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llvm-project/llvm/test/Transforms/SimplifyCFG/switch-dead-default.ll
Qiongsi Wu 7dc2f66022
Reland "[SimplifyCFG] switch: Do Not Transform the Default Case if the Condition is Too Wide (#77831)" 
https://github.com/llvm/llvm-project/pull/76669 taught SimplifyCFG to
handle switches when `default` has only one case. When the `switch`'s
condition is wider than 64 bit, the current implementation can calculate
the wrong default value. This PR skips cases where the condition is too
wide.

(cherry picked from commit 39bb790b906f4921a5d9fc09e856abe53ae7a320)
2024-05-25 10:38:44 +08:00

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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
; RUN: opt %s -S -passes='simplifycfg<switch-to-lookup>' -simplifycfg-require-and-preserve-domtree=1 -switch-range-to-icmp | FileCheck %s
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
declare void @foo(i32)
define void @test(i1 %a) {
; CHECK-LABEL: define void @test(
; CHECK-SAME: i1 [[A:%.*]]) {
; CHECK-NEXT: [[A_OFF:%.*]] = add i1 [[A]], true
; CHECK-NEXT: [[SWITCH:%.*]] = icmp ult i1 [[A_OFF]], true
; CHECK-NEXT: br i1 [[SWITCH]], label [[TRUE:%.*]], label [[FALSE:%.*]]
; CHECK: common.ret:
; CHECK-NEXT: ret void
; CHECK: true:
; CHECK-NEXT: call void @foo(i32 1)
; CHECK-NEXT: br label [[COMMON_RET:%.*]]
; CHECK: false:
; CHECK-NEXT: call void @foo(i32 3)
; CHECK-NEXT: br label [[COMMON_RET]]
;
switch i1 %a, label %default [i1 1, label %true
i1 0, label %false]
true:
call void @foo(i32 1)
ret void
false:
call void @foo(i32 3)
ret void
default:
call void @foo(i32 2)
ret void
}
define void @test2(i2 %a) {
; CHECK-LABEL: define void @test2(
; CHECK-SAME: i2 [[A:%.*]]) {
; CHECK-NEXT: switch i2 [[A]], label [[DOTUNREACHABLEDEFAULT:%.*]] [
; CHECK-NEXT: i2 0, label [[CASE0:%.*]]
; CHECK-NEXT: i2 1, label [[CASE1:%.*]]
; CHECK-NEXT: i2 -2, label [[CASE2:%.*]]
; CHECK-NEXT: i2 -1, label [[CASE3:%.*]]
; CHECK-NEXT: ]
; CHECK: common.ret:
; CHECK-NEXT: ret void
; CHECK: case0:
; CHECK-NEXT: call void @foo(i32 0)
; CHECK-NEXT: br label [[COMMON_RET:%.*]]
; CHECK: case1:
; CHECK-NEXT: call void @foo(i32 1)
; CHECK-NEXT: br label [[COMMON_RET]]
; CHECK: case2:
; CHECK-NEXT: call void @foo(i32 2)
; CHECK-NEXT: br label [[COMMON_RET]]
; CHECK: case3:
; CHECK-NEXT: call void @foo(i32 3)
; CHECK-NEXT: br label [[COMMON_RET]]
; CHECK: .unreachabledefault:
; CHECK-NEXT: unreachable
;
switch i2 %a, label %default [i2 0, label %case0
i2 1, label %case1
i2 2, label %case2
i2 3, label %case3]
case0:
call void @foo(i32 0)
ret void
case1:
call void @foo(i32 1)
ret void
case2:
call void @foo(i32 2)
ret void
case3:
call void @foo(i32 3)
ret void
default:
call void @foo(i32 4)
ret void
}
; We can replace the default branch with case 3 since it is the only case that is missing.
