From 26f6fbe2be1dfb6e734ba34b650606cd18a2a4f7 Mon Sep 17 00:00:00 2001
From: David Green <david.green@arm.com>
Date: Tue, 14 Dec 2021 12:49:27 +0000
Subject: [PATCH] [ARM] Add AddrModeT2_i8neg addressing mode support for frame
 lowering.

As reported from a failing firefox build, we can sometimes get frame
indices with negative offsets from a t2LDRi8. This adds support for
them, to prevent the crash.
---
 llvm/lib/Target/ARM/ARMBaseRegisterInfo.cpp  |   4 +
 llvm/test/CodeGen/ARM/stack_frame_offset.mir | 189 +++++++++++++++++++
 2 files changed, 193 insertions(+)
 create mode 100644 llvm/test/CodeGen/ARM/stack_frame_offset.mir

diff --git a/llvm/lib/Target/ARM/ARMBaseRegisterInfo.cpp b/llvm/lib/Target/ARM/ARMBaseRegisterInfo.cpp
index b53efe58e8de..c543d02ff75a 100644
--- a/llvm/lib/Target/ARM/ARMBaseRegisterInfo.cpp
+++ b/llvm/lib/Target/ARM/ARMBaseRegisterInfo.cpp
@@ -530,6 +530,8 @@ getFrameIndexInstrOffset(const MachineInstr *MI, int Idx) const {
   unsigned ImmIdx = 0;
   switch (AddrMode) {
   case ARMII::AddrModeT2_i8:
+  case ARMII::AddrModeT2_i8neg:
+  case ARMII::AddrModeT2_i8pos:
   case ARMII::AddrModeT2_i12:
   case ARMII::AddrMode_i12:
     InstrOffs = MI->getOperand(Idx+1).getImm();
@@ -728,6 +730,8 @@ bool ARMBaseRegisterInfo::isFrameOffsetLegal(const MachineInstr *MI,
   bool isSigned = true;
   switch (AddrMode) {
   case ARMII::AddrModeT2_i8:
+  case ARMII::AddrModeT2_i8pos:
+  case ARMII::AddrModeT2_i8neg:
   case ARMII::AddrModeT2_i12:
     // i8 supports only negative, and i12 supports only positive, so
     // based on Offset sign, consider the appropriate instruction
diff --git a/llvm/test/CodeGen/ARM/stack_frame_offset.mir b/llvm/test/CodeGen/ARM/stack_frame_offset.mir
new file mode 100644
index 000000000000..f2cdb8007e55
--- /dev/null
+++ b/llvm/test/CodeGen/ARM/stack_frame_offset.mir
@@ -0,0 +1,189 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -run-pass=prologepilog %s -o - | FileCheck %s
+
+--- |
+  target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
+  target triple = "thumbv7m-none-eabi"
+
+  define i32 @testpos() {
+  entry:
+    %a = alloca i32, align 4
+    call void @other(i32* %a)
+    %b = load i32, i32* %a, align 4
+    ret i32 %b
+  }
+  define i32 @testneg4() {
+  entry:
+    %a = alloca i32, align 4
+    call void @other(i32* %a)
+    %b = load i32, i32* %a, align 4
+    ret i32 %b
+  }
+  define i32 @testneg8() {
+  entry:
+    %a = alloca i32, align 4
+    call void @other(i32* %a)
+    %b = load i32, i32* %a, align 4
+    ret i32 %b
+  }
+
+  declare void @other(i32*)
+
+...
