i965: Handle negated unsigned immediate values in constant propagation.

Negation of UD/UW sources behaves the same as for D/W sources, taking
the two's complement of the source, except for bitwise logical
operations on Gen8 and up which take the one's complement.  Fixes
crash in a GLSL shader with subtraction of two unsigned values.

Reviewed-by: Matt Turner <mattst88@gmail.com>

1 files changed, 13 insertions, 11 deletions

diff --git a/src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp b/src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp
index 81567d2..4614e07 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp
@@ -96,6 +96,15 @@ swizzle_vf_imm(unsigned vf4, unsigned swizzle)
 }
 
 static bool
+is_logic_op(enum opcode opcode)
+{
+   return (opcode == BRW_OPCODE_AND ||
+           opcode == BRW_OPCODE_OR  ||
+           opcode == BRW_OPCODE_XOR ||
+           opcode == BRW_OPCODE_NOT);
+}
+
+static bool
 try_constant_propagate(struct brw_context *brw, vec4_instruction *inst,
                        int arg, struct copy_entry *entry)
 {
@@ -114,13 +123,15 @@ try_constant_propagate(struct brw_context *brw, vec4_instruction *inst,
       return false;
 
    if (inst->src[arg].abs) {
-      if (!brw_abs_immediate(value.type, &value.fixed_hw_reg)) {
+      if ((brw->gen >= 8 && is_logic_op(inst->opcode)) ||
+          !brw_abs_immediate(value.type, &value.fixed_hw_reg)) {
          return false;
       }
    }
 
    if (inst->src[arg].negate) {
-      if (!brw_negate_immediate(value.type, &value.fixed_hw_reg)) {
+      if ((brw->gen >= 8 && is_logic_op(inst->opcode)) ||
+          !brw_negate_immediate(value.type, &value.fixed_hw_reg)) {
          return false;
       }
    }
@@ -226,15 +237,6 @@ try_constant_propagate(struct brw_context *brw, vec4_instruction *inst,
 }
 
 static bool
-is_logic_op(enum opcode opcode)
-{
-   return (opcode == BRW_OPCODE_AND ||
-           opcode == BRW_OPCODE_OR  ||
-           opcode == BRW_OPCODE_XOR ||
-           opcode == BRW_OPCODE_NOT);
-}
-
-static bool
 try_copy_propagate(struct brw_context *brw, vec4_instruction *inst,
                    int arg, struct copy_entry *entry, int reg)
 {