Re: linearize bug?

[Kamil Dudka <kdudka@redhat.com>]

[-- Attachment #1: Type: text/plain, Size: 660 bytes --]

On Saturday 27 August 2011 17:53:23 Linus Torvalds wrote:
> The attached patch is ENTIRELY UNTESTED. The only thing I tested it on
> is your test-case. Running "make test" requires stuff that I don't
> even have installed, and I'm lazy ;^o

It seems to break loops with no conditions.  The following piece of code:

#include <stdio.h>

int main()
{
    for(;;)
        printf("");
}

... translates into:

main:
.L0x7f233ed67010:
        <entry-point>
        call.32     %r2 <- printf, ""
        ret.32

... which is obviously wrong.  I am not sure if handling that special case 
separately (as done in the attached patch) is a correct way to fix it.

Kamil

[-- Attachment #2: follow-up.diff --]
[-- Type: text/x-diff, Size: 1314 bytes --]

 linearize.c |   11 +++++++----
 1 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/linearize.c b/linearize.c
index 30e0c9d..9e4b6a4 100644
--- a/linearize.c
+++ b/linearize.c
@@ -2055,7 +2055,7 @@ pseudo_t linearize_statement(struct entrypoint *ep, struct statement *stmt)
 		struct statement  *statement = stmt->iterator_statement;
 		struct statement  *post_statement = stmt->iterator_post_statement;
 		struct expression *post_condition = stmt->iterator_post_condition;
-		struct basic_block *loop_top, *loop_body, *loop_continue, *loop_end;
+		struct basic_block *loop_body, *loop_continue, *loop_end;
 
 		concat_symbol_list(stmt->iterator_syms, &ep->syms);
 		linearize_statement(ep, pre_statement);
@@ -2078,9 +2078,12 @@ pseudo_t linearize_statement(struct entrypoint *ep, struct statement *stmt)
 		linearize_statement(ep, post_statement);
 
 		/* No post-condition means that it's the same as the pre-condition */
-		if (!post_condition)
-			linearize_cond_branch(ep, pre_condition, loop_body, loop_end);
-		else
+		if (!post_condition) {
+			if (pre_condition)
+				linearize_cond_branch(ep, pre_condition, loop_body, loop_end);
+			else
+				add_goto(ep, loop_body);
+		} else
 			linearize_cond_branch(ep, post_condition, loop_body, loop_end);
 		set_activeblock(ep, loop_end);
 		break;