[SPIR-V] Fix BB ordering & register lifetime (#111026)

The "topological" sorting was behaving incorrectly in some cases: 
the exit of a loop could have a lower rank than a node in the loop.
This causes issues when structurizing some patterns, and also codegen
issues as we could generate BBs in the incorrect order in regard to the
SPIR-V spec.

Fixing this ordering alone broke other parts of the structurizer, which
by luck worked. Had to fix those.

Added more test cases, especially to test basic patterns.

I also needed to tweak/disable some tests for 2 reasons:
 - SPIR-V now required reg2mem/mem2reg to run. Meaning dead stores
   are optimized away. Some tests require tweaks to avoid having the
   whole function removed.
 - Mem2Reg will generate variable & load/stores. This generates
   G_BITCAST in several cases. And there is currently something wrong
   we do with G_BITCAST which causes MIR verifier to complain.
   Until this is resolved, I disabled -verify-machineinstrs flag on
   those tests.

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Signed-off-by: Nathan Gauër <brioche@google.com>

0 files changed, 0 insertions, 0 deletions