[Pixman] [PATCH 1/1] Disable implementations mentioned in the PIXMAN_DISABLE environment variable.

[Søren Sandmann]

From: Søren Sandmann Pedersen <ssp at redhat.com>

With this, it becomes possible to do

     PIXMAN_DISABLE="sse2 mmx" some_app

which will run some_app without SSE2 and MMX enabled. This is useful
for benchmarking, testing and narrowing down bugs.
---
 pixman/pixman-cpu.c |   44 ++++++++++++++++++++++++++++++++------------
 1 files changed, 32 insertions(+), 12 deletions(-)

diff --git a/pixman/pixman-cpu.c b/pixman/pixman-cpu.c
index fcf591a..ba89df5 100644
--- a/pixman/pixman-cpu.c
+++ b/pixman/pixman-cpu.c
@@ -24,6 +24,7 @@
 #endif
 
 #include <string.h>
+#include <stdlib.h>
 
 #if defined(USE_ARM_SIMD) && defined(_MSC_VER)
 /* Needed for EXCEPTION_ILLEGAL_INSTRUCTION */
@@ -328,7 +329,6 @@ pixman_arm_read_auxv_or_cpu_features ()
 
 #elif defined (__linux__) /* linux ELF */
 
-#include <stdlib.h>
 #include <unistd.h>
 #include <sys/types.h>
 #include <sys/stat.h>
@@ -711,51 +711,71 @@ pixman_have_sse2 (void)
 #endif /* __amd64__ */
 #endif
 
+static pixman_bool_t
+disabled (const char *name)
+{
+    const char *e;
+
+    if ((e = getenv ("PIXMAN_DISABLE")))
+    {
+	if (strstr (e, name))
+	{
+	    printf ("pixman: disabled %s implementation\n", name);
+	    return TRUE;
+	}
+    }
+
+    return FALSE;
+}
+
 pixman_implementation_t *
 _pixman_choose_implementation (void)
 {
     pixman_implementation_t *imp;
 
     imp = _pixman_implementation_create_general();
-    imp = _pixman_implementation_create_fast_path (imp);
-    
+
+    if (!disabled ("fast"))
+	imp = _pixman_implementation_create_fast_path (imp);
+
 #ifdef USE_X86_MMX
-    if (pixman_have_mmx ())
+    if (pixman_have_mmx () && !disabled ("mmx"))
 	imp = _pixman_implementation_create_mmx (imp);
 #endif
 
 #ifdef USE_SSE2
-    if (pixman_have_sse2 ())
+    if (pixman_have_sse2 () && !disabled ("sse2"))
 	imp = _pixman_implementation_create_sse2 (imp);
 #endif
 
 #ifdef USE_ARM_SIMD
-    if (pixman_have_arm_simd ())
+    if (pixman_have_arm_simd () && !disabled ("arm-simd"))
 	imp = _pixman_implementation_create_arm_simd (imp);
 #endif
 
 #ifdef USE_ARM_IWMMXT
-    if (pixman_have_arm_iwmmxt ())
+    if (pixman_have_arm_iwmmxt () && !disabled ("arm-iwmmxt"))
 	imp = _pixman_implementation_create_mmx (imp);
 #endif
 
 #ifdef USE_ARM_NEON
-    if (pixman_have_arm_neon ())
+    if (pixman_have_arm_neon () && !disabled ("arm-neon"))
 	imp = _pixman_implementation_create_arm_neon (imp);
 #endif
 
 #ifdef USE_MIPS_DSPR2
-    if (pixman_have_mips_dspr2 ())
+    if (pixman_have_mips_dspr2 () && !disabled ("mips-dspr2"))
 	imp = _pixman_implementation_create_mips_dspr2 (imp);
 #endif
 
 #ifdef USE_VMX
-    if (pixman_have_vmx ())
+    if (pixman_have_vmx () && !disabled ("vmx"))
 	imp = _pixman_implementation_create_vmx (imp);
 #endif
 
-    imp = _pixman_implementation_create_noop (imp);
-    
+    if (!disabled ("noop"))
+	imp = _pixman_implementation_create_noop (imp);
+
     return imp;
 }
 
-- 
1.6.0.6