[llvm][X86] REX profile for UEFI

[Prabhuk]

Use the appropriate REX profile for UEFI X86_64 target.

[llvmbot]

@llvm/pr-subscribers-backend-x86

Author: Prabhu Rajasekaran (Prabhuk)

Changes

Use the appropriate REX profile for UEFI X86_64 target.

---

Full diff: https://github.com/llvm/llvm-project/pull/138362.diff

1 Files Affected:

• (modified) llvm/lib/Target/X86/X86ExpandPseudo.cpp (+6-5)

diff --git a/llvm/lib/Target/X86/X86ExpandPseudo.cpp b/llvm/lib/Target/X86/X86ExpandPseudo.cpp
index 398b738b85697..5d1f7f7f0fe9d 100644
--- a/llvm/lib/Target/X86/X86ExpandPseudo.cpp
+++ b/llvm/lib/Target/X86/X86ExpandPseudo.cpp
@@ -302,7 +302,7 @@ bool X86ExpandPseudo::expandMI(MachineBasicBlock &MBB,
     }
 
     // Jump to label or value in register.
-    bool IsWin64 = STI->isTargetWin64();
+    bool IsWinOrUEFI64 = STI->isTargetWin64() || STI->isTargetUEFI64();
     if (Opcode == X86::TCRETURNdi || Opcode == X86::TCRETURNdicc ||
         Opcode == X86::TCRETURNdi64 || Opcode == X86::TCRETURNdi64cc) {
       unsigned Op;
@@ -339,16 +339,17 @@ bool X86ExpandPseudo::expandMI(MachineBasicBlock &MBB,
       }
 
     } else if (Opcode == X86::TCRETURNmi || Opcode == X86::TCRETURNmi64) {
-      unsigned Op = (Opcode == X86::TCRETURNmi)
-                        ? X86::TAILJMPm
-                        : (IsWin64 ? X86::TAILJMPm64_REX : X86::TAILJMPm64);
+      unsigned Op =
+          (Opcode == X86::TCRETURNmi)
+              ? X86::TAILJMPm
+              : (IsWinOrUEFI64 ? X86::TAILJMPm64_REX : X86::TAILJMPm64);
       MachineInstrBuilder MIB = BuildMI(MBB, MBBI, DL, TII->get(Op));
       for (unsigned i = 0; i != X86::AddrNumOperands; ++i)
         MIB.add(MBBI->getOperand(i));
     } else if (Opcode == X86::TCRETURNri64) {
       JumpTarget.setIsKill();
       BuildMI(MBB, MBBI, DL,
-              TII->get(IsWin64 ? X86::TAILJMPr64_REX : X86::TAILJMPr64))
+              TII->get(IsWinOrUEFI64 ? X86::TAILJMPr64_REX : X86::TAILJMPr64))
           .add(JumpTarget);
     } else {
       JumpTarget.setIsKill();

[petrhosek]

Would it be possible to include a test?

[Prabhuk]

Added a new test for REX profile check.

[RossComputerGuy]

LGTM, one of the next things I'd like to see happen is if we can fix lld-link to actually link a libc and start file for UEFI using LLVM libc. Currently, we have to manually supply the paths. Ideally, this should be done automatically.