From 077d2ea485c4da12f2cf1eb511964c719b0e2aba Mon Sep 17 00:00:00 2001
From: gnezdo <gnezdo@openbsd.org>
Date: Fri, 14 Nov 2025 09:57:02 +0000
Subject: [PATCH] Fix llvm x86 frame lowering for -msave-args

The problem only shows up with KASAN builds where it causes registers
saved below SP leading to fills not finding what was spilled.

go for it dlg@
---
 gnu/llvm/llvm/lib/Target/X86/X86FrameLowering.cpp | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/gnu/llvm/llvm/lib/Target/X86/X86FrameLowering.cpp b/gnu/llvm/llvm/lib/Target/X86/X86FrameLowering.cpp
index 33edb2654c6..d96acb59366 100644
--- a/gnu/llvm/llvm/lib/Target/X86/X86FrameLowering.cpp
+++ b/gnu/llvm/llvm/lib/Target/X86/X86FrameLowering.cpp
@@ -2576,8 +2576,8 @@ void X86FrameLowering::emitEpilogue(MachineFunction &MF,
     if (TRI->hasStackRealignment(MF))
       MBBI = FirstCSPop;
     unsigned SEHFrameOffset = calculateSetFPREG(SEHStackAllocAmt);
-    uint64_t LEAAmount =
-        IsWin64Prologue ? SEHStackAllocAmt - SEHFrameOffset : -CSSize;
+    uint64_t LEAAmount = IsWin64Prologue ? SEHStackAllocAmt - SEHFrameOffset
+                                         : -(CSSize + X86FI->getSaveArgSize());
 
     if (X86FI->hasSwiftAsyncContext())
       LEAAmount -= 16;
@@ -2726,7 +2726,7 @@ StackOffset X86FrameLowering::getFrameIndexReference(const MachineFunction &MF,
            "FPDelta isn't aligned per the Win64 ABI!");
   }
 
-  if (FI >= 0)
+  if (FI >= 0 && FrameReg != TRI->getStackRegister())
     Offset -= X86FI->getSaveArgSize();
 
   if (FrameReg == TRI->getFramePtr()) {