soft-fp64/fadd: Instead of tracking "b < a", track sign of the difference

[mesa.git] / src / compiler / glsl / float64.glsl

diff --git a/src/compiler/glsl/float64.glsl b/src/compiler/glsl/float64.glsl
index 3cc8aa7fa4b4e6adde8696efb3acc278312e1be1..46cae0a4cdbb9a315a1ddf8da66dc1fdb6a62663 100644 (file)
--- a/src/compiler/glsl/float64.glsl
+++ b/src/compiler/glsl/float64.glsl
@@ -771,14 +771,14 @@ __fadd64(uint64_t a, uint64_t b)
       bExp = mix(bExp, 1, aExp == 0);
       aExp = mix(aExp, 1, aExp == 0);
       bool zexp_normal = false;
-      bool blta = true;
+      uint sign_of_difference = 0;
       if (bFracHi < aFracHi) {
          __sub64(aFracHi, aFracLo, bFracHi, bFracLo, zFrac0, zFrac1);
          zexp_normal = true;
       }
       else if (aFracHi < bFracHi) {
          __sub64(bFracHi, bFracLo, aFracHi, aFracLo, zFrac0, zFrac1);
-         blta = false;
+         sign_of_difference = 0x80000000;
          zexp_normal = true;
       }
       else if (bFracLo < aFracLo) {
@@ -787,11 +787,11 @@ __fadd64(uint64_t a, uint64_t b)
       }
       else if (aFracLo < bFracLo) {
          __sub64(bFracHi, bFracLo, aFracHi, aFracLo, zFrac0, zFrac1);
-          blta = false;
+         sign_of_difference = 0x80000000;
           zexp_normal = true;
       }
-      zExp = mix(bExp, aExp, blta);
-      aSign = mix(aSign ^ 0x80000000u, aSign, blta);
+      zExp = mix(bExp, aExp, sign_of_difference == 0u);
+      aSign ^= sign_of_difference;
       uint64_t retval_0 = __packFloat64(uint(FLOAT_ROUNDING_MODE == FLOAT_ROUND_DOWN) << 31, 0, 0u, 0u);
       uint64_t retval_1 = __normalizeRoundAndPackFloat64(aSign, zExp - 11, zFrac0, zFrac1);
       return mix(retval_0, retval_1, zexp_normal);