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[Qemu-devel] [PULL 8/8] softfloat: Specialize udiv_qrnnd for ppc64
From: |
Richard Henderson |
Subject: |
[Qemu-devel] [PULL 8/8] softfloat: Specialize udiv_qrnnd for ppc64 |
Date: |
Fri, 5 Oct 2018 13:02:01 -0500 |
The ISA has a 128/64-bit division instruction, though it assumes the
low 64-bits of the numerator are 0, and so requires a bit more fixup
than a full 128-bit division insn.
Reviewed-by: David Gibson <address@hidden>
Signed-off-by: Richard Henderson <address@hidden>
---
include/fpu/softfloat-macros.h | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/include/fpu/softfloat-macros.h b/include/fpu/softfloat-macros.h
index eafc68932b..c86687fa5e 100644
--- a/include/fpu/softfloat-macros.h
+++ b/include/fpu/softfloat-macros.h
@@ -647,6 +647,22 @@ static inline uint64_t udiv_qrnnd(uint64_t *r, uint64_t n1,
asm("dlgr %0, %1" : "+r"(n) : "r"(d));
*r = n >> 64;
return n;
+#elif defined(_ARCH_PPC64)
+ /* From Power ISA 3.0B, programming note for divdeu. */
+ uint64_t q1, q2, Q, r1, r2, R;
+ asm("divdeu %0,%2,%4; divdu %1,%3,%4"
+ : "=&r"(q1), "=r"(q2)
+ : "r"(n1), "r"(n0), "r"(d));
+ r1 = -(q1 * d); /* low part of (n1<<64) - (q1 * d) */
+ r2 = n0 - (q2 * d);
+ Q = q1 + q2;
+ R = r1 + r2;
+ if (R >= d || R < r2) { /* overflow implies R > d */
+ Q += 1;
+ R -= d;
+ }
+ *r = R;
+ return Q;
#else
uint64_t d0, d1, q0, q1, r1, r0, m;
--
2.17.1
- [Qemu-devel] [PULL 0/8] softfloat queue, Richard Henderson, 2018/10/05
- [Qemu-devel] [PULL 1/8] softfloat: remove float64_trunc_to_int, Richard Henderson, 2018/10/05
- [Qemu-devel] [PULL 2/8] gitmodules: add berkeley's softfloat + testfloat version 3, Richard Henderson, 2018/10/05
- [Qemu-devel] [PULL 4/8] softfloat: Replace countLeadingZeros32/64 with clz32/64, Richard Henderson, 2018/10/05
- [Qemu-devel] [PULL 6/8] softfloat: Specialize udiv_qrnnd for x86_64, Richard Henderson, 2018/10/05
- [Qemu-devel] [PULL 8/8] softfloat: Specialize udiv_qrnnd for ppc64,
Richard Henderson <=
- [Qemu-devel] [PULL 7/8] softfloat: Specialize udiv_qrnnd for s390x, Richard Henderson, 2018/10/05
- [Qemu-devel] [PULL 5/8] softfloat: Fix division, Richard Henderson, 2018/10/05
- [Qemu-devel] [PULL 3/8] tests/fp/fp-test: add floating point tests, Richard Henderson, 2018/10/05
- Re: [Qemu-devel] [PULL 0/8] softfloat queue, Peter Maydell, 2018/10/08