xref: /llvm-project/llvm/test/Transforms/InstCombine/phi-with-multiple-unsimplifiable-values.ll (revision b189b89bdeb74a933016bef6d85ae42b0c62b40e)

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
; RUN: opt < %s -passes=instcombine -S | FileCheck %s

declare void @use(i8 %value);

; Since we know that any comparison of ucmp/scmp with a constant will result in
; a comparison of ucmp/scmp's operands, we can propagate such a comparison
; through the phi node and let the next iteration of instcombine simplify it.
define i1 @icmp_of_phi_of_scmp_with_constant(i1 %c, i16 %x, i16 %y)
; CHECK-LABEL: define i1 @icmp_of_phi_of_scmp_with_constant(
; CHECK-SAME: i1 [[C:%.*]], i16 [[X:%.*]], i16 [[Y:%.*]]) {
; CHECK-NEXT:  [[ENTRY:.*:]]
; CHECK-NEXT:    br i1 [[C]], label %[[TRUE:.*]], label %[[FALSE:.*]]
; CHECK:       [[TRUE]]:
; CHECK-NEXT:    [[TMP0:%.*]] = icmp slt i16 [[X]], [[Y]]
; CHECK-NEXT:    br label %[[EXIT:.*]]
; CHECK:       [[FALSE]]:
; CHECK-NEXT:    [[TMP1:%.*]] = icmp slt i16 [[Y]], [[X]]
; CHECK-NEXT:    br label %[[EXIT]]
; CHECK:       [[EXIT]]:
; CHECK-NEXT:    [[R:%.*]] = phi i1 [ [[TMP0]], %[[TRUE]] ], [ [[TMP1]], %[[FALSE]] ]
; CHECK-NEXT:    ret i1 [[R]]
;
{
entry:
  br i1 %c, label %true, label %false
true:
  %cmp1 = call i8 @llvm.scmp(i16 %x, i16 %y)
  br label %exit
false:
  %cmp2 = call i8 @llvm.scmp(i16 %y, i16 %x)
  br label %exit
exit:
  %phi = phi i8 [%cmp1, %true], [%cmp2, %false]
  %r = icmp slt i8 %phi, 0
  ret i1 %r
}

; When one of the incoming values is ucmp/scmp and the other is not we can still perform the transformation
define i1 @icmp_of_phi_of_one_scmp_with_constant(i1 %c, i16 %x, i16 %y, i8 %false_val)
; CHECK-LABEL: define i1 @icmp_of_phi_of_one_scmp_with_constant(
; CHECK-SAME: i1 [[C:%.*]], i16 [[X:%.*]], i16 [[Y:%.*]], i8 [[FALSE_VAL:%.*]]) {
; CHECK-NEXT:  [[ENTRY:.*:]]
; CHECK-NEXT:    br i1 [[C]], label %[[TRUE:.*]], label %[[FALSE:.*]]
; CHECK:       [[TRUE]]:
; CHECK-NEXT:    [[TMP0:%.*]] = icmp slt i16 [[X]], [[Y]]
; CHECK-NEXT:    br label %[[EXIT:.*]]
; CHECK:       [[FALSE]]:
; CHECK-NEXT:    [[TMP1:%.*]] = icmp slt i8 [[FALSE_VAL]], 0
; CHECK-NEXT:    br label %[[EXIT]]
; CHECK:       [[EXIT]]:
; CHECK-NEXT:    [[PHI:%.*]] = phi i1 [ [[TMP0]], %[[TRUE]] ], [ [[TMP1]], %[[FALSE]] ]
; CHECK-NEXT:    ret i1 [[PHI]]
;
{
entry:
  br i1 %c, label %true, label %false
true:
  %cmp1 = call i8 @llvm.scmp(i16 %x, i16 %y)
  br label %exit
false:
  br label %exit
exit:
  %phi = phi i8 [%cmp1, %true], [%false_val, %false]
  %r = icmp slt i8 %phi, 0
  ret i1 %r
}

; Negative test: the RHS of comparison that uses the phi node is not constant
define i1 @icmp_of_phi_of_scmp_with_non_constant(i1 %c, i16 %x, i16 %y, i8 %cmp)
; CHECK-LABEL: define i1 @icmp_of_phi_of_scmp_with_non_constant(
; CHECK-SAME: i1 [[C:%.*]], i16 [[X:%.*]], i16 [[Y:%.*]], i8 [[CMP:%.*]]) {
; CHECK-NEXT:  [[ENTRY:.*:]]
; CHECK-NEXT:    br i1 [[C]], label %[[TRUE:.*]], label %[[FALSE:.*]]
; CHECK:       [[TRUE]]:
; CHECK-NEXT:    [[CMP1:%.*]] = call i8 @llvm.scmp.i8.i16(i16 [[X]], i16 [[Y]])
; CHECK-NEXT:    br label %[[EXIT:.*]]
; CHECK:       [[FALSE]]:
; CHECK-NEXT:    [[CMP2:%.*]] = call i8 @llvm.scmp.i8.i16(i16 [[Y]], i16 [[X]])
; CHECK-NEXT:    br label %[[EXIT]]
; CHECK:       [[EXIT]]:
; CHECK-NEXT:    [[PHI:%.*]] = phi i8 [ [[CMP1]], %[[TRUE]] ], [ [[CMP2]], %[[FALSE]] ]
; CHECK-NEXT:    [[R:%.*]] = icmp slt i8 [[PHI]], [[CMP]]
; CHECK-NEXT:    ret i1 [[R]]
;
{
entry:
  br i1 %c, label %true, label %false
true:
  %cmp1 = call i8 @llvm.scmp(i16 %x, i16 %y)
  br label %exit
false:
  %cmp2 = call i8 @llvm.scmp(i16 %y, i16 %x)
  br label %exit
exit:
  %phi = phi i8 [%cmp1, %true], [%cmp2, %false]
  %r = icmp slt i8 %phi, %cmp
  ret i1 %r
}

