Adapt expression JIT to stdbool.h introduction.

The LLVM JIT provider uses clang to synchronize types between normal C
code and runtime generated code. Clang represents stdbool.h style
booleans in return values & parameters differently from booleans
stored in variables.

Thus the expression compilation code from 2a0faed needs to be
adapted to 9a95a77. Instead of hardcoding i8 as the type for
booleans (which already was wrong on some edge case platforms!), use
postgres' notion of a boolean as used for storage and for parameters.

Per buildfarm animal xenodermus.

Author: Andres Freund

Author: anarazel

src/backend/jit/llvm/llvmjit.c

@@ -46,6 +46,8 @@ typedef struct LLVMJitHandle
 
 /* types & functions commonly needed for JITing */
 LLVMTypeRef TypeSizeT;
+LLVMTypeRef TypeParamBool;
+LLVMTypeRef TypeStorageBool;
 LLVMTypeRef TypePGFunction;
 LLVMTypeRef StructHeapTupleFieldsField3;
 LLVMTypeRef StructHeapTupleFields;
@@ -682,7 +684,7 @@ llvm_shutdown(int code, Datum arg)
 	}
 }
 
-/* helper for llvm_create_types */
+/* helper for llvm_create_types, returning a global var's type */
 static LLVMTypeRef
 load_type(LLVMModuleRef mod, const char *name)
 {
@@ -702,6 +704,31 @@ load_type(LLVMModuleRef mod, const char *name)
 	return typ;
 }
 
+/* helper for llvm_create_types, returning a function's return type */
+static LLVMTypeRef
+load_return_type(LLVMModuleRef mod, const char *name)
+{
+	LLVMValueRef value;
+	LLVMTypeRef typ;
+
+	/* this'll return a *pointer* to the function */
+	value = LLVMGetNamedFunction(mod, name);
+	if (!value)
+		elog(ERROR, "function %s is unknown", name);
+
+	/* get type of function pointer */
+	typ = LLVMTypeOf(value);
+	Assert(typ != NULL);
+	/* dereference pointer */
+	typ = LLVMGetElementType(typ);
+	Assert(typ != NULL);
+	/* and look at return type */
+	typ = LLVMGetReturnType(typ);
+	Assert(typ != NULL);
+
+	return typ;
+}
+
 /*
  * Load required information, types, function signatures from llvmjit_types.c
  * and make them available in global variables.
@@ -740,6 +767,8 @@ llvm_create_types(void)
 	llvm_layout = pstrdup(LLVMGetDataLayoutStr(mod));
 
 	TypeSizeT = load_type(mod, "TypeSizeT");
+	TypeParamBool = load_return_type(mod, "FunctionReturningBool");
+	TypeStorageBool = load_type(mod, "TypeStorageBool");
 	TypePGFunction = load_type(mod, "TypePGFunction");
 	StructExprContext = load_type(mod, "StructExprContext");
 	StructExprEvalStep = load_type(mod, "StructExprEvalStep");