define void @test3(i2 %a) {
; CHECK-LABEL: define void @test3(
; CHECK-SAME: i2 [[A:%.*]]) {
; CHECK-NEXT: switch i2 [[A]], label [[DOTUNREACHABLEDEFAULT:%.*]] [
; CHECK-NEXT: i2 0, label [[CASE0:%.*]]
; CHECK-NEXT: i2 1, label [[CASE1:%.*]]
; CHECK-NEXT: i2 -2, label [[CASE2:%.*]]
; CHECK-NEXT: i2 -1, label [[DEFAULT:%.*]]
; CHECK-NEXT: ]
; CHECK: common.ret:
; CHECK-NEXT: ret void
; CHECK: case0:
; CHECK-NEXT: call void @foo(i32 0)
; CHECK-NEXT: br label [[COMMON_RET:%.*]]
; CHECK: case1:
; CHECK-NEXT: call void @foo(i32 1)
; CHECK-NEXT: br label [[COMMON_RET]]
; CHECK: case2:
; CHECK-NEXT: call void @foo(i32 2)
; CHECK-NEXT: br label [[COMMON_RET]]
; CHECK: .unreachabledefault:
; CHECK-NEXT: unreachable
; CHECK: default:
; CHECK-NEXT: call void @foo(i32 3)
; CHECK-NEXT: br label [[COMMON_RET]]
;
switch i2 %a, label %default [i2 0, label %case0
i2 1, label %case1
i2 2, label %case2]
case0:
call void @foo(i32 0)
ret void
case1:
call void @foo(i32 1)
ret void
case2:
call void @foo(i32 2)
ret void
default:
call void @foo(i32 3)
ret void
}
define void @test3_prof(i2 %a) {
; CHECK-LABEL: define void @test3_prof(
; CHECK-SAME: i2 [[A:%.*]]) {
; CHECK-NEXT: switch i2 [[A]], label [[DOTUNREACHABLEDEFAULT:%.*]] [
; CHECK-NEXT: i2 0, label [[CASE0:%.*]]
; CHECK-NEXT: i2 1, label [[CASE1:%.*]]
; CHECK-NEXT: i2 -2, label [[CASE2:%.*]]
; CHECK-NEXT: i2 -1, label [[DEFAULT:%.*]]
; CHECK-NEXT: ], !prof [[PROF0:![0-9]+]]
; CHECK: common.ret:
; CHECK-NEXT: ret void
; CHECK: case0:
; CHECK-NEXT: call void @foo(i32 0)
; CHECK-NEXT: br label [[COMMON_RET:%.*]]
; CHECK: case1:
; CHECK-NEXT: call void @foo(i32 1)
; CHECK-NEXT: br label [[COMMON_RET]]
; CHECK: case2:
; CHECK-NEXT: call void @foo(i32 2)
; CHECK-NEXT: br label [[COMMON_RET]]
; CHECK: .unreachabledefault:
; CHECK-NEXT: unreachable
; CHECK: default:
; CHECK-NEXT: call void @foo(i32 3)
; CHECK-NEXT: br label [[COMMON_RET]]
;
switch i2 %a, label %default [i2 0, label %case0
i2 1, label %case1
i2 2, label %case2], !prof !0
case0:
call void @foo(i32 0)
ret void
case1:
call void @foo(i32 1)
ret void
case2:
call void @foo(i32 2)
ret void
default:
call void @foo(i32 3)
ret void
}
; Negative test - check for possible overflow when computing
; number of possible cases.
define void @test4(i128 %a) {
; CHECK-LABEL: define void @test4(
; CHECK-SAME: i128 [[A:%.*]]) {
; CHECK-NEXT: switch i128 [[A]], label [[DEFAULT:%.*]] [
; CHECK-NEXT: i128 0, label [[CASE0:%.*]]
; CHECK-NEXT: i128 1, label [[CASE1:%.*]]
; CHECK-NEXT: ]
; CHECK: common.ret:
; CHECK-NEXT: ret void
; CHECK: case0:
; CHECK-NEXT: call void @foo(i32 0)
; CHECK-NEXT: br label [[COMMON_RET:%.*]]
; CHECK: case1:
; CHECK-NEXT: call void @foo(i32 1)
; CHECK-NEXT: br label [[COMMON_RET]]
; CHECK: default:
; CHECK-NEXT: call void @foo(i32 2)
; CHECK-NEXT: br label [[COMMON_RET]]
;
switch i128 %a, label %default [i128 0, label %case0
i128 1, label %case1]
case0:
call void @foo(i32 0)
ret void
case1:
call void @foo(i32 1)
ret void
default:
call void @foo(i32 2)
ret void
}
; All but one bit known zero
define void @test5(i8 %a) {
; CHECK-LABEL: define void @test5(
; CHECK-SAME: i8 [[A:%.*]]) {
; CHECK-NEXT: [[CMP:%.*]] = icmp ult i8 [[A]], 2
; CHECK-NEXT: call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: [[A_OFF:%.*]] = add i8 [[A]], -1
; CHECK-NEXT: [[SWITCH:%.*]] = icmp ult i8 [[A_OFF]], 1
; CHECK-NEXT: br i1 [[SWITCH]], label [[TRUE:%.*]], label [[FALSE:%.*]]
; CHECK: common.ret:
; CHECK-NEXT: ret void
; CHECK: true:
; CHECK-NEXT: call void @foo(i32 1)
; CHECK-NEXT: br label [[COMMON_RET:%.*]]
; CHECK: false:
; CHECK-NEXT: call void @foo(i32 3)
; CHECK-NEXT: br label [[COMMON_RET]]
;
%cmp = icmp ult i8 %a, 2
call void @llvm.assume(i1 %cmp)
