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Mark GPR15 volatile for JIT Helper calls on 64-bit z/OS #22852

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Merged
merged 1 commit into from
Nov 4, 2025
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Mark GPR15 volatile for JIT Helper calls on 64-bit z/OS #22852

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5 changes: 3 additions & 2 deletions runtime/compiler/z/codegen/S390CHelperLinkage.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -66,7 +66,6 @@ J9::Z::CHelperLinkage::CHelperLinkage(TR::CodeGenerator * codeGen,TR_LinkageConv
setRegisterFlag(TR::RealRegister::GPR10, Preserved);
setRegisterFlag(TR::RealRegister::GPR11, Preserved);
setRegisterFlag(TR::RealRegister::GPR13, Preserved);
setRegisterFlag(TR::RealRegister::GPR15, Preserved);

#if defined(ENABLE_PRESERVED_FPRS)
// In case of 32bit Linux on Z, System Linkage only preserves FPR4 and FPR6. For all other targets, FPR8-FPR15 is
Expand Down Expand Up @@ -95,6 +94,7 @@ J9::Z::CHelperLinkage::CHelperLinkage(TR::CodeGenerator * codeGen,TR_LinkageConv
setRegisterFlag(TR::RealRegister::GPR6, Preserved);
setRegisterFlag(TR::RealRegister::GPR7, Preserved);
setRegisterFlag(TR::RealRegister::GPR12, Preserved);
setRegisterFlag(TR::RealRegister::GPR15, Preserved);

setReturnAddressRegister(TR::RealRegister::GPR14);
setIntegerReturnRegister(TR::RealRegister::GPR2);
Expand Down Expand Up @@ -123,10 +123,11 @@ J9::Z::CHelperLinkage::CHelperLinkage(TR::CodeGenerator * codeGen,TR_LinkageConv
{
setRegisterFlag(TR::RealRegister::GPR12, Preserved);

setPreservedRegisterMapForGC(0x0000FF00);
setPreservedRegisterMapForGC(0x00007F00);
}
else
{
setRegisterFlag(TR::RealRegister::GPR15, Preserved);
// 31-Bit zOS will need GPR12 for CAA register so it won't be preserved. For all other variant it is preserved
setPreservedRegisterMapForGC(0x0000EF00);
}
Expand Down