Add soft error handling to some expression nodes

This adjusts the expression evaluation code for CoerceViaIO and
CoerceToDomain to handle errors softly if needed.

For CoerceViaIo, this means using InputFunctionCallSafe(), which
provides the option to handle errors softly, instead of calling the
type input function directly.

For CoerceToDomain, this simply entails replacing the ereport() in
ExecEvalConstraintCheck() by errsave().

In both cases, the ErrorSaveContext to be used when evaluating the
expression is stored by ExecInitExprRec() in the expression's struct
in the expression's ExprEvalStep.  The ErrorSaveContext is passed by
setting ExprState.escontext to point to it when calling
ExecInitExprRec() on the expression whose errors are to be handled
softly.

Note that no call site of ExecInitExprRec() has been changed in this
commit, so there's no functional change.  This is intended for
implementing new SQL/JSON expression nodes in future commits that
will use to it suppress errors that may occur during type coercions.

Reviewed-by: Álvaro Herrera
Discussion: https://postgr.es/m/CA+HiwqE4XTdfb1nW=Ojoy_tQSRhYt-q_kb6i5d4xcKyrLC1Nbg@mail.gmail.com

src/backend/executor/execExpr.c

@@ -139,6 +139,7 @@ ExecInitExpr(Expr *node, PlanState *parent)
 	state->expr = node;
 	state->parent = parent;
 	state->ext_params = NULL;
+	state->escontext = NULL;
 
 	/* Insert setup steps as needed */
 	ExecCreateExprSetupSteps(state, (Node *) node);
@@ -176,6 +177,7 @@ ExecInitExprWithParams(Expr *node, ParamListInfo ext_params)
 	state->expr = node;
 	state->parent = NULL;
 	state->ext_params = ext_params;
+	state->escontext = NULL;
 
 	/* Insert setup steps as needed */
 	ExecCreateExprSetupSteps(state, (Node *) node);
@@ -228,6 +230,7 @@ ExecInitQual(List *qual, PlanState *parent)
 	state->expr = (Expr *) qual;
 	state->parent = parent;
 	state->ext_params = NULL;
+	state->escontext = NULL;
 
 	/* mark expression as to be used with ExecQual() */
 	state->flags = EEO_FLAG_IS_QUAL;
@@ -373,6 +376,7 @@ ExecBuildProjectionInfo(List *targetList,
 	state->expr = (Expr *) targetList;
 	state->parent = parent;
 	state->ext_params = NULL;
+	state->escontext = NULL;
 
 	state->resultslot = slot;
 
@@ -544,6 +548,7 @@ ExecBuildUpdateProjection(List *targetList,
 		state->expr = NULL;		/* not used */
 	state->parent = parent;
 	state->ext_params = NULL;
+	state->escontext = NULL;
 
 	state->resultslot = slot;
 
@@ -1549,8 +1554,6 @@ ExecInitExprRec(Expr *node, ExprState *state,
 				CoerceViaIO *iocoerce = (CoerceViaIO *) node;
 				Oid			iofunc;
 				bool		typisvarlena;
-				Oid			typioparam;
-				FunctionCallInfo fcinfo_in;
 
 				/* evaluate argument into step's result area */
 				ExecInitExprRec(iocoerce->arg, state, resv, resnull);
@@ -1579,25 +1582,13 @@ ExecInitExprRec(Expr *node, ExprState *state,
 
 				/* lookup the result type's input function */
 				scratch.d.iocoerce.finfo_in = palloc0(sizeof(FmgrInfo));
-				scratch.d.iocoerce.fcinfo_data_in = palloc0(SizeForFunctionCallInfo(3));
-
 				getTypeInputInfo(iocoerce->resulttype,
-								 &iofunc, &typioparam);
+								 &iofunc, &scratch.d.iocoerce.typioparam);
 				fmgr_info(iofunc, scratch.d.iocoerce.finfo_in);
 				fmgr_info_set_expr((Node *) node, scratch.d.iocoerce.finfo_in);
-				InitFunctionCallInfoData(*scratch.d.iocoerce.fcinfo_data_in,
-										 scratch.d.iocoerce.finfo_in,
-										 3, InvalidOid, NULL, NULL);
 
