[AsmWriter] Combine IsConstant and GetConstant (NFCI)

[jph-13]

There was an assert in GetConstant checked if Bound is constant. However, GetConstant was only called when IsConstant==true.

This refactor attempts to get rid of the assert by combining GetConstant and IsContstant.

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[llvmbot]

@llvm/pr-subscribers-llvm-ir

Author: JP Hafer (jph-13)

Changes

The assert in GetConstant checks if Bound is constant. However, GetConstant is only called when IsConstant==true.

---

Full diff: https://github.com/llvm/llvm-project/pull/129288.diff

1 Files Affected:

• (modified) llvm/lib/IR/AsmWriter.cpp (-1)

diff --git a/llvm/lib/IR/AsmWriter.cpp b/llvm/lib/IR/AsmWriter.cpp
index a52c4d88ac836..306186d200e26 100644
--- a/llvm/lib/IR/AsmWriter.cpp
+++ b/llvm/lib/IR/AsmWriter.cpp
@@ -2117,7 +2117,6 @@ static void writeDIGenericSubrange(raw_ostream &Out, const DIGenericSubrange *N,
   };
 
   auto GetConstant = [&](Metadata *Bound) -> int64_t {
-    assert(IsConstant(Bound) && "Expected constant");
     auto *BE = dyn_cast_or_null<DIExpression>(Bound);
     return static_cast<int64_t>(BE->getElement(1));
   };

[nikic]

The assert in GetConstant checks if Bound is constant. However, GetConstant is only called when IsConstant==true.

Yes -- and the assert ensures that GetConstant is only used in cases where it is valid.

I think if you want to change this code, the better change would be to drop IsConstant and instead have GetConstant return an std::optional. Then you don't need separate IsConstant and GetConstant calls.

[jph-13]

Reverted the abort deletion and implented the solution @nikic recommend.

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[jph-13]

Addressed code format violations.

[MacDue]

Can you rewrite the PR title/description? I don't think it matches what this changes does anymore.

[MacDue]

This looks like a reasonable refactor to me.

Nit on the PR title, I'd go for something shorter and leave the why in the description. Maybe:
[AsmWriter] Combine IsConstant and GetConstant (NFCI) -- which also says where the change is (AsmWriter) and that no functional changes are intended (NFCI).

[github-actions]

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