Add the missing backports for riscv64

Signed-off-by: David Abdurachmanov <david.abdurachmanov@sifive.com>

D68899-de1c2877a9ff12899ef50e179ade748fba8ab0c0.patch

@@ -0,0 +1,52 @@
+From de1c2877a9ff12899ef50e179ade748fba8ab0c0 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Lu=C3=ADs=20Marques?= <luismarques@lowrisc.org>
+Date: Fri, 14 Feb 2020 11:49:18 +0000
+Subject: [PATCH] llvm/cmake/config.guess: add support for riscv32 and  riscv64
+
+Summary: LLVM configuration fails with 'unable to guess system type' on riscv64.
+Add support for detecting riscv32 and riscv64 systems.
+
+Patch by Gokturk Yuksek (gokturk)
+Reviewers: erichkeane, rengolin, mgorny, aaron.ballman, beanz, luismarques
+Reviewed By: luismarques
+Tags: #llvm
+Differential Revision: https://reviews.llvm.org/D68899
+---
+ llvm/cmake/config.guess | 24 ++++++++++++++++++++++++
+ 1 file changed, 24 insertions(+)
+
+diff --git a/llvm/cmake/config.guess b/llvm/cmake/config.guess
+index ccb30f4e75e8..26d120601e49 100644
+--- a/llvm/cmake/config.guess
++++ b/llvm/cmake/config.guess
+@@ -973,6 +973,30 @@ EOF
+     ppc:Linux:*:*)
+ 	echo powerpc-unknown-linux-gnu
+ 	exit ;;
++    riscv32:Linux:*:* | riscv64:Linux:*:*)
++	LIBC=gnu
++	eval $set_cc_for_build
++	# Do not check for __GLIBC__ because uclibc defines it too
++	sed 's/^	//' << EOF >$dummy.c
++	#include <features.h>
++	#if defined(__UCLIBC__)
++	LIBC=uclibc
++	#elif defined(__dietlibc__)
++	LIBC=dietlibc
++	#endif
++EOF
++	eval `$CC_FOR_BUILD -E $dummy.c 2>/dev/null | grep '^LIBC'`
++
++	# There is no features test macro for musl
++	# Follow the GNU's config.guess approach of
++	# checking the output of ldd
++	if command -v ldd >/dev/null && \
++		ldd --version 2>&1 | grep -q ^musl; then
++	    LIBC=musl
++	fi
++
++	echo ${UNAME_MACHINE}-unknown-linux-${LIBC}
++	exit ;;
+     s390:Linux:*:* | s390x:Linux:*:*)
+ 	echo ${UNAME_MACHINE}-ibm-linux
+ 	exit ;;

D68964-cef85193b2cc1817ca43199a0ae9c6f25723997d.patch

@@ -0,0 +1,49 @@
+From cef85193b2cc1817ca43199a0ae9c6f25723997d Mon Sep 17 00:00:00 2001
+From: Gokturk Yuksek <gokturk@binghamton.edu>
+Date: Mon, 17 Feb 2020 18:36:18 +0000
+Subject: [PATCH] [CMake] CheckAtomic.cmake: catch false positives in RISC-V
+
+The check for 'HAVE_CXX_ATOMICS_WITHOUT_LIB' may create false
+positives in RISC-V. This is reproducible when compiling LLVM natively
+using GCC on a rv64gc (rv64imafdgc) host. Due to the 'A' (atomic)
+extension, g++ replaces calls to libatomic operations on the
+std::atomic<int> type with the native hardware instructions. As a
+result, the compilation succeeds and the build system thinks it
+doesn't need to pass '-latomic'.
+
+Improve the reliability of the 'HAVE_CXX_ATOMICS_WITHOUT_LIB' test in
+two steps:
+
+1. Force a pre-increment on x (++x), which should force a call to a
+libatomic function;
+
+2. Because step 1 would resolve the increment to 'amoadd.w.aq' under
+the 'A' extension, force the same operation on sub-word types, for
+which there is no hardware support.
+
+Reviewers: jfb, hintonda, smeenai, mgorny, JDevlieghere, jyknight
+Reviewed By: jfb
+Tags: #llvm
+Differential Revision: https://reviews.llvm.org/D68964
+---
+ llvm/cmake/modules/CheckAtomic.cmake | 6 +++++-
+ 1 file changed, 5 insertions(+), 1 deletion(-)
+
+diff --git a/llvm/cmake/modules/CheckAtomic.cmake b/llvm/cmake/modules/CheckAtomic.cmake
+index af925f5bf9ec..5d22a131e5cb 100644
+--- a/llvm/cmake/modules/CheckAtomic.cmake
++++ b/llvm/cmake/modules/CheckAtomic.cmake
+@@ -12,8 +12,12 @@ function(check_working_cxx_atomics varname)
+   CHECK_CXX_SOURCE_COMPILES("
+ #include <atomic>
+ std::atomic<int> x;
++std::atomic<short> y;
++std::atomic<char> z;
+ int main() {
+-  return x;
++  ++z;
++  ++y;
++  return ++x;
+ }
+ " ${varname})
+   set(CMAKE_REQUIRED_FLAGS ${OLD_CMAKE_REQUIRED_FLAGS})

