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llvm-mirror/test/Transforms/DCE/basic.ll
zoecarver 03bc2a070d Re-commit: Mark values as trivially dead when their only use is a start or end lifetime intrinsic.
Summary:
If the only use of a value is a start or end lifetime intrinsic then mark the intrinsic as trivially dead. This should allow for that value to then be removed as well.

Currently, this only works for allocas, globals, and arguments.

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D79355
2020-05-08 12:24:10 -07:00

74 lines
2.5 KiB
LLVM

; RUN: opt -debugify -dce -S < %s | FileCheck %s
; RUN: opt -passes='module(debugify),function(dce)' -S < %s | FileCheck %s
; CHECK-LABEL: @test
define void @test() {
%add = add i32 1, 2
; CHECK-NEXT: call void @llvm.dbg.value(metadata i32 1, metadata [[add:![0-9]+]], metadata !DIExpression(DW_OP_plus_uconst, 2, DW_OP_stack_value))
%sub = sub i32 %add, 1
; CHECK-NEXT: call void @llvm.dbg.value(metadata i32 1, metadata [[sub:![0-9]+]], metadata !DIExpression(DW_OP_plus_uconst, 2, DW_OP_constu, 1, DW_OP_minus, DW_OP_stack_value))
; CHECK-NEXT: ret void
ret void
}
declare void @llvm.lifetime.start.p0i8(i64, i8* nocapture) nounwind
declare void @llvm.lifetime.end.p0i8(i64, i8* nocapture) nounwind
; CHECK-LABEL: @test_lifetime_alloca
define i32 @test_lifetime_alloca() {
; Check that lifetime intrinsics are removed along with the pointer.
; CHECK-NEXT: @llvm.dbg.value
; CHECK-NEXT: ret i32 0
; CHECK-NOT: llvm.lifetime.start
; CHECK-NOT: llvm.lifetime.end
%i = alloca i8, align 4
call void @llvm.lifetime.start.p0i8(i64 -1, i8* %i)
call void @llvm.lifetime.end.p0i8(i64 -1, i8* %i)
ret i32 0
}
; CHECK-LABEL: @test_lifetime_arg
define i32 @test_lifetime_arg(i8*) {
; Check that lifetime intrinsics are removed along with the pointer.
; CHECK-NEXT: llvm.dbg.value
; CHECK-NEXT: ret i32 0
; CHECK-NOT: llvm.lifetime.start
; CHECK-NOT: llvm.lifetime.end
call void @llvm.lifetime.start.p0i8(i64 -1, i8* %0)
call void @llvm.lifetime.end.p0i8(i64 -1, i8* %0)
ret i32 0
}
@glob = global i8 1
; CHECK-LABEL: @test_lifetime_global
define i32 @test_lifetime_global() {
; Check that lifetime intrinsics are removed along with the pointer.
; CHECK-NEXT: llvm.dbg.value
; CHECK-NEXT: ret i32 0
; CHECK-NOT: llvm.lifetime.start
; CHECK-NOT: llvm.lifetime.end
call void @llvm.lifetime.start.p0i8(i64 -1, i8* @glob)
call void @llvm.lifetime.end.p0i8(i64 -1, i8* @glob)
ret i32 0
}
; CHECK-LABEL: @test_lifetime_bitcast
define i32 @test_lifetime_bitcast(i32*) {
; Check that lifetime intrinsics are NOT removed when the pointer is a bitcast.
; It's not uncommon for two bitcasts to be made: one for lifetime, one for use.
; TODO: Support the above case.
; CHECK-NEXT: bitcast
; CHECK-NEXT: llvm.dbg.value
; CHECK-NEXT: llvm.lifetime.start
; CHECK-NEXT: llvm.lifetime.end
; CHECK-NEXT: ret i32 0
%2 = bitcast i32* %0 to i8*
call void @llvm.lifetime.start.p0i8(i64 -1, i8* %2)
call void @llvm.lifetime.end.p0i8(i64 -1, i8* %2)
ret i32 0
}
; CHECK: [[add]] = !DILocalVariable
; CHECK: [[sub]] = !DILocalVariable