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llvm-mirror/test/Transforms/SimplifyCFG/switch-to-select-two-case.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

69 lines
1.8 KiB
LLVM

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
; int foo1_with_default(int a) {
; switch(a) {
; case 10:
; return 10;
; case 20:
; return 2;
; }
; return 4;
; }
define i32 @foo1_with_default(i32 %a) {
; CHECK-LABEL: @foo1_with_default(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[SWITCH_SELECTCMP:%.*]] = icmp eq i32 [[A:%.*]], 20
; CHECK-NEXT: [[SWITCH_SELECT:%.*]] = select i1 [[SWITCH_SELECTCMP]], i32 2, i32 4
; CHECK-NEXT: [[SWITCH_SELECTCMP1:%.*]] = icmp eq i32 [[A]], 10
; CHECK-NEXT: [[SWITCH_SELECT2:%.*]] = select i1 [[SWITCH_SELECTCMP1]], i32 10, i32 [[SWITCH_SELECT]]
; CHECK-NEXT: ret i32 [[SWITCH_SELECT2]]
;
entry:
switch i32 %a, label %sw.epilog [
i32 10, label %sw.bb
i32 20, label %sw.bb1
]
sw.bb:
br label %return
sw.bb1:
br label %return
sw.epilog:
br label %return
return:
%retval.0 = phi i32 [ 4, %sw.epilog ], [ 2, %sw.bb1 ], [ 10, %sw.bb ]
ret i32 %retval.0
}
; Same as above, but both cases have the same value.
define i32 @same_value(i32 %a) {
; CHECK-LABEL: @same_value(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[SWITCH_SELECTCMP_CASE1:%.*]] = icmp eq i32 [[A:%.*]], 10
; CHECK-NEXT: [[SWITCH_SELECTCMP_CASE2:%.*]] = icmp eq i32 [[A]], 20
; CHECK-NEXT: [[SWITCH_SELECTCMP:%.*]] = or i1 [[SWITCH_SELECTCMP_CASE1]], [[SWITCH_SELECTCMP_CASE2]]
; CHECK-NEXT: [[TMP0:%.*]] = select i1 [[SWITCH_SELECTCMP]], i32 10, i32 4
; CHECK-NEXT: ret i32 [[TMP0]]
;
entry:
switch i32 %a, label %sw.epilog [
i32 10, label %sw.bb
i32 20, label %sw.bb
]
sw.bb:
br label %return
sw.epilog:
br label %return
return:
%retval.0 = phi i32 [ 4, %sw.epilog ], [ 10, %sw.bb ]
ret i32 %retval.0
}