[all-commits] [llvm/llvm-project] a2b779: [SystemZ] Fix off-by-one error in backend (#200141)

[Dominik Steenken via All-commits]

  Branch: refs/heads/release/22.x
  Home:   https://github.com/llvm/llvm-project
  Commit: a2b77904509333f5c9aa8e71427c694961e417c9
      https://github.com/llvm/llvm-project/commit/a2b77904509333f5c9aa8e71427c694961e417c9
  Author: Dominik Steenken <dost at de.ibm.com>
  Date:   2026-06-01 (Mon, 01 Jun 2026)

  Changed paths:
    M llvm/lib/Target/SystemZ/SystemZISelLowering.cpp
    A llvm/test/CodeGen/SystemZ/combine-ccmask-tm-full.ll

  Log Message:
  -----------
  [SystemZ] Fix off-by-one error in backend (#200141)

When combineCCMask is called on a TM node with two constant operands,
and all of the bits in the mask are active, the existing APInt bit
access goes off the overall length of the integer by one. This commit
fixes that by using the index value of the leftmost active bit, rather
than the number of active bits.

(cherry picked from commit 78eca55b542b6bca573f34a1b359fa949c3a8c89)



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