Adding type information to instructions

[David Given <dg@cowlark.com>]

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I've been having trouble finding the types of pseudos; the approach I've
been using, which is to follow the chain of pseudo's definers until I
find an instruction with enough type information to use, turns out to
fail utterly on OP_LOAD instructions; I can't find any way of getting
enough information from the opcode's arguments to determine the type of
the target.

As a result, I've had to make a minor patch to the lineariser code.
Given that the lineariser knows the information I need at the point
where it generates the instruction, it would seem to make sense to tag
the instruction with the type. This is made quite easy by the way that
the lineariser has a allocate-typed-instruction function.

Patch enclosed; it's very simple.

Does this seem like a reasonable approach? Is it something that would be
useful to have in the base builds? Are there any ramifications I should
be aware of?

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diff -rwu sparse.orig/linearize.c sparse/linearize.c
--- sparse.orig/linearize.c	2008-06-28 22:44:21.714555764 +0100
+++ sparse/linearize.c	2008-06-30 23:20:30.777932755 +0100
@@ -55,7 +55,9 @@
 
 static struct instruction *alloc_typed_instruction(int opcode, struct symbol *type)
 {
-	return alloc_instruction(opcode, type_size(type));
+	struct instruction *insn = alloc_instruction(opcode, type_size(type));
+	insn->type = type;
+	return insn;
 }
 
 static struct entrypoint *alloc_entrypoint(void)
diff -rwu sparse.orig/linearize.h sparse/linearize.h
--- sparse.orig/linearize.h	2008-06-28 22:44:21.714555764 +0100
+++ sparse/linearize.h	2008-06-30 23:20:04.425933822 +0100
@@ -71,6 +71,7 @@
 		 size:24;
 	struct basic_block *bb;
 	struct position pos;
+	struct symbol *type;
 	union {
 		pseudo_t target;
 		pseudo_t cond;		/* for branch and switch */

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