-				/*
+				/* Set ErrorSaveContext if passed by the caller. */
-				 * We can preload the second and third arguments for the input
+				scratch.d.iocoerce.escontext = state->escontext;
-				 * function, since they're constants.
-				 */
-				fcinfo_in = scratch.d.iocoerce.fcinfo_data_in;
-				fcinfo_in->args[1].value = ObjectIdGetDatum(typioparam);
-				fcinfo_in->args[1].isnull = false;
-				fcinfo_in->args[2].value = Int32GetDatum(-1);
-				fcinfo_in->args[2].isnull = false;
 
 				ExprEvalPushStep(state, &scratch);
 				break;
@@ -1628,6 +1619,7 @@ ExecInitExprRec(Expr *node, ExprState *state,
 				elemstate->expr = acoerce->elemexpr;
 				elemstate->parent = state->parent;
 				elemstate->ext_params = state->ext_params;
+				state->escontext = NULL;
 
 				elemstate->innermost_caseval = (Datum *) palloc(sizeof(Datum));
 				elemstate->innermost_casenull = (bool *) palloc(sizeof(bool));
@@ -3306,6 +3298,8 @@ ExecInitCoerceToDomain(ExprEvalStep *scratch, CoerceToDomain *ctest,
 	/* we'll allocate workspace only if needed */
 	scratch->d.domaincheck.checkvalue = NULL;
 	scratch->d.domaincheck.checknull = NULL;
+	/* Set ErrorSaveContext if passed by the caller. */
+	scratch->d.domaincheck.escontext = state->escontext;
 
 	/*
 	 * Evaluate argument - it's fine to directly store it into resv/resnull,

src/backend/executor/execExprInterp.c

@@ -1177,29 +1177,27 @@ ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
 			/* call input function (similar to InputFunctionCall) */
 			if (!op->d.iocoerce.finfo_in->fn_strict || str != NULL)
 			{
-				FunctionCallInfo fcinfo_in;
+				bool		error;
-				Datum		d;
 
-				fcinfo_in = op->d.iocoerce.fcinfo_data_in;
+				/*
-				fcinfo_in->args[0].value = PointerGetDatum(str);
+				 * InputFunctionCallSafe() writes directly into *op->resvalue.
-				fcinfo_in->args[0].isnull = *op->resnull;
+				 * Return NULL if an error is reported.
-				/* second and third arguments are already set up */
+				 */
+				error = !InputFunctionCallSafe(op->d.iocoerce.finfo_in, str,
+											   op->d.iocoerce.typioparam, -1,
+											   (Node *) op->d.iocoerce.escontext,
+											   op->resvalue);
+				if (error)
+					*op->resnull = true;
 
-				fcinfo_in->isnull = false;
+				/*
-				d = FunctionCallInvoke(fcinfo_in);
+				 * Should get null result if and only if str is NULL or if we
-				*op->resvalue = d;
+				 * got an error above.
-
+				 */
-				/* Should get null result if and only if str is NULL */
+				if (str == NULL || error)
-				if (str == NULL)
-				{
 					Assert(*op->resnull);
-					Assert(fcinfo_in->isnull);
-				}
 				else
-				{
 					Assert(!*op->resnull);
-					Assert(!fcinfo_in->isnull);
-				}
 			}
 