switch i8 %a, label %default [i8 1, label %true
i8 0, label %false]
true:
call void @foo(i32 1)
ret void
false:
call void @foo(i32 3)
ret void
default:
call void @foo(i32 2)
ret void
}
;; All but one bit known one
define void @test6(i8 %a) {
; CHECK-LABEL: define void @test6(
; CHECK-SAME: i8 [[A:%.*]]) {
; CHECK-NEXT: [[AND:%.*]] = and i8 [[A]], -2
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i8 [[AND]], -2
; CHECK-NEXT: call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: [[A_OFF:%.*]] = add i8 [[A]], 1
; CHECK-NEXT: [[SWITCH:%.*]] = icmp ult i8 [[A_OFF]], 1
; CHECK-NEXT: br i1 [[SWITCH]], label [[TRUE:%.*]], label [[FALSE:%.*]]
; CHECK: common.ret:
; CHECK-NEXT: ret void
; CHECK: true:
; CHECK-NEXT: call void @foo(i32 1)
; CHECK-NEXT: br label [[COMMON_RET:%.*]]
; CHECK: false:
; CHECK-NEXT: call void @foo(i32 3)
; CHECK-NEXT: br label [[COMMON_RET]]
;
%and = and i8 %a, 254
%cmp = icmp eq i8 %and, 254
call void @llvm.assume(i1 %cmp)
switch i8 %a, label %default [i8 255, label %true
i8 254, label %false]
true:
call void @foo(i32 1)
ret void
false:
call void @foo(i32 3)
ret void
default:
call void @foo(i32 2)
ret void
}
; Check that we can eliminate both dead cases and dead defaults
; within a single run of simplifycfg
define void @test7(i8 %a) {
; CHECK-LABEL: define void @test7(
; CHECK-SAME: i8 [[A:%.*]]) {
; CHECK-NEXT: [[AND:%.*]] = and i8 [[A]], -2
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i8 [[AND]], -2
; CHECK-NEXT: call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: [[A_OFF:%.*]] = add i8 [[A]], 1
; CHECK-NEXT: [[SWITCH:%.*]] = icmp ult i8 [[A_OFF]], 1
; CHECK-NEXT: br i1 [[SWITCH]], label [[TRUE:%.*]], label [[FALSE:%.*]]
; CHECK: common.ret:
; CHECK-NEXT: ret void
; CHECK: true:
; CHECK-NEXT: call void @foo(i32 1)
; CHECK-NEXT: br label [[COMMON_RET:%.*]]
; CHECK: false:
; CHECK-NEXT: call void @foo(i32 3)
; CHECK-NEXT: br label [[COMMON_RET]]
;
%and = and i8 %a, 254
%cmp = icmp eq i8 %and, 254
call void @llvm.assume(i1 %cmp)
switch i8 %a, label %default [i8 255, label %true
i8 254, label %false
i8 0, label %also_dead]
true:
call void @foo(i32 1)
ret void
false:
call void @foo(i32 3)
ret void
also_dead:
call void @foo(i32 5)
ret void
default:
call void @foo(i32 2)
ret void
}
declare void @llvm.assume(i1)
define zeroext i1 @test8(i128 %a) {
; We should not transform conditions wider than 64 bit.
; CHECK-LABEL: define zeroext i1 @test8(
; CHECK-SAME: i128 [[A:%.*]]) {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = and i128 [[A]], 3894222643901120721397872246915072
; CHECK-NEXT: switch i128 [[TMP0]], label [[LOR_RHS:%.*]] [
; CHECK-NEXT: i128 1298074214633706907132624082305024, label [[LOR_END:%.*]]
; CHECK-NEXT: i128 2596148429267413814265248164610048, label [[LOR_END]]
; CHECK-NEXT: i128 3894222643901120721397872246915072, label [[LOR_END]]
; CHECK-NEXT: ]
; CHECK: lor.rhs:
; CHECK-NEXT: br label [[LOR_END]]
; CHECK: lor.end:
; CHECK-NEXT: [[TMP1:%.*]] = phi i1 [ true, [[ENTRY:%.*]] ], [ false, [[LOR_RHS]] ], [ true, [[ENTRY]] ], [ true, [[ENTRY]] ]
; CHECK-NEXT: ret i1 [[TMP1]]
;
entry:
%0 = and i128 %a, 3894222643901120721397872246915072
switch i128 %0, label %lor.rhs [
i128 1298074214633706907132624082305024, label %lor.end
i128 2596148429267413814265248164610048, label %lor.end
i128 3894222643901120721397872246915072, label %lor.end
]
lor.rhs: ; preds = %entry
br label %lor.end
lor.end: ; preds = %entry, %entry, %entry, %lor.rhs
%1 = phi i1 [ true, %entry ], [ false, %lor.rhs ], [ true, %entry ], [ true, %entry ]
ret i1 %1
}
!0 = !{!"branch_weights", i32 8, i32 4, i32 2, i32 1}
;.
; CHECK: [[PROF0]] = !{!"branch_weights", i32 0, i32 4, i32 2, i32 1, i32 8}
;.
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