[PULL 04/13] tests/tcg/ppc64le: drop __int128 usage in bcdsub

[Cédric Le Goater]

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

Using __int128 with inline asm constraints like "v" generates incorrect
code when compiling with LLVM/Clang (e.g., only one doubleword of the
VSR is loaded). Instead, use a GPR pair to pass the 128-bits value and
load the VSR with mtvsrd/xxmrghd.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Matheus Ferst <matheus.ferst@eldorado.org.br>
Message-Id: <20220304165417.1981159-4-matheus.ferst@eldorado.org.br>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
---
 tests/tcg/ppc64le/bcdsub.c | 129 ++++++++++++++++++-------------------
 1 file changed, 61 insertions(+), 68 deletions(-)

diff --git a/tests/tcg/ppc64le/bcdsub.c b/tests/tcg/ppc64le/bcdsub.c
index 8c188cae6d28..12da19b78ef3 100644
--- a/tests/tcg/ppc64le/bcdsub.c
+++ b/tests/tcg/ppc64le/bcdsub.c
@@ -1,6 +1,7 @@
 #include <assert.h>
 #include <unistd.h>
 #include <signal.h>
+#include <stdint.h>
 
 #define CRF_LT  (1 << 3)
 #define CRF_GT  (1 << 2)
@@ -8,24 +9,39 @@
 #define CRF_SO  (1 << 0)
 #define UNDEF   0
 
-#define BCDSUB(vra, vrb, ps)                    \
-    asm ("bcdsub. %1,%2,%3,%4;"                 \
-         "mfocrf %0,0b10;"                      \
-         : "=r" (cr), "=v" (vrt)                \
-         : "v" (vra), "v" (vrb), "i" (ps)       \
-         : );
-
-#define TEST(vra, vrb, ps, exp_res, exp_cr6)    \
+/*
+ * 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 {                                        \
-        __int128 vrt = 0;                       \
         int cr = 0;                             \
-        BCDSUB(vra, vrb, ps);                   \
-        if (exp_res)                            \
-            assert(vrt == exp_res);             \
-        assert((cr >> 4) == exp_cr6);           \
+        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);               \
     } while (0)
 
-
 /*
  * Unbounded result is equal to zero:
  *   sign = (PS) ? 0b1111 : 0b1100
@@ -33,13 +49,13 @@
  */
 void test_bcdsub_eq(void)
 {
-    __int128 a, b;
-
     /* maximum positive BCD value */
-    a = b = (((__int128) 0x9999999999999999) << 64 | 0x999999999999999c);
-
-    TEST(a, b, 0, 0xc, CRF_EQ);
-    TEST(a, b, 1, 0xf, CRF_EQ);
+    TEST(0x9999999999999999, 0x999999999999999c,
+         0x9999999999999999, 0x999999999999999c,
+         0, 0x0, 0xc, CRF_EQ);
+    TEST(0x9999999999999999, 0x999999999999999c,
+         0x9999999999999999, 0x999999999999999c,
+         1, 0x0, 0xf, CRF_EQ);
 }
 
 /*
@@ -49,21 +65,16 @@ void test_bcdsub_eq(void)
  */
 void test_bcdsub_gt(void)
 {
-    __int128 a, b, c;
-
-    /* maximum positive BCD value */
-    a = (((__int128) 0x9999999999999999) << 64 | 0x999999999999999c);
-
-    /* negative one BCD value */
-    b = (__int128) 0x1d;
-
-    TEST(a, b, 0, 0xc, (CRF_GT | CRF_SO));
-    TEST(a, b, 1, 0xf, (CRF_GT | CRF_SO));
-
-    c = (((__int128) 0x9999999999999999) << 64 | 0x999999999999998c);
-
-    TEST(c, b, 0, a, CRF_GT);
-    TEST(c, b, 1, (a | 0x3), CRF_GT);
+    /* maximum positive and negative one BCD values */
+    TEST(0x9999999999999999, 0x999999999999999c, 0x0, 0x1d, 0,
+         0x0, 0xc, (CRF_GT | CRF_SO));
+    TEST(0x9999999999999999, 0x999999999999999c, 0x0, 0x1d, 1,
+         0x0, 0xf, (CRF_GT | CRF_SO));
+
+    TEST(0x9999999999999999, 0x999999999999998c, 0x0, 0x1d, 0,
+         0x9999999999999999, 0x999999999999999c, CRF_GT);
+    TEST(0x9999999999999999, 0x999999999999998c, 0x0, 0x1d, 1,
+         0x9999999999999999, 0x999999999999999f, CRF_GT);
 }
 
 /*
@@ -73,45 +84,27 @@ void test_bcdsub_gt(void)
  */
 void test_bcdsub_lt(void)
 {
-    __int128 a, b;
-
-    /* positive zero BCD value */
-    a = (__int128) 0xc;
-
-    /* positive one BCD value */
-    b = (__int128) 0x1c;
-
-    TEST(a, b, 0, 0x1d, CRF_LT);
-    TEST(a, b, 1, 0x1d, CRF_LT);
-
-    /* maximum negative BCD value */
-    a = (((__int128) 0x9999999999999999) << 64 | 0x999999999999999d);
-
-    /* positive one BCD value */
-    b = (__int128) 0x1c;
-
-    TEST(a, b, 0, 0xd, (CRF_LT | CRF_SO));
-    TEST(a, b, 1, 0xd, (CRF_LT | CRF_SO));
+    /* positive zero and positive one BCD values */
+    TEST(0x0, 0xc, 0x0, 0x1c, 0, 0x0, 0x1d, CRF_LT);
+    TEST(0x0, 0xc, 0x0, 0x1c, 1, 0x0, 0x1d, CRF_LT);
+
+    /* maximum negative and positive one BCD values */
+    TEST(0x9999999999999999, 0x999999999999999d, 0x0, 0x1c, 0,
+         0x0, 0xd, (CRF_LT | CRF_SO));
+    TEST(0x9999999999999999, 0x999999999999999d, 0x0, 0x1c, 1,
+         0x0, 0xd, (CRF_LT | CRF_SO));
 }
 
 void test_bcdsub_invalid(void)
 {
-    __int128 a, b;
-
-    /* positive one BCD value */
-    a = (__int128) 0x1c;
-    b = 0xf00;
-
-    TEST(a, b, 0, UNDEF, CRF_SO);
-    TEST(a, b, 1, UNDEF, CRF_SO);
-
-    TEST(b, a, 0, UNDEF, CRF_SO);
-    TEST(b, a, 1, UNDEF, CRF_SO);
+    TEST(0x0, 0x1c, 0x0, 0xf00, 0, UNDEF, UNDEF, CRF_SO);
+    TEST(0x0, 0x1c, 0x0, 0xf00, 1, UNDEF, UNDEF, CRF_SO);
 
-    a = 0xbad;
+    TEST(0x0, 0xf00, 0x0, 0x1c, 0, UNDEF, UNDEF, CRF_SO);
+    TEST(0x0, 0xf00, 0x0, 0x1c, 1, UNDEF, UNDEF, CRF_SO);
 
-    TEST(a, b, 0, UNDEF, CRF_SO);
-    TEST(a, b, 1, UNDEF, CRF_SO);
+    TEST(0x0, 0xbad, 0x0, 0xf00, 0, UNDEF, UNDEF, CRF_SO);
+    TEST(0x0, 0xbad, 0x0, 0xf00, 1, UNDEF, UNDEF, CRF_SO);
 }
 
 int main(void)
-- 
2.34.1