[llvm] [llvm] Optimize usub.sat fix for #79690 (PR #151044)

[Yingwei Zheng via llvm-commits]

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@@ -0,0 +1,206 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+
+; RUN: opt -passes=instcombine -S < %s 2>&1 | FileCheck %s
+
+declare i8 @llvm.usub.sat.i8(i8, i8)
+declare i16 @llvm.usub.sat.i16(i16, i16)
+declare i32 @llvm.usub.sat.i32(i32, i32)
+declare i64 @llvm.usub.sat.i64(i64, i64)
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dtcxzyw wrote:

```suggestion
```
Explicit intrinsic declaration is not needed.

https://github.com/llvm/llvm-project/pull/151044