The analyze_read() methods on GuestSource, GuestPairSource,
SystemSource, and SystemPairSource were no-ops because these
source registers do not need read-tracking in the analyze phase.
However, gen_analyze_funcs.py unconditionally declares the
register-number variable (e.g. GsN) via decl_reg_num() for all
registers that are read or written.  When building with
hexagon-softmmu, the generated analyze function bodies are
compiled (outside the #ifndef CONFIG_USER_ONLY guard), and the
declared-but-unreferenced register-number variable triggers
-Werror=unused-variable under both gcc and clang.

Override decl_reg_num() in each class to declare the register number with
G_GNUC_UNUSED, suppressing the warning.

Reviewed-by: Taylor Simpson <ltaylorsimpson@gmail.com>
Signed-off-by: Brian Cain <brian.cain@oss.qualcomm.com>
---
 target/hexagon/hex_common.py | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/target/hexagon/hex_common.py b/target/hexagon/hex_common.py
index ceb4b6812d6..1daf7239fc4 100755
--- a/target/hexagon/hex_common.py
+++ b/target/hexagon/hex_common.py
@@ -1068,6 +1068,10 @@ def analyze_write(self, f, tag, regno):
         """))
 
 class GuestSource(GuestRegister, Single, OldSource):
+    def decl_reg_num(self, f, regno):
+        f.write(code_fmt(f"""\
+            const int {self.reg_num} G_GNUC_UNUSED = insn->regno[{regno}];
+        """))
     def decl_tcg(self, f, tag, regno):
         self.decl_reg_num(f, regno)
         f.write(code_fmt(f"""\
@@ -1093,6 +1097,10 @@ def analyze_write(self, f, tag, regno):
         """))
 
 class GuestPairSource(GuestRegister, Pair, OldSource):
+    def decl_reg_num(self, f, regno):
+        f.write(code_fmt(f"""\
+            const int {self.reg_num} G_GNUC_UNUSED = insn->regno[{regno}];
+        """))
     def decl_tcg(self, f, tag, regno):
         self.decl_reg_num(f, regno)
         f.write(code_fmt(f"""\
@@ -1118,6 +1126,10 @@ def analyze_write(self, f, tag, regno):
         """))
 
 class SystemSource(Register, Single, OldSource):
+    def decl_reg_num(self, f, regno):
+        f.write(code_fmt(f"""\
+            const int {self.reg_num} G_GNUC_UNUSED = insn->regno[{regno}];
+        """))
     def decl_tcg(self, f, tag, regno):
         self.decl_reg_num(f, regno)
         f.write(code_fmt(f"""\
@@ -1143,6 +1155,10 @@ def analyze_write(self, f, tag, regno):
         """))
 
 class SystemPairSource(Register, Pair, OldSource):
+    def decl_reg_num(self, f, regno):
+        f.write(code_fmt(f"""\
+            const int {self.reg_num} G_GNUC_UNUSED = insn->regno[{regno}];
+        """))
     def decl_tcg(self, f, tag, regno):
         self.decl_reg_num(f, regno)
         f.write(code_fmt(f"""\
-- 
2.34.1