; Negative test: more than one incoming value of the phi node is not one-use
define i1 @icmp_of_phi_of_scmp_with_constant_not_one_use(i1 %c, i16 %x, i16 %y)
; CHECK-LABEL: define i1 @icmp_of_phi_of_scmp_with_constant_not_one_use(
; CHECK-SAME: i1 [[C:%.*]], i16 [[X:%.*]], i16 [[Y:%.*]]) {
; CHECK-NEXT:  [[ENTRY:.*:]]
; CHECK-NEXT:    br i1 [[C]], label %[[TRUE:.*]], label %[[FALSE:.*]]
; CHECK:       [[TRUE]]:
; CHECK-NEXT:    [[CMP1:%.*]] = call i8 @llvm.scmp.i8.i16(i16 [[X]], i16 [[Y]])
; CHECK-NEXT:    call void @use(i8 [[CMP1]])
; CHECK-NEXT:    br label %[[EXIT:.*]]
; CHECK:       [[FALSE]]:
; CHECK-NEXT:    [[CMP2:%.*]] = call i8 @llvm.scmp.i8.i16(i16 [[Y]], i16 [[X]])
; CHECK-NEXT:    call void @use(i8 [[CMP2]])
; CHECK-NEXT:    br label %[[EXIT]]
; CHECK:       [[EXIT]]:
; CHECK-NEXT:    [[PHI:%.*]] = phi i8 [ [[CMP1]], %[[TRUE]] ], [ [[CMP2]], %[[FALSE]] ]
; CHECK-NEXT:    [[R:%.*]] = icmp slt i8 [[PHI]], 0
; CHECK-NEXT:    ret i1 [[R]]
;
{
entry:
  br i1 %c, label %true, label %false
true:
  %cmp1 = call i8 @llvm.scmp(i16 %x, i16 %y)
  call void @use(i8 %cmp1)
  br label %exit
false:
  %cmp2 = call i8 @llvm.scmp(i16 %y, i16 %x)
  call void @use(i8 %cmp2)
  br label %exit
exit:
  %phi = phi i8 [%cmp1, %true], [%cmp2, %false]
  %r = icmp slt i8 %phi, 0
  ret i1 %r
}

; Same as the first transformation, but the phi node uses the result of scmp twice. This verifies that we don't clone values more than once per block
define i1 @icmp_of_phi_of_scmp_with_constant_one_user_two_uses(i8 %c, i16 %x, i16 %y, i8 %false_val) {
; CHECK-LABEL: define i1 @icmp_of_phi_of_scmp_with_constant_one_user_two_uses(
; CHECK-SAME: i8 [[C:%.*]], i16 [[X:%.*]], i16 [[Y:%.*]], i8 [[FALSE_VAL:%.*]]) {
; CHECK-NEXT:  [[ENTRY:.*]]:
; CHECK-NEXT:    [[TMP0:%.*]] = icmp slt i16 [[X]], [[Y]]
; CHECK-NEXT:    switch i8 [[C]], label %[[BB_2:.*]] [
; CHECK-NEXT:      i8 0, label %[[BB:.*]]
; CHECK-NEXT:      i8 1, label %[[BB]]
; CHECK-NEXT:    ]
; CHECK:       [[BB_2]]:
; CHECK-NEXT:    br label %[[BB]]
; CHECK:       [[BB]]:
; CHECK-NEXT:    [[R:%.*]] = phi i1 [ [[TMP0]], %[[ENTRY]] ], [ [[TMP0]], %[[ENTRY]] ], [ false, %[[BB_2]] ]
; CHECK-NEXT:    ret i1 [[R]]
;
entry:
  %cmp = call i8 @llvm.scmp(i16 %x, i16 %y)
  switch i8 %c, label %bb_2 [
  i8 0, label %bb
  i8 1, label %bb
  ]

bb_2:
  br label %bb

bb:
  %phi = phi i8 [ %cmp, %entry ], [ %cmp, %entry ], [ 0, %bb_2 ]
  %r = icmp slt i8 %phi, 0
  ret i1 %r
}