i965: Add negative_equals methods

This method is similar to the existing ::equals methods.  Instead of
testing that two src_regs are equal to each other, it tests that one is
the negation of the other.

v2: Simplify various checks based on suggestions from Matt.  Use
src_reg::type instead of fixed_hw_reg.type in a check.  Also suggested
by Matt.

v3: Rebase on 3 years.  Fix some problems with negative_equals with VF
constants.  Add fs_reg::negative_equals.

v4: Replace the existing default case with BRW_REGISTER_TYPE_UB,
BRW_REGISTER_TYPE_B, and BRW_REGISTER_TYPE_NF.  Suggested by Matt.
Expand the FINISHME comment to better explain why it isn't already
finished.

Signed-off-by: Ian Romanick <[email protected]>
Reviewed-by: Alejandro Piñeiro <[email protected]> [v3]
Reviewed-by: Matt Turner <[email protected]>

1 files changed, 49 insertions, 0 deletions

diff --git a/src/intel/compiler/brw_reg.h b/src/intel/compiler/brw_reg.h
index 7ad144bdfd5..68158cc0cc8 100644
--- a/src/intel/compiler/brw_reg.h
+++ b/src/intel/compiler/brw_reg.h
@@ -255,6 +255,55 @@ brw_regs_equal(const struct brw_reg *a, const struct brw_reg *b)
    return a->bits == b->bits && (df ? a->u64 == b->u64 : a->ud == b->ud);
 }
 
+static inline bool
+brw_regs_negative_equal(const struct brw_reg *a, const struct brw_reg *b)
+{
+   if (a->file == IMM) {
+      if (a->bits != b->bits)
+         return false;
+
+      switch (a->type) {
+      case BRW_REGISTER_TYPE_UQ:
+      case BRW_REGISTER_TYPE_Q:
+         return a->d64 == -b->d64;
+      case BRW_REGISTER_TYPE_DF:
+         return a->df == -b->df;
+      case BRW_REGISTER_TYPE_UD:
+      case BRW_REGISTER_TYPE_D:
+         return a->d == -b->d;
+      case BRW_REGISTER_TYPE_F:
+         return a->f == -b->f;
+      case BRW_REGISTER_TYPE_VF:
+         /* It is tempting to treat 0 as a negation of 0 (and -0 as a negation
+          * of -0).  There are occasions where 0 or -0 is used and the exact
+          * bit pattern is desired.  At the very least, changing this to allow
+          * 0 as a negation of 0 causes some fp64 tests to fail on IVB.
+          */
+         return a->ud == (b->ud ^ 0x80808080);
+      case BRW_REGISTER_TYPE_UW:
+      case BRW_REGISTER_TYPE_W:
+      case BRW_REGISTER_TYPE_UV:
+      case BRW_REGISTER_TYPE_V:
+      case BRW_REGISTER_TYPE_HF:
+         /* FINISHME: Implement support for these types once there is
+          * something in the compiler that can generate them.  Until then,
+          * they cannot be tested.
+          */
+         return false;
+      case BRW_REGISTER_TYPE_UB:
+      case BRW_REGISTER_TYPE_B:
+      case BRW_REGISTER_TYPE_NF:
+         unreachable("not reached");
+      }
+   } else {
+      struct brw_reg tmp = *a;
+
+      tmp.negate = !tmp.negate;
+
+      return brw_regs_equal(&tmp, b);
+   }
+}
+
 struct brw_indirect {
    unsigned addr_subnr:4;
    int addr_offset:10;