[DAGCombiner] Add tests for `computeKnownBits` of `sdiv` and `udiv`; NFC

[RKSimon]

LGTM

[goldstein.w.n]

This comment was removed by goldstein.w.n.

[goldstein.w.n]

Rebase

[goldstein.w.n]

Rebase

[foad]

llvm/test/CodeGen/X86/knownbits-div.ll

14

Typo "denom"

llvm/test/CodeGen/X86/knownbits-div.ll

+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=x86_64-unknown | FileCheck %s
+
+define i8 @sdiv_neg_neg_high_bits(i8 %x, i8 %y) {
+; CHECK-LABEL: sdiv_neg_neg_high_bits:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    orb $-128, %dil
+; CHECK-NEXT:    orb $-125, %sil
+; CHECK-NEXT:    movsbl %dil, %eax
+; CHECK-NEXT:    idivb %sil
+; CHECK-NEXT:    andb $-128, %al
+; CHECK-NEXT:    retq
+  %num = or i8 %x, 128
+  %denum = or i8 %y, 131
+  %div = sdiv i8 %num, %denum
+  %r = and i8 %div, 128
+  ret i8 %r
+}
+
+define i8 @sdiv_exact_odd_odd(i8 %x, i8 %y) {
+; CHECK-LABEL: sdiv_exact_odd_odd:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    orb $1, %dil
+; CHECK-NEXT:    orb $1, %sil
+; CHECK-NEXT:    movsbl %dil, %eax
+; CHECK-NEXT:    idivb %sil
+; CHECK-NEXT:    andb $1, %al
+; CHECK-NEXT:    retq
+  %num = or i8 %x, 1
+  %denum = or i8 %y, 1
+  %div = sdiv exact i8 %num, %denum
+  %r = and i8 %div, 1
+  ret i8 %r
+}
+
+define i8 @sdiv_exact_even_even_fail_unknown(i8 %x, i8 %y) {
+; CHECK-LABEL: sdiv_exact_even_even_fail_unknown:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    andb $-2, %dil
+; CHECK-NEXT:    andb $-2, %sil
+; CHECK-NEXT:    movsbl %dil, %eax
+; CHECK-NEXT:    idivb %sil
+; CHECK-NEXT:    andb $1, %al
+; CHECK-NEXT:    retq
+  %num = and i8 %x, -2
+  %denum = and i8 %y, -2
+  %div = sdiv exact i8 %num, %denum
+  %r = and i8 %div, 1
+  ret i8 %r
+}
+
+define i8 @udiv_exact_even_odd(i8 %x, i8 %y) {
+; CHECK-LABEL: udiv_exact_even_odd:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    andb $-2, %dil
+; CHECK-NEXT:    orb $1, %sil
+; CHECK-NEXT:    movzbl %dil, %eax
+; CHECK-NEXT:    divb %sil
+; CHECK-NEXT:    andb $1, %al
+; CHECK-NEXT:    retq
+  %num = and i8 %x, -2
+  %denum = or i8 %y, 1
+  %div = udiv exact i8 %num, %denum
+  %r = and i8 %div, 1
+  ret i8 %r
+}
+
+define i8 @udiv_exact_even_even_fail_unknown(i8 %x, i8 %y) {
+; CHECK-LABEL: udiv_exact_even_even_fail_unknown:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    andb $-2, %dil
+; CHECK-NEXT:    andb $-2, %sil
+; CHECK-NEXT:    movzbl %dil, %eax
+; CHECK-NEXT:    divb %sil
+; CHECK-NEXT:    andb $1, %al
+; CHECK-NEXT:    retq
+  %num = and i8 %x, -2
+  %denum = and i8 %y, -2
+  %div = udiv exact i8 %num, %denum
+  %r = and i8 %div, 1
+  ret i8 %r
+}