[PATCH] D143618: [X86] Fix for offsets of CFA directives

[Theodoros Kasampalis via Phabricator via llvm-commits]

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`emitPrologue` may insert stack pointer adjustment in tail call optimized functions where the callee argument stack size is bigger than the caller's. In such a case, the adjustment must be taken into account when generating CFA directives.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D143618

Files:
  llvm/lib/Target/X86/X86FrameLowering.cpp


Index: llvm/lib/Target/X86/X86FrameLowering.cpp
===================================================================
--- llvm/lib/Target/X86/X86FrameLowering.cpp
+++ llvm/lib/Target/X86/X86FrameLowering.cpp
@@ -1649,14 +1649,16 @@
       // Define the current CFA rule to use the provided offset.
       assert(StackSize);
       BuildCFI(MBB, MBBI, DL,
-               MCCFIInstruction::cfiDefCfaOffset(nullptr, -2 * stackGrowth),
+               MCCFIInstruction::cfiDefCfaOffset(
+                   nullptr, -2 * stackGrowth + (int)TailCallArgReserveSize),
                MachineInstr::FrameSetup);
 
       // Change the rule for the FramePtr to be an "offset" rule.
       unsigned DwarfFramePtr = TRI->getDwarfRegNum(MachineFramePtr, true);
       BuildCFI(MBB, MBBI, DL,
-               MCCFIInstruction::createOffset(nullptr, DwarfFramePtr,
-                                              2 * stackGrowth),
+               MCCFIInstruction::createOffset(
+                   nullptr, DwarfFramePtr,
+                   2 * stackGrowth - (int)TailCallArgReserveSize),
                MachineInstr::FrameSetup);
     }
 


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