This patch adds a class for tracking the life times of temporary registers
in the glsl to tgsi translation. The algorithm runs in three steps:
First, in order to minimize the number of needed memory allocations the
program is scanned to evaluate the number of scopes.
Then, the program is scanned  second time to record the important register
access time points: first and last reads and writes and their link to the
execution scope (loop, if/else branch, switch case).
In the third step for each register the actual minimal life time is
evaluated.

In addition, when compiled in debug mode (i.e. NDEBUG is not defined)
the shaders and estimated temporary life times can be logged to stderr
by setting the environment variable GLSL_TO_TGSI_RENAME_DEBUG.
---
 .../state_tracker/st_glsl_to_tgsi_temprename.cpp   | 881 +++++++++++++++++++++
 .../state_tracker/st_glsl_to_tgsi_temprename.h     |  55 ++
 2 files changed, 936 insertions(+)
 create mode 100644 src/mesa/state_tracker/st_glsl_to_tgsi_temprename.cpp
 create mode 100644 src/mesa/state_tracker/st_glsl_to_tgsi_temprename.h

diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi_temprename.cpp 
b/src/mesa/state_tracker/st_glsl_to_tgsi_temprename.cpp
new file mode 100644
index 0000000000..46a707ec74
--- /dev/null
+++ b/src/mesa/state_tracker/st_glsl_to_tgsi_temprename.cpp
@@ -0,0 +1,881 @@
+/*
+ * Copyright © 2017 Gert Wollny
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#include "st_glsl_to_tgsi_temprename.h"
+#include <tgsi/tgsi_info.h>
+#include <tgsi/tgsi_strings.h>
+#include <program/prog_instruction.h>
+#include <limits>
+#include <cstdlib>
+
+/* std::sort is significantly faster than qsort */
+#define USE_STL_SORT
+#ifdef USE_STL_SORT
+#include <algorithm>
+#endif
+
+#ifndef NDEBUG
+#include <iostream>
+#include <iomanip>
+#include <program/prog_print.h>
+#include <util/debug.h>
+using std::cerr;
+using std::setw;
+#endif
+
+using std::numeric_limits;
+
+/* Without c++11 define the nullptr for forward-compatibility
+ * and better readibility */
+#if __cplusplus < 201103L
+#define nullptr 0
+#endif
+
+#ifndef NDEBUG
+/* Helper function to check whether we want to seen debugging output */
+static inline bool is_debug_enabled ()
+{
+   static int debug_enabled = -1;
+   if (debug_enabled < 0)
+      debug_enabled = env_var_as_boolean("GLSL_TO_TGSI_RENAME_DEBUG", false);
+   return debug_enabled > 0;
+}
+#define RENAME_DEBUG(X) if (is_debug_enabled()) do { X; } while (false);
+#else
+#define RENAME_DEBUG(X)
+#endif
+
+namespace {
+
+enum prog_scope_type {
+   outer_scope,           /* Outer program scope */
+   loop_body,             /* Inside a loop */
+   if_branch,             /* Inside if branch */
+   else_branch,           /* Inside else branch */
+   switch_body,           /* Inside switch statmenet */
+   switch_case_branch,    /* Inside switch case statmenet */
+   switch_default_branch, /* Inside switch default statmenet */
+   undefined_scope
+};
+
+class prog_scope {
+public:
+   prog_scope(prog_scope *parent, prog_scope_type type, int id,
+              int depth, int begin);
+
+   prog_scope_type type() const;
+   prog_scope *parent() const;
+   int nesting_depth() const;
+   int id() const;
+   int end() const;
+   int begin() const;
+   int loop_break_line() const;
+
+   const prog_scope *in_ifelse_scope() const;
+   const prog_scope *in_switchcase_scope() const;
+   const prog_scope *innermost_loop() const;
