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[X86] Fix missing ByValTemporaries update in CopyViaTemp path for musttail calls #190540

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Merged
RKSimon merged 2 commits into from
Apr 8, 2026
Merged

[X86] Fix missing ByValTemporaries update in CopyViaTemp path for musttail calls #190540

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[X86] Fix missing ByValTemporaries update in CopyViaTemp path for mus…
Withmm Apr 5, 2026
990c47c
Merge branch 'main' into musttail-fix
RKSimon Apr 8, 2026
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1 change: 1 addition & 0 deletions llvm/lib/Target/X86/X86ISelLoweringCall.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2237,6 +2237,7 @@ X86TargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
SDValue CopyChain =
CreateCopyOfByValArgument(Src, Temp, Chain, Flags, DAG, dl);
ByValCopyChains.push_back(CopyChain);
ByValTemporaries[ArgIdx] = Temp;

@folkertdev folkertdev Apr 6, 2026

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The fix here is consistent with the arm implementation that the x86 implementation is based on

llvm-project/llvm/lib/Target/ARM/ARMISelLowering.cpp

Lines 2193 to 2201 in e7ac60c

SDVTList VTs = DAG.getVTList(MVT::Other, MVT::Glue);
SDValue Ops[] = {Chain, Temp, Src, SizeNode, AlignNode};
ByValCopyChains.push_back(
DAG.getNode(ARMISD::COPY_STRUCT_BYVAL, dl, VTs, Ops));
ByValTemporaries[ArgIdx] = Temp;
}
}
if (!ByValCopyChains.empty())
ByValTempChain =

That line must have gotten lost at some point...

