63c2b746be
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]59eb767e11[3]c933c2eb33Reviewed-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>
135 lines
5.0 KiB
C
135 lines
5.0 KiB
C
#include <assert.h>
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#include <unistd.h>
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#include <signal.h>
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#include <stdint.h>
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#define CRF_LT (1 << 3)
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#define CRF_GT (1 << 2)
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#define CRF_EQ (1 << 1)
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#define CRF_SO (1 << 0)
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#define UNDEF 0
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#ifdef __has_builtin
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#if !__has_builtin(__builtin_bcdsub)
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#define NO_BUILTIN_BCDSUB
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#endif
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#endif
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#ifdef NO_BUILTIN_BCDSUB
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#define BCDSUB(T, A, B, PS) \
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".long 4 << 26 | (" #T ") << 21 | (" #A ") << 16 | (" #B ") << 11" \
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" | 1 << 10 | (" #PS ") << 9 | 65\n\t"
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#else
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#define BCDSUB(T, A, B, PS) "bcdsub. " #T ", " #A ", " #B ", " #PS "\n\t"
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#endif
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#define TEST(AH, AL, BH, BL, PS, TH, TL, CR6) \
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do { \
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int cr = 0; \
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uint64_t th, tl; \
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/* \
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* Use GPR pairs to load the VSR values and place the resulting VSR and\
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* CR6 in th, tl, and cr. Note that we avoid newer instructions (e.g., \
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* mtvsrdd/mfvsrld) so we can run this test on POWER8 machines. \
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*/ \
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asm ("mtvsrd 32, %3\n\t" \
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"mtvsrd 33, %4\n\t" \
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"xxmrghd 32, 32, 33\n\t" \
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"mtvsrd 33, %5\n\t" \
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"mtvsrd 34, %6\n\t" \
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"xxmrghd 33, 33, 34\n\t" \
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BCDSUB(0, 0, 1, PS) \
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"mfocrf %0, 0b10\n\t" \
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"mfvsrd %1, 32\n\t" \
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"xxswapd 32, 32\n\t" \
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"mfvsrd %2, 32\n\t" \
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: "=r" (cr), "=r" (th), "=r" (tl) \
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: "r" (AH), "r" (AL), "r" (BH), "r" (BL) \
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: "v0", "v1", "v2"); \
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if (TH != UNDEF || TL != UNDEF) { \
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assert(tl == TL); \
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assert(th == TH); \
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} \
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assert((cr >> 4) == CR6); \
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} while (0)
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/*
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* Unbounded result is equal to zero:
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* sign = (PS) ? 0b1111 : 0b1100
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* CR6 = 0b0010
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*/
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void test_bcdsub_eq(void)
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{
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/* maximum positive BCD value */
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TEST(0x9999999999999999, 0x999999999999999c,
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0x9999999999999999, 0x999999999999999c,
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0, 0x0, 0xc, CRF_EQ);
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TEST(0x9999999999999999, 0x999999999999999c,
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0x9999999999999999, 0x999999999999999c,
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1, 0x0, 0xf, CRF_EQ);
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}
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/*
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* Unbounded result is greater than zero:
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* sign = (PS) ? 0b1111 : 0b1100
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* CR6 = (overflow) ? 0b0101 : 0b0100
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*/
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void test_bcdsub_gt(void)
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{
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/* maximum positive and negative one BCD values */
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TEST(0x9999999999999999, 0x999999999999999c, 0x0, 0x1d, 0,
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0x0, 0xc, (CRF_GT | CRF_SO));
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TEST(0x9999999999999999, 0x999999999999999c, 0x0, 0x1d, 1,
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0x0, 0xf, (CRF_GT | CRF_SO));
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TEST(0x9999999999999999, 0x999999999999998c, 0x0, 0x1d, 0,
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0x9999999999999999, 0x999999999999999c, CRF_GT);
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TEST(0x9999999999999999, 0x999999999999998c, 0x0, 0x1d, 1,
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0x9999999999999999, 0x999999999999999f, CRF_GT);
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}
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/*
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* Unbounded result is less than zero:
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* sign = 0b1101
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* CR6 = (overflow) ? 0b1001 : 0b1000
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*/
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void test_bcdsub_lt(void)
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{
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/* positive zero and positive one BCD values */
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TEST(0x0, 0xc, 0x0, 0x1c, 0, 0x0, 0x1d, CRF_LT);
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TEST(0x0, 0xc, 0x0, 0x1c, 1, 0x0, 0x1d, CRF_LT);
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/* maximum negative and positive one BCD values */
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TEST(0x9999999999999999, 0x999999999999999d, 0x0, 0x1c, 0,
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0x0, 0xd, (CRF_LT | CRF_SO));
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TEST(0x9999999999999999, 0x999999999999999d, 0x0, 0x1c, 1,
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0x0, 0xd, (CRF_LT | CRF_SO));
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}
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void test_bcdsub_invalid(void)
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{
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TEST(0x0, 0x1c, 0x0, 0xf00, 0, UNDEF, UNDEF, CRF_SO);
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TEST(0x0, 0x1c, 0x0, 0xf00, 1, UNDEF, UNDEF, CRF_SO);
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TEST(0x0, 0xf00, 0x0, 0x1c, 0, UNDEF, UNDEF, CRF_SO);
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TEST(0x0, 0xf00, 0x0, 0x1c, 1, UNDEF, UNDEF, CRF_SO);
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TEST(0x0, 0xbad, 0x0, 0xf00, 0, UNDEF, UNDEF, CRF_SO);
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TEST(0x0, 0xbad, 0x0, 0xf00, 1, UNDEF, UNDEF, CRF_SO);
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}
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int main(void)
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{
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struct sigaction action;
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action.sa_handler = _exit;
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sigaction(SIGABRT, &action, NULL);
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test_bcdsub_eq();
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test_bcdsub_gt();
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test_bcdsub_lt();
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test_bcdsub_invalid();
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return 0;
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}
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