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https://github.com/KhronosGroup/SPIRV-Tools
synced 2024-10-19 11:30:15 +00:00
089d716d25
Fix dangling phi bug from loop-unroll When unrolling the following loop: ``` %const0 = OpConstant ... %const1 = OpConstant ... ... %LoopHeader = OpLabel %phi0 = OpPhi %float %const0 %PreHeader %phi1 %Latch %phi1 = OpPhi %float %const1 %PreHeader %x %Latch ... %LoopBody = OpLabel %x = OpFSub %float %phi1 %phi0 ... ``` the loop-unroll pass sets the value of `%phi0` as `%phi1` for the second copy of the loop body. For example, the second copy of `%x = OpFSub %float %phi1 %phi0` will be `%y = OpFSub %float %x %phi1`. Since all phi instructions for inductions will are removed after the loop unrolling, `%phi1` will be a dead dangling phi. It happens only for the phi values of the first loop iteration. Replacing those dangling phis with their initial values fixes this issue. For example, the second copy of `%x = OpFSub %float %phi1 %phi0` should be `%y = OpFSub %float %x %const1` because the value of `%phi1` from the first loop iteration is `%const1`. |
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| .. | ||
| CMakeLists.txt | ||
| dependence_analysis_helpers.cpp | ||
| dependence_analysis.cpp | ||
| fusion_compatibility.cpp | ||
| fusion_illegal.cpp | ||
| fusion_legal.cpp | ||
| fusion_pass.cpp | ||
| hoist_all_loop_types.cpp | ||
| hoist_double_nested_loops.cpp | ||
| hoist_from_independent_loops.cpp | ||
| hoist_simple_case.cpp | ||
| hoist_single_nested_loops.cpp | ||
| hoist_without_preheader.cpp | ||
| lcssa.cpp | ||
| loop_descriptions.cpp | ||
| loop_fission.cpp | ||
| nested_loops.cpp | ||
| pch_test_opt_loop.cpp | ||
| pch_test_opt_loop.h | ||
| peeling_pass.cpp | ||
| peeling.cpp | ||
| unroll_assumptions.cpp | ||
| unroll_simple.cpp | ||
| unswitch.cpp | ||