}
}
if (!ByValCopyChains.empty())
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58 changes: 45 additions & 13 deletions llvm/test/CodeGen/X86/musttail-struct.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -104,8 +104,10 @@ define dso_local i32 @swapByValArguments(ptr byval(%struct.1xi32) %0, ptr byval(
; X32-NEXT: .cfi_def_cfa_offset 12
; X32-NEXT: mov eax, dword ptr [esp + 12]
; X32-NEXT: mov dword ptr [esp], eax
; X32-NEXT: mov eax, dword ptr [esp + 16]
; X32-NEXT: mov dword ptr [esp + 4], eax
; X32-NEXT: mov ecx, dword ptr [esp + 16]
; X32-NEXT: mov dword ptr [esp + 4], ecx
; X32-NEXT: mov dword ptr [esp + 12], ecx
; X32-NEXT: mov dword ptr [esp + 16], eax
; X32-NEXT: add esp, 8
; X32-NEXT: .cfi_def_cfa_offset 4
; X32-NEXT: jmp swap # TAILCALL
Expand All @@ -114,8 +116,10 @@ define dso_local i32 @swapByValArguments(ptr byval(%struct.1xi32) %0, ptr byval(
; X64: # %bb.0:
; X64-NEXT: mov eax, dword ptr [rsp + 8]
; X64-NEXT: mov dword ptr [rsp - 16], eax
; X64-NEXT: mov eax, dword ptr [rsp + 16]
; X64-NEXT: mov dword ptr [rsp - 8], eax
; X64-NEXT: mov ecx, dword ptr [rsp + 16]
; X64-NEXT: mov dword ptr [rsp - 8], ecx
; X64-NEXT: mov dword ptr [rsp + 8], ecx
; X64-NEXT: mov dword ptr [rsp + 16], eax
; X64-NEXT: jmp swap # TAILCALL
%r = musttail call i32 @swap(ptr byval(%struct.1xi32) %1, ptr byval(%struct.1xi32) %0)
ret i32 %r
Expand Down Expand Up @@ -218,22 +222,50 @@ define void @swap_byvals(%twenty_bytes* byval(%twenty_bytes) align 4 %a, %twenty
; X32-NEXT: mov ecx, dword ptr [esp + 68]
; X32-NEXT: mov dword ptr [esp + 24], ecx
; X32-NEXT: mov dword ptr [esp + 20], eax
; X32-NEXT: mov eax, dword ptr [esp + 16]
; X32-NEXT: mov dword ptr [esp + 80], eax
; X32-NEXT: mov eax, dword ptr [esp + 12]
; X32-NEXT: mov dword ptr [esp + 76], eax
; X32-NEXT: mov eax, dword ptr [esp + 8]
; X32-NEXT: mov dword ptr [esp + 72], eax
; X32-NEXT: mov eax, dword ptr [esp]
; X32-NEXT: mov ecx, dword ptr [esp + 4]
; X32-NEXT: mov dword ptr [esp + 68], ecx
; X32-NEXT: mov dword ptr [esp + 64], eax
; X32-NEXT: mov eax, dword ptr [esp + 36]
; X32-NEXT: mov dword ptr [esp + 60], eax
; X32-NEXT: mov eax, dword ptr [esp + 32]
; X32-NEXT: mov dword ptr [esp + 56], eax
; X32-NEXT: mov eax, dword ptr [esp + 28]
; X32-NEXT: mov dword ptr [esp + 52], eax
; X32-NEXT: mov eax, dword ptr [esp + 20]
; X32-NEXT: mov ecx, dword ptr [esp + 24]
; X32-NEXT: mov dword ptr [esp + 48], ecx
; X32-NEXT: mov dword ptr [esp + 44], eax
; X32-NEXT: add esp, 40
; X32-NEXT: .cfi_def_cfa_offset 4
; X32-NEXT: jmp two_byvals_callee@PLT # TAILCALL
;
; X64-LABEL: swap_byvals:
; X64: # %bb.0: # %entry
; X64-NEXT: mov eax, dword ptr [rsp + 24]
; X64-NEXT: mov dword ptr [rsp - 8], eax
; X64-NEXT: movaps xmm0, xmmword ptr [rsp + 8]
; X64-NEXT: movaps xmmword ptr [rsp - 24], xmm0
; X64-NEXT: mov eax, dword ptr [rsp + 48]
; X64-NEXT: mov dword ptr [rsp - 32], eax
; X64-NEXT: mov rax, qword ptr [rsp + 32]
; X64-NEXT: mov rcx, qword ptr [rsp + 40]
; X64-NEXT: mov qword ptr [rsp - 40], rcx
; X64-NEXT: mov qword ptr [rsp - 48], rax
; X64-NEXT: movaps xmmword ptr [rsp - 56], xmm0
; X64-NEXT: mov eax, dword ptr [rsp + 24]
; X64-NEXT: mov dword ptr [rsp - 40], eax
; X64-NEXT: mov ecx, dword ptr [rsp + 48]
; X64-NEXT: mov dword ptr [rsp - 8], ecx
; X64-NEXT: mov rdx, qword ptr [rsp + 32]
; X64-NEXT: mov rsi, qword ptr [rsp + 40]
; X64-NEXT: mov qword ptr [rsp - 16], rsi
; X64-NEXT: mov qword ptr [rsp - 24], rdx
; X64-NEXT: mov qword ptr [rsp + 8], rdx
; X64-NEXT: mov qword ptr [rsp + 16], rsi
; X64-NEXT: mov dword ptr [rsp + 24], ecx
; X64-NEXT: mov dword ptr [rsp + 48], eax
; X64-NEXT: mov rax, qword ptr [rsp - 56]
; X64-NEXT: mov rcx, qword ptr [rsp - 48]
; X64-NEXT: mov qword ptr [rsp + 32], rax
; X64-NEXT: mov qword ptr [rsp + 40], rcx
; X64-NEXT: jmp two_byvals_callee@PLT # TAILCALL
entry:
musttail call void @two_byvals_callee(%twenty_bytes* byval(%twenty_bytes) align 4 %b, %twenty_bytes* byval(%twenty_bytes) align 4 %a)
Expand Down
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