[llvm] [RISCV] Add hasREV8Like helper to RISCVSubtarget. NFC (PR #158775)

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Mon Sep 15 21:48:38 PDT 2025


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-risc-v

Author: Craig Topper (topperc)

<details>
<summary>Changes</summary>



---
Full diff: https://github.com/llvm/llvm-project/pull/158775.diff


2 Files Affected:

- (modified) llvm/lib/Target/RISCV/RISCVISelLowering.cpp (+1-6) 
- (modified) llvm/lib/Target/RISCV/RISCVSubtarget.h (+3) 


``````````diff
diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
index 5485b916c2031..f5bb70b8a93e0 100644
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -378,13 +378,8 @@ RISCVTargetLowering::RISCVTargetLowering(const TargetMachine &TM,
     setOperationAction({ISD::ROTL, ISD::ROTR}, XLenVT, Expand);
   }
 
-  // With Zbb we have an XLen rev8 instruction, but not GREVI. So we'll
-  // pattern match it directly in isel.
   setOperationAction(ISD::BSWAP, XLenVT,
-                     (Subtarget.hasStdExtZbb() || Subtarget.hasStdExtZbkb() ||
-                      Subtarget.hasVendorXTHeadBb())
-                         ? Legal
-                         : Expand);
+                     Subtarget.hasREV8Like() ? Legal : Expand);
 
   if ((Subtarget.hasVendorXCVbitmanip() || Subtarget.hasVendorXqcibm()) &&
       !Subtarget.is64Bit()) {
diff --git a/llvm/lib/Target/RISCV/RISCVSubtarget.h b/llvm/lib/Target/RISCV/RISCVSubtarget.h
index 0d9cd16a77937..d4aca90816d81 100644
--- a/llvm/lib/Target/RISCV/RISCVSubtarget.h
+++ b/llvm/lib/Target/RISCV/RISCVSubtarget.h
@@ -196,6 +196,9 @@ class RISCVSubtarget : public RISCVGenSubtargetInfo {
   bool hasCPOPLike() const {
     return HasStdExtZbb || (HasVendorXCVbitmanip && !IsRV64);
   }
+  bool hasREV8Like() const {
+    return HasStdExtZbb | HasStdExtZbkb || HasVendorXTHeadBb;
+  }
 
   bool hasBEXTILike() const { return HasStdExtZbs || HasVendorXTHeadBs; }
 

``````````

</details>


https://github.com/llvm/llvm-project/pull/158775


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