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[X86] Better handling of impossibly large stack frames #124217

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Merged
merged 1 commit into from
Jan 25, 2025
Merged

[X86] Better handling of impossibly large stack frames #124217

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13 changes: 9 additions & 4 deletions llvm/lib/Target/X86/X86FrameLowering.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -234,6 +234,14 @@ void X86FrameLowering::emitSPUpdate(MachineBasicBlock &MBB,
MachineInstr::MIFlag Flag =
isSub ? MachineInstr::FrameSetup : MachineInstr::FrameDestroy;

if (!Uses64BitFramePtr && !isUInt<32>(Offset)) {
// We're being asked to adjust a 32-bit stack pointer by 4 GiB or more.
// This might be unreachable code, so don't complain now; just trap if
// it's reached at runtime.
BuildMI(MBB, MBBI, DL, TII.get(X86::TRAP));
return;
}

uint64_t Chunk = (1LL << 31) - 1;

MachineFunction &MF = *MBB.getParent();
Expand Down Expand Up @@ -829,10 +837,7 @@ void X86FrameLowering::emitStackProbeInlineGenericLoop(
.addReg(StackPtr)
.setMIFlag(MachineInstr::FrameSetup);
} else {
// We're being asked to probe a stack frame that's 4 GiB or larger,
// but our stack pointer is only 32 bits. This might be unreachable
// code, so don't complain now; just trap if it's reached at runtime.
BuildMI(MBB, MBBI, DL, TII.get(X86::TRAP));
llvm_unreachable("Offset too large for 32-bit stack pointer");
}

// while in the loop, use loop-invariant reg for CFI,
Expand Down
8 changes: 3 additions & 5 deletions llvm/test/CodeGen/X86/huge-stack-offset.ll
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Expand Up @@ -13,11 +13,9 @@ define void @foo() nounwind {
; CHECK-64-NEXT: addq [[RAX]], %rsp

; CHECK-32-LABEL: foo:
; CHECK-32: movl $50000000{{..}}, %eax
; CHECK-32-NEXT: subl %eax, %esp
; CHECK-32: ud2
; CHECK-32-NOT: subl $2147483647, %esp
; CHECK-32: movl $50000000{{..}}, [[EAX:%e..]]
; CHECK-32-NEXT: addl [[EAX]], %esp
; CHECK-32: ud2
%1 = alloca [5000000000 x i8], align 16
call void @bar(ptr %1)
ret void
Expand Down Expand Up @@ -46,7 +44,7 @@ define i32 @foo3(i32 inreg %x) nounwind {
; CHECK-64-NEXT: subq %rax, %rsp

; CHECK-32-LABEL: foo3:
; CHECK-32: subl $2147483647, %esp
; CHECK-32: ud2
; CHECK-32-NOT: movl ${{.*}}, %eax
%1 = alloca [5000000000 x i8], align 16
call void @bar(ptr %1)
Expand Down
26 changes: 2 additions & 24 deletions llvm/test/CodeGen/X86/stack-clash-extra-huge.ll
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Expand Up @@ -30,44 +30,22 @@ define i32 @foo() local_unnamed_addr #0 {
; CHECK-X86-LABEL: foo:
; CHECK-X86: # %bb.0:
; CHECK-X86-NEXT: ud2
; CHECK-X86-NEXT: .cfi_def_cfa_register %eax
; CHECK-X86-NEXT: .cfi_adjust_cfa_offset 4800000000
; CHECK-X86-NEXT: .LBB0_1: # =>This Inner Loop Header: Depth=1
; CHECK-X86-NEXT: subl $4096, %esp # imm = 0x1000
; CHECK-X86-NEXT: movl $0, (%esp)
; CHECK-X86-NEXT: cmpl %eax, %esp
; CHECK-X86-NEXT: jne .LBB0_1
; CHECK-X86-NEXT: # %bb.2:
; CHECK-X86-NEXT: subl $12, %esp
; CHECK-X86-NEXT: .cfi_def_cfa_register %esp
; CHECK-X86-NEXT: .cfi_def_cfa_offset 4800000016
; CHECK-X86-NEXT: movl $1, 392(%esp)
; CHECK-X86-NEXT: movl $1, 28792(%esp)
; CHECK-X86-NEXT: movl (%esp), %eax
; CHECK-X86-NEXT: movl $4800000012, %ecx # imm = 0x11E1A300C
; CHECK-X86-NEXT: addl %ecx, %esp
; CHECK-X86-NEXT: ud2
; CHECK-X86-NEXT: .cfi_def_cfa_offset 4
; CHECK-X86-NEXT: retl
;
; CHECK-X32-LABEL: foo:
; CHECK-X32: # %bb.0:
; CHECK-X32-NEXT: ud2
; CHECK-X32-NEXT: .cfi_def_cfa_register %r11
; CHECK-X32-NEXT: .cfi_adjust_cfa_offset 4799995904
; CHECK-X32-NEXT: .LBB0_1: # =>This Inner Loop Header: Depth=1
; CHECK-X32-NEXT: subl $4096, %esp # imm = 0x1000
; CHECK-X32-NEXT: movq $0, (%esp)
; CHECK-X32-NEXT: cmpl %r11d, %esp
; CHECK-X32-NEXT: jne .LBB0_1
; CHECK-X32-NEXT: # %bb.2:
; CHECK-X32-NEXT: subl $3976, %esp # imm = 0xF88
; CHECK-X32-NEXT: .cfi_def_cfa_register %rsp
; CHECK-X32-NEXT: .cfi_def_cfa_offset 4799999888
; CHECK-X32-NEXT: movl $1, 264(%esp)
; CHECK-X32-NEXT: movl $1, 28664(%esp)
; CHECK-X32-NEXT: movl -128(%esp), %eax
; CHECK-X32-NEXT: movl $4799999880, %ecx # imm = 0x11E1A2F88
; CHECK-X32-NEXT: addl %ecx, %esp
; CHECK-X32-NEXT: ud2
; CHECK-X32-NEXT: .cfi_def_cfa_offset 8
; CHECK-X32-NEXT: retq
%a = alloca i32, i64 1200000000, align 16
Expand Down
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