| Issue |
134575
|
| Summary |
[DirectX] Strip loop metadata that will trip up the validator when generating DXIL
|
| Labels |
backend:DirectX
|
| Assignees |
|
| Reporter |
bogner
|
Compiling [particle_life](https://github.com/damyanp/dplife/blob/main/src/particle_life/particle_life.hlsl) with clang fails the validator with an error about `llvm.loop.mustprogress` being invalid. This particular metadata node is newer than the version of LLVM that DXIL is based off of, so it makes sense that it's a problem.
We need to strip metadata that the DXIL validator (and thus, potentially, DXIL drivers) isn't aware of. This may be as simple as the following:
```diff
--- a/llvm/lib/Target/DirectX/DXILPrepare.cpp
+++ b/llvm/lib/Target/DirectX/DXILPrepare.cpp
@@ -189,6 +189,26 @@ public:
for (auto &BB : F) {
IRBuilder<> Builder(&BB);
for (auto &I : make_early_inc_range(BB)) {
+
+ // TODO: Audit this list - is it enough? Too much?
+ static unsigned DXILCompatibleMDs[] = {
+ LLVMContext::MD_dbg,
+ LLVMContext::MD_tbaa,
+ LLVMContext::MD_prof,
+ LLVMContext::MD_fpmath,
+ LLVMContext::MD_range,
+ LLVMContext::MD_tbaa_struct,
+ LLVMContext::MD_invariant_load,
+ LLVMContext::MD_alias_scope,
+ LLVMContext::MD_noalias,
+ LLVMContext::MD_nontemporal,
+ LLVMContext::MD_mem_parallel_loop_access,
+ LLVMContext::MD_nonnull,
+ LLVMContext::MD_dereferenceable,
+ LLVMContext::MD_dereferenceable_or_null,
+ };
+ I.dropUnknownNonDebugMetadata(DXILCompatibleMDs);
+
if (I.getOpcode() == Instruction::FNeg) {
Builder.SetInsertPoint(&I);
Value *In = I.getOperand(0);
```
Here, we strip anything that isn't listed in DXC's set of pinned metadata names in `LLVMContext.h`. We need to determine if this is the right granularity.
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