Mesa (mesa_7_6_branch): mesa: check dst reg in _mesa_find_free_register()

[Brian Paul]

Module: Mesa
Branch: mesa_7_6_branch
Commit: 5076a4f53a2f34cc9116b45951037f639885c7a1
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=5076a4f53a2f34cc9116b45951037f639885c7a1

Author: Brian Paul <brianp at vmware.com>
Date:   Fri Dec 11 09:16:25 2009 -0700

mesa: check dst reg in _mesa_find_free_register()

If a register was only being used as a destination (as will happen when
generated condition-codes) we missed its use.  So we'd errantly return
a register index that was really in-use, not free.

Fixes bug 25579.

---

 src/mesa/shader/program.c |   14 +++++++++++---
 1 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/src/mesa/shader/program.c b/src/mesa/shader/program.c
index 2cd6eb8..18d4ef9 100644
--- a/src/mesa/shader/program.c
+++ b/src/mesa/shader/program.c
@@ -813,9 +813,17 @@ _mesa_find_free_register(const struct gl_program *prog, GLuint regFile)
       const struct prog_instruction *inst = prog->Instructions + i;
       const GLuint n = _mesa_num_inst_src_regs(inst->Opcode);
 
-      for (k = 0; k < n; k++) {
-         if (inst->SrcReg[k].File == regFile) {
-            used[inst->SrcReg[k].Index] = GL_TRUE;
+      /* check dst reg first */
+      if (inst->DstReg.File == regFile) {
+         used[inst->DstReg.Index] = GL_TRUE;
+      }
+      else {
+         /* check src regs otherwise */
+         for (k = 0; k < n; k++) {
+            if (inst->SrcReg[k].File == regFile) {
+               used[inst->SrcReg[k].Index] = GL_TRUE;
+               break;
+            }
          }
       }
    }