[Mesa-dev] [PATCH 3/3] gallivm: Reenable PPC VSX (v3)

[Ben Crocker]

Reenable the PPC64LE Vector-Scalar Extension for LLVM versions >= 3.8.1,
now that LLVM bug 26775 and its corollary, 25503, are fixed.

Amendment: remove extraneous spaces in macro def & invocations.

We would prefer a runtime check, e.g. via an LLVMQueryString
(analogous to glGetString, eglQueryString) or LLVMGetVersion API,
but no such API exists at this time.

Signed-off-by: Ben Crocker <bcrocker at redhat.com>
Cc: 12.0 13.0 17.0 <mesa-stable at lists.freedesktop.org>
---
 src/gallium/auxiliary/gallivm/lp_bld_misc.cpp | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp b/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp
index 20868bb..c210303 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp
+++ b/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp
@@ -50,6 +50,8 @@
 
 #include <stddef.h>
 
+#define LLVM_VERSION(MAJOR_MINOR, PATCH_LEVEL) ((MAJOR_MINOR << 8) + PATCH_LEVEL)
+
 // Workaround http://llvm.org/PR23628
 #if HAVE_LLVM >= 0x0307
 #  pragma push_macro("DEBUG")
@@ -614,7 +616,8 @@ 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
+#if (HAVE_LLVM >= 0x0304) && \
+   (LLVM_VERSION(HAVE_LLVM, MESA_LLVM_VERSION_PATCH) <= LLVM_VERSION(0x0308, 0x00))
    /*
     * Make sure VSX instructions are disabled
     * See LLVM bug https://llvm.org/bugs/show_bug.cgi?id=25503#c7
@@ -622,6 +625,16 @@ lp_build_create_jit_compiler_for_module(LLVMExecutionEngineRef *OutJIT,
    if (util_cpu_caps.has_altivec) {
       MAttrs.push_back("-vsx");
    }
+#elif LLVM_VERSION(HAVE_LLVM, MESA_LLVM_VERSION_PATCH) > LLVM_VERSION(0x0308, 0x00))
+   /*
+    * However, bug 25503 is fixed, by the same fix that fixed
+    * bug 26775, in versions of LLVM later than 3.8 (starting with 3.8.1):
+    * Make sure VSX instructions are ENABLED
+    * See LLVM bug https://llvm.org/bugs/show_bug.cgi?id=26775
+    */
+   if (util_cpu_caps.has_altivec) {
+      MAttrs.push_back("+vsx");
+   }
 #endif
 #endif
 
-- 
2.7.4