[Mesa-stable] [PATCH v2] llvmpipe: disable vsx in ppc due to LLVM PPC bug

[Oded Gabbay]

This patch makes sure that if we use altivec (VMX) instructions, we don't
use VSX instructions as well, as this cause piglit tests to fail

For more details, see: https://llvm.org/bugs/show_bug.cgi?id=25503#c7

With this patch, ppc64le reaches parity with x86-64 as far as piglit test
suite is concerned.

v2:
- Added check that we have at least LLVM 3.4
- Added the LLVM bug URL as a comment in the code

Signed-off-by: Oded Gabbay <oded.gabbay at gmail.com>
Cc: "11.0" <mesa-stable at lists.freedesktop.org>
---
 src/gallium/auxiliary/gallivm/lp_bld_misc.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp b/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp
index 7bda118..152593a 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp
+++ b/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp
@@ -536,6 +536,10 @@ lp_build_create_jit_compiler_for_module(LLVMExecutionEngineRef *OutJIT,
 
 #if defined(PIPE_ARCH_PPC)
    MAttrs.push_back(util_cpu_caps.has_altivec ? "+altivec" : "-altivec");
+#if HAVE_LLVM >= 0x0304
+   /* See LLVM bug https://llvm.org/bugs/show_bug.cgi?id=25503#c7 */
+   MAttrs.push_back("-vsx");
+#endif
 #endif
 
    builder.setMAttrs(MAttrs);
-- 
2.5.0