| Issue |
120630
|
| Summary |
[DirectX] Transform fast math flags to LLVM 3.7 for bitcode writer
|
| Labels |
backend:DirectX
|
| Assignees |
|
| Reporter |
llvm-beanz
|
The DXIL bitcode writer is currently encoding modern LLVM fast math flags instead of LLVM 3.7's equivalent. The patch below is probably a starting point, but is likely not everything that needs to change to address this problem.
```diff
diff --git a/llvm/lib/Target/DirectX/DXILWriter/DXILBitcodeWriter.cpp b/llvm/lib/Target/DirectX/DXILWriter/DXILBitcodeWriter.cpp
index 45aadac86194..4ea31dde3e00 100644
--- a/llvm/lib/Target/DirectX/DXILWriter/DXILBitcodeWriter.cpp
+++ b/llvm/lib/Target/DirectX/DXILWriter/DXILBitcodeWriter.cpp
@@ -749,20 +749,14 @@ uint64_t DXILBitcodeWriter::getOptimizationFlags(const Value *V) {
if (PEO->isExact())
Flags |= 1 << bitc::PEO_EXACT;
} else if (const auto *FPMO = dyn_cast<FPMathOperator>(V)) {
- if (FPMO->hasAllowReassoc())
- Flags |= bitc::AllowReassoc;
+ if (FPMO->hasAllowReassoc() || FPMO->hasAllowContract())
+ Flags |= bitc::UnsafeAlgebra;
if (FPMO->hasNoNaNs())
Flags |= bitc::NoNaNs;
if (FPMO->hasNoInfs())
Flags |= bitc::NoInfs;
if (FPMO->hasNoSignedZeros())
Flags |= bitc::NoSignedZeros;
- if (FPMO->hasAllowReciprocal())
- Flags |= bitc::AllowReciprocal;
- if (FPMO->hasAllowContract())
- Flags |= bitc::AllowContract;
- if (FPMO->hasApproxFunc())
- Flags |= bitc::ApproxFunc;
}
return Flags;
```
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