tests/tcg: Suppress compiler false-positive warning on sha1.c

GCC versions at least 12 through 15 incorrectly report a warning
about code in sha1.c:

tests/tcg/multiarch/sha1.c:161:13: warning: ‘SHA1Transform’ reading 64 bytes from a region of size 0 [-Wstringop-overread]
  161 |             SHA1Transform(context->state, &data[i]);
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This is a piece of stock library code for doing SHA1 which we've
simply copied, rather than writing ourselves. The bug has been
reported to upstream GCC (about a different library's use of this
code):
 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106709

For our test case, since this isn't our original code and there isn't
actually a bug in it, suppress the incorrect warning rather than
trying to modify the code to work around the compiler issue.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2328
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20250227141343.1675415-1-peter.maydell@linaro.org>
[AJB: -Wno-unknown-warning-option for clang's sake]
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20250304222439.2035603-18-alex.bennee@linaro.org>

tests/tcg/aarch64/Makefile.target

@@ -83,7 +83,8 @@ test-aes: CFLAGS += -O -march=armv8-a+aes
 test-aes: test-aes-main.c.inc
 
 # Vector SHA1
-sha1-vector: CFLAGS=-O3
+# Work around compiler false-positive warning, as we do for the 'sha1' test
+sha1-vector: CFLAGS=-O3 -Wno-stringop-overread
 sha1-vector: sha1.c
 	$(CC) $(CFLAGS) $(EXTRA_CFLAGS) $< -o $@ $(LDFLAGS)
 run-sha1-vector: sha1-vector run-sha1

tests/tcg/arm/Makefile.target

@@ -61,7 +61,8 @@ endif
 ARM_TESTS += commpage
 
 # Vector SHA1
-sha1-vector: CFLAGS=-O3
+# Work around compiler false-positive warning, as we do for the 'sha1' test
+sha1-vector: CFLAGS=-O3 -Wno-stringop-overread
 sha1-vector: sha1.c
 	$(CC) $(CFLAGS) $(EXTRA_CFLAGS) $< -o $@ $(LDFLAGS)
 run-sha1-vector: sha1-vector run-sha1

tests/tcg/hexagon/Makefile.target

@@ -18,7 +18,7 @@
 # Hexagon doesn't support gdb, so skip the EXTRA_RUNS
 EXTRA_RUNS =
 
-CFLAGS += -Wno-incompatible-pointer-types -Wno-undefined-internal
+CFLAGS += -Wno-incompatible-pointer-types -Wno-undefined-internal -Wno-unknown-warning-option
 CFLAGS += -fno-unroll-loops -fno-stack-protector
 
 HEX_SRC=$(SRC_PATH)/tests/tcg/hexagon

tests/tcg/multiarch/Makefile.target

@@ -45,6 +45,14 @@ vma-pthread: LDFLAGS+=-pthread
 sigreturn-sigmask: CFLAGS+=-pthread
 sigreturn-sigmask: LDFLAGS+=-pthread
 
+# GCC versions 12/13/14/15 at least incorrectly complain about
+# "'SHA1Transform' reading 64 bytes from a region of size 0"; see the gcc bug
+# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106709
+# Since this is just a standard piece of library code we've borrowed for a
+# TCG test case, suppress the warning rather than trying to modify the
+# code to work around the compiler.
+sha1: CFLAGS+=-Wno-stringop-overread
+
 # The vma-pthread seems very sensitive on gitlab and we currently
 # don't know if its exposing a real bug or the test is flaky.
 ifneq ($(GITLAB_CI),)