 			EEO_NEXT();
@@ -3745,7 +3743,7 @@ ExecEvalConstraintCheck(ExprState *state, ExprEvalStep *op)
 {
 	if (!*op->d.domaincheck.checknull &&
 		!DatumGetBool(*op->d.domaincheck.checkvalue))
-		ereport(ERROR,
+		errsave((Node *) op->d.domaincheck.escontext,
 				(errcode(ERRCODE_CHECK_VIOLATION),
 				 errmsg("value for domain %s violates check constraint \"%s\"",
 						format_type_be(op->d.domaincheck.resulttype),

src/backend/jit/llvm/llvmjit.c

@@ -70,12 +70,14 @@ LLVMTypeRef StructHeapTupleTableSlot;
 LLVMTypeRef StructMinimalTupleTableSlot;
 LLVMTypeRef StructMemoryContextData;
 LLVMTypeRef StructFunctionCallInfoData;
+LLVMTypeRef StructFmgrInfo;
 LLVMTypeRef StructExprContext;
 LLVMTypeRef StructExprEvalStep;
 LLVMTypeRef StructExprState;
 LLVMTypeRef StructAggState;
 LLVMTypeRef StructAggStatePerGroupData;
 LLVMTypeRef StructAggStatePerTransData;
+LLVMTypeRef StructErrorSaveContext;
 
 LLVMValueRef AttributeTemplate;
 
@@ -1118,6 +1120,7 @@ llvm_create_types(void)
 	StructExprEvalStep = llvm_pg_var_type("StructExprEvalStep");
 	StructExprState = llvm_pg_var_type("StructExprState");
 	StructFunctionCallInfoData = llvm_pg_var_type("StructFunctionCallInfoData");
+	StructFmgrInfo = llvm_pg_var_type("StructFmgrInfo");
 	StructMemoryContextData = llvm_pg_var_type("StructMemoryContextData");
 	StructTupleTableSlot = llvm_pg_var_type("StructTupleTableSlot");
 	StructHeapTupleTableSlot = llvm_pg_var_type("StructHeapTupleTableSlot");
@@ -1127,6 +1130,7 @@ llvm_create_types(void)
 	StructAggState = llvm_pg_var_type("StructAggState");
 	StructAggStatePerGroupData = llvm_pg_var_type("StructAggStatePerGroupData");
 	StructAggStatePerTransData = llvm_pg_var_type("StructAggStatePerTransData");
+	StructErrorSaveContext = llvm_pg_var_type("StructErrorSaveContext");
 
 	AttributeTemplate = LLVMGetNamedFunction(llvm_types_module, "AttributeTemplate");
 }

src/backend/jit/llvm/llvmjit_expr.c

@@ -1251,14 +1251,9 @@ llvm_compile_expr(ExprState *state)
 
 			case EEOP_IOCOERCE:
 				{
-					FunctionCallInfo fcinfo_out,
+					FunctionCallInfo fcinfo_out;
-								fcinfo_in;
+					LLVMValueRef v_fn_out;
-					LLVMValueRef v_fn_out,
+					LLVMValueRef v_fcinfo_out;
-								v_fn_in;
-					LLVMValueRef v_fcinfo_out,
-								v_fcinfo_in;
-					LLVMValueRef v_fcinfo_in_isnullp;
-					LLVMValueRef v_retval;
 					LLVMValueRef v_resvalue;
 					LLVMValueRef v_resnull;
 
@@ -1271,7 +1266,6 @@ llvm_compile_expr(ExprState *state)
 					LLVMBasicBlockRef b_inputcall;
 
 					fcinfo_out = op->d.iocoerce.fcinfo_data_out;
-					fcinfo_in = op->d.iocoerce.fcinfo_data_in;
 
 					b_skipoutput = l_bb_before_v(opblocks[opno + 1],
 												 "op.%d.skipoutputnull", opno);
@@ -1283,14 +1277,7 @@ llvm_compile_expr(ExprState *state)
 												"op.%d.inputcall", opno);
 
 					v_fn_out = llvm_function_reference(context, b, mod, fcinfo_out);
-					v_fn_in = llvm_function_reference(context, b, mod, fcinfo_in);
 					v_fcinfo_out = l_ptr_const(fcinfo_out, l_ptr(StructFunctionCallInfoData));
-					v_fcinfo_in = l_ptr_const(fcinfo_in, l_ptr(StructFunctionCallInfoData));
-
-					v_fcinfo_in_isnullp =
-						LLVMBuildStructGEP(b, v_fcinfo_in,
-										   FIELDNO_FUNCTIONCALLINFODATA_ISNULL,
-										   "v_fcinfo_in_isnull");
 
