/// Optionally generate inline code for the \p abs opcode
+///
+/// \param Argument      input value for abs
+/// \param Result [out]  resulting absolute value, if we decided to expand
+/// \returns             true if Result represents the absolute value.
+bool GenIR::abs(IRNode *Argument, IRNode **Result) {
+  Type *Ty = Argument->getType();
+
+  // Only the floating point cases of System.Math.Abs are implemented via
+  // 'internallcall'.
+  if (Ty->isFloatingPointTy()) {
+    Type *Types[] = {Ty};
+    Value *FAbs = Intrinsic::getDeclaration(JitContext->CurrentModule,
+                                            Intrinsic::fabs, Types);
+    Value *Abs = LLVMBuilder->CreateCall(FAbs, Argument);
+    *Result = (IRNode *)Abs;
+    return true;
+  }
+
+  return false;
+}
+
 #pragma endregion
 
 #pragma region STACK MAINTENANCE