i915: Fail without crashing if a Mesa IR program uses too many registers

This can only happen in GLSL shaders because assembly shaders that use
too many temps are rejected by core Mesa.  It is easiest to make this
happen with shaders that contain flow-control that could not be lowered.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Eric Anholt <eric@anholt.net>

diff --git a/src/mesa/drivers/dri/i915/i915_fragprog.c b/src/mesa/drivers/dri/i915/i915_fragprog.c
index 6e1d709..32050ce 100644 (file)
--- a/src/mesa/drivers/dri/i915/i915_fragprog.c
+++ b/src/mesa/drivers/dri/i915/i915_fragprog.c
@@ -303,7 +303,7 @@ do {                                                                        \
 /* 
  * TODO: consider moving this into core 
  */
-static void calc_live_regs( struct i915_fragment_program *p )
+static bool calc_live_regs( struct i915_fragment_program *p )
 {
     const struct gl_fragment_program *program = &p->FragProg;
     GLuint regsUsed = 0xffff0000;
@@ -317,6 +317,9 @@ static void calc_live_regs( struct i915_fragment_program *p )
 
         /* Register is written to: unmark as live for this and preceeding ops */ 
         if (inst->DstReg.File == PROGRAM_TEMPORARY) {
+           if (inst->DstReg.Index > 16)
+              return false;
+
             live_components[inst->DstReg.Index] &= ~inst->DstReg.WriteMask;
             if (live_components[inst->DstReg.Index] == 0)
                 regsUsed &= ~(1 << inst->DstReg.Index);
@@ -327,6 +330,9 @@ static void calc_live_regs( struct i915_fragment_program *p )
             if (inst->SrcReg[a].File == PROGRAM_TEMPORARY) {
                 unsigned c;
 
+               if (inst->SrcReg[a].Index > 16)
+                  return false;
+
                 regsUsed |= 1 << inst->SrcReg[a].Index;
 
                 for (c = 0; c < 4; c++) {
@@ -340,6 +346,8 @@ static void calc_live_regs( struct i915_fragment_program *p )
 
         p->usedRegs[i] = regsUsed;
     }
+
+    return true;
 }
 
 static GLuint get_live_regs( struct i915_fragment_program *p, 
@@ -394,7 +402,10 @@ upload_program(struct i915_fragment_program *p)
 
    /* Not always needed:
     */
-   calc_live_regs(p);
+   if (!calc_live_regs(p)) {
+      i915_program_error(p, "Could not allocate registers");
+      return;
+   }
 
    while (1) {
       GLuint src0, src1, src2, flags;