D69003-09856feb3cc141f4f9c8b9edec28602ac4f21575.patch

@@ -0,0 +1,28 @@
+From 09856feb3cc141f4f9c8b9edec28602ac4f21575 Mon Sep 17 00:00:00 2001
+From: Gokturk Yuksek <gokturk@binghamton.edu>
+Date: Mon, 17 Feb 2020 22:26:59 +0000
+Subject: [PATCH] [dsymutil] Explicitly link against libatomic when necessary
+
+In some systems, such as RISC-V, atomic support requires explicit linking
+against '-latomic' (see https://github.com/riscv/riscv-gcc/issues/12).
+
+Reviewers: davezarzycki, hhb, beanz, jfb, JDevlieghere
+Reviewed By: beanz, JDevlieghere
+Tags: #llvm
+Differential Revision: https://reviews.llvm.org/D69003
+---
+ llvm/tools/dsymutil/CMakeLists.txt | 4 ++++
+ 1 file changed, 4 insertions(+)
+
+diff --git a/llvm/tools/dsymutil/CMakeLists.txt b/llvm/tools/dsymutil/CMakeLists.txt
+index a6543c9ff2ce..dc31b86b2fc9 100644
+--- a/llvm/tools/dsymutil/CMakeLists.txt
++++ b/llvm/tools/dsymutil/CMakeLists.txt
+@@ -37,3 +37,7 @@ add_llvm_tool(dsymutil
+ if(APPLE)
+   target_link_libraries(dsymutil PRIVATE "-framework CoreFoundation")
+ endif(APPLE)
++
++if(HAVE_CXX_ATOMICS_WITH_LIB OR HAVE_CXX_ATOMICS64_WITH_LIB)
++  target_link_libraries(dsymutil PRIVATE atomic)
++endif()

D69444-d4a4a32cd94eccbaaa4608b0daac8b820e041214.patch

@@ -0,0 +1,32 @@
+From d4a4a32cd94eccbaaa4608b0daac8b820e041214 Mon Sep 17 00:00:00 2001
+From: Gokturk Yuksek <gokturk@binghamton.edu>
+Date: Tue, 18 Feb 2020 07:52:29 +0000
+Subject: [PATCH] [Support] Check for atomics64 when deciding if '-latomic'  is
+ needed
+
+The CheckAtomic module performs two tests to determine if passing
+'-latomic' to the linker is required: one for 64-bit atomics, and
+another for non-64-bit atomics. Include the missing check for 64-bit
+atomics.
+
+Reviewers: beanz, compnerd
+Reviewed By: beanz, compnerd
+Tags: #llvm
+Differential Revision: https://reviews.llvm.org/D69444
+---
+ llvm/lib/Support/CMakeLists.txt | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/llvm/lib/Support/CMakeLists.txt b/llvm/lib/Support/CMakeLists.txt
+index 26332d4f539c..41c5258d0b2b 100644
+--- a/llvm/lib/Support/CMakeLists.txt
++++ b/llvm/lib/Support/CMakeLists.txt
+@@ -26,7 +26,7 @@ elseif( CMAKE_HOST_UNIX )
+       set(system_libs ${system_libs} ${TERMINFO_LIBS})
+     endif()
+   endif()
+-  if( LLVM_ENABLE_THREADS AND HAVE_LIBATOMIC )
++  if( LLVM_ENABLE_THREADS AND (HAVE_LIBATOMIC OR HAVE_CXX_LIBATOMICS64) )
+     set(system_libs ${system_libs} atomic)
+   endif()
+   set(system_libs ${system_libs} ${LLVM_PTHREAD_LIB})

f128f442a3d23674bee19ae18e29f92c9dfe40cd.patch

@@ -0,0 +1,27 @@
+From f128f442a3d23674bee19ae18e29f92c9dfe40cd Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Lu=C3=ADs=20Marques?= <luismarques@lowrisc.org>
+Date: Mon, 17 Feb 2020 15:21:41 +0000
+Subject: [PATCH] [CMake] Fix setting result of libatomic check for MSVC
+
+We were skipping the libatomic requirement check for MSVC, but not setting
+the corresponding variable, HAVE_CXX_ATOMICS_WITHOUT_LIB. D69869 seems to
+have to failed to build on ARM MSVC because of that, and was reverted. This
+should probably fix the issue. The plan is to check the result of the build
+bots and then submit a more thoroughly refactored version for review.
+---
+ llvm/cmake/modules/CheckAtomic.cmake | 2 ++
+ 1 file changed, 2 insertions(+)
+
+diff --git a/llvm/cmake/modules/CheckAtomic.cmake b/llvm/cmake/modules/CheckAtomic.cmake
+index 29f3bdd57f03..af925f5bf9ec 100644
+--- a/llvm/cmake/modules/CheckAtomic.cmake
++++ b/llvm/cmake/modules/CheckAtomic.cmake
+@@ -53,6 +53,8 @@ if (LLVM_COMPILER_IS_GCC_COMPATIBLE)
+       message(FATAL_ERROR "Host compiler appears to require libatomic, but cannot find it.")
+     endif()
+   endif()
++elseif(MSVC)
++  set(HAVE_CXX_ATOMICS_WITHOUT_LIB True)
+ endif()
+ 
+ # Check for 64 bit atomic operations.