From: Rudolf Polzer <divverent@xonotic.org>
Date: Mon, 26 Aug 2013 08:43:30 +0000 (+0200)
Subject: Fix aliasing.
X-Git-Url: https://git.rm.cloudns.org/?a=commitdiff_plain;h=d4ed8f2802afa8add0461fd6538b8500054b1a23;p=xonotic%2Fgmqcc.git

Fix aliasing.
---

diff --git a/ir.c b/ir.c
index 6ffe959..f73e5c0 100644
--- a/ir.c
+++ b/ir.c
@@ -628,6 +628,7 @@ static bool ir_function_pass_peephole(ir_function *self)
                 if (!instr_is_operation(oper->opcode))
                     continue;
 
+                /* Old engine's mul for vector+float cannot deal with aliased inputs. */
                 if (OPTS_FLAG(LEGACY_VECTOR_MATHS)) {
                     if (oper->opcode == INSTR_MUL_VF && oper->_ops[2]->memberof == oper->_ops[1])
                         continue;
@@ -635,6 +636,12 @@ static bool ir_function_pass_peephole(ir_function *self)
                         continue;
                 }
 
+                /* Emulated bitand/bitor for vector+float cannot deal with aliased inputs. */
+                if (oper->opcode == VINSTR_BITAND_VF && oper->_ops[2]->memberof == oper->_ops[1])
+                    continue;
+                if (oper->opcode == VINSTR_BITOR_VF && oper->_ops[2]->memberof == oper->_ops[1])
+                    continue;
+
                 value = oper->_ops[0];
 
                 /* only do it for SSA values */
@@ -2487,8 +2494,12 @@ static bool ir_block_life_propagate(ir_block *self, bool *changed)
             }
         }
 
-        /* TODO(divVerent) what does this do? */
-        if (instr->opcode == INSTR_MUL_VF)
+        /* These operations need a special case as they can break when using
+         * same source and destination operand otherwise, as the engine may
+         * read the source multiple times. */
+        if (instr->opcode == INSTR_MUL_VF ||
+            instr->opcode == VINSTR_BITAND_VF ||
+            instr->opcode == VINSTR_BITOR_VF)
         {
             value = instr->_ops[2];
             /* the float source will get an additional lifetime */