+---
+name:            testpos
+tracksRegLiveness: true
+frameInfo:
+  isFrameAddressTaken: false
+  isReturnAddressTaken: false
+  hasStackMap:     false
+  hasPatchPoint:   false
+  stackSize:       0
+  offsetAdjustment: 0
+  maxAlignment:    4
+  adjustsStack:    true
+  hasCalls:        true
+  stackProtector:  ''
+  maxCallFrameSize: 0
+  cvBytesOfCalleeSavedRegisters: 0
+  hasOpaqueSPAdjustment: false
+  hasVAStart:      false
+  hasMustTailInVarArgFunc: false
+  hasTailCall:     false
+  localFrameSize:  4
+  savePoint:       ''
+  restorePoint:    ''
+stack:
+  - { id: 0, name: a, type: default, offset: 0, size: 4, alignment: 4,
+      stack-id: default, callee-saved-register: '', callee-saved-restored: true,
+      local-offset: -4, debug-info-variable: '', debug-info-expression: '',
+      debug-info-location: '' }
+body:             |
+  bb.0.entry:
+    ; CHECK-LABEL: name: testpos
+    ; CHECK: liveins: $r7, $lr
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: $sp = frame-setup t2STMDB_UPD $sp, 14 /* CC::al */, $noreg, killed $r7, killed $lr
+    ; CHECK-NEXT: frame-setup CFI_INSTRUCTION def_cfa_offset 8
+    ; CHECK-NEXT: frame-setup CFI_INSTRUCTION offset $lr, -4
+    ; CHECK-NEXT: frame-setup CFI_INSTRUCTION offset $r7, -8
+    ; CHECK-NEXT: $sp = frame-setup tSUBspi $sp, 2, 14 /* CC::al */, $noreg
+    ; CHECK-NEXT: frame-setup CFI_INSTRUCTION def_cfa_offset 16
+    ; CHECK-NEXT: renamable $r0 = t2ADDri $sp, 4, 14 /* CC::al */, $noreg, $noreg
+    ; CHECK-NEXT: tBL 14 /* CC::al */, $noreg, @other, csr_aapcs, implicit-def dead $lr, implicit $sp, implicit $r0, implicit-def $sp
+    ; CHECK-NEXT: renamable $r0 = t2LDRi12 $sp, 8, 14 /* CC::al */, $noreg :: (dereferenceable load (s32) from %ir.a)
+    ; CHECK-NEXT: $sp = frame-destroy tADDspi $sp, 2, 14 /* CC::al */, $noreg
+    ; CHECK-NEXT: $sp = frame-destroy t2LDMIA_RET $sp, 14 /* CC::al */, $noreg, def $r7, def $pc, implicit $r0
+    ADJCALLSTACKDOWN 0, 0, 14 /* CC::al */, $noreg, implicit-def dead $sp, implicit $sp
+    renamable $r0 = t2ADDri %stack.0.a, 0, 14 /* CC::al */, $noreg, $noreg
+    tBL 14 /* CC::al */, $noreg, @other, csr_aapcs, implicit-def dead $lr, implicit $sp, implicit $r0, implicit-def $sp
+    ADJCALLSTACKUP 0, -1, 14 /* CC::al */, $noreg, implicit-def dead $sp, implicit $sp
+    renamable $r0 = t2LDRi12 %stack.0.a, 4, 14 /* CC::al */, $noreg :: (dereferenceable load (s32) from %ir.a)
+    tBX_RET 14 /* CC::al */, $noreg, implicit $r0
+
+...
+---
+name:            testneg4
+tracksRegLiveness: true
+frameInfo:
+  isFrameAddressTaken: false
+  isReturnAddressTaken: false
+  hasStackMap:     false
+  hasPatchPoint:   false
+  stackSize:       0
+  offsetAdjustment: 0
+  maxAlignment:    4
+  adjustsStack:    true
+  hasCalls:        true
+  stackProtector:  ''
+  maxCallFrameSize: 0
+  cvBytesOfCalleeSavedRegisters: 0
+  hasOpaqueSPAdjustment: false
+  hasVAStart:      false
+  hasMustTailInVarArgFunc: false
+  hasTailCall:     false
+  localFrameSize:  4
+  savePoint:       ''
+  restorePoint:    ''
+stack:
+  - { id: 0, name: a, type: default, offset: 0, size: 4, alignment: 4,
+      stack-id: default, callee-saved-register: '', callee-saved-restored: true,
+      local-offset: -4, debug-info-variable: '', debug-info-expression: '',
+      debug-info-location: '' }
+body:             |
+  bb.0.entry:
+    ; CHECK-LABEL: name: testneg4
+    ; CHECK: liveins: $r7, $lr
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: $sp = frame-setup t2STMDB_UPD $sp, 14 /* CC::al */, $noreg, killed $r7, killed $lr
+    ; CHECK-NEXT: frame-setup CFI_INSTRUCTION def_cfa_offset 8
+    ; CHECK-NEXT: frame-setup CFI_INSTRUCTION offset $lr, -4
+    ; CHECK-NEXT: frame-setup CFI_INSTRUCTION offset $r7, -8
+    ; CHECK-NEXT: $sp = frame-setup tSUBspi $sp, 2, 14 /* CC::al */, $noreg
+    ; CHECK-NEXT: frame-setup CFI_INSTRUCTION def_cfa_offset 16
+    ; CHECK-NEXT: renamable $r0 = t2ADDri $sp, 4, 14 /* CC::al */, $noreg, $noreg
+    ; CHECK-NEXT: tBL 14 /* CC::al */, $noreg, @other, csr_aapcs, implicit-def dead $lr, implicit $sp, implicit $r0, implicit-def $sp
+    ; CHECK-NEXT: renamable $r0 = t2LDRi12 $sp, 0, 14 /* CC::al */, $noreg :: (dereferenceable load (s32) from %ir.a)
+    ; CHECK-NEXT: $sp = frame-destroy tADDspi $sp, 2, 14 /* CC::al */, $noreg
+    ; CHECK-NEXT: $sp = frame-destroy t2LDMIA_RET $sp, 14 /* CC::al */, $noreg, def $r7, def $pc, implicit $r0
+    ADJCALLSTACKDOWN 0, 0, 14 /* CC::al */, $noreg, implicit-def dead $sp, implicit $sp
+    renamable $r0 = t2ADDri %stack.0.a, 0, 14 /* CC::al */, $noreg, $noreg
+    tBL 14 /* CC::al */, $noreg, @other, csr_aapcs, implicit-def dead $lr, implicit $sp, implicit $r0, implicit-def $sp
+    ADJCALLSTACKUP 0, -1, 14 /* CC::al */, $noreg, implicit-def dead $sp, implicit $sp
+    renamable $r0 = t2LDRi8 %stack.0.a, -4, 14 /* CC::al */, $noreg :: (dereferenceable load (s32) from %ir.a)
+    tBX_RET 14 /* CC::al */, $noreg, implicit $r0
+
+...
