[Beignet] [PATCH] fix 32-bit signed version of "sub_sat"

[Homer Hsing]

This patch makes following piglit test case pass.
  piglit/framework/../bin/cl-program-tester generated_tests/cl/builtin/int/builtin-int-sub_sat-1.0.generated.cl

Signed-off-by: Homer Hsing <homer.xing at intel.com>
---
 backend/src/ocl_stdlib.tmpl.h | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/backend/src/ocl_stdlib.tmpl.h b/backend/src/ocl_stdlib.tmpl.h
index d4e436d..8c50279 100644
--- a/backend/src/ocl_stdlib.tmpl.h
+++ b/backend/src/ocl_stdlib.tmpl.h
@@ -182,9 +182,14 @@ INLINE_OVERLOADABLE TYPE add_sat(TYPE x, TYPE y) { return ocl_sadd_sat(x, y); }
 INLINE_OVERLOADABLE TYPE sub_sat(TYPE x, TYPE y) { return ocl_ssub_sat(x, y); }
 SDEF(char);
 SDEF(short);
-SDEF(int);
 SDEF(long);
 #undef SDEF
+OVERLOADABLE int ocl_sadd_sat(int x, int y);
+INLINE_OVERLOADABLE int add_sat(int x, int y) { return ocl_sadd_sat(x, y); }
+OVERLOADABLE int ocl_ssub_sat(int x, int y);
+INLINE_OVERLOADABLE int sub_sat(int x, int y) {
+  return (y == 0x80000000u) ? (x & 0x7FFFFFFF) : ocl_ssub_sat(x, y);
+}
 #define UDEF(TYPE)                                                              \
 OVERLOADABLE TYPE ocl_uadd_sat(TYPE x, TYPE y);                          \
 OVERLOADABLE TYPE ocl_usub_sat(TYPE x, TYPE y);                          \
-- 
1.8.1.2