+   const prog_scope *outermost_loop() const;
+   const prog_scope *enclosing_conditional() const;
+
+   bool is_loop() const;
+   bool is_in_loop() const;
+   bool is_conditional() const;
+   bool is_conditional_in_loop() const;
+
+   bool break_is_for_switchcase() const;
+   bool contains_range_of(const prog_scope& other) const;
+   const st_src_reg *switch_register() const;
+
+   void set_end(int end);
+   void set_loop_break_line(int line);
+
+private:
+   prog_scope_type scope_type;
+   int scope_id;
+   int scope_nesting_depth;
+   int scope_begin;
+   int scope_end;
+   int break_loop_line;
+   prog_scope *parent_scope;
+   const st_src_reg *switch_reg;
+};
+
+/* Some storage class to encapsulate the prog_scope (de-)allocations */
+class prog_scope_storage {
+public:
+   prog_scope_storage(void *mem_ctx, int n);
+   ~prog_scope_storage();
+   prog_scope * create(prog_scope *p, prog_scope_type type, int id,
+                       int lvl, int s_begin);
+private:
+   void *mem_ctx;
+   int current_slot;
+   prog_scope *storage;
+};
+
+class temp_comp_access {
+public:
+   temp_comp_access();
+   void record_read(int line, prog_scope *scope);
+   void record_write(int line, prog_scope *scope);
+   lifetime get_required_lifetime();
+private:
+   void propagate_lifetime_to_dominant_write_scope();
+
+   prog_scope *last_read_scope;
+   prog_scope *first_read_scope;
+   prog_scope *first_write_scope;
+   int first_write;
+   int last_read;
+   int last_write;
+   int first_read;
+   bool keep_for_full_loop;
+};
+
+class temp_access {
+public:
+   temp_access();
+   void record_read(int line, prog_scope *scope, int swizzle);
+   void record_write(int line, prog_scope *scope, int writemask);
+   lifetime get_required_lifetime();
+private:
+   void update_access_mask(int mask);
+
+   temp_comp_access comp[4];
+   int access_mask;
+   bool needs_component_tracking;
+};
+
+prog_scope_storage::prog_scope_storage(void *mc, int n):
+   mem_ctx(mc),
+   current_slot(0)
+{
+   storage = ralloc_array(mem_ctx, prog_scope, n);
+}
+
+prog_scope_storage::~prog_scope_storage()
+{
+   ralloc_free(storage);
+}
+
+prog_scope*
+prog_scope_storage::create(prog_scope *p, prog_scope_type type, int id,
+                           int lvl, int s_begin)
+{
+   storage[current_slot] = prog_scope(p, type, id, lvl, s_begin);
+   return &storage[current_slot++];
+}
+
+prog_scope::prog_scope(prog_scope *parent, prog_scope_type type, int id,
+                       int depth, int scope_begin):
+   scope_type(type),
+   scope_id(id),
+   scope_nesting_depth(depth),
+   scope_begin(scope_begin),
+   scope_end(-1),
+   break_loop_line(numeric_limits<int>::max()),
+   parent_scope(parent),
+   switch_reg(nullptr)
+{
+}
+
+prog_scope_type prog_scope::type() const
+{
+   return scope_type;
+}
+
+prog_scope *prog_scope::parent() const
+{
+   return parent_scope;
+}
+
+int prog_scope::nesting_depth() const
+{
+   return scope_nesting_depth;
+}
+
+bool prog_scope::is_loop() const
+{
+   return (scope_type == loop_body);
+}
+
+bool prog_scope::is_in_loop() const
+{
+   if (scope_type == loop_body)
+      return true;
+
+   if (parent_scope)
+      return parent_scope->is_in_loop();
+
+   return false;
+}
+
+bool prog_scope::is_conditional_in_loop() const
+{
+   return is_conditional() && is_in_loop();
+}
+
+const prog_scope *prog_scope::innermost_loop() const
+{
+   if (scope_type == loop_body)
+      return this;
+
+   if (parent_scope)