+---
+name:            testneg8
+tracksRegLiveness: true
+frameInfo:
+  isFrameAddressTaken: false
+  isReturnAddressTaken: false
+  hasStackMap:     false
+  hasPatchPoint:   false
+  stackSize:       0
+  offsetAdjustment: 0
+  maxAlignment:    4
+  adjustsStack:    true
+  hasCalls:        true
+  stackProtector:  ''
+  maxCallFrameSize: 0
+  cvBytesOfCalleeSavedRegisters: 0
+  hasOpaqueSPAdjustment: false
+  hasVAStart:      false
+  hasMustTailInVarArgFunc: false
+  hasTailCall:     false
+  localFrameSize:  4
+  savePoint:       ''
+  restorePoint:    ''
+stack:
+  - { id: 0, name: a, type: default, offset: 0, size: 4, alignment: 4,
+      stack-id: default, callee-saved-register: '', callee-saved-restored: true,
+      local-offset: -4, debug-info-variable: '', debug-info-expression: '',
+      debug-info-location: '' }
+body:             |
+  bb.0.entry:
+    ; CHECK-LABEL: name: testneg8
+    ; CHECK: liveins: $r7, $lr
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: $sp = frame-setup t2STMDB_UPD $sp, 14 /* CC::al */, $noreg, killed $r7, killed $lr
+    ; CHECK-NEXT: frame-setup CFI_INSTRUCTION def_cfa_offset 8
+    ; CHECK-NEXT: frame-setup CFI_INSTRUCTION offset $lr, -4
+    ; CHECK-NEXT: frame-setup CFI_INSTRUCTION offset $r7, -8
+    ; CHECK-NEXT: $sp = frame-setup tSUBspi $sp, 2, 14 /* CC::al */, $noreg
+    ; CHECK-NEXT: frame-setup CFI_INSTRUCTION def_cfa_offset 16
+    ; CHECK-NEXT: renamable $r0 = t2ADDri $sp, 4, 14 /* CC::al */, $noreg, $noreg
+    ; CHECK-NEXT: tBL 14 /* CC::al */, $noreg, @other, csr_aapcs, implicit-def dead $lr, implicit $sp, implicit $r0, implicit-def $sp
+    ; CHECK-NEXT: renamable $r0 = t2LDRi8 $sp, -4, 14 /* CC::al */, $noreg :: (dereferenceable load (s32) from %ir.a)
+    ; CHECK-NEXT: $sp = frame-destroy tADDspi $sp, 2, 14 /* CC::al */, $noreg
+    ; CHECK-NEXT: $sp = frame-destroy t2LDMIA_RET $sp, 14 /* CC::al */, $noreg, def $r7, def $pc, implicit $r0
+    ADJCALLSTACKDOWN 0, 0, 14 /* CC::al */, $noreg, implicit-def dead $sp, implicit $sp
+    renamable $r0 = t2ADDri %stack.0.a, 0, 14 /* CC::al */, $noreg, $noreg
+    tBL 14 /* CC::al */, $noreg, @other, csr_aapcs, implicit-def dead $lr, implicit $sp, implicit $r0, implicit-def $sp
+    ADJCALLSTACKUP 0, -1, 14 /* CC::al */, $noreg, implicit-def dead $sp, implicit $sp
+    renamable $r0 = t2LDRi8 %stack.0.a, -8, 14 /* CC::al */, $noreg :: (dereferenceable load (s32) from %ir.a)
+    tBX_RET 14 /* CC::al */, $noreg, implicit $r0
+
+...
+
-- 
2.34.1.703.g22d0c6ccf7-goog