[llvm] [SelectionDAG] Improve wide integer squaring (PR #226403)

[Simon Pilgrim via llvm-commits]

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@@ -0,0 +1,809 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu | FileCheck %s --check-prefix=X64
+; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu -mattr=+bmi2 | FileCheck %s --check-prefix=BMI2
+
+; truncated square, 4 x 4 limbs
+define void @sqr_i256(ptr %out, ptr %in) {
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RKSimon wrote:

Use nounwind in all tests to silence cfi noise
```suggestion
define void @sqr_i256(ptr %out, ptr %in) nounwind {
```

https://github.com/llvm/llvm-project/pull/226403