From c771cb52fad4ea07971c2a5f178139991c6fb904 Mon Sep 17 00:00:00 2001
From: Michael Matz <matz@suse.de>
Date: Tue, 7 Mar 2023 18:10:02 +0100
Subject: [PATCH] Fix code suppression during nocode_wanted

we activate code (CODE_ON) only when the target labels are used,
which doesn't happen during nocode_wanted regions.  So, we cannot
just switch off code either during nocode_wanted regions, nothing
would switch it on again (except in the happy coincidences when we
outright save/restore nocode_wanted).  See the testcase for one
example, reduced from code generated by yarpgen: in
  ext = (xxx || 1)           // #1
        || ((xxx && 1) || 1) // #2
code is first suppressed in #1 normally, then (before this commit)
was suppressed via CODE_OFF during #2 (via indirect gjmp),
then the suppression from #1 was undone, but nothing undoes the
suppression from #2 anymore as everything therein was generated
while nocode_wanted was active.

So, we would either need to save/restore nocode_wanted around
some more expressions, activate CODE_ON also with unused labels (breaks
some optimizations we want), or deactivate CODE_OFF only when not
already in nocode_wanted state.  This does the latter.
---
 tccgen.c                       |  2 +-
 tests/tests2/88_codeopt.c      | 11 +++++++++++
 tests/tests2/88_codeopt.expect |  1 +
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/tccgen.c b/tccgen.c
index ceff794e..0809760f 100644
--- a/tccgen.c
+++ b/tccgen.c
@@ -56,7 +56,7 @@ ST_DATA int nocode_wanted; /* no code generation wanted */
 #define unevalmask 0xffff /* unevaluated subexpression */
 #define NODATA_WANTED (nocode_wanted > 0) /* no static data output wanted either */
 #define DATA_ONLY_WANTED 0x80000000 /* ON outside of functions and for static initializers */
-#define CODE_OFF() (nocode_wanted |= 0x20000000)
+#define CODE_OFF() if(!nocode_wanted)(nocode_wanted |= 0x20000000)
 #define CODE_ON() (nocode_wanted &= ~0x20000000)
 
 ST_DATA int global_expr;  /* true if compound literals must be allocated globally (used during initializers parsing */
diff --git a/tests/tests2/88_codeopt.c b/tests/tests2/88_codeopt.c
index 2ab4c8a8..3faa5fac 100644
--- a/tests/tests2/88_codeopt.c
+++ b/tests/tests2/88_codeopt.c
@@ -44,6 +44,16 @@ void bla(void)
   get_args(!!__ret, sizeof(__ret));
 }
 
+int ext;
+
+void broken_jumpopt (int xxx)
+{
+  /* This was broken in 8227db3a2 by code suppression during suppressed
+     code :) */
+  ext = (xxx || 1) || ((xxx && 1) || 1);
+  printf("okay: %d %d\n", xxx, ext);
+}
+
 _Bool chk(unsigned long addr, unsigned long limit, unsigned long size)
 {
   _Bool ret;
@@ -65,5 +75,6 @@ int main()
   else
     printf("okay\n");
   bla();
+  broken_jumpopt(42);
   return 0;
 }
diff --git a/tests/tests2/88_codeopt.expect b/tests/tests2/88_codeopt.expect
index 439edfd8..76b582b3 100644
--- a/tests/tests2/88_codeopt.expect
+++ b/tests/tests2/88_codeopt.expect
@@ -1,2 +1,3 @@
 okay
 okay
+okay: 42 1