 					/* output functions are not called on nulls */
 					v_resnull = LLVMBuildLoad(b, v_resnullp, "");
@@ -1356,24 +1343,44 @@ llvm_compile_expr(ExprState *state)
 						LLVMBuildBr(b, b_inputcall);
 					}
 
+					/*
+					 * Call the input function.
+					 *
+					 * If op->d.iocoerce.escontext references an
+					 * ErrorSaveContext, InputFunctionCallSafe() would return
+					 * false upon encountering an error.
+					 */
 					LLVMPositionBuilderAtEnd(b, b_inputcall);
-					/* set arguments */
+					{
-					/* arg0: output */
+						Oid			ioparam = op->d.iocoerce.typioparam;
-					LLVMBuildStore(b, v_output,
+						LLVMValueRef v_params[6];
-								   l_funcvaluep(b, v_fcinfo_in, 0));
+						LLVMValueRef v_success;
-					LLVMBuildStore(b, v_resnull,
-								   l_funcnullp(b, v_fcinfo_in, 0));
 
-					/* arg1: ioparam: preset in execExpr.c */
+						v_params[0] = l_ptr_const(op->d.iocoerce.finfo_in,
-					/* arg2: typmod: preset in execExpr.c  */
+												  l_ptr(StructFmgrInfo));
+						v_params[1] = v_output;
+						v_params[2] = l_oid_const(lc, ioparam);
+						v_params[3] = l_int32_const(lc, -1);
+						v_params[4] = l_ptr_const(op->d.iocoerce.escontext,
+												  l_ptr(StructErrorSaveContext));
 
-					/* reset fcinfo_in->isnull */
+						/*
-					LLVMBuildStore(b, l_sbool_const(0), v_fcinfo_in_isnullp);
+						 * InputFunctionCallSafe() will write directly into
-					/* and call function */
+						 * *op->resvalue.
-					v_retval = LLVMBuildCall(b, v_fn_in, &v_fcinfo_in, 1,
+						 */
-											 "funccall_iocoerce_in");
+						v_params[5] = v_resvaluep;
 
-					LLVMBuildStore(b, v_retval, v_resvaluep);
+						v_success = LLVMBuildCall(b, llvm_pg_func(mod, "InputFunctionCallSafe"),
+												  v_params, lengthof(v_params),
+												  "funccall_iocoerce_in_safe");
+
+						/*
+						 * Return null if InputFunctionCallSafe() encountered
+						 * an error.
+						 */
+						v_resnullp = LLVMBuildICmp(b, LLVMIntEQ, v_success,
+												   l_sbool_const(0), "");
+					}
 
 					LLVMBuildBr(b, opblocks[opno + 1]);
 					break;

src/backend/jit/llvm/llvmjit_types.c

@@ -59,6 +59,7 @@ AggStatePerTransData StructAggStatePerTransData;
 ExprContext StructExprContext;
 ExprEvalStep StructExprEvalStep;
 ExprState	StructExprState;
+FmgrInfo	StructFmgrInfo;
 FunctionCallInfoBaseData StructFunctionCallInfoData;
 HeapTupleData StructHeapTupleData;
 MemoryContextData StructMemoryContextData;
@@ -66,6 +67,7 @@ TupleTableSlot StructTupleTableSlot;
 HeapTupleTableSlot StructHeapTupleTableSlot;
 MinimalTupleTableSlot StructMinimalTupleTableSlot;
 TupleDescData StructTupleDescData;
+ErrorSaveContext StructErrorSaveContext;
 
