harec

commit b5e6f0bf3c6c1c0cd060f5a2439ba1ec0060682f
parent 14c0158d7c84182c913e860efd011991109a9d52
Author: Drew DeVault <sir@cmpwn.com>
Date:   Mon, 28 Dec 2020 10:28:48 -0500

gen: add better docs and tracing around values

Diffstat:
M
include/qbe.h
 | 
22
+++++++++++++++++-----
M
src/gen.c
 | 
3
+++

2 files changed, 20 insertions(+), 5 deletions(-)
diff --git a/include/qbe.h b/include/qbe.h
@@ -5,14 +5,14 @@
 #include <stdint.h>
 
 enum qbe_stype {
-	Q__VOID = 0,
+	Q__VOID = 'V',
 	Q_BYTE = 'b',
 	Q_HALF = 'h',
 	Q_WORD = 'w',
 	Q_LONG = 'l',
 	Q_SINGLE = 's',
 	Q_DOUBLE = 'd',
-	Q__AGGREGATE,
+	Q__AGGREGATE = 'A',
 };
 
 struct qbe_type {
@@ -41,10 +41,22 @@ enum qbe_value_kind {
 };
 
 // Represents a value which can be an argument to a QBE instruction.
+// 
+// If the value is a non-aggregate type, indirect determines if it is a pointer
+// to the value, or the value itself.
 //
-// If indirect, this value is a pointer to the actual value, which is allocated
-// elsewhere (e.g. the stack). This is usually true unless we have temporarily
-// loaded a value as an input into an instruction.
+// let x = 10;	// %x =l alloc4 4; storew 10, %x
+// 		// qbe_value{QV_TEMPORARY, =l, true, %x}
+// x;		// %temp =w loadw %x
+// 		// qbe_value{QV_TEMPORARY, =w, false, %temp}
+//
+// Aggregate types cannot be directly stored in temporaries, so if direct is
+// set, the value is still a pointer to an aggregate type.
+//
+// let x = [1, 2, 3];	// %x =l alloc4 12; storew 1, %x; ...
+// 			// qbe_value{QV_TEMPORARY, :aggregate, true, %x }
+// let y = &x;		// %y =l alloc8 8; storel %x, %y
+// 			// qbe_value{QV_TEMPORARY, =l, true, %y }
 struct qbe_value {
 	enum qbe_value_kind kind;
 	const struct qbe_type *type;
diff --git a/src/gen.c b/src/gen.c
@@ -70,6 +70,9 @@ binding_alloc(struct gen_context *ctx, const struct scope_object *obj,
 	binding->object = obj;
 	binding->next = ctx->bindings;
 	ctx->bindings = binding;
+	pushc(ctx->current, "alloc binding: %s -> %%%s, =%c, indirect: %d",
+			obj->ident.name, binding->name,
+			(char)val->type->stype, val->indirect);
 	return binding;
 }