[llvm] [RISCV][CostModel] Remove cost of icmp inst in icmp+select with SFB. (PR #91158)

[Kito Cheng via llvm-commits]

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@@ -0,0 +1,258 @@
+; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py
+; RUN: opt < %s -mtriple=riscv64 -mcpu=sifive-u74 -passes="print<cost-model>" -cost-kind=throughput 2>&1 -disable-output | FileCheck %s --check-prefixes=SFB64
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kito-cheng wrote:

```suggestion
; RUN: opt < %s -mtriple=riscv64 -mattr=+v,+f,+short-forward-branch-opt -passes="print<cost-model>" -cost-kind=throughput 2>&1 -disable-output | FileCheck %s --check-prefixes=SFB64
```

Use mattr list instead of mcpu to minimized that diff between  SFB64 and RV64

https://github.com/llvm/llvm-project/pull/91158