[PATCH] target/sh4: Return error if CPUClass::get_phys_page_debug() fails

["Philippe Mathieu-Daudé" <f4bug@amsat.org>]

If the get_physical_address() call fails, the SH4 get_phys_page_debug()
handler returns an uninitialized address. Instead return -1, which
correspond to "no page found" (see cpu_get_phys_page_debug() doc
string).

This fixes a warning emitted when building with CFLAGS=-O3
(using GCC 10.2.1 20201125):

  target/sh4/helper.c: In function ‘superh_cpu_get_phys_page_debug’:
  target/sh4/helper.c:446:12: warning: ‘physical’ may be used uninitialized in this function [-Wmaybe-uninitialized]
    446 |     return physical;
        |            ^~~~~~~~

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
---
 target/sh4/helper.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/target/sh4/helper.c b/target/sh4/helper.c
index bd8e034f174..2d622081e85 100644
--- a/target/sh4/helper.c
+++ b/target/sh4/helper.c
@@ -441,9 +441,12 @@ hwaddr superh_cpu_get_phys_page_debug(CPUState *cs, vaddr addr)
     target_ulong physical;
     int prot;
 
-    get_physical_address(&cpu->env, &physical, &prot, addr, MMU_DATA_LOAD);
+    if (get_physical_address(&cpu->env, &physical, &prot, addr, MMU_DATA_LOAD)
+            == MMU_OK) {
+        return physical;
+    }
 
-    return physical;
+    return -1;
 }
 
 void cpu_load_tlb(CPUSH4State * env)
-- 
2.26.3