[PULL 05/13] tests/tcg/ppc64le: emit bcdsub with .long when needed

["Cédric Le Goater" <clg@kaod.org>]

From: Matheus Ferst <matheus.ferst@eldorado.org.br>

Based on GCC docs[1], we use the '-mpower8-vector' flag at config-time
to detect the toolchain support to the bcdsub instruction. LLVM/Clang
supports this flag since version 3.6[2], but the instruction and related
builtins were only added in LLVM 14[3]. In the absence of other means to
detect this support at config-time, we resort to __has_builtin to
identify the presence of __builtin_bcdsub at compile-time. If the
builtin is not available, the instruction is emitted with a ".long".

[1] https://gcc.gnu.org/onlinedocs/gcc-8.3.0/gcc/PowerPC-AltiVec_002fVSX-Built-in-Functions.html
[2] https://github.com/llvm/llvm-project/commit/59eb767e11d4ffefb5f55409524e5c8416b2b0db
[3] https://github.com/llvm/llvm-project/commit/c933c2eb334660c131f4afc9d194fafb0cec0423

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Matheus Ferst <matheus.ferst@eldorado.org.br>
Message-Id: <20220304165417.1981159-5-matheus.ferst@eldorado.org.br>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
---
 tests/tcg/ppc64le/bcdsub.c | 73 ++++++++++++++++++++++----------------
 1 file changed, 42 insertions(+), 31 deletions(-)

diff --git a/tests/tcg/ppc64le/bcdsub.c b/tests/tcg/ppc64le/bcdsub.c
index 12da19b78ef3..87c8c44a4493 100644
--- a/tests/tcg/ppc64le/bcdsub.c
+++ b/tests/tcg/ppc64le/bcdsub.c
@@ -9,37 +9,48 @@
 #define CRF_SO  (1 << 0)
 #define UNDEF   0
 
-/*
- * Use GPR pairs to load the VSR values and place the resulting VSR and CR6 in
- * th, tl, and cr. Note that we avoid newer instructions (e.g., mtvsrdd/mfvsrld)
- * so we can run this test on POWER8 machines.
- */
-#define BCDSUB(AH, AL, BH, BL, PS)                          \
-    asm ("mtvsrd 32, %3\n\t"                                \
-         "mtvsrd 33, %4\n\t"                                \
-         "xxmrghd 32, 32, 33\n\t"                           \
-         "mtvsrd 33, %5\n\t"                                \
-         "mtvsrd 34, %6\n\t"                                \
-         "xxmrghd 33, 33, 34\n\t"                           \
-         "bcdsub. 0, 0, 1, %7\n\t"                          \
-         "mfocrf %0, 0b10\n\t"                              \
-         "mfvsrd %1, 32\n\t"                                \
-         "xxswapd 32, 32\n\t"                               \
-         "mfvsrd %2, 32\n\t"                                \
-         : "=r" (cr), "=r" (th), "=r" (tl)                  \
-         : "r" (AH), "r" (AL), "r" (BH), "r" (BL), "i" (PS) \
-         : "v0", "v1", "v2");
-
-#define TEST(AH, AL, BH, BL, PS, TH, TL, CR6)   \
-    do {                                        \
-        int cr = 0;                             \
-        uint64_t th, tl;                        \
-        BCDSUB(AH, AL, BH, BL, PS);             \
-        if (TH != UNDEF || TL != UNDEF) {       \
-            assert(tl == TL);                   \
-            assert(th == TH);                   \
-        }                                       \
-        assert((cr >> 4) == CR6);               \
+#ifdef __has_builtin
+#if !__has_builtin(__builtin_bcdsub)
+#define NO_BUILTIN_BCDSUB
+#endif
+#endif
+
+#ifdef NO_BUILTIN_BCDSUB
+#define BCDSUB(T, A, B, PS) \
+    ".long 4 << 26 | (" #T ") << 21 | (" #A ") << 16 | (" #B ") << 11"  \
+    " | 1 << 10 | (" #PS ") << 9 | 65\n\t"
+#else
+#define BCDSUB(T, A, B, PS) "bcdsub. " #T ", " #A ", " #B ", " #PS "\n\t"
+#endif
+
+#define TEST(AH, AL, BH, BL, PS, TH, TL, CR6)                                  \
+    do {                                                                       \
+        int cr = 0;                                                            \
+        uint64_t th, tl;                                                       \
+        /*                                                                     \
+         * Use GPR pairs to load the VSR values and place the resulting VSR and\
+         * CR6 in th, tl, and cr. Note that we avoid newer instructions (e.g., \
+         * mtvsrdd/mfvsrld) so we can run this test on POWER8 machines.        \
+         */                                                                    \
+        asm ("mtvsrd 32, %3\n\t"                                               \
+             "mtvsrd 33, %4\n\t"                                               \
+             "xxmrghd 32, 32, 33\n\t"                                          \
+             "mtvsrd 33, %5\n\t"                                               \
+             "mtvsrd 34, %6\n\t"                                               \
+             "xxmrghd 33, 33, 34\n\t"                                          \
+             BCDSUB(0, 0, 1, PS)                                               \
+             "mfocrf %0, 0b10\n\t"                                             \
+             "mfvsrd %1, 32\n\t"                                               \
+             "xxswapd 32, 32\n\t"                                              \
+             "mfvsrd %2, 32\n\t"                                               \
+             : "=r" (cr), "=r" (th), "=r" (tl)                                 \
+             : "r" (AH), "r" (AL), "r" (BH), "r" (BL)                          \
+             : "v0", "v1", "v2");                                              \
+        if (TH != UNDEF || TL != UNDEF) {                                      \
+            assert(tl == TL);                                                  \
+            assert(th == TH);                                                  \
+        }                                                                      \
+        assert((cr >> 4) == CR6);                                              \
     } while (0)
 
 /*
-- 
2.34.1