precommit test for pr60855

[nickdesaulniers]

Summary

This test demonstrates an issue with callbr outputs being used along
indirect edges when using regallocfast.

Link: https://github.com/llvm/llvm-project/issues/60855

[nickdesaulniers]

• add fixme

llvm/test/CodeGen/X86/callbr-asm-outputs-regallocfast.mir

+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -run-pass=regallocfast -verify-machineinstrs %s -o - | FileCheck %s
+--- |
+  ; ModuleID = 'x.c'
+  source_filename = "x.c"
+  target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+  target triple = "x86_64-unknown-linux-gnu"
+
+  ; Function Attrs: noinline nounwind optnone
+  define dso_local i32 @main() #0 {
+  entry:
+    %retval = alloca i32, align 4
+    %x = alloca i32, align 4
+    store i32 0, ptr %retval, align 4
+    store i32 123, ptr %x, align 4
+    %0 = callbr i32 asm "mov $1, $0\0A\09jmp ${2:l}", "=r,r,!i,~{dirflag},~{fpsr},~{flags}"(i32 45) #2
+            to label %asm.fallthrough [label %label.split], !srcloc !5
+
+  asm.fallthrough:                                  ; preds = %entry
+    store i32 %0, ptr %x, align 4
+    store i32 6, ptr %x, align 4
+    br label %label
+
+  label:                                            ; preds = %asm.fallthrough, %label.split
+    %1 = load i32, ptr %x, align 4
+    ret i32 %1
+
+  label.split:                                      ; preds = %entry
+    %2 = call i32 @llvm.callbr.landingpad.i32(i32 %0)
+    store i32 %2, ptr %x, align 4
+    br label %label
+  }
+
+  ; Function Attrs: nomerge nounwind
+  declare i32 @llvm.callbr.landingpad.i32(i32) #1
+
+  attributes #0 = { noinline nounwind optnone "frame-pointer"="all" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+  attributes #1 = { nomerge nounwind }
+  attributes #2 = { nounwind memory(none) }
+
+  !llvm.module.flags = !{!0, !1, !2, !3}
+  !llvm.ident = !{!4}
+
+  !0 = !{i32 1, !"wchar_size", i32 4}
+  !1 = !{i32 8, !"PIC Level", i32 2}
+  !2 = !{i32 7, !"PIE Level", i32 2}
+  !3 = !{i32 7, !"frame-pointer", i32 2}
+  !4 = !{!"clang version 17.0.0 ([e-mail]:llvm/llvm-project.git cf86855c4453d029a9b9ed8c4c4c18cefc1bc895)"}
+  !5 = !{i64 166, i64 179}
+
+...
+---
+name:            main
+alignment:       16
+exposesReturnsTwice: false
+legalized:       false
+regBankSelected: false
+selected:        false
+failedISel:      false
+tracksRegLiveness: true
+hasWinCFI:       false
+callsEHReturn:   false
+callsUnwindInit: false
+hasEHCatchret:   false
+hasEHScopes:     false
+hasEHFunclets:   false
+debugInstrRef:   false
+failsVerification: false
+tracksDebugUserValues: false
+registers:
+  - { id: 0, class: gr32, preferred-register: '' }
+  - { id: 1, class: gr32, preferred-register: '' }
+  - { id: 2, class: gr32, preferred-register: '' }
+  - { id: 3, class: gr32, preferred-register: '' }
+  - { id: 4, class: gr32, preferred-register: '' }
+  - { id: 5, class: gr32, preferred-register: '' }
+  - { id: 6, class: gr32, preferred-register: '' }
+liveins:         []
+frameInfo:
+  isFrameAddressTaken: false
+  isReturnAddressTaken: false
+  hasStackMap:     false
+  hasPatchPoint:   false
+  stackSize:       0
+  offsetAdjustment: 0
+  maxAlignment:    4
+  adjustsStack:    false
+  hasCalls:        false
+  stackProtector:  ''
+  functionContext: ''
+  maxCallFrameSize: 4294967295
+  cvBytesOfCalleeSavedRegisters: 0
+  hasOpaqueSPAdjustment: false
+  hasVAStart:      false
+  hasMustTailInVarArgFunc: false
+  hasTailCall:     false
+  localFrameSize:  0
+  savePoint:       ''
+  restorePoint:    ''
+fixedStack:      []
+stack:
+  - { id: 0, name: retval, type: default, offset: 0, size: 4, alignment: 4,
+      stack-id: default, callee-saved-register: '', callee-saved-restored: true,
