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authorRichard Henderson <richard.henderson@linaro.org>2023-01-19 06:46:16 -1000
committerRichard Henderson <richard.henderson@linaro.org>2023-01-23 14:39:48 -1000
commit6aa89be5c5ff9a534280b06fad9b01604e2155cb (patch)
treecf6ffa0ea9620d850652cc270c0541f34463f830 /include/exec
parent2466bb3b083f965ef1ec12368c07e7d1e2f0b4c4 (diff)
tcg: Mark tcg helpers noinline to avoid an issue with LTO
Marking helpers __attribute__((noinline)) prevents an issue with GCC's ipa-split pass under --enable-lto. Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1454 Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org> Tested-by: Idan Horowitz <idan.horowitz@gmail.com> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Diffstat (limited to 'include/exec')
-rw-r--r--include/exec/helper-proto.h32
1 files changed, 24 insertions, 8 deletions
diff --git a/include/exec/helper-proto.h b/include/exec/helper-proto.h
index c4b1bda632..7a3f04b58c 100644
--- a/include/exec/helper-proto.h
+++ b/include/exec/helper-proto.h
@@ -6,34 +6,49 @@
#include "exec/helper-head.h"
+/*
+ * Work around an issue with --enable-lto, in which GCC's ipa-split pass
+ * decides to split out the noreturn code paths that raise an exception,
+ * taking the __builtin_return_address() along into the new function,
+ * where it no longer computes a value that returns to TCG generated code.
+ * Despite the name, the noinline attribute affects splitter, so this
+ * prevents the optimization in question. Given that helpers should not
+ * otherwise be called directly, this should have any other visible effect.
+ *
+ * See https://gitlab.com/qemu-project/qemu/-/issues/1454
+ */
+#define DEF_HELPER_ATTR __attribute__((noinline))
+
#define DEF_HELPER_FLAGS_0(name, flags, ret) \
-dh_ctype(ret) HELPER(name) (void);
+dh_ctype(ret) HELPER(name) (void) DEF_HELPER_ATTR;
#define DEF_HELPER_FLAGS_1(name, flags, ret, t1) \
-dh_ctype(ret) HELPER(name) (dh_ctype(t1));
+dh_ctype(ret) HELPER(name) (dh_ctype(t1)) DEF_HELPER_ATTR;
#define DEF_HELPER_FLAGS_2(name, flags, ret, t1, t2) \
-dh_ctype(ret) HELPER(name) (dh_ctype(t1), dh_ctype(t2));
+dh_ctype(ret) HELPER(name) (dh_ctype(t1), dh_ctype(t2)) DEF_HELPER_ATTR;
#define DEF_HELPER_FLAGS_3(name, flags, ret, t1, t2, t3) \
-dh_ctype(ret) HELPER(name) (dh_ctype(t1), dh_ctype(t2), dh_ctype(t3));
+dh_ctype(ret) HELPER(name) (dh_ctype(t1), dh_ctype(t2), \
+ dh_ctype(t3)) DEF_HELPER_ATTR;
#define DEF_HELPER_FLAGS_4(name, flags, ret, t1, t2, t3, t4) \
dh_ctype(ret) HELPER(name) (dh_ctype(t1), dh_ctype(t2), dh_ctype(t3), \
- dh_ctype(t4));
+ dh_ctype(t4)) DEF_HELPER_ATTR;
#define DEF_HELPER_FLAGS_5(name, flags, ret, t1, t2, t3, t4, t5) \
dh_ctype(ret) HELPER(name) (dh_ctype(t1), dh_ctype(t2), dh_ctype(t3), \
- dh_ctype(t4), dh_ctype(t5));
+ dh_ctype(t4), dh_ctype(t5)) DEF_HELPER_ATTR;
#define DEF_HELPER_FLAGS_6(name, flags, ret, t1, t2, t3, t4, t5, t6) \
dh_ctype(ret) HELPER(name) (dh_ctype(t1), dh_ctype(t2), dh_ctype(t3), \
- dh_ctype(t4), dh_ctype(t5), dh_ctype(t6));
+ dh_ctype(t4), dh_ctype(t5), \
+ dh_ctype(t6)) DEF_HELPER_ATTR;
#define DEF_HELPER_FLAGS_7(name, flags, ret, t1, t2, t3, t4, t5, t6, t7) \
dh_ctype(ret) HELPER(name) (dh_ctype(t1), dh_ctype(t2), dh_ctype(t3), \
dh_ctype(t4), dh_ctype(t5), dh_ctype(t6), \
- dh_ctype(t7));
+ dh_ctype(t7)) DEF_HELPER_ATTR;
#define IN_HELPER_PROTO
@@ -51,5 +66,6 @@ dh_ctype(ret) HELPER(name) (dh_ctype(t1), dh_ctype(t2), dh_ctype(t3), \
#undef DEF_HELPER_FLAGS_5
#undef DEF_HELPER_FLAGS_6
#undef DEF_HELPER_FLAGS_7
+#undef DEF_HELPER_ATTR
#endif /* HELPER_PROTO_H */