[llvm] 2896bbe - [X86] getFauxShuffleMask - use std::iota for insert_subvector shuffle mask population. NFC.

[Simon Pilgrim via llvm-commits]

Author: Simon Pilgrim
Date: 2025-04-09T12:51:49+01:00
New Revision: 2896bbe1488b628a27cdf893fc8bcc5febe128db

URL: https://github.com/llvm/llvm-project/commit/2896bbe1488b628a27cdf893fc8bcc5febe128db
DIFF: https://github.com/llvm/llvm-project/commit/2896bbe1488b628a27cdf893fc8bcc5febe128db.diff

LOG: [X86] getFauxShuffleMask - use std::iota for insert_subvector shuffle mask population. NFC.

Added: 
    

Modified: 
    llvm/lib/Target/X86/X86ISelLowering.cpp

Removed: 
    


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diff  --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 908b81d896e34..11bea60d941ff 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -6180,7 +6180,7 @@ static bool getFauxShuffleMask(SDValue N, const APInt &DemandedElts,
     uint64_t InsertIdx = N.getConstantOperandVal(2);
     // Subvector isn't demanded - just return the base vector.
     if (DemandedElts.extractBits(NumSubElts, InsertIdx) == 0) {
-      Mask.resize(NumElts, SM_SentinelUndef);
+      Mask.resize(NumElts);
       std::iota(Mask.begin(), Mask.end(), 0);
       Ops.push_back(Src);
       return true;
@@ -6194,10 +6194,9 @@ static bool getFauxShuffleMask(SDValue N, const APInt &DemandedElts,
         Src.getConstantOperandVal(2) == 0 &&
         (NumBitsPerElt == 64 || Src.getOperand(1) == Sub) &&
         SDNode::areOnlyUsersOf({N.getNode(), Src.getNode()}, Sub.getNode())) {
-      for (int i = 0; i != (int)NumSubElts; ++i)
-        Mask.push_back(i);
-      for (int i = 0; i != (int)NumSubElts; ++i)
-        Mask.push_back(i + NumElts);
+      Mask.resize(NumElts);
+      std::iota(Mask.begin(), Mask.begin() + NumSubElts, 0);
+      std::iota(Mask.begin() + NumSubElts, Mask.end(), NumElts);
       Ops.push_back(Src.getOperand(1));
       Ops.push_back(Sub);
       return true;