+      return parent_scope->innermost_loop();
+
+   return nullptr;
+}
+
+const prog_scope *prog_scope::outermost_loop() const
+{
+   const prog_scope *loop = nullptr;
+   const prog_scope *p = this;
+
+   do {
+      if (p->type() == loop_body)
+         loop = p;
+      p = p->parent();
+   } while (p);
+
+   return loop;
+}
+
+const prog_scope *prog_scope::enclosing_conditional() const
+{
+   if (is_conditional())
+      return this;
+
+   if (parent_scope)
+      return parent_scope->enclosing_conditional();
+
+   return nullptr;
+}
+
+bool prog_scope::contains_range_of(const prog_scope& other) const
+{
+   return (begin() <= other.begin()) && (end() >= other.end());
+}
+
+bool prog_scope::is_conditional() const
+{
+   return scope_type == if_branch ||
+         scope_type == else_branch ||
+         scope_type == switch_case_branch ||
+         scope_type == switch_default_branch;
+}
+
+const prog_scope *prog_scope::in_ifelse_scope() const
+{
+   if (scope_type == if_branch ||
+       scope_type == else_branch)
+      return this;
+
+   if (parent_scope)
+      return parent_scope->in_ifelse_scope();
+
+   return nullptr;
+}
+
+const st_src_reg *prog_scope::switch_register() const
+{
+   return switch_reg;
+}
+
+const prog_scope *prog_scope::in_switchcase_scope() const
+{
+   if (scope_type == switch_case_branch ||
+       scope_type == switch_default_branch)
+      return this;
+
+   if (parent_scope)
+      return parent_scope->in_switchcase_scope();
+
+   return nullptr;
+}
+
+bool prog_scope::break_is_for_switchcase() const
+{
+   if (scope_type == loop_body)
+      return false;
+
+   if (scope_type == switch_case_branch ||
+       scope_type == switch_default_branch ||
+       scope_type == switch_body)
+      return true;
+
+   if (parent_scope)
+      return parent_scope->break_is_for_switchcase();
+
+   return false;
+}
+
+int prog_scope::id() const
+{
+   return scope_id;
+}
+
+int prog_scope::begin() const
+{
+   return scope_begin;
+}
+
+int prog_scope::end() const
+{
+   return scope_end;
+}
+
+void prog_scope::set_end(int end)
+{
+   if (scope_end == -1)
+      scope_end = end;
+}
+
+void prog_scope::set_loop_break_line(int line)
+{
+   if (scope_type == loop_body) {
+      break_loop_line = MIN2(break_loop_line, line);
+   } else {
+      if (parent_scope)
+         parent()->set_loop_break_line(line);
+   }
+}
+
+int prog_scope::loop_break_line() const
+{
+   return break_loop_line;
+}
+
+temp_access::temp_access():
+   access_mask(0),
+   needs_component_tracking(false)
+{
+}
+
+void temp_access::update_access_mask(int mask)
+{
+   if (access_mask && access_mask != mask)
+      needs_component_tracking = true;
+   access_mask |= mask;
+}
+
+void temp_access::record_write(int line, prog_scope *scope, int writemask)
+{
+   update_access_mask(writemask);
+
+   if (writemask & WRITEMASK_X)
+      comp[0].record_write(line, scope);
+   if (writemask & WRITEMASK_Y)
+      comp[1].record_write(line, scope);
+   if (writemask & WRITEMASK_Z)
+      comp[2].record_write(line, scope);
+   if (writemask & WRITEMASK_W)
+      comp[3].record_write(line, scope);
+}
+
+void temp_access::record_read(int line, prog_scope *scope, int swizzle)
+{
+   int readmask = 0;
+   for (int idx = 0; idx < 4; ++idx) {
+      int swz = GET_SWZ(swizzle, idx);
+      readmask |= (1 << swz) & 0xF;
+   }
+   update_access_mask(readmask);
+
+   if (readmask & WRITEMASK_X)
+      comp[0].record_read(line, scope);
