[PATCH] target/xtensa/mmu: Avoid maybe-uninitialized error in get_phys_page()

[Philippe Mathieu-Daudé]

Fix when using GCC v11.4 (Ubuntu 11.4.0-1ubuntu1~22.04) with CFLAGS=-Og:

  target/xtensa/mmu_helper.c: In function ‘helper_pptlb’:
  target/xtensa/mmu_helper.c:986:35: error: ‘bg_segment’ may be used 
uninitialized in this function [-Werror=maybe-uninitialized]
    986 |         return env->config->mpu_bg[bg_segment].attr | segment;
        |                                   ^
  target/xtensa/mmu_helper.c: In function ‘xtensa_get_physical_addr’:
  target/xtensa/mmu_helper.c:1011:35: error: ‘segment’ may be used 
uninitialized in this function [-Werror=maybe-uninitialized]
   1011 |         attr = env->config->mpu_bg[segment].attr;
        |                                   ^
  target/xtensa/mmu_helper.c:996:14: note: ‘segment’ was declared here
    996 |     unsigned segment;
        |              ^~~~~~~

Signed-off-by: Philippe Mathieu-Daudé <phi...@linaro.org>
---
 target/xtensa/mmu_helper.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/target/xtensa/mmu_helper.c b/target/xtensa/mmu_helper.c
index fa66e8e867..93e3866217 100644
--- a/target/xtensa/mmu_helper.c
+++ b/target/xtensa/mmu_helper.c
@@ -980,9 +980,10 @@ uint32_t HELPER(pptlb)(CPUXtensaState *env, uint32_t v)
     } else if (nhits == 1 && (env->sregs[MPUENB] & (1u << segment))) {
         return env->mpu_fg[segment].attr | segment | XTENSA_MPU_PROBE_V;
     } else {
-        xtensa_mpu_lookup(env->config->mpu_bg,
-                          env->config->n_mpu_bg_segments,
-                          v, &bg_segment);
+        nhits = xtensa_mpu_lookup(env->config->mpu_bg,
+                                  env->config->n_mpu_bg_segments,
+                                  v, &bg_segment);
+        assert(nhits > 0);
         return env->config->mpu_bg[bg_segment].attr | segment;
     }
 }
@@ -1005,9 +1006,10 @@ static int get_physical_addr_mpu(CPUXtensaState *env,
     } else if (nhits == 1 && (env->sregs[MPUENB] & (1u << segment))) {
         attr = env->mpu_fg[segment].attr;
     } else {
-        xtensa_mpu_lookup(env->config->mpu_bg,
-                          env->config->n_mpu_bg_segments,
-                          vaddr, &segment);
+        nhits = xtensa_mpu_lookup(env->config->mpu_bg,
+                                  env->config->n_mpu_bg_segments,
+                                  vaddr, &segment);
+        assert(nhits > 0);
         attr = env->config->mpu_bg[segment].attr;
     }
 
-- 
2.41.0