llvm-project/llvm/test/CodeGen/X86/PR37310.mir

# RUN: llc -mtriple=x86_64-unknown-linux-gnu -mcpu=corei7 -no-stack-coloring=false -run-pass stack-coloring -o - %s

# Test to insure that the liveness analysis in the StackColoring
# pass gracefully handles statically unreachable blocks. See PR 37310.

# This MIR testcase was created by compiling the following test, first
# with "clang -emit-llvm -S" and then "llc -stop-before stack-coloring",
# and finally editing the resulting MIR by hand to introduce a statically
# unreachable BB (to wit: rename all bb.3 to bb.4, rename bb.2 to bb.3,
# then add bb.2 with unconditional jump to bb.4).

# Original C code:
# extern int inita(int *);
# void foo(int x) {
#   if (x != 3) {
#     int q[128];
#     inita(&q[0]);
#     return;
#   }
#   int r[128];
#   inita(&r[x]);
# }

--- |
  
  define void @foo(i32 %x) {
  entry:
    %q = alloca [128 x i32], align 16
    %r = alloca [128 x i32], align 16
    %cmp = icmp eq i32 %x, 3
    br i1 %cmp, label %if.end, label %if.then
  
  if.then:                                          ; preds = %entry
    %0 = bitcast [128 x i32]* %q to i8*
    call void @llvm.lifetime.start.p0i8(i64 512, i8* nonnull %0)
    %arrayidx2 = bitcast [128 x i32]* %q to i32*
    %call = call i32 @inita(i32* nonnull %arrayidx2)
    call void @llvm.lifetime.end.p0i8(i64 512, i8* nonnull %0)
    br label %return

  unreachable:
    br label %return
  
  if.end:                                           ; preds = %entry
    %1 = bitcast [128 x i32]* %r to i8*
    call void @llvm.lifetime.start.p0i8(i64 512, i8* nonnull %1)
    %arrayidx1 = getelementptr inbounds [128 x i32], [128 x i32]* %r, i64 0, i64 3
    %call2 = call i32 @inita(i32* nonnull %arrayidx1)
    call void @llvm.lifetime.end.p0i8(i64 512, i8* nonnull %1)
    br label %return
  
  return:                                           ; preds = %if.end, %if.then
    ret void
  }
  
  declare void @llvm.lifetime.start.p0i8(i64, i8* nocapture)
  
  declare i32 @inita(i32*)
  
  declare void @llvm.lifetime.end.p0i8(i64, i8* nocapture)
  
  declare void @llvm.stackprotector(i8*, i8**)
  
...
---
name:            foo
alignment:       4
exposesReturnsTwice: false
legalized:       false
regBankSelected: false
selected:        false
failedISel:      false
tracksRegLiveness: true
registers:       
  - { id: 0, class: gr32, preferred-register: '' }
  - { id: 1, class: gr32, preferred-register: '' }
  - { id: 2, class: gr64, preferred-register: '' }
  - { id: 3, class: gr32, preferred-register: '' }
  - { id: 4, class: gr64, preferred-register: '' }
  - { id: 5, class: gr32, preferred-register: '' }
liveins:         
  - { reg: '$edi' }
frameInfo:       
  isFrameAddressTaken: false
  isReturnAddressTaken: false
  hasStackMap:     false
  hasPatchPoint:   false
  stackSize:       0
  offsetAdjustment: 0
  maxAlignment:    16
  adjustsStack:    false
  hasCalls:        true
  stackProtector:  ''
  maxCallFrameSize: 4294967295
  hasOpaqueSPAdjustment: false
  hasVAStart:      false
  hasMustTailInVarArgFunc: false
  localFrameSize:  0
  savePoint:       ''
  restorePoint:    ''
fixedStack:      
stack:           
  - { id: 0, name: q, type: default, offset: 0, size: 512, alignment: 16, 
      stack-id: default, callee-saved-register: '', callee-saved-restored: true,
      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
  - { id: 1, name: r, type: default, offset: 0, size: 512, alignment: 16, 
      stack-id: default, callee-saved-register: '', callee-saved-restored: true,
      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
constants:       
body:             |
  bb.0.entry:
    successors: %bb.3(0x40000000), %bb.1(0x40000000)
    liveins: $edi
  
    %0:gr32 = COPY $edi
    %1:gr32 = SUB32ri8 %0, 3, implicit-def $eflags
    JCC_1 %bb.3, 4, implicit $eflags
    JMP_1 %bb.1
  
  bb.1.if.then:
    successors: %bb.4(0x80000000)
  
    LIFETIME_START %stack.0.q
    ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
    %2:gr64 = LEA64r %stack.0.q, 1, $noreg, 0, $noreg
    $rdi = COPY %2
    CALL64pcrel32 @inita, csr_64, implicit $rsp, implicit $ssp, implicit $rdi, implicit-def $rsp, implicit-def $ssp, implicit-def $eax
    ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
    %3:gr32 = COPY $eax
    LIFETIME_END %stack.0.q
    JMP_1 %bb.4

  bb.2.unreachable:
    successors: %bb.4(0x80000000)
  
    JMP_1 %bb.4
  
  bb.3.if.end:
    successors: %bb.4(0x80000000)
  
    LIFETIME_START %stack.1.r
    %4:gr64 = LEA64r %stack.1.r, 1, $noreg, 12, $noreg
    ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
    $rdi = COPY %4
    CALL64pcrel32 @inita, csr_64, implicit $rsp, implicit $ssp, implicit $rdi, implicit-def $rsp, implicit-def $ssp, implicit-def $eax
    ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
    %5:gr32 = COPY $eax
    LIFETIME_END %stack.1.r
  
  bb.4.return:
    RET 0

...