llvm-project/llvm/test/Transforms/StructurizeCFG
Nicolai Haehnle eb7311ffb1 StructurizeCFG: Test for branch divergence correctly
Fixes cases like the new test @nonuniform. In that test, %cc itself
is a uniform value; however, when reading it after the end of the loop in
basic block %if, its value is effectively non-uniform, so the branch is
non-uniform.

This problem was encountered in
https://bugs.freedesktop.org/show_bug.cgi?id=103743; however, this change
in itself is not sufficient to fix that bug, as there is another issue
in the AMDGPU backend.

As discovered after committing an earlier version of this change, this
exposes a subtle interaction between this pass and DivergenceAnalysis:
since we remove and re-create branch instructions, we can no longer rely
on DivergenceAnalysis for branches in subregions that were already
processed by the pass.

Explicitly remove branch instructions from DivergenceAnalysis to
avoid dangling pointers as a matter of defensive programming, and
change how we detect non-uniform subregions.

Change-Id: I32bbffece4a32f686fab54964dae1a5dd72949d4

Differential Revision: https://reviews.llvm.org/D43743

llvm-svn: 329165
2018-04-04 10:58:15 +00:00
..
AMDGPU StructurizeCFG: Test for branch divergence correctly 2018-04-04 10:58:15 +00:00
branch-on-argument.ll [Dominators] Include infinite loops in PostDominatorTree 2017-08-15 18:14:57 +00:00
bug36015.ll Revert r321751, "StructurizeCFG: Fix broken backedge detection" 2018-01-24 18:02:05 +00:00
invert-constantexpr.ll [StructurizeCFG] fix test to be independent of FP undef 2018-03-08 17:13:57 +00:00
loop-multiple-exits.ll
nested-loop-order.ll Revert r321751, "StructurizeCFG: Fix broken backedge detection" 2018-01-24 18:02:05 +00:00
no-branch-to-entry.ll [Dominators] Include infinite loops in PostDominatorTree 2017-08-15 18:14:57 +00:00
one-loop-multiple-backedges.ll Revert "StructurizeCFG: Directly invert cmp instructions" 2017-04-24 20:25:01 +00:00
post-order-traversal-bug.ll Revert "StructurizeCFG: Directly invert cmp instructions" 2017-04-24 20:25:01 +00:00
rebuild-ssa-infinite-loop.ll AMDGPU: Remove llvm.SI.vs.load.input 2017-04-03 21:45:13 +00:00
switch.ll