From: Bernhard Beschow <shentey@gmail.com>

When compiling for i386-softmmu under MSYS2, GCC emits the following warning:

  In function 'get_reg_val',
      inlined from 'calc_modrm_operand64' at ../src/target/i386/emulate/x86_decode.c:1796:15:
  ../src/target/i386/emulate/x86_decode.c:1703:5: error: 'memcpy' forming offset [4, 7] is out of the bounds [0, 4] of object 'val' with type 'target_ulong' {aka 'unsigned int'} [-Werror=array-bounds=]
   1703 |     memcpy(&val,
        |     ^~~~~~~~~~~~
   1704 |            get_reg_ref(env, reg, rex_present, is_extended, size),
        |            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   1705 |            size);
        |            ~~~~~
  ../src/target/i386/emulate/x86_decode.c: In function 'calc_modrm_operand64':
  ../src/target/i386/emulate/x86_decode.c:1702:18: note: 'val' declared here
   1702 |     target_ulong val = 0;
        |                  ^~~

In the calc_modrm_operand64() case the compiler sees size == 8 to be mem-copied
to a target_ulong variable which is only 4 bytes wide in case of i386-softmmu.
Note that when size != 1, get_reg_ref() always returns a pointer to an 8 byte
register, regardless of the target_ulong size. Fix the compiler warning by
always providing 8 bytes of storage by means of uint64_t.

Fixes: 77a2dba45cc9 ("target/i386/emulate: stop overloading decode->op[N].ptr")
cc: qemu-stable
Signed-off-by: Bernhard Beschow <shentey@gmail.com>
Reviewed-by: Mohamed Mediouni <mohamed@unpredictable.fr>
Reviewed-by: Wei Liu (Microsoft) <wei.liu@kernel.org>
Link: https://lore.kernel.org/r/20260223233950.96076-2-mohamed@unpredictable.fr
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 target/i386/emulate/x86_decode.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/target/i386/emulate/x86_decode.c b/target/i386/emulate/x86_decode.c
index d037ed11420..6ad03b71b07 100644
--- a/target/i386/emulate/x86_decode.c
+++ b/target/i386/emulate/x86_decode.c
@@ -1699,7 +1699,7 @@ void *get_reg_ref(CPUX86State *env, int reg, int rex_present,
 target_ulong get_reg_val(CPUX86State *env, int reg, int rex_present,
                          int is_extended, int size)
 {
-    target_ulong val = 0;
+    uint64_t val = 0;
     memcpy(&val,
            get_reg_ref(env, reg, rex_present, is_extended, size),
            size);
-- 
2.53.0