[Beignet] [PATCH] fix one bug of long mad_sat.

[junyan.he at inbox.com]

From: Junyan He <junyan.he at linux.intel.com>

The bug caused because we didn't consider two overflow
cases when type is long, which do not cause carry and
are easy to be ignored.

Signed-off-by: Junyan He <junyan.he at linux.intel.com>
---
 backend/src/backend/gen8_context.cpp | 35 ++++++++++++++++++++++++++++++++++-
 utests/compiler_long_hi_sat.cpp      |  8 ++++++--
 2 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/backend/src/backend/gen8_context.cpp b/backend/src/backend/gen8_context.cpp
index cde87de..26bc50d 100644
--- a/backend/src/backend/gen8_context.cpp
+++ b/backend/src/backend/gen8_context.cpp
@@ -390,10 +390,15 @@ namespace gbe
       /* saturate logic:
       if(dst_h > 0)
         sum = CL_LONG_MAX;
-      else if(dst_h < -1)
+      else if (dst_h == 0 && sum > 0x7FFFFFFFFFFFFFFFLL) {
+        sum = CL_LONG_MAX;
+      else if (dst_h == -1 && sum < 0x8000000000000000)
+        sum = CL_LONG_MIN;
+      else (dst_h < -1)
         sum = CL_LONG_MIN;
       cl_long result = (cl_long) sum; */
       p->MOV(dst_l, sum);
+      tmp0.type = GEN_TYPE_UL;
 
       dst_h.type = GEN_TYPE_L;
       p->push();
@@ -411,6 +416,34 @@ namespace gbe
       p->curr.predicate = GEN_PREDICATE_NONE;
       p->curr.noMask = 1;
       p->curr.useFlag(flagReg.flag_nr(), flagReg.flag_subnr());
+      p->CMP(GEN_CONDITIONAL_EQ, dst_h, GenRegister::immd(0x0L), tmp1);
+      p->curr.noMask = 0;
+      p->curr.predicate = GEN_PREDICATE_NORMAL;
+      p->MOV(tmp0, GenRegister::immuint64(0x7FFFFFFFFFFFFFFFUL));
+      p->CMP(GEN_CONDITIONAL_G, dst_l, tmp0, tmp1);
+      p->MOV(dst_l, GenRegister::immint64(0x7FFFFFFFFFFFFFFFLL));
+      p->pop();
+      p->NOP();
+
+      p->push();
+      p->curr.predicate = GEN_PREDICATE_NONE;
+      p->curr.noMask = 1;
+      p->curr.useFlag(flagReg.flag_nr(), flagReg.flag_subnr());
+      /* Fixme: HW bug ? 0xFFFFFFFFFFFFFFFF != 0xFFFFFFFFFFFFFFFF */
+      p->ADD(tmp0, dst_h, GenRegister::immud(1));
+      p->CMP(GEN_CONDITIONAL_EQ, tmp0, GenRegister::immud(0), tmp1);
+      p->curr.noMask = 0;
+      p->curr.predicate = GEN_PREDICATE_NORMAL;
+      p->MOV(tmp0, GenRegister::immuint64(0x8000000000000000UL));
+      p->CMP(GEN_CONDITIONAL_L, dst_l, tmp0, tmp1);
+      p->MOV(dst_l, GenRegister::immint64(-0x7FFFFFFFFFFFFFFFLL - 1LL));
+      p->pop();
+      p->NOP();
+
+      p->push();
+      p->curr.predicate = GEN_PREDICATE_NONE;
+      p->curr.noMask = 1;
+      p->curr.useFlag(flagReg.flag_nr(), flagReg.flag_subnr());
       p->CMP(GEN_CONDITIONAL_L, dst_h, GenRegister::immd(-1), tmp1);
       p->curr.noMask = 0;
       p->curr.predicate = GEN_PREDICATE_NORMAL;
diff --git a/utests/compiler_long_hi_sat.cpp b/utests/compiler_long_hi_sat.cpp
index e1d5f3b..a0f2bfa 100644
--- a/utests/compiler_long_hi_sat.cpp
+++ b/utests/compiler_long_hi_sat.cpp
@@ -57,7 +57,7 @@ static void __mad_sat(int64_t sourceA, int64_t sourceB, int64_t sourceC, int64_t
   cl_long multHi;
   cl_ulong multLo;
   __64_mul_64(sourceA, sourceB, multLo, multHi);
-
+  //printf("hi is %lx, lo is %lx\n", multHi, multLo);
   cl_ulong sum = multLo + sourceC;
 
   // carry if overflow
@@ -82,6 +82,10 @@ static void __mad_sat(int64_t sourceA, int64_t sourceB, int64_t sourceC, int64_t
   // saturate
   if( multHi > 0 )
     sum = CL_LONG_MAX;
+  else if ( multHi == 0 && sum > CL_LONG_MAX)
+    sum = CL_LONG_MAX;
+  else if ( multHi == -1 && sum < (cl_ulong)CL_LONG_MIN)
+    sum = CL_LONG_MIN;
   else if( multHi < -1 )
     sum = CL_LONG_MIN;
 
@@ -161,7 +165,7 @@ void compiler_long_mul_sat(void)
     uint64_t a = rand();
     a = a <<32 | a;
     src[i] = a;
-//    printf(" 0x%lx", src[i]);
+    //printf(" 0x%lx", src[i]);
   }
 
   OCL_MAP_BUFFER(0);
-- 
1.9.1