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[X86] Fix invalid instructions on x32 with large stack frames #124041

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merged 2 commits into from
Jan 23, 2025
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[X86] Fix invalid instructions on x32 with large stack frames #124041

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38ec566
Fix invalid instructions with large stack frames
mconst Jan 22, 2025
a6f2049
don't worry about impossibly-large stack frames for now
mconst Jan 23, 2025
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30 changes: 19 additions & 11 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)) {
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@phoebewang phoebewang Jan 23, 2025

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isUInt<31>?

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@mconst mconst Jan 23, 2025

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I believe it's correct -- it's valid to have a 2.5 GB stack frame on 32-bit x86 (and x32), and I think the code handles it properly. There's even a test case for it (stack-clash-huge.ll).

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@phoebewang phoebewang Jan 23, 2025

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Ok, can we split this change into another patch. We should use this to fix the failure of #113219 only.

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@mconst mconst Jan 23, 2025

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Sure, done. This means that for now, the stack-clash-extra-huge.ll test will generate the invalid instruction movl $4799999880, %ecx on x32, just like the preexisting huge-stack-offset.ll test.

// 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 All @@ -253,17 +261,19 @@ void X86FrameLowering::emitSPUpdate(MachineBasicBlock &MBB,
// Rather than emit a long series of instructions for large offsets,
// load the offset into a register and do one sub/add
unsigned Reg = 0;
unsigned Rax = (unsigned)(Is64Bit ? X86::RAX : X86::EAX);
unsigned Rax = (unsigned)(Uses64BitFramePtr ? X86::RAX : X86::EAX);

if (isSub && !isEAXLiveIn(MBB))
Reg = Rax;
else
Reg = TRI->findDeadCallerSavedReg(MBB, MBBI);
Reg = getX86SubSuperRegister(TRI->findDeadCallerSavedReg(MBB, MBBI),
Uses64BitFramePtr ? 64 : 32);

unsigned AddSubRROpc =
isSub ? getSUBrrOpcode(Is64Bit) : getADDrrOpcode(Is64Bit);
unsigned AddSubRROpc = isSub ? getSUBrrOpcode(Uses64BitFramePtr)
: getADDrrOpcode(Uses64BitFramePtr);
if (Reg) {
BuildMI(MBB, MBBI, DL, TII.get(getMOVriOpcode(Is64Bit, Offset)), Reg)
BuildMI(MBB, MBBI, DL, TII.get(getMOVriOpcode(Uses64BitFramePtr, Offset)),
Reg)
.addImm(Offset)
.setMIFlag(Flag);
MachineInstr *MI = BuildMI(MBB, MBBI, DL, TII.get(AddSubRROpc), StackPtr)
Expand All @@ -279,7 +289,7 @@ void X86FrameLowering::emitSPUpdate(MachineBasicBlock &MBB,
// addq %rsp, %rax
// xchg %rax, (%rsp)
// movq (%rsp), %rsp
assert(Is64Bit && "can't have 32-bit 16GB stack frame");
assert(Uses64BitFramePtr && "can't have 32-bit 16GB stack frame");
BuildMI(MBB, MBBI, DL, TII.get(X86::PUSH64r))
.addReg(Rax, RegState::Kill)
.setMIFlag(Flag);
Expand All @@ -289,7 +299,8 @@ void X86FrameLowering::emitSPUpdate(MachineBasicBlock &MBB,
Offset = -(Offset - SlotSize);
else
Offset = Offset + SlotSize;
BuildMI(MBB, MBBI, DL, TII.get(getMOVriOpcode(Is64Bit, Offset)), Rax)
BuildMI(MBB, MBBI, DL, TII.get(getMOVriOpcode(Uses64BitFramePtr, Offset)),
Rax)
.addImm(Offset)
.setMIFlag(Flag);
MachineInstr *MI = BuildMI(MBB, MBBI, DL, TII.get(X86::ADD64rr), Rax)
Expand Down Expand Up @@ -826,10 +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
32 changes: 5 additions & 27 deletions llvm/test/CodeGen/X86/stack-clash-extra-huge.ll
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@@ -1,7 +1,7 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --no_x86_scrub_sp
; RUN: llc -mtriple=x86_64-linux-android < %s | FileCheck -check-prefix=CHECK-X64 %s
; RUN: llc -mtriple=i686-linux-android < %s | FileCheck -check-prefix=CHECK-X86 %s
; RUN: llc -mtriple=x86_64-linux-gnux32 < %s | FileCheck -check-prefix=CHECK-X32 %s
; RUN: llc -mtriple=x86_64-linux-android -verify-machineinstrs < %s | FileCheck -check-prefix=CHECK-X64 %s
; RUN: llc -mtriple=i686-linux-android -verify-machineinstrs < %s | FileCheck -check-prefix=CHECK-X86 %s
; RUN: llc -mtriple=x86_64-linux-gnux32 -verify-machineinstrs < %s | FileCheck -check-prefix=CHECK-X32 %s

define i32 @foo() local_unnamed_addr #0 {
; CHECK-X64-LABEL: foo:
Expand Down 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: movabsq $4799999880, %rcx # imm = 0x11E1A2F88
; CHECK-X32-NEXT: addq %rcx, %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
8 changes: 4 additions & 4 deletions llvm/test/CodeGen/X86/stack-clash-huge.ll
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --no_x86_scrub_sp
; RUN: llc -mtriple=x86_64-linux-android < %s | FileCheck -check-prefix=CHECK-X64 %s
; RUN: llc -mtriple=i686-linux-android < %s | FileCheck -check-prefix=CHECK-X86 %s
; RUN: llc -mtriple=x86_64-linux-gnux32 < %s | FileCheck -check-prefix=CHECK-X32 %s
; RUN: llc -mtriple=x86_64-linux-android -verify-machineinstrs < %s | FileCheck -check-prefix=CHECK-X64 %s
; RUN: llc -mtriple=i686-linux-android -verify-machineinstrs < %s | FileCheck -check-prefix=CHECK-X86 %s
; RUN: llc -mtriple=x86_64-linux-gnux32 -verify-machineinstrs < %s | FileCheck -check-prefix=CHECK-X32 %s

define i32 @foo() local_unnamed_addr #0 {
; CHECK-X64-LABEL: foo:
Expand Down Expand Up @@ -69,7 +69,7 @@ define i32 @foo() local_unnamed_addr #0 {
; CHECK-X32-NEXT: movl $1, 28664(%esp)
; CHECK-X32-NEXT: movl -128(%esp), %eax
; CHECK-X32-NEXT: movl $2399999880, %ecx # imm = 0x8F0D1788
; CHECK-X32-NEXT: addq %rcx, %esp
; CHECK-X32-NEXT: addl %ecx, %esp
; CHECK-X32-NEXT: .cfi_def_cfa_offset 8
; CHECK-X32-NEXT: retq
%a = alloca i32, i64 600000000, align 16
Expand Down
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