Turn 64-bit integer division and modulus by constants into multiply-high

This trick was already implemented for 32-bit integer division and modulus.  Here we extend it to the 64-bit case.

For 32-bit target processors, the runtime library must implement 64-bit multiply-high (signed and unsigned).  Tentative implementations are provided for IA32 and PowerPC, but need testing.

2 files changed, 140 insertions, 0 deletions

diff --git a/runtime/powerpc/i64_smul.s b/runtime/powerpc/i64_smul.s
new file mode 100644
index 00000000..9eb453d4
--- /dev/null
+++ b/runtime/powerpc/i64_smul.s
@@ -0,0 +1,76 @@
+# *****************************************************************
+#
+#               The Compcert verified compiler
+#
+#           Xavier Leroy, INRIA Paris
+#
+# Copyright (c) 2016 Institut National de Recherche en Informatique et
+#  en Automatique.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are met:
+#     * Redistributions of source code must retain the above copyright
+#       notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above copyright
+#       notice, this list of conditions and the following disclaimer in the
+#       documentation and/or other materials provided with the distribution.
+#     * Neither the name of the <organization> nor the
+#       names of its contributors may be used to endorse or promote products
+#       derived from this software without specific prior written permission.
+# 
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT
+# HOLDER> BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+# LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+# *********************************************************************
+
+# Helper functions for 64-bit integer arithmetic.  PowerPC version.
+
+        .text
+
+# Signed multiply high
+	
+# Reference C implementation in ../c/i64_smul.c
+
+        .balign 16
+        .globl __i64_smulh
+__i64_smulh:
+     # u1 in r3; u0 in r4; v1 in r5; v0 in r6
+     # First compute unsigned product (see i64_umul.s)
+        mulhwu   r0, r4, r6     # k (in r0) = high((u64) u0 * (u64) v0)
+        mullw    r8, r3, r6
+        mulhwu   r7, r3, r6     # t (in r8:r7) = (u64) u1 * (u64) v0
+        addc     r0, r8, r0     # w1 (in r0) = low (t + k)
+        addze    r9, r7         # w2 (in r9) = high (t + k)
+        mullw    r8, r4, r5
+        mulhwu   r7, r4, r5     # t (in r8:r7) = (u64) u0 * (u64) v1
+        addc     r0, r8, r0     # tmp (in r0) = low (t + w1)
+        addze    r0, r7         # k (in r0) = high(t + w1)
+        mullw    r8, r3, r5
+        mulhwu   r7, r3, r5     # t (in r8:r7) = (u64) u1 * (u64) v1
+        addc     r8, r8, r9     # add w2
+        addze    r7, r7
+        addc     r8, r8, r0     # add k
+        addze    r7, r7
+     # Here r8:r7 contains the high 64 bits of the unsigned product
+        srawi    r0, r3, 31     # r0 = 0 if U >= 0, -1 if U < 0
+        srawi    r9, r5, 31     # r9 = 0 if V >= 0, -1 if V < 0
+        and      r3, r3, r9
+        and      r4, r4, r9     # r3:r4 = U if V < 0, = 0 if V >= 0
+        and      r5, r5, r0
+        and      r6, r6, r0     # r5:r6 = V if U < 0, = 0 if U >= 0
+        subfc    r8, r4, r8
+        subfe    r7, r3, r7
+        subfc    r4, r6, r8
+        subfe    r3, r5, r7     # result is r8:r7 - r3:r4 - r5:r6
+        blr
+        .type __i64_umulh, @function
+        .size __i64_umulh, .-__i64_umulh
diff --git a/runtime/powerpc/i64_umul.s b/runtime/powerpc/i64_umul.s
new file mode 100644
index 00000000..e734b93c
--- /dev/null
+++ b/runtime/powerpc/i64_umul.s
@@ -0,0 +1,64 @@
+# *****************************************************************
+#
+#               The Compcert verified compiler
+#
+#           Xavier Leroy, INRIA Paris
+#
+# Copyright (c) 2016 Institut National de Recherche en Informatique et
+#  en Automatique.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are met:
+#     * Redistributions of source code must retain the above copyright
+#       notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above copyright
+#       notice, this list of conditions and the following disclaimer in the
+#       documentation and/or other materials provided with the distribution.
+#     * Neither the name of the <organization> nor the
+#       names of its contributors may be used to endorse or promote products
+#       derived from this software without specific prior written permission.
+# 
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT
+# HOLDER> BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+# LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+# *********************************************************************
+
+# Helper functions for 64-bit integer arithmetic.  PowerPC version.
+
+        .text
+
+# Unsigned multiply high
+	
+# Reference C implementation in ../c/i64_umul.c
+
+        .balign 16
+        .globl __i64_umulh
+__i64_umulh:
+     # u1 in r3; u0 in r4; v1 in r5; v0 in r6
+        mulhwu   r0, r4, r6     # k (in r0) = high((u64) u0 * (u64) v0)
+        mullw    r8, r3, r6
+        mulhwu   r7, r3, r6     # t (in r8:r7) = (u64) u1 * (u64) v0
+        addc     r0, r8, r0     # w1 (in r0) = low (t + k)
+        addze    r9, r7         # w2 (in r9) = high (t + k)
+        mullw    r8, r4, r5
+        mulhwu   r7, r4, r5     # t (in r8:r7) = (u64) u0 * (u64) v1
+        addc     r0, r8, r0     # tmp (in r0) = low (t + w1)
+        addze    r0, r7         # k (in r0) = high(t + w1)
+        mullw    r8, r3, r5
+        mulhwu   r7, r3, r5     # t (in r8:r7) = (u64) u1 * (u64) v1
+        addc     r4, r8, r9     # add w2
+        addze    r3, r7
+        addc     r4, r4, r0     # add k
+        addze    r3, r3
+        blr
+        .type __i64_umulh, @function
+        .size __i64_umulh, .-__i64_umulh