cbalint13 commented on code in PR #18586:
URL: https://github.com/apache/tvm/pull/18586#discussion_r2617613861
##########
src/target/llvm/codegen_aarch64.cc:
##########
@@ -59,9 +59,11 @@ void CodeGenAArch64::SetTargetAttributes(llvm::Function*
func) {
// Add vscale_range() function attribute when appropriate.
if (llvm_target_->TargetHasCPUFeature("sve") ||
llvm_target_->TargetHasCPUFeature("sme")) {
auto kVScaleValues = arith::GetVScaleValues(Target::Current());
- unsigned int max_val = *std::max_element(kVScaleValues.begin(),
kVScaleValues.end());
- func->addFnAttr(
- llvm::Attribute::getWithVScaleRangeArgs(*llvm_target_->GetContext(),
1, max_val));
+ if (!kVScaleValues.empty()) {
Review Comment:
It would be fine to protect this way, but we will miss the origin of issue.
My concern is that if we have SVE/SME isa presence (deduced from valid
target) why the list is empty !?
For a proper fix, I would be curious what is the string value of
```target``` and what value have ```vector_width``` .
Here is the generator part responsible with population, missing the
```vector_width``` (zero) will **not populate**:
https://github.com/apache/tvm/blob/6248b5db43505fbcfb13cc289d11877d5d2649e8/src/arith/scalable_expression.cc#L106-L123
---
How ```vector_width``` is populated:
* I am afraid that TVM fails to pickup proper ```vector_width``` during
initial parsing of arch properties based on target provided, the **initial
default value** population is happening here:
https://github.com/apache/tvm/blob/6248b5db43505fbcfb13cc289d11877d5d2649e8/src/target/llvm/llvm_instance.cc#L913
* VecWidth default may be **later overriden** based on vector ISA presence
and properties, the riscv case is more complex:
https://github.com/apache/tvm/blob/6248b5db43505fbcfb13cc289d11877d5d2649e8/src/target/llvm/llvm_instance.cc#L305
----
If could help me with these two info I can come up with a proper fix.
I could also go the long way to test it on arm machine but then I need a
clear reproducer case.
Thanks @mshr-h !
LATER EDIT:
I updated (edit) my comments here in order to get a clean view.
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