llvmjit: Also copy parameter / return value attributes from template functions.

anarazel · anarazel · commit f3dee5b9aba6 · 2020-10-15T15:06:16.000-07:00
Previously we only copied the function attributes. That caused problems at least on s390x: Because we didn't copy the 'zeroext' attribute for ExecAggTransReparent()'s *IsNull parameters, expressions invoking it didn't ensure that the upper bytes of the registers were zeroed. In the - relatively rare - cases where not, ExecAggTransReparent() wrongly ended up in the newValueIsNull branch due to the register not being zero. Subsequently causing a crash. It's quite possible that this would cause problems on other platforms, and in other places than just ExecAggTransReparent() on s390x. Thanks to Christoph (and the Debian project) for providing me with access to a s390x machine, allowing me to debug this. Reported-By: Christoph Berg Author: Andres Freund Discussion: https://postgr.es/m/20201015083246.kie5726xerdt3ael@alap3.anarazel.de Backpatch: 11-, where JIT was added
diff --git a/src/backend/jit/llvm/llvmjit.c b/src/backend/jit/llvm/llvmjit.c
@@ -327,26 +327,48 @@ llvm_get_decl(LLVMModuleRef mod, LLVMValueRef v_src)
 }
 
 /*
- * Copy attributes from one function to another.
+ * Copy attributes from one function to another, for a specific index (an
+ * index can reference return value, function and parameter attributes).
  */
-void
-llvm_copy_attributes(LLVMValueRef v_from, LLVMValueRef v_to)
+static void
+llvm_copy_attributes_at_index(LLVMValueRef v_from, LLVMValueRef v_to, uint32 index)
 {
 	int			num_attributes;
-	int			attno;
 	LLVMAttributeRef *attrs;
+	int			attno;
 
-	num_attributes =
-		LLVMGetAttributeCountAtIndex(v_from, LLVMAttributeFunctionIndex);
+	num_attributes = LLVMGetAttributeCountAtIndex(v_from, index);
 
 	attrs = palloc(sizeof(LLVMAttributeRef) * num_attributes);
-	LLVMGetAttributesAtIndex(v_from, LLVMAttributeFunctionIndex, attrs);
+	LLVMGetAttributesAtIndex(v_from, index, attrs);
 
 	for (attno = 0; attno < num_attributes; attno++)
-	{
-		LLVMAddAttributeAtIndex(v_to, LLVMAttributeFunctionIndex,
-								attrs[attno]);
-	}
+		LLVMAddAttributeAtIndex(v_to, index, attrs[attno]);
+
+	pfree(attrs);
+}
+
+/*
+ * Copy all attributes from one function to another. I.e. function, return and
+ * parameters will be copied.
+ */
+void
+llvm_copy_attributes(LLVMValueRef v_from, LLVMValueRef v_to)
+{
+	uint32		param_count;
+	int			paramidx;
+
+	/* copy function attributes */
+	llvm_copy_attributes_at_index(v_from, v_to, LLVMAttributeFunctionIndex);
+
+	/* and the return value attributes */
+	llvm_copy_attributes_at_index(v_from, v_to, LLVMAttributeReturnIndex);
+
+	/* and each function parameter's attribute */
+	param_count = LLVMCountParams(v_from);
+
+	for (paramidx = 1; paramidx <= param_count; paramidx++)
+		llvm_copy_attributes_at_index(v_from, v_to, paramidx);
 }
 
 /*
