[Mesa-dev] [PATCH 1/6] i965: Add negative_equals methods

[Ian Romanick]

From: Ian Romanick <ian.d.romanick at intel.com>

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.

Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
---
 src/intel/compiler/brw_fs.cpp     |  7 ++++++
 src/intel/compiler/brw_ir_fs.h    |  1 +
 src/intel/compiler/brw_ir_vec4.h  |  1 +
 src/intel/compiler/brw_reg.h      | 46 +++++++++++++++++++++++++++++++++++++++
 src/intel/compiler/brw_shader.cpp |  6 +++++
 src/intel/compiler/brw_shader.h   |  1 +
 src/intel/compiler/brw_vec4.cpp   |  7 ++++++
 7 files changed, 69 insertions(+)

diff --git a/src/intel/compiler/brw_fs.cpp b/src/intel/compiler/brw_fs.cpp
index 6eea532..3d454c3 100644
--- a/src/intel/compiler/brw_fs.cpp
+++ b/src/intel/compiler/brw_fs.cpp
@@ -454,6 +454,13 @@ fs_reg::equals(const fs_reg &r) const
 }
 
 bool
+fs_reg::negative_equals(const fs_reg &r) const
+{
+   return (this->backend_reg::negative_equals(r) &&
+           stride == r.stride);
+}
+
+bool
 fs_reg::is_contiguous() const
 {
    return stride == 1;
diff --git a/src/intel/compiler/brw_ir_fs.h b/src/intel/compiler/brw_ir_fs.h
index 54797ff..f06a33c 100644
--- a/src/intel/compiler/brw_ir_fs.h
+++ b/src/intel/compiler/brw_ir_fs.h
@@ -41,6 +41,7 @@ public:
    fs_reg(enum brw_reg_file file, int nr, enum brw_reg_type type);
 
    bool equals(const fs_reg &r) const;
+   bool negative_equals(const fs_reg &r) const;
    bool is_contiguous() const;
 
    /**
diff --git a/src/intel/compiler/brw_ir_vec4.h b/src/intel/compiler/brw_ir_vec4.h
index cbaff2f..95c5119 100644
--- a/src/intel/compiler/brw_ir_vec4.h
+++ b/src/intel/compiler/brw_ir_vec4.h
@@ -43,6 +43,7 @@ public:
    src_reg(struct ::brw_reg reg);
 
    bool equals(const src_reg &r) const;
+   bool negative_equals(const src_reg &r) const;
 
    src_reg(class vec4_visitor *v, const struct glsl_type *type);
    src_reg(class vec4_visitor *v, const struct glsl_type *type, int size);
diff --git a/src/intel/compiler/brw_reg.h b/src/intel/compiler/brw_reg.h
index 7ad144b..732bddf 100644
--- a/src/intel/compiler/brw_reg.h
+++ b/src/intel/compiler/brw_reg.h
@@ -255,6 +255,52 @@ 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:
+      case BRW_REGISTER_TYPE_UB:
+      case BRW_REGISTER_TYPE_B:
+         /* FINISHME: Implement support for these types. */
+         return false;
+      default:
+         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;
diff --git a/src/intel/compiler/brw_shader.cpp b/src/intel/compiler/brw_shader.cpp
index 054962b..9cdf9fc 100644
--- a/src/intel/compiler/brw_shader.cpp
+++ b/src/intel/compiler/brw_shader.cpp
@@ -685,6 +685,12 @@ backend_reg::equals(const backend_reg &r) const
 }
 
 bool
+backend_reg::negative_equals(const backend_reg &r) const
+{
+   return brw_regs_negative_equal(this, &r) && offset == r.offset;
+}
+
+bool
 backend_reg::is_zero() const
 {
    if (file != IMM)
diff --git a/src/intel/compiler/brw_shader.h b/src/intel/compiler/brw_shader.h
index fd02feb..7d97ddb 100644
--- a/src/intel/compiler/brw_shader.h
+++ b/src/intel/compiler/brw_shader.h
@@ -59,6 +59,7 @@ struct backend_reg : private brw_reg
    }
 
    bool equals(const backend_reg &r) const;
+   bool negative_equals(const backend_reg &r) const;
 
    bool is_zero() const;
    bool is_one() const;
diff --git a/src/intel/compiler/brw_vec4.cpp b/src/intel/compiler/brw_vec4.cpp
index e483814..6680410 100644
--- a/src/intel/compiler/brw_vec4.cpp
+++ b/src/intel/compiler/brw_vec4.cpp
@@ -376,6 +376,13 @@ src_reg::equals(const src_reg &r) const
 }
 
 bool
+src_reg::negative_equals(const src_reg &r) const
+{
+   return this->backend_reg::negative_equals(r) &&
+          !reladdr && !r.reladdr;
+}
+
+bool
 vec4_visitor::opt_vector_float()
 {
    bool progress = false;
-- 
2.9.5