+   if (readmask & WRITEMASK_Y)
+      comp[1].record_read(line, scope);
+   if (readmask & WRITEMASK_Z)
+      comp[2].record_read(line, scope);
+   if (readmask & WRITEMASK_W)
+      comp[3].record_read(line, scope);
+}
+
+inline static lifetime make_lifetime(int b, int e)
+{
+   lifetime lt;
+   lt.begin = b;
+   lt.end = e;
+   return lt;
+}
+
+lifetime temp_access::get_required_lifetime()
+{
+   lifetime result = make_lifetime(-1, -1);
+
+   unsigned mask = access_mask;
+   while (mask) {
+      unsigned chan = u_bit_scan(&mask);
+      lifetime lt = comp[chan].get_required_lifetime();
+
+      if (lt.begin >= 0) {
+         if ((result.begin < 0) || (result.begin > lt.begin))
+            result.begin = lt.begin;
+      }
+
+      if (lt.end > result.end)
+         result.end = lt.end;
+
+      if (!needs_component_tracking)
+         break;
+   }
+   return result;
+}
+
+temp_comp_access::temp_comp_access():
+   last_read_scope(nullptr),
+   first_read_scope(nullptr),
+   first_write_scope(nullptr),
+   first_write(-1),
+   last_read(-1),
+   last_write(-1),
+   first_read(numeric_limits<int>::max())
+{
+}
+
+void temp_comp_access::record_read(int line, prog_scope *scope)
+{
+   last_read_scope = scope;
+   last_read = line;
+
+   if (first_read > line) {
+      first_read = line;
+      first_read_scope = scope;
+   }
+}
+
+void temp_comp_access::record_write(int line, prog_scope *scope)
+{
+   last_write = line;
+
+   if (first_write < 0) {
+      first_write = line;
+      first_write_scope = scope;
+   }
+}
+
+void temp_comp_access::propagate_lifetime_to_dominant_write_scope()
+{
+   first_write = first_write_scope->begin();
+   int lr = first_write_scope->end();
+
+   if (last_read < lr)
+      last_read = lr;
+}
+
+lifetime temp_comp_access::get_required_lifetime()
+{
+   bool keep_for_full_loop = false;
+
+   /* This register component is not used at all, or only read,
+    * mark it as unused and ignore it when renaming.
+    * glsl_to_tgsi_visitor::renumber_registers will take care of
+    * eliminating registers that are not written to.
+    */
+   if (last_write < 0)
+      return make_lifetime(-1, -1);
+
+   assert(first_write_scope);
+
+   /* Only written to, just make sure the register component is not
+    * reused in the range it is used to write to
+    */
+   if (!last_read_scope)
+      return make_lifetime(first_write, last_write + 1);
+
+   const prog_scope *enclosing_scope_first_read = first_read_scope;
+   const prog_scope *enclosing_scope_first_write = first_write_scope;
+
+   /* We read before writing in a loop
+    * hence the value must survive the loops
+    */
+   if ((first_read <= first_write) &&
+       first_read_scope->is_in_loop()) {
+      keep_for_full_loop = true;
+      enclosing_scope_first_read = first_read_scope->outermost_loop();
+   }
+
+   /* A conditional write within a nested loop must survive
+    * the outermost loop, but only if it is read outside
+    * the condition scope where we write.
+    */
+   const prog_scope *conditional = 
enclosing_scope_first_write->enclosing_conditional();
+   if (conditional && conditional->is_in_loop() &&
+       !conditional->contains_range_of(*last_read_scope)) {
+      keep_for_full_loop = true;
+      enclosing_scope_first_write = conditional->outermost_loop();
+   }
+
+   /* Evaluate the scope that is shared by all: required first write scope,
+    * required first read before write scope, and last read scope.
