From 15f58d2489f09971cad4ddaf4f3d7bae6e854f12 Mon Sep 17 00:00:00 2001 From: Craig Topper Date: Tue, 25 Nov 2025 09:54:43 -0800 Subject: [PATCH] [RISCV] Don't add Zilsd pairing hints if part of the pair is reserved. --- llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp b/llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp index 263d6a1fc2220..a5aef4bea46ab 100644 --- a/llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp +++ b/llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp @@ -895,11 +895,9 @@ bool RISCVRegisterInfo::getRegAllocationHints( // Check if this register matches the even/odd requirement bool IsOdd = (RegNum % 2 != 0); - // Verify the pair register exists and is in the same register class - // TODO: Skip unallocatable registers: we need to prevent any of odd/even - // to be reserved, so if we need odd, we need to check if corresponding - // even is preserved, vice versa. - if ((WantOdd && IsOdd) || (!WantOdd && !IsOdd)) + // Don't provide hints that are paired to a reserved register. + MCRegister Paired = PhysReg + (IsOdd ? -1 : 1); + if (WantOdd == IsOdd && !MRI->isReserved(Paired)) Hints.push_back(PhysReg); } }