From 0abce6d7700ee42eb00c787732ec1fdefe250d03 Mon Sep 17 00:00:00 2001
From: Dylan Baker <dylan@pnwbakers.com>
Date: Fri, 7 Sep 2018 13:09:23 -0700
Subject: [PATCH] utils/u_math: break dependency on gallium/utils

Currently u_math needs gallium utils for cpu detection.  Most of what
u_math uses out of u_cpu_detection is duplicated in src/mesa/x86
(surprise!), so I've just reworked it as much as possible to use the
x86/common_x86_features.h macros instead of the gallium ones. The mesa
implementation is a header only approach, with no external dependencies.
There is one small function that was copied over, as promoting
u_cpu_detection is itself a fairly hefty undertaking, as it depends on
u_debug, and this fixes the bug for now.

bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107870
Tested-by: Vinson Lee <vlee@freedesktop.org>
---
 src/util/u_math.c | 43 ++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 38 insertions(+), 5 deletions(-)

diff --git a/src/util/u_math.c b/src/util/u_math.c
index c58af911be7..bf0c398eeec 100644
--- a/src/util/u_math.c
+++ b/src/util/u_math.c
@@ -29,7 +29,7 @@
 
 #include "pipe/p_config.h"
 #include "util/u_math.h"
-#include "util/u_cpu_detect.h"
+#include "x86/common_x86_features.h"
 
 #if defined(PIPE_ARCH_SSE)
 #include <xmmintrin.h>
@@ -90,7 +90,7 @@ util_fpstate_get(void)
    unsigned mxcsr = 0;
 
 #if defined(PIPE_ARCH_SSE)
-   if (util_cpu_caps.has_sse) {
+   if (cpu_has_xmm) {
       mxcsr = _mm_getcsr();
    }
 #endif
@@ -98,6 +98,31 @@ util_fpstate_get(void)
    return mxcsr;
 }
 
+/* TODO: this was copied from u_cpu_detection. It's another case of duplication
+ * between gallium and core mesa, and it would be nice to get rid of that
+ * duplication as well.
+ */
+#if defined(PIPE_ARCH_X86)
+PIPE_ALIGN_STACK static inline bool sse2_has_daz(void)
+{
+   struct {
+      uint32_t pad1[7];
+      uint32_t mxcsr_mask;
+      uint32_t pad2[128-8];
+   } PIPE_ALIGN_VAR(16) fxarea;
+
+   fxarea.mxcsr_mask = 0;
+#if defined(PIPE_CC_GCC)
+   __asm __volatile ("fxsave %0" : "+m" (fxarea));
+#elif defined(PIPE_CC_MSVC) || defined(PIPE_CC_ICL)
+   _fxsave(&fxarea);
+#else
+   fxarea.mxcsr_mask = 0;
+#endif
+   return !!(fxarea.mxcsr_mask & (1 << 6));
+}
+#endif
+
 /**
  * Make sure that the fp treats the denormalized floating
  * point numbers as zero.
@@ -108,13 +133,21 @@ unsigned
 util_fpstate_set_denorms_to_zero(unsigned current_mxcsr)
 {
 #if defined(PIPE_ARCH_SSE)
-   if (util_cpu_caps.has_sse) {
+   if (cpu_has_xmm) {
       /* Enable flush to zero mode */
       current_mxcsr |= _MM_FLUSH_ZERO_MASK;
-      if (util_cpu_caps.has_daz) {
+      /* x86_64 cpus always have daz, as do cpus with sse3 in fact, there's
+       * basically only a handful of very early pentium 4's that have sse2 but
+       * not daz.
+       */
+# if !defined(PIPE_ARCH_x86_64) && !defined(PIPE_ARCH_SSSE3)
+      if (sse2_has_daz()) {
+# endif
          /* Enable denormals are zero mode */
          current_mxcsr |= _MM_DENORMALS_ZERO_MASK;
+# if !defined(PIPE_ARCH_x86_64) && !defined(PIPE_ARCH_SSSE3)
       }
+#endif
       util_fpstate_set(current_mxcsr);
    }
 #endif
@@ -130,7 +163,7 @@ void
 util_fpstate_set(unsigned mxcsr)
 {
 #if defined(PIPE_ARCH_SSE)
-   if (util_cpu_caps.has_sse) {
+   if (cpu_has_xmm) {
       _mm_setcsr(mxcsr);
    }
 #endif
-- 
2.30.2