Shader crashes on iPad 2

iPad2Crash.shader

/* Both vertex & fragment shaders (define VERTEX or FRAGMENT before loading each).

Looks like crash caused by indexing into uniform array. Crash goes away if:
1) replacing array indices [i] with actual constants (0 & 1) and removing index math, OR
2) removing unrelated ALU ops (' - viewpos'), OR
3) rewriting shader to not be unrolled; using for (int i = 0; i < 2; ++i) loop.

Shader by itself does not make any practical sense, I just simplified a more complex shader to smallest that still crashes.

Crashes inside PVR driver on iPad 2, iOS 4.3:
#0	0x30efeb92 in UpdateShaderParams
#1	0x30eff5f2 in glrUpdateCtxSysVertexProgram
#2	0x30ef7b16 in glrUpdateVertexProgramInline
#3	0x30ef7cd8 in glrLoadCurrentPipelinePrograms
#4	0x30f00552 in gldUpdateDispatch
#5	0x35f77bb2 in gleDoDrawDispatchCore
#6	0x35efe5d2 in glDrawArrays_IMM_Exec
#7	0x30ea8ee2 in glDrawArrays

Does NOT crash on iPhone 3Gs (iOS 4.3).
*/

#ifdef VERTEX
uniform mat4 glstate_matrix_mvp;
uniform mat4 glstate_matrix_modelview0;

attribute vec4 _glesVertex;

uniform vec4 uniformPositions[4];
uniform vec4 uniformColors[4];

varying lowp vec4 varColor;

void main ()
{
  highp vec3 viewpos = (glstate_matrix_modelview0 * _glesVertex).xyz;
  highp vec3 col = vec3(0.0);

  int i = 0;
  
  col += uniformColors[i].xyz * length(uniformPositions[i].xyz - viewpos);
  ++i;
  
  col += uniformColors[i].xyz * length(uniformPositions[i].xyz - viewpos);
  ++i;
  
  gl_Position = glstate_matrix_mvp * _glesVertex;
  varColor = vec4(col, 1.0);
}
#endif

#ifdef FRAGMENT
varying lowp vec4 varColor;
void main ()
{
  gl_FragColor = varColor + vec4(0.7,0.2,0.1,0.0);
}
#endif