+    */
+   const prog_scope *enclosing_scope = enclosing_scope_first_read;
+   if (enclosing_scope_first_write->contains_range_of(*enclosing_scope))
+      enclosing_scope = enclosing_scope_first_write;
+
+   if (enclosing_scope_first_read->contains_range_of(*enclosing_scope))
+      enclosing_scope = enclosing_scope_first_read;
+
+   while (!enclosing_scope->contains_range_of(*enclosing_scope_first_write) ||
+          !enclosing_scope->contains_range_of(*last_read_scope)) {
+      enclosing_scope = enclosing_scope->parent();
+      assert(enclosing_scope);
+   }
+
+   /* Propagate the last read scope to the target scope */
+   while (enclosing_scope->nesting_depth() < last_read_scope->nesting_depth()) 
{
+      /* If the read is in a loop and we have to move up the scope we need to
+       * extend the life time to the end of this current loop because at this
+       * point we don't know whether the component was written before
+       * un-conditionally in the same loop.
+       */
+      if (last_read_scope->is_loop())
+         last_read = last_read_scope->end();
+
+      last_read_scope = last_read_scope->parent();
+   }
+
+   /* If the variable has to be kept for the whole loop, and we
+    * are currently in a loop, then propagate the life time.
+    */
+   if (keep_for_full_loop && first_write_scope->is_loop())
+      propagate_lifetime_to_dominant_write_scope();
+
+   /* Propagate the first_dominant_write scope to the target scope */
+   while (enclosing_scope->nesting_depth() < 
first_write_scope->nesting_depth()) {
+      /* Propagate lifetime if there was a break in a loop and the write was
+       * after the break inside that loop. Note, that this is only needed if
+       * we move up in the scopes.
+       */
+      if (first_write_scope->loop_break_line() < first_write) {
+         keep_for_full_loop = true;
+         propagate_lifetime_to_dominant_write_scope();
+      }
+
+      first_write_scope = first_write_scope->parent();
+
+      /* Propagte lifetime if we are now in a loop */
+      if (keep_for_full_loop && first_write_scope->is_loop())
+          propagate_lifetime_to_dominant_write_scope();
+   }
+
+   /* The last write past the last read is dead code, but we have to
+    * ensure that the component is not reused too early, hence extend the
+    * lifetime past the last write.
+    */
+   if (last_write >= last_read)
+      last_read = last_write + 1;
+
+   /* Here we are at the same scope, all is resolved */
+   return make_lifetime(first_write, last_read);
+}
+
+}
+
+#ifndef NDEBUG
+/* Function used for debugging. */
+static void dump_instruction(int line, prog_scope *scope,
+                             const glsl_to_tgsi_instruction& inst);
+#endif
+
+/* Scan the program and estimate the required register life times.
+ * The array lifetimes must be pre-allocated
+ */
+void
+get_temp_registers_required_lifetimes(void *mem_ctx, exec_list *instructions,
+                                      int ntemps, struct lifetime *lifetimes)
+{
+   int line = 0;
+   int loop_id = 0;
+   int if_id = 0;
+   int switch_id = 0;
+   bool is_at_end = false;
+   int n_scopes = 1;
+
+   /* Count scopes to allocate the needed space without the need for
+    * re-allocation
+    */
+   foreach_in_list(glsl_to_tgsi_instruction, inst, instructions) {
+      if (inst->op == TGSI_OPCODE_BGNLOOP ||
+          inst->op == TGSI_OPCODE_SWITCH ||
+          inst->op == TGSI_OPCODE_CASE ||
+          inst->op == TGSI_OPCODE_IF ||
+          inst->op == TGSI_OPCODE_UIF ||
+          inst->op == TGSI_OPCODE_ELSE ||
+          inst->op == TGSI_OPCODE_DEFAULT)
+         ++n_scopes;
+   }
+
+   prog_scope_storage scopes(mem_ctx, n_scopes);