+      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+  - { id: 1, name: x, type: default, offset: 0, size: 4, alignment: 4,
+      stack-id: default, callee-saved-register: '', callee-saved-restored: true,
+      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+callSites:       []
+debugValueSubstitutions: []
+constants:       []
+machineFunctionInfo: {}
+body:             |
+  ; CHECK-LABEL: name: main
+  ; CHECK: bb.0.entry:
+  ; CHECK-NEXT:   successors: %bb.1(0x40000000), %bb.3(0x40000000)
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   MOV32mi %stack.0.retval, 1, $noreg, 0, $noreg, 0 :: (store (s32) into %ir.retval)
+  ; CHECK-NEXT:   MOV32mi %stack.1.x, 1, $noreg, 0, $noreg, 123 :: (store (s32) into %ir.x)
+  ; CHECK-NEXT:   renamable $eax = MOV32ri 45
+  ; CHECK-NEXT:   INLINEASM_BR &"mov $1, $0\0A\09jmp ${2:l}", 0 /* attdialect */, 2359306 /* regdef:GR32 */, def renamable $eax, 2359305 /* reguse:GR32 */, killed renamable $eax, 13 /* imm */, %bb.3, 12 /* clobber */, implicit-def dead early-clobber $df, 12 /* clobber */, implicit-def early-clobber $fpsw, 12 /* clobber */, implicit-def dead early-clobber $eflags, !5
+  ; CHECK-NEXT:   MOV32mr %stack.3, 1, $noreg, 0, $noreg, $eax :: (store (s32) into %stack.3)
+  ; CHECK-NEXT:   MOV32mr %stack.2, 1, $noreg, 0, $noreg, killed $eax :: (store (s32) into %stack.2)
+  ; CHECK-NEXT:   JMP_1 %bb.1
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.1.asm.fallthrough:
+  ; CHECK-NEXT:   successors: %bb.2(0x80000000)
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   $eax = MOV32rm %stack.2, 1, $noreg, 0, $noreg :: (load (s32) from %stack.2)
+  ; CHECK-NEXT:   MOV32mr %stack.1.x, 1, $noreg, 0, $noreg, renamable $eax :: (store (s32) into %ir.x)
+  ; CHECK-NEXT:   MOV32mi %stack.1.x, 1, $noreg, 0, $noreg, 6 :: (store (s32) into %ir.x)
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.2.label:
+  ; CHECK-NEXT:   renamable $eax = MOV32rm %stack.1.x, 1, $noreg, 0, $noreg :: (load (s32) from %ir.x)
+  ; CHECK-NEXT:   RET64 implicit killed $eax
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.3.label.split (machine-block-address-taken, inlineasm-br-indirect-target):
+  ; CHECK-NEXT:   successors: %bb.2(0x80000000)
+  ; CHECK-NEXT: {{  $}}
+  ; FIXME: this is a load from a stack slot that hasn't been stored to yet!
+  ; CHECK-NEXT:   $eax = MOV32rm %stack.3, 1, $noreg, 0, $noreg :: (load (s32) from %stack.3)
+  ; CHECK-NEXT:   MOV32mr %stack.1.x, 1, $noreg, 0, $noreg, killed renamable $eax :: (store (s32) into %ir.x)
+  ; CHECK-NEXT:   JMP_1 %bb.2
+  bb.0.entry:
+    successors: %bb.1(0x40000000), %bb.3(0x40000000)
+
+    MOV32mi %stack.0.retval, 1, $noreg, 0, $noreg, 0 :: (store (s32) into %ir.retval)
+    MOV32mi %stack.1.x, 1, $noreg, 0, $noreg, 123 :: (store (s32) into %ir.x)
+    %2:gr32 = MOV32ri 45
+    INLINEASM_BR &"mov $1, $0\0A\09jmp ${2:l}", 0 /* attdialect */, 2359306 /* regdef:GR32 */, def %1, 2359305 /* reguse:GR32 */, %2, 13 /* imm */, %bb.3, 12 /* clobber */, implicit-def early-clobber $df, 12 /* clobber */, implicit-def early-clobber $fpsw, 12 /* clobber */, implicit-def early-clobber $eflags, !5
+    %0:gr32 = COPY %1
+    JMP_1 %bb.1
+
+  bb.1.asm.fallthrough:
+    successors: %bb.2(0x80000000)
+
+    MOV32mr %stack.1.x, 1, $noreg, 0, $noreg, %0 :: (store (s32) into %ir.x)
+    MOV32mi %stack.1.x, 1, $noreg, 0, $noreg, 6 :: (store (s32) into %ir.x)
+
+  bb.2.label:
+    %6:gr32 = MOV32rm %stack.1.x, 1, $noreg, 0, $noreg :: (load (s32) from %ir.x)
+    $eax = COPY %6
+    RET64 implicit $eax
+
+  bb.3.label.split (machine-block-address-taken, inlineasm-br-indirect-target):
+    successors: %bb.2(0x80000000)
+
+    %3:gr32 = COPY %1
+    MOV32mr %stack.1.x, 1, $noreg, 0, $noreg, %3 :: (store (s32) into %ir.x)
+    JMP_1 %bb.2
+
+...