From: Claudio Jeker <claudio@openbsd.org>
Subject: Re: ctfconv fix ctt_size for integer and floats
To: Martin Pieuchot <mpi@openbsd.org>, tech@openbsd.org
Date: Thu, 22 Feb 2024 12:47:06 +0100

On Wed, Feb 21, 2024 at 05:06:08PM +0100, Claudio Jeker wrote:
> The ctf spec has:
>     2.3.4 Integer types
>     Integral types are all represented as types of kind CTF_K_INTEGER.
>     These types fill out ctt_size in the ctf_stype_t with the size in
>     bytes of the integral type in question.
> 
> The same text is used for floating point numbers.
> 
> Our ctfconf tool fills in a size in bits not bytes.
> I'm not sure if what I did is the best way of handling this. My worry is
> that bitfields may show up with e.g. 17bits and that must be rounded up to
> a ctt_size of 4.
> 
> Now the dummy void object ends up with a size of 1, do we care about that?

This handles the void object a bit better:

  [1] INTEGER void encoding=SIGNED offset=0 bits=0

-- 
:wq Claudio

Index: generate.c
===================================================================
RCS file: /cvs/src/usr.bin/ctfconv/generate.c,v
diff -u -p -r1.5 generate.c
--- generate.c	14 Aug 2022 14:54:13 -0000	1.5
+++ generate.c	22 Feb 2024 09:32:12 -0000
@@ -196,7 +196,20 @@ imcs_add_type(struct imcs *imcs, struct 
 		ctt.ctt_type = it->it_refp->it_idx;
 		ctsz = sizeof(struct ctf_stype);
 	} else if (size <= CTF_MAX_SIZE) {
-		ctt.ctt_size = size;
+		if (kind == CTF_K_INTEGER || kind == CTF_K_FLOAT) {
+			assert(size <= 64);
+			if (size == 0)
+				ctt.ctt_size = 0;
+			else if (size <= 8)
+				ctt.ctt_size = 1;
+			else if (size <= 16)
+				ctt.ctt_size = 2;
+			else if (size <= 32)
+				ctt.ctt_size = 4;
+			else
+				ctt.ctt_size = 8;
+		} else
+			ctt.ctt_size = size;
 		ctsz = sizeof(struct ctf_stype);
 	} else {
 		ctt.ctt_lsizehi = CTF_SIZE_TO_LSIZE_HI(size);