[llvm] [RISCV] Add helper method for detecting BEXTI or TH_TST is supported. NFC (PR #157915)

[Craig Topper via llvm-commits]

https://github.com/topperc updated https://github.com/llvm/llvm-project/pull/157915

>From 6adf6d3e321647bee1a809a3c78dbdd0f252f8f7 Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper at sifive.com>
Date: Wed, 10 Sep 2025 10:56:07 -0700
Subject: [PATCH 1/2] [RISCV] Add helper method for detecting BEXTI or TH_TST
 is supported. NFC

These instructions both extract single bit to bit 0 and fill
the upper bits with 0.

There's at least one place where we check for BEXTI but not TH_TST.
I wanted to keep this patch NFC so that will be a follow up fix.
---
 llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp | 2 +-
 llvm/lib/Target/RISCV/RISCVISelLowering.cpp | 2 +-
 llvm/lib/Target/RISCV/RISCVSubtarget.h      | 4 ++++
 3 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp b/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp
index 756422dfa29e5..c7f15415ebb91 100644
--- a/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp
@@ -1052,7 +1052,7 @@ void RISCVDAGToDAGISel::Select(SDNode *Node) {
   SDLoc DL(Node);
   MVT VT = Node->getSimpleValueType(0);
 
-  bool HasBitTest = Subtarget->hasStdExtZbs() || Subtarget->hasVendorXTHeadBs();
+  bool HasBitTest = Subtarget->hasBEXTILike();
 
   switch (Opcode) {
   case ISD::Constant: {
diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
index 409f98b348903..a68a3c14dc41d 100644
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -2173,7 +2173,7 @@ bool RISCVTargetLowering::isMaskAndCmp0FoldingBeneficial(
   // on the basis that it's possible the sinking+duplication of the AND in
   // CodeGenPrepare triggered by this hook wouldn't decrease the instruction
   // count and would increase code size (e.g. ANDI+BNEZ => BEXTI+BNEZ).
-  if (!Subtarget.hasStdExtZbs() && !Subtarget.hasVendorXTHeadBs())
+  if (!Subtarget.hasBEXTILike())
     return false;
   ConstantInt *Mask = dyn_cast<ConstantInt>(AndI.getOperand(1));
   if (!Mask)
diff --git a/llvm/lib/Target/RISCV/RISCVSubtarget.h b/llvm/lib/Target/RISCV/RISCVSubtarget.h
index 4429d760a6cb0..9baaa9d347ecc 100644
--- a/llvm/lib/Target/RISCV/RISCVSubtarget.h
+++ b/llvm/lib/Target/RISCV/RISCVSubtarget.h
@@ -186,6 +186,10 @@ class RISCVSubtarget : public RISCVGenSubtargetInfo {
     return HasStdExtZfhmin || HasStdExtZfbfmin;
   }
 
+  bool hasBEXTILike() const {
+    return HasStdExtZbs || HasVendorXTHeadBs;
+  }
+
   bool hasCZEROLike() const {
     return HasStdExtZicond || HasVendorXVentanaCondOps;
   }

>From bd1b6368f40f719f9b59d2b0b071c8e5f22fecb5 Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper at sifive.com>
Date: Wed, 10 Sep 2025 11:07:41 -0700
Subject: [PATCH 2/2] fixup! clang-format

---
 llvm/lib/Target/RISCV/RISCVSubtarget.h | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/llvm/lib/Target/RISCV/RISCVSubtarget.h b/llvm/lib/Target/RISCV/RISCVSubtarget.h
index 9baaa9d347ecc..50e76df56e575 100644
--- a/llvm/lib/Target/RISCV/RISCVSubtarget.h
+++ b/llvm/lib/Target/RISCV/RISCVSubtarget.h
@@ -186,9 +186,7 @@ class RISCVSubtarget : public RISCVGenSubtargetInfo {
     return HasStdExtZfhmin || HasStdExtZfbfmin;
   }
 
-  bool hasBEXTILike() const {
-    return HasStdExtZbs || HasVendorXTHeadBs;
-  }
+  bool hasBEXTILike() const { return HasStdExtZbs || HasVendorXTHeadBs; }
 
   bool hasCZEROLike() const {
     return HasStdExtZicond || HasVendorXVentanaCondOps;