 
 /*
@@ -136,6 +138,7 @@ void	   *referenced_functions[] =
 	ExecEvalJsonConstructor,
 	ExecEvalJsonIsPredicate,
 	MakeExpandedObjectReadOnlyInternal,
+	InputFunctionCallSafe,
 	slot_getmissingattrs,
 	slot_getsomeattrs_int,
 	strlen,

src/include/executor/execExpr.h

@@ -16,6 +16,7 @@
 
 #include "executor/nodeAgg.h"
 #include "nodes/execnodes.h"
+#include "nodes/miscnodes.h"
 
 /* forward references to avoid circularity */
 struct ExprEvalStep;
@@ -416,7 +417,8 @@ typedef struct ExprEvalStep
 			FunctionCallInfo fcinfo_data_out;
 			/* lookup and call info for result type's input function */
 			FmgrInfo   *finfo_in;
-			FunctionCallInfo fcinfo_data_in;
+			Oid			typioparam;
+			ErrorSaveContext *escontext;
 		}			iocoerce;
 
 		/* for EEOP_SQLVALUEFUNCTION */
@@ -547,6 +549,7 @@ typedef struct ExprEvalStep
 			bool	   *checknull;
 			/* OID of domain type */
 			Oid			resulttype;
+			ErrorSaveContext *escontext;
 		}			domaincheck;
 
 		/* for EEOP_CONVERT_ROWTYPE */

src/include/jit/llvmjit.h

@@ -75,6 +75,7 @@ extern PGDLLIMPORT LLVMTypeRef StructTupleTableSlot;
 extern PGDLLIMPORT LLVMTypeRef StructHeapTupleTableSlot;
 extern PGDLLIMPORT LLVMTypeRef StructMinimalTupleTableSlot;
 extern PGDLLIMPORT LLVMTypeRef StructMemoryContextData;
+extern PGDLLIMPORT LLVMTypeRef StructFmgrInfo;
 extern PGDLLIMPORT LLVMTypeRef StructFunctionCallInfoData;
 extern PGDLLIMPORT LLVMTypeRef StructExprContext;
 extern PGDLLIMPORT LLVMTypeRef StructExprEvalStep;
@@ -82,6 +83,7 @@ extern PGDLLIMPORT LLVMTypeRef StructExprState;
 extern PGDLLIMPORT LLVMTypeRef StructAggState;
 extern PGDLLIMPORT LLVMTypeRef StructAggStatePerTransData;
 extern PGDLLIMPORT LLVMTypeRef StructAggStatePerGroupData;
+extern PGDLLIMPORT LLVMTypeRef StructErrorSaveContext;
 
 extern PGDLLIMPORT LLVMValueRef AttributeTemplate;
 

src/include/jit/llvmjit_emit.h

@@ -85,6 +85,15 @@ l_sizet_const(size_t i)
 	return LLVMConstInt(TypeSizeT, i, false);
 }
 
+/*
+ * Emit constant oid.
+ */
+static inline LLVMValueRef
+l_oid_const(LLVMContextRef lc, Oid i)
+{
+	return LLVMConstInt(LLVMInt32TypeInContext(lc), i, false);
+}
+
 /*
  * Emit constant boolean, as used for storage (e.g. global vars, structs).
  */

src/include/nodes/execnodes.h

@@ -34,6 +34,7 @@
 #include "fmgr.h"
 #include "lib/ilist.h"
 #include "lib/pairingheap.h"
+#include "nodes/miscnodes.h"
 #include "nodes/params.h"
 #include "nodes/plannodes.h"
 #include "nodes/tidbitmap.h"
@@ -129,6 +130,12 @@ typedef struct ExprState
 
 	Datum	   *innermost_domainval;
 	bool	   *innermost_domainnull;
+
+	/*
+	 * For expression nodes that support soft errors.  Should be set to NULL
+	 * before calling ExecInitExprRec() if the caller wants errors thrown.
+	 */
+	ErrorSaveContext *escontext;
 } ExprState;