luajit: patch: PPC/e500 SPE: use soft float instead of failing

makes LuaJit builds for mpc85xx targets with SPE ISA extension
enabled possible

Quoting inner commit message:

This allows building LuaJit for systems with Power ISA SPE
extension[^1] support by using soft float on LuaJit side.

While e500 CPU cores support SPE instruction set extension
allowing them to perform floating point arithmetic natively,
this isn't required. They can function with software floating
point to integer arithmetic translation as well,
just like FPU-less PowerPC CPUs without SPE support.

Therefore I see no need to prevent them from running LuaJit
explicitly.

[^1]: https://www.nxp.com/docs/en/reference-manual/SPEPEM.pdf

Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Šimon Bořek <simon.borek@nic.cz>
(cherry picked from commit a4a484fbca)

lang/luajit/patches/300-PPC-e500-with-SPE-enabled-use-soft-float.patch

@@ -0,0 +1,58 @@
+From 2c8b9d5807a515a0ff859899065f512beabcbaed Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?=C5=A0imon=20Bo=C5=99ek?= <simon.borek@nic.cz>
+Date: Sat, 16 Jul 2022 18:39:55 +0200
+Subject: [PATCH] PPC/e500 with SPE enabled: use soft float instead of failing
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+This allows building LuaJit for systems with Power ISA SPE
+extension[^1] support by using soft float on LuaJit side.
+
+While e500 CPU cores support SPE instruction set extension
+allowing them to perform floating point arithmetic natively,
+this isn't required. They can function with software floating
+point to integer arithmetic translation as well,
+just like FPU-less PowerPC CPUs without SPE support.
+
+Therefore I see no need to prevent them from running LuaJit
+explicitly.
+
+[^1]: https://www.nxp.com/docs/en/reference-manual/SPEPEM.pdf
+
+Signed-off-by: Pali Rohár <pali@kernel.org>
+Signed-off-by: Šimon Bořek <simon.borek@nic.cz>
+---
+ src/lj_arch.h | 7 ++-----
+ 1 file changed, 2 insertions(+), 5 deletions(-)
+
+--- a/src/lj_arch.h
++++ b/src/lj_arch.h
+@@ -256,7 +256,7 @@
+ #define LJ_ARCH_NAME		"ppc"
+ 
+ #if !defined(LJ_ARCH_HASFPU)
+-#if defined(_SOFT_FLOAT) || defined(_SOFT_DOUBLE)
++#if defined(_SOFT_FLOAT) || defined(_SOFT_DOUBLE) || defined(__NO_FPRS__)
+ #define LJ_ARCH_HASFPU		0
+ #else
+ #define LJ_ARCH_HASFPU		1
+@@ -264,7 +264,7 @@
+ #endif
+ 
+ #if !defined(LJ_ABI_SOFTFP)
+-#if defined(_SOFT_FLOAT) || defined(_SOFT_DOUBLE)
++#if defined(_SOFT_FLOAT) || defined(_SOFT_DOUBLE) || defined(__NO_FPRS__)
+ #define LJ_ABI_SOFTFP		1
+ #else
+ #define LJ_ABI_SOFTFP		0
+@@ -442,9 +442,6 @@
+ #if LJ_ARCH_PPC64
+ #error "No support for PowerPC 64 bit mode (yet)"
+ #endif
+-#if defined(__NO_FPRS__) && !defined(_SOFT_FLOAT)
+-#error "No support for PPC/e500 anymore (use LuaJIT 2.0)"
+-#endif
+ #elif LJ_TARGET_MIPS32
+ #if !((defined(_MIPS_SIM_ABI32) && _MIPS_SIM == _MIPS_SIM_ABI32) || (defined(_ABIO32) && _MIPS_SIM == _ABIO32))
+ #error "Only o32 ABI supported for MIPS32"