From 2b833f7228a8cfd23ed9f03815c069865dcb9786 Mon Sep 17 00:00:00 2001
From: Mark Abraham <Mark.J.Abraham@gmail.com>
Date: Sat, 23 Oct 2010 04:57:04 +1300
Subject: [PATCH] Made GMX_POWERPC_INVSQRT work properly on Power6 and BlueGene

---
 CMakeLists.txt       | 7 +++++++
 configure.ac         | 4 +++-
 src/config.h.cmakein | 3 +++
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0c2d026f59..0003f37ad5 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -81,6 +81,8 @@ option(GMX_MPI    "Build a parallel (message-passing) version of GROMACS" OFF)
 option(GMX_THREADS    "Build a parallel (thread-based) version of GROMACS (cannot be combined with MPI yet)" ON)
 option(GMX_SOFTWARE_INVSQRT "Use GROMACS software 1/sqrt" ON)
 mark_as_advanced(GMX_SOFTWARE_INVSQRT)
+option(GMX_POWERPC_INVSQRT "Use PowerPC hardware 1/sqrt" ON)
+mark_as_advanced(GMX_POWERPC_INVSQRT)
 option(GMX_FAHCORE "Build a library with mdrun functionality" OFF)
 mark_as_advanced(GMX_FAHCORE)
 option(GMX_OPENMM "Accelerated execution on GPUs through the OpenMM library (rerun cmake after changing to see relevant options)" OFF)
@@ -150,6 +152,9 @@ endif(GMX_DOUBLE)
 if(GMX_SOFTWARE_INVSQRT)
   set(PKG_CFLAGS "${PKG_CFLAGS} -DGMX_SOFTWARE_INVSQRT")
 endif(GMX_SOFTWARE_INVSQRT)
+if(GMX_POWERPC_INVSQRT)
+  set(PKG_CFLAGS "${PKG_CFLAGS} -DGMX_POWERPC_INVSQRT")
+endif(GMX_POWERPC_INVSQRT)
 
 ########################################################################
 #Process MPI settings
@@ -546,6 +551,8 @@ elseif(${GMX_ACCELERATION} STREQUAL "BLUEGENE")
     set(GMX_BLUEGENE 1)
 elseif(${GMX_ACCELERATION} STREQUAL "POWER6")
     set(GMX_POWER6 1)
+    set(GMX_SOFTWARE_INVSQRT OFF CACHE BOOL "Do not use software reciprocal square root on Power6" FORCE)
+    set(GMX_POWERPC_INVSQRT ON CACHE BOOL "Use hardware reciprocal square root on Power6" FORCE)
 elseif(${GMX_ACCELERATION} STREQUAL "IA64")
     set(GMX_IA64_ASM 1)
     set(DISABLE_WATERWATER_NLIST 1)
diff --git a/configure.ac b/configure.ac
index d47e5a60f1..258598aef5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -174,7 +174,7 @@ AC_ARG_ENABLE(software-invsqrt,
               [AC_HELP_STRING([--disable-software-invsqrt],
                               [No software 1/sqrt (disabled on sgi,ibm,ia64)])],,
 [case "${host_cpu}-${host_os}" in
-  mips*-irix* | rs6000*-aix* | powerpc*-aix | ia64*-*) enable_software_invsqrt=no ;;
+  mips*-irix* | rs6000*-aix* | powerpc*-aix | powerpc*-none | ia64*-*) enable_software_invsqrt=no ;;
   *) enable_software_invsqrt=yes ;;
 esac])
 if test "$enable_software_invsqrt" = "yes"; then
@@ -1126,6 +1126,8 @@ fi
 
 if test "$enable_bluegene" = "yes"; then
   AC_DEFINE(GMX_BLUEGENE,,[Use assembly intrinsics kernels for BlueGene])
+  AC_DEFINE_UNQUOTED(GMX_POWERPC_INVSQRT,,[Use the PowerPC hardware 1/sqrt(x)])
+  PKG_CFLAGS="$PKG_CFLAGS -DGMX_POWERPC_INVSQRT"
 fi
 
 if test "$enable_fortran" = "yes"; then
diff --git a/src/config.h.cmakein b/src/config.h.cmakein
index a8c687baa0..6b51da84d4 100644
--- a/src/config.h.cmakein
+++ b/src/config.h.cmakein
@@ -146,6 +146,9 @@
 /* Use the GROMACS software 1/sqrt(x) */
 #cmakedefine GMX_SOFTWARE_INVSQRT
 
+/* Use the PowerPC hardware 1/sqrt(x) */
+#cmakedefine GMX_POWERPC_INVSQRT
+
 /* Compile with dlopen */
 #cmakedefine GMX_DLOPEN
 
-- 
2.11.4.GIT