+   temp_access *acc = new temp_access[ntemps];
+
+   prog_scope *cur_scope = scopes.create(nullptr, outer_scope, 0, 0, line);
+
+   RENAME_DEBUG(cerr << "========= Begin shader ============\n");
+
+   foreach_in_list(glsl_to_tgsi_instruction, inst, instructions) {
+      if (is_at_end) {
+         assert(!"GLSL_TO_TGSI: shader has instructions past end marker");
+         break;
+      }
+
+      RENAME_DEBUG(dump_instruction(line, cur_scope, *inst));
+
+      switch (inst->op) {
+      case TGSI_OPCODE_BGNLOOP: {
+         cur_scope = scopes.create(cur_scope, loop_body, loop_id++,
+                                   cur_scope->nesting_depth() + 1, line);
+         break;
+      }
+      case TGSI_OPCODE_ENDLOOP: {
+         cur_scope->set_end(line);
+         cur_scope = cur_scope->parent();
+         assert(cur_scope);
+         break;
+      }
+      case TGSI_OPCODE_IF:
+      case TGSI_OPCODE_UIF: {
+         assert(num_inst_src_regs(inst) == 1);
+         const st_src_reg& src = inst->src[0];
+         if (src.file == PROGRAM_TEMPORARY)
+            acc[src.index].record_read(line, cur_scope, src.swizzle);
+         cur_scope = scopes.create(cur_scope, if_branch, if_id++,
+                                   cur_scope->nesting_depth() + 1, line + 1);
+         break;
+      }
+      case TGSI_OPCODE_ELSE: {
+         assert(cur_scope->type() == if_branch);
+         cur_scope->set_end(line - 1);
+         cur_scope = scopes.create(cur_scope->parent(), else_branch,
+                                   cur_scope->id(), cur_scope->nesting_depth(),
+                                   line + 1);
+         break;
+      }
+      case TGSI_OPCODE_END: {
+         cur_scope->set_end(line);
+         is_at_end = true;
+         break;
+      }
+      case TGSI_OPCODE_ENDIF: {
+         cur_scope->set_end(line - 1);
+         cur_scope = cur_scope->parent();
+         assert(cur_scope);
+         break;
+      }
+      case TGSI_OPCODE_SWITCH: {
+         assert(num_inst_src_regs(inst) == 1);
+         const st_src_reg& src = inst->src[0];
+         prog_scope *scope = scopes.create(cur_scope, switch_body, switch_id++,
+                                           cur_scope->nesting_depth() + 1, 
line);
+         /* We record the read only for the SWITCH statement itself, like it
+          * is used by the only consumer of TGSI_OPCODE_SWITCH in tgsi_exec.c.
+          */
+         if (src.file == PROGRAM_TEMPORARY)
+            acc[src.index].record_read(line, cur_scope, src.swizzle);
+         cur_scope = scope;
+         break;
+      }
+      case TGSI_OPCODE_ENDSWITCH: {
+         cur_scope->set_end(line - 1);
+         /* Remove the case level, it might not have been
+          * closed with a break.
+          */
+         if (cur_scope->type() != switch_body)
+            cur_scope = cur_scope->parent();
+
+         cur_scope = cur_scope->parent();
+         assert(cur_scope);
+         break;
+      }
+      case TGSI_OPCODE_CASE: {
+         /* Take care of tracking the registers. */
+         prog_scope *switch_scope = cur_scope->type() == switch_body ?
+                                       cur_scope : cur_scope->parent();
+
+         assert(num_inst_src_regs(inst) == 1);
+         const st_src_reg& src = inst->src[0];
+         if (src.file == PROGRAM_TEMPORARY)
+            acc[src.index].record_read(line, switch_scope, src.swizzle);
+
+         /* Fall through to allocate the scope. */
+      }
+      case TGSI_OPCODE_DEFAULT: {
+         prog_scope_type t = inst->op == TGSI_OPCODE_CASE ? switch_case_branch
+                                                       : switch_default_branch;
+         prog_scope *switch_scope = (cur_scope->type() == switch_body) ?
