glsl/linker: Safely generate mask of possible locations

If MaxAttribs were ever raised to 32, undefined behavior would occur.
We had already gone to the effort (albeit incorrectly) handle this in
one case, so fix them all.

CID: 1369628
Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Alejandro Piñeiro <apinheiro@igalia.com>

diff --git a/src/compiler/glsl/linker.cpp b/src/compiler/glsl/linker.cpp
index d1f10eeecd86ba59deacc060608678988b560b1c..86ef5831b750d8776bbcde586e5338a7e78b38ca 100644 (file)
--- a/src/compiler/glsl/linker.cpp
+++ b/src/compiler/glsl/linker.cpp
@@ -2552,6 +2552,8 @@ find_available_slots(unsigned used_mask, unsigned needed_count)
 }
 
 
+#define SAFE_MASK_FROM_INDEX(i) (((i) >= 32) ? ~0 : ((1 << (i)) - 1))
+
 /**
  * Assign locations for either VS inputs or FS outputs
  *
@@ -2582,8 +2584,7 @@ assign_attribute_or_color_locations(void *mem_ctx,
 
    /* Mark invalid locations as being used.
     */
-   unsigned used_locations = (max_index >= 32)
-      ? 0 : ~((1 << max_index) - 1);
+   unsigned used_locations = ~SAFE_MASK_FROM_INDEX(max_index);
    unsigned double_storage_locations = 0;
 
    assert((target_index == MESA_SHADER_VERTEX)
@@ -2936,7 +2937,7 @@ assign_attribute_or_color_locations(void *mem_ctx,
 
    if (target_index == MESA_SHADER_VERTEX) {
       unsigned total_attribs_size =
-         _mesa_bitcount(used_locations & ((1 << max_index) - 1)) +
+         _mesa_bitcount(used_locations & SAFE_MASK_FROM_INDEX(max_index)) +
          _mesa_bitcount(double_storage_locations);
       if (total_attribs_size > max_index) {
          linker_error(prog,
@@ -3000,7 +3001,7 @@ assign_attribute_or_color_locations(void *mem_ctx,
     */
    if (target_index == MESA_SHADER_VERTEX) {
       unsigned total_attribs_size =
-         _mesa_bitcount(used_locations & ((1 << max_index) - 1)) +
+         _mesa_bitcount(used_locations & SAFE_MASK_FROM_INDEX(max_index)) +
          _mesa_bitcount(double_storage_locations);
       if (total_attribs_size > max_index) {
          linker_error(prog,