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llvm-mirror/test/Transforms/PhaseOrdering/partialord-ule.ll
Nikita Popov 9f9d5e9617 [SimplifyCFG] Handle two equal cases in switch to select
When converting a switch with two cases and a default into a
select, also handle the denegerate case where two cases have the
same value.

Generate this case directly as

  %or = or i1 %cmp1, %cmp2
  %res = select i1 %or, i32 %val, i32 %default

rather than

  %sel1 = select i1 %cmp1, i32 %val, i32 %default
  %res = select i1 %cmp2, i32 %val, i32 %sel1

as InstCombine is going to canonicalize to the former anyway.
2021-04-04 17:27:28 +02:00

31 lines
805 B
LLVM

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -O1 -S < %s | FileCheck %s
; This is a very convoluted way to write an icmp ule, which comes about by
; matching against a three-way comparison result.
define i1 @ule(i32 %a, i32 %b) {
; CHECK-LABEL: @ule(
; CHECK-NEXT: start:
; CHECK-NEXT: [[DOTNOT:%.*]] = icmp ule i32 [[A:%.*]], [[B:%.*]]
; CHECK-NEXT: ret i1 [[DOTNOT]]
;
start:
%cmp1 = icmp eq i32 %a, %b
%cmp2 = icmp ult i32 %a, %b
%cmp3 = icmp ne i32 %a, %b
%zext = zext i1 %cmp3 to i64
%sel1 = select i1 %cmp2, i64 -1, i64 %zext
%sel2 = select i1 %cmp1, i64 0, i64 %sel1
switch i64 %sel2, label %exit [
i64 -1, label %bb
i64 0, label %bb
]
bb:
br label %exit
exit:
%res = phi i1 [ true, %bb ], [ false, %start ]
ret i1 %res
}