+            cur_scope : cur_scope->parent();
+         assert(switch_scope->type() == switch_body);
+         prog_scope *scope = scopes.create(switch_scope, t,
+                                           switch_scope->id(),
+                                           switch_scope->nesting_depth() + 1,
+                                           line);
+         /* Previous case falls through, so scope was not yet closed. */
+         if ((cur_scope != switch_scope) && (cur_scope->end() == -1))
+            cur_scope->set_end(line - 1);
+         cur_scope = scope;
+         break;
+      }
+      case TGSI_OPCODE_BRK: {
+         if (cur_scope->break_is_for_switchcase()) {
+            cur_scope->set_end(line - 1);
+         } else {
+            cur_scope->set_loop_break_line(line);
+         }
+         break;
+      }
+      default: {
+         for (unsigned j = 0; j < num_inst_src_regs(inst); j++) {
+            const st_src_reg& src = inst->src[j];
+            if (src.file == PROGRAM_TEMPORARY)
+               acc[src.index].record_read(line, cur_scope, src.swizzle);
+         }
+         for (unsigned j = 0; j < inst->tex_offset_num_offset; j++) {
+            const st_src_reg& src = inst->tex_offsets[j];
+            if (src.file == PROGRAM_TEMPORARY)
+               acc[src.index].record_read(line, cur_scope, src.swizzle);
+         }
+         for (unsigned j = 0; j < num_inst_dst_regs(inst); j++) {
+            const st_dst_reg& dst = inst->dst[j];
+            if (dst.file == PROGRAM_TEMPORARY)
+               acc[dst.index].record_write(line, cur_scope, dst.writemask);
+         }
+      }
+      }
+      ++line;
+   }
+
+   RENAME_DEBUG(cerr << "==================================\n\n");
+
+   /* Make sure last scope is closed, even though no
+    * TGSI_OPCODE_END was given.
+    */
+   if (cur_scope->end() < 0)
+      cur_scope->set_end(line - 1);
+
+   RENAME_DEBUG(cerr << "========= lifetimes ==============\n");
+   for(int i = 0; i < ntemps; ++i) {
+      RENAME_DEBUG(cerr << setw(4) << i);
+      lifetimes[i] = acc[i].get_required_lifetime();
+      RENAME_DEBUG(cerr << ": [" << lifetimes[i].begin << ", "
+                        << lifetimes[i].end << "]\n");
+   }
+   RENAME_DEBUG(cerr << "==================================\n\n");
+
+   delete[] acc;
+}
+
+/* Code below used for debugging */
+#ifndef NDEBUG
+static const char swizzle_txt[] = "xyzw";
+
+static const char *tgsi_file_names[PROGRAM_FILE_MAX] =  {
+   "TEMP",  "ARRAY",   "IN", "OUT", "STATE", "CONST",
+   "UNIFORM",  "WO", "ADDR", "SAMPLER",  "SV", "UNDEF",
+   "IMM", "BUF",  "MEM",  "IMAGE"
+};
+
+static
+void dump_instruction(int line, prog_scope *scope,
+                      const glsl_to_tgsi_instruction& inst)
+{
+   const struct tgsi_opcode_info *info = tgsi_get_opcode_info(inst.op);
+
+   int indent = scope->nesting_depth();
+   if ((scope->type() == switch_case_branch ||
+        scope->type() == switch_default_branch) &&
+       (info->opcode == TGSI_OPCODE_CASE ||
+        info->opcode == TGSI_OPCODE_DEFAULT))
+      --indent;
+
+   if (info->opcode == TGSI_OPCODE_ENDIF ||
+       info->opcode == TGSI_OPCODE_ELSE ||
+       info->opcode == TGSI_OPCODE_ENDLOOP ||
+       info->opcode == TGSI_OPCODE_ENDSWITCH)
+      --indent;
+
+   cerr << setw(4) << line << ": ";
+   for (int i = 0; i < indent; ++i)
+      cerr << "    ";
+   cerr << tgsi_get_opcode_name(info->opcode) << " ";
+
+   bool has_operators = false;
+   for (unsigned j = 0; j < num_inst_dst_regs(&inst); j++) {
+      has_operators = true;
+      if (j > 0)
