2 files changed, 96 insertions, 2 deletions

diff --git a/src/mesa/shader/programopt.c b/src/mesa/shader/programopt.c
index 9eeb71db1b6..7d560c74a54 100644
--- a/src/mesa/shader/programopt.c
+++ b/src/mesa/shader/programopt.c
@@ -35,6 +35,7 @@
 #include "context.h"
 #include "prog_parameter.h"
 #include "prog_statevars.h"
+#include "program.h"
 #include "programopt.h"
 #include "prog_instruction.h"
 
@@ -102,7 +103,7 @@ _mesa_insert_mvp_code(GLcontext *ctx, struct gl_vertex_program *vprog)
    _mesa_copy_instructions (newInst + 4, vprog->Base.Instructions, origLen);
 
    /* free old instructions */
-   _mesa_free(vprog->Base.Instructions);
+   _mesa_free_instructions(vprog->Base.Instructions, origLen);
 
    /* install new instructions */
    vprog->Base.Instructions = newInst;
@@ -274,7 +275,7 @@ _mesa_append_fog_code(GLcontext *ctx, struct gl_fragment_program *fprog)
    inst++;
 
    /* free old instructions */
-   _mesa_free(fprog->Base.Instructions);
+   _mesa_free_instructions(fprog->Base.Instructions, origLen);
 
    /* install new instructions */
    fprog->Base.Instructions = newInst;
@@ -364,3 +365,94 @@ _mesa_count_texture_instructions(struct gl_program *prog)
    }
 }
 
+
+/**
+ * Scan/rewrite program to remove reads of varying (output) registers.
+ * In GLSL vertex shaders, varying vars can be read and written.
+ * Normally, vertex varying vars are implemented as output registers.
+ * On some hardware, trying to read an output register causes trouble.
+ * So, rewrite the program to use a temporary register in this case.
+ */
+void
+_mesa_remove_varying_reads(struct gl_program *prog)
+{
+   GLuint i;
+   GLint outputMap[VERT_RESULT_MAX];
+   GLuint numVaryingReads = 0;
+
+   assert(prog->Target == GL_VERTEX_PROGRAM_ARB);
+
+   for (i = 0; i < VERT_RESULT_MAX; i++)
+      outputMap[i] = -1;
+
+   /* look for instructions which read from varying vars */
+   for (i = 0; i < prog->NumInstructions; i++) {
+      struct prog_instruction *inst = prog->Instructions + i;
+      const GLuint numSrc = _mesa_num_inst_src_regs(inst->Opcode);
+      GLuint j;
+      for (j = 0; j < numSrc; j++) {
+         if (inst->SrcReg[j].File == PROGRAM_VARYING) {
+            /* replace the read with a temp reg */
+            const GLuint var = inst->SrcReg[j].Index;
+            if (outputMap[var] == -1) {
+               numVaryingReads++;
+               outputMap[var] = _mesa_find_free_register(prog,
+                                                         PROGRAM_TEMPORARY);
+            }
+            inst->SrcReg[j].File = PROGRAM_TEMPORARY;
+            inst->SrcReg[j].Index = outputMap[var];
+         }
+      }
+   }
+
+   if (numVaryingReads == 0)
+      return; /* nothing to be done */
+
+   /* look for instructions which write to the varying vars identified above */
+   for (i = 0; i < prog->NumInstructions; i++) {
+      struct prog_instruction *inst = prog->Instructions + i;
+      const GLuint numSrc = _mesa_num_inst_src_regs(inst->Opcode);
+      GLuint j;
+      for (j = 0; j < numSrc; j++) {
+         if (inst->DstReg.File == PROGRAM_VARYING &&
+             outputMap[inst->DstReg.Index] >= 0) {
+            /* change inst to write to the temp reg, instead of the varying */
+            inst->DstReg.File = PROGRAM_TEMPORARY;
+            inst->DstReg.Index = outputMap[inst->DstReg.Index];
+         }
+      }
+   }
+
+   /* insert new instructions to copy the temp vars to the varying vars */
+   {
+      struct prog_instruction *inst;
+      GLint endPos, var;
+
+      /* Look for END instruction and insert the new varying writes */
+      endPos = -1;
+      for (i = 0; i < prog->NumInstructions; i++) {
+         struct prog_instruction *inst = prog->Instructions + i;
+         if (inst->Opcode == OPCODE_END) {
+            endPos = i;
+            _mesa_insert_instructions(prog, i, numVaryingReads);
+            break;
+         }
+      }
+
+      assert(endPos >= 0);
+
+      /* insert new MOV instructions here */
+      inst = prog->Instructions + endPos;
+      for (var = 0; var < VERT_RESULT_MAX; var++) {
+         if (outputMap[var] >= 0) {
+            /* MOV VAR[var], TEMP[tmp]; */
+            inst->Opcode = OPCODE_MOV;
+            inst->DstReg.File = PROGRAM_VARYING;
+            inst->DstReg.Index = var;
+            inst->SrcReg[0].File = PROGRAM_TEMPORARY;
+            inst->SrcReg[0].Index = outputMap[var];
+            inst++;
+         }
+      }
+   }
+}
diff --git a/src/mesa/shader/programopt.h b/src/mesa/shader/programopt.h
index ce63644bbf5..47ff2f0c7be 100644
--- a/src/mesa/shader/programopt.h
+++ b/src/mesa/shader/programopt.h
@@ -39,5 +39,7 @@ _mesa_count_texture_indirections(struct gl_program *prog);
 extern void
 _mesa_count_texture_instructions(struct gl_program *prog);
 
+extern void
+_mesa_remove_varying_reads(struct gl_program *prog);
 
 #endif /* PROGRAMOPT_H */