Propagate OpLine to all applied instructions in spirv-opt (#3951)

Based on the OpLine spec, an OpLine instruction must be applied to
the instructions physically following it up to the first occurrence
of the next end of block, the next OpLine instruction, or the next
OpNoLine instruction.

```
OpLine %file 0 0
OpNoLine
OpLine %file 1 1
OpStore %foo %int_1
%value = OpLoad %int %foo
OpLine %file 2 2
```

For the above code, the current spirv-opt keeps three line
instructions `OpLine %file 0 0`, `OpNoLine`, and `OpLine %file 1 1`
in `std::vector<Instruction> dbg_line_insts_` of Instruction class
for `OpStore %foo %int_1`. It does not put any line instruction to
`std::vector<Instruction> dbg_line_insts_` of
`%value = OpLoad %int %foo` even though `OpLine %file 1 1` must be
applied to `%value = OpLoad %int %foo` based on the spec.

This results in the missing line information for
`%value = OpLoad %int %foo` while each spirv-opt pass optimizes the
code. We have to put `OpLine %file 1 1` to
`std::vector<Instruction> dbg_line_insts_` of
both `%value = OpLoad %int %foo` and `OpStore %foo %int_1`.

This commit conducts the line instruction propagation and skips
emitting the eliminated line instructions at the end, which are the same
with PropagateLineInfoPass and RedundantLineInfoElimPass. This
commit removes PropagateLineInfoPass and RedundantLineInfoElimPass.

KhronosGroup/glslang#2440 is a related PR that stop using
PropagateLineInfoPass and RedundantLineInfoElimPass from glslang.
When the code in this PR applied, the glslang tests will pass.

1 files changed, 0 insertions, 24 deletions

diff --git a/include/spirv-tools/optimizer.hpp b/include/spirv-tools/optimizer.hpp
index d89d3b6fc..7f993cc3a 100644
--- a/include/spirv-tools/optimizer.hpp
+++ b/include/spirv-tools/optimizer.hpp
@@ -536,30 +536,6 @@ Optimizer::PassToken CreateDeadInsertElimPass();
 // eliminated with standard dead code elimination.
 Optimizer::PassToken CreateAggressiveDCEPass();
 
-// Create line propagation pass
-// This pass propagates line information based on the rules for OpLine and
-// OpNoline and clones an appropriate line instruction into every instruction
-// which does not already have debug line instructions.
-//
-// This pass is intended to maximize preservation of source line information
-// through passes which delete, move and clone instructions. Ideally it should
-// be run before any such pass. It is a bookend pass with EliminateDeadLines
-// which can be used to remove redundant line instructions at the end of a
-// run of such passes and reduce final output file size.
-Optimizer::PassToken CreatePropagateLineInfoPass();
-
-// Create dead line elimination pass
-// This pass eliminates redundant line instructions based on the rules for
-// OpLine and OpNoline. Its main purpose is to reduce the size of the file
-// need to store the SPIR-V without losing line information.
-//
-// This is a bookend pass with PropagateLines which attaches line instructions
-// to every instruction to preserve line information during passes which
-// delete, move and clone instructions. DeadLineElim should be run after
-// PropagateLines and all such subsequent passes. Normally it would be one
-// of the last passes to be run.
-Optimizer::PassToken CreateRedundantLineInfoElimPass();
-
 // Creates a compact ids pass.
 // The pass remaps result ids to a compact and gapless range starting from %1.
 Optimizer::PassToken CreateCompactIdsPass();