Mesa (master): gallivm: Fixed erroneous optimisation in lp_build_min/max.

[Jose Fonseca]

Module: Mesa
Branch: master
Commit: a3d4af0c00a198bba00c0965131a14223d426dd4
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=a3d4af0c00a198bba00c0965131a14223d426dd4

Author: James Benton <jbenton at vmware.com>
Date:   Fri May 18 16:06:44 2012 +0100

gallivm: Fixed erroneous optimisation in lp_build_min/max.

Previously assumed normalised was 0 to 1, but it can be -1 to 1
if type is signed.
Tested with lp_test_conv and lp_test_format, reduced errors.

Signed-off-by: José Fonseca <jfonseca at vmware.com>

---

 src/gallium/auxiliary/gallivm/lp_bld_arit.c |   21 ++++++++++++++-------
 1 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/src/gallium/auxiliary/gallivm/lp_bld_arit.c b/src/gallium/auxiliary/gallivm/lp_bld_arit.c
index d112f1a..9fc5762 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_arit.c
+++ b/src/gallium/auxiliary/gallivm/lp_bld_arit.c
@@ -763,9 +763,12 @@ lp_build_min(struct lp_build_context *bld,
    if(a == b)
       return a;
 
-   if(bld->type.norm) {
-      if(a == bld->zero || b == bld->zero)
-         return bld->zero;
+   if (bld->type.norm) {
+      if (!bld->type.sign) {
+         if (a == bld->zero || b == bld->zero) {
+            return bld->zero;
+         }
+      }
       if(a == bld->one)
          return b;
       if(b == bld->one)
@@ -797,10 +800,14 @@ lp_build_max(struct lp_build_context *bld,
    if(bld->type.norm) {
       if(a == bld->one || b == bld->one)
          return bld->one;
-      if(a == bld->zero)
-         return b;
-      if(b == bld->zero)
-         return a;
+      if (!bld->type.sign) {
+         if (a == bld->zero) {
+            return b;
+         }
+         if (b == bld->zero) {
+            return a;
+         }
+      }
    }
 
    return lp_build_max_simple(bld, a, b);