The compiler creates this prologue for _ZN4llvm15runPassPipelineENS_9StringRefERNS_6ModuleEPNS_13TargetMachineEPNS_21TargetLibraryInfoImplEPNS_14ToolOutputFileES8_S8_S0_NS_8ArrayRefINS_10PassPluginEEENS9_ISt8functionIFvRNS_11PassBuilderEEEEENS_8opt_tool10OutputKindENSI_12VerifierKindEbbbbbbb (aka llvm::runPassPipeline(llvm::StringRef, llvm::Module&, llvm::TargetMachine*, llvm::TargetLibraryInfoImpl*, llvm::ToolOutputFile*, llvm::ToolOutputFile*, llvm::ToolOutputFile*, llvm::StringRef, llvm::ArrayRefllvm::PassPlugin, llvm::ArrayRef<std::function<void (llvm::PassBuilder&)> >, llvm::opt_tool::OutputKind, llvm::opt_tool::VerifierKind, bool, bool, bool, bool, bool, bool, bool)) from tools/opt/NewPMDriver.cpp:

000000000001ce60 <_ZN4llvm15runPassPipelineENS_9StringRefERNS_6ModuleEPNS_13TargetMachineEPNS_21TargetLibraryInfoImplEPNS_14ToolOutputFileES8_S8_S0_NS_8ArrayRefINS_10PassPluginEEENS9_ISt8functionIFvRNS_11PassBuilderEEEEENS_8opt_tool10OutputKindENSI_12VerifierKindEbbbbbbb@@base>:
1ce60: 7141 addi sp,sp,-496
1ce62: f786 sd ra,488(sp)
1ce64: f3a2 sd s0,480(sp)
1ce66: efa6 sd s1,472(sp)
1ce68: ebca sd s2,464(sp)
1ce6a: e7ce sd s3,456(sp)
1ce6c: e3d2 sd s4,448(sp)
1ce6e: ff56 sd s5,440(sp)
1ce70: fb5a sd s6,432(sp)
1ce72: f75e sd s7,424(sp)
1ce74: f362 sd s8,416(sp)
1ce76: ef66 sd s9,408(sp)
1ce78: eb6a sd s10,400(sp)
1ce7a: e76e sd s11,392(sp)
1ce7c: 6285 lui t0,0x1
1ce7e: 40510133 sub sp,sp,t0
1ce82: e002 sd zero,0(sp)
1ce84: 80010113 addi sp,sp,-2048
1ce88: d4010113 addi sp,sp,-704

At 1ce8c the CFA is at sp + 496 + 4096 + 2048 + 704 = sp+7344. But the unwind info for that function starts like this:

00000ed8 0000000000000050 00000eb4 FDE cie=00000028 pc=000000000001ce60..0000000000020368
DW_CFA_advance_loc: 2 to 000000000001ce62
DW_CFA_def_cfa_offset: 496
DW_CFA_advance_loc: 26 to 000000000001ce7c
DW_CFA_offset: r1 (ra) at cfa-8
DW_CFA_offset: r8 (s0) at cfa-16
DW_CFA_offset: r9 (s1) at cfa-24
DW_CFA_offset: r18 (s2) at cfa-32
DW_CFA_offset: r19 (s3) at cfa-40
DW_CFA_offset: r20 (s4) at cfa-48
DW_CFA_offset: r21 (s5) at cfa-56
DW_CFA_offset: r22 (s6) at cfa-64
DW_CFA_offset: r23 (s7) at cfa-72
DW_CFA_offset: r24 (s8) at cfa-80
DW_CFA_offset: r25 (s9) at cfa-88
DW_CFA_offset: r26 (s10) at cfa-96
DW_CFA_offset: r27 (s11) at cfa-104
DW_CFA_advance_loc: 8 to 000000000001ce84
DW_CFA_def_cfa_offset: 4096
DW_CFA_advance_loc: 8 to 000000000001ce8c
DW_CFA_def_cfa_offset: 6848

This places the CFA at sp + 6848, off by the initial 496 frame offset.

Later in the function:

1fec4: 6589 lui a1,0x2
1fec6: ac058593 addi a1,a1,-1344 # 1ac0 _ZN4llvm41initializeExpandLargeDivRemLegacyPassPassERNS_12PassRegistryE@plt-0x118d0
1feca: 912e add sp,sp,a1

This adds 6848 to sp, which sets the frame offset back to 496. The unwind info records that correctly again:

DW_CFA_advance_loc2: 12352 to 000000000001fecc
DW_CFA_def_cfa_offset: 496