+         cerr << ", ";
+
+      const st_dst_reg& dst = inst.dst[j];
+      cerr << tgsi_file_names[dst.file]
+           << "[" << dst.index << "]";
+      if (dst.writemask != TGSI_WRITEMASK_XYZW) {
+         cerr << ".";
+         if (dst.writemask & TGSI_WRITEMASK_X) cerr << "x";
+         if (dst.writemask & TGSI_WRITEMASK_Y) cerr << "y";
+         if (dst.writemask & TGSI_WRITEMASK_Z) cerr << "z";
+         if (dst.writemask & TGSI_WRITEMASK_W) cerr << "w";
+      }
+   }
+   if (has_operators)
+      cerr << " := ";
+
+   for (unsigned j = 0; j < num_inst_src_regs(&inst); j++) {
+      if (j > 0)
+         cerr << ", ";
+
+      const st_src_reg& src = inst.src[j];
+      cerr << tgsi_file_names[src.file]
+           << "[" << src.index << "]";
+      if (src.swizzle != SWIZZLE_XYZW) {
+         cerr << ".";
+         for (int idx = 0; idx < 4; ++idx) {
+            int swz = GET_SWZ(src.swizzle, idx);
+            if (swz < 4) {
+               cerr << swizzle_txt[swz];
+            }
+         }
+      }
+   }
+
+   if (inst.tex_offset_num_offset > 0) {
+      cerr << ", TEXOFS: ";
+      for (unsigned j = 0; j < inst.tex_offset_num_offset; j++) {
+         if (j > 0)
+            cerr << ", ";
+
+         const st_src_reg& src = inst.tex_offsets[j];
+         cerr << tgsi_file_names[src.file]
+               << "[" << src.index << "]";
+         if (src.swizzle != SWIZZLE_XYZW) {
+            cerr << ".";
+            for (int idx = 0; idx < 4; ++idx) {
+               int swz = GET_SWZ(src.swizzle, idx);
+               if (swz < 4) {
+                  cerr << swizzle_txt[swz];
+               }
+            }
+         }
+      }
+   }
+   cerr << "\n";
+}
+#endif
\ No newline at end of file
diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi_temprename.h 
b/src/mesa/state_tracker/st_glsl_to_tgsi_temprename.h
new file mode 100644
index 0000000000..44998cca97
--- /dev/null
+++ b/src/mesa/state_tracker/st_glsl_to_tgsi_temprename.h
@@ -0,0 +1,55 @@
+/*
+ * Copyright © 2017 Gert Wollny
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#ifndef MESA_GLSL_TO_TGSI_TEMPRENAME_H
+#define MESA_GLSL_TO_TGSI_TEMPRENAME_H
+
+#include "st_glsl_to_tgsi_private.h"
+
+/** Storage to record the required life time of a temporary register
+ * begin == end == -1 indicates that the register can be reused without
+ * limitations. Otherwise, "begin" indicates the first instruction in which
+ * a write operation may target this temporary, and end indicates the
+ * last instruction in which a value can be read from this temporary.
+ * Hence, a register R2 can be merged with a register R1 if R1.end <= R2.begin.
+ */
+struct lifetime {
+   int begin;
+   int end;
+};
+
+/** Evaluates the required life times of temporary registers in a shader
+ * @param[in] mem_ctx a memory context that can be used with the ralloc_* 
functions
+ * @param[in] instructions the shader to be anlzyed
+ * @param[in] ntemps number of temporaries reserved for this shader
+ * @param[in,out] lifetimes memory location to store the estimated required
+ *   life times for each temporary register. The parameter must point to
+ *   allocated memory that can hold ntemps lifetime structures. On output
+ *   the life times contains the life times for the registers with the
+ *   exception of TEMP[0].
+ */
+void
+get_temp_registers_required_lifetimes(void *mem_ctx, exec_list *instructions,
+                                      int ntemps, struct lifetime *lifetimes);
+
+#endif
\ No newline at end of file
-- 
2.13.0

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