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llvm-mirror/test/Transforms/DeadStoreElimination/simple.ll
Erik Eckstein 724d66d0e1 [DeadStoreElimination] remove a redundant store even if the load is in a different block. 
DeadStoreElimination does eliminate a store if it stores a value which was loaded from the same memory location.
So far this worked only if the store is in the same block as the load.
Now we can also handle stores which are in a different block than the load.
Example:

define i32 @test(i1, i32*) {
entry:
  %l2 = load i32, i32* %1, align 4
  br i1 %0, label %bb1, label %bb2
bb1:
  br label %bb3
bb2:
  ; This store is redundant
  store i32 %l2, i32* %1, align 4
  br label %bb3
bb3:
  ret i32 0
}

Differential Revision: http://reviews.llvm.org/D11854

llvm-svn: 244901
2015-08-13 15:36:11 +00:00

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; RUN: opt < %s -basicaa -dse -S | FileCheck %s
target datalayout = "E-p:64:64:64-a0:0:8-f32:32:32-f64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-v64:64:64-v128:128:128"
declare void @llvm.memset.p0i8.i64(i8* nocapture, i8, i64, i32, i1) nounwind
declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture, i64, i32, i1) nounwind
declare void @llvm.init.trampoline(i8*, i8*, i8*)
define void @test1(i32* %Q, i32* %P) {
%DEAD = load i32, i32* %Q
store i32 %DEAD, i32* %P
store i32 0, i32* %P
ret void
; CHECK-LABEL: @test1(
; CHECK-NEXT: store i32 0, i32* %P
; CHECK-NEXT: ret void
}
; PR8576 - Should delete store of 10 even though p/q are may aliases.
define void @test2(i32 *%p, i32 *%q) {
store i32 10, i32* %p, align 4
store i32 20, i32* %q, align 4
store i32 30, i32* %p, align 4
ret void
; CHECK-LABEL: @test2(
; CHECK-NEXT: store i32 20
}
; PR8677
@g = global i32 1
define i32 @test3(i32* %g_addr) nounwind {
; CHECK-LABEL: @test3(
; CHECK: load i32, i32* %g_addr
%g_value = load i32, i32* %g_addr, align 4
store i32 -1, i32* @g, align 4
store i32 %g_value, i32* %g_addr, align 4
%tmp3 = load i32, i32* @g, align 4
ret i32 %tmp3
}
define void @test4(i32* %Q) {
%a = load i32, i32* %Q
store volatile i32 %a, i32* %Q
ret void
; CHECK-LABEL: @test4(
; CHECK-NEXT: load i32
; CHECK-NEXT: store volatile
; CHECK-NEXT: ret void
}
define void @test5(i32* %Q) {
%a = load volatile i32, i32* %Q
store i32 %a, i32* %Q
ret void
; CHECK-LABEL: @test5(
; CHECK-NEXT: load volatile
; CHECK-NEXT: ret void
}
; Should delete store of 10 even though memset is a may-store to P (P and Q may
; alias).
define void @test6(i32 *%p, i8 *%q) {
store i32 10, i32* %p, align 4 ;; dead.
call void @llvm.memset.p0i8.i64(i8* %q, i8 42, i64 900, i32 1, i1 false)
store i32 30, i32* %p, align 4
ret void
; CHECK-LABEL: @test6(
; CHECK-NEXT: call void @llvm.memset
}
; Should delete store of 10 even though memcpy is a may-store to P (P and Q may
; alias).
define void @test7(i32 *%p, i8 *%q, i8* noalias %r) {
store i32 10, i32* %p, align 4 ;; dead.
call void @llvm.memcpy.p0i8.p0i8.i64(i8* %q, i8* %r, i64 900, i32 1, i1 false)
store i32 30, i32* %p, align 4
ret void
; CHECK-LABEL: @test7(
; CHECK-NEXT: call void @llvm.memcpy
}
; Do not delete stores that are only partially killed.
define i32 @test8() {
%V = alloca i32
store i32 1234567, i32* %V
%V2 = bitcast i32* %V to i8*
store i8 0, i8* %V2
%X = load i32, i32* %V
ret i32 %X
; CHECK-LABEL: @test8(
; CHECK: store i32 1234567
}
; Test for byval handling.
%struct.x = type { i32, i32, i32, i32 }
define void @test9(%struct.x* byval %a) nounwind {
%tmp2 = getelementptr %struct.x, %struct.x* %a, i32 0, i32 0
store i32 1, i32* %tmp2, align 4
ret void
; CHECK-LABEL: @test9(
; CHECK-NEXT: ret void
}
; Test for inalloca handling.
define void @test9_2(%struct.x* inalloca %a) nounwind {
%tmp2 = getelementptr %struct.x, %struct.x* %a, i32 0, i32 0
store i32 1, i32* %tmp2, align 4
ret void
; CHECK-LABEL: @test9_2(
; CHECK-NEXT: ret void
}
; va_arg has fuzzy dependence, the store shouldn't be zapped.
define double @test10(i8* %X) {
%X_addr = alloca i8*
store i8* %X, i8** %X_addr
%tmp.0 = va_arg i8** %X_addr, double
ret double %tmp.0
; CHECK-LABEL: @test10(
; CHECK: store
}
; DSE should delete the dead trampoline.
declare void @test11f()
define void @test11() {
; CHECK-LABEL: @test11(
%storage = alloca [10 x i8], align 16 ; <[10 x i8]*> [#uses=1]
; CHECK-NOT: alloca
%cast = getelementptr [10 x i8], [10 x i8]* %storage, i32 0, i32 0 ; <i8*> [#uses=1]
call void @llvm.init.trampoline( i8* %cast, i8* bitcast (void ()* @test11f to i8*), i8* null ) ; <i8*> [#uses=1]
; CHECK-NOT: trampoline
ret void
; CHECK: ret void
}
; PR2599 - load -> store to same address.
define void @test12({ i32, i32 }* %x) nounwind {
%tmp4 = getelementptr { i32, i32 }, { i32, i32 }* %x, i32 0, i32 0
%tmp5 = load i32, i32* %tmp4, align 4
%tmp7 = getelementptr { i32, i32 }, { i32, i32 }* %x, i32 0, i32 1
%tmp8 = load i32, i32* %tmp7, align 4
%tmp17 = sub i32 0, %tmp8
store i32 %tmp5, i32* %tmp4, align 4
store i32 %tmp17, i32* %tmp7, align 4
ret void
; CHECK-LABEL: @test12(
; CHECK-NOT: tmp5
; CHECK: ret void
}
; %P doesn't escape, the DEAD instructions should be removed.
declare void @test13f()
define i32* @test13() {
%p = tail call i8* @malloc(i32 4)
%P = bitcast i8* %p to i32*
%DEAD = load i32, i32* %P
%DEAD2 = add i32 %DEAD, 1
store i32 %DEAD2, i32* %P
call void @test13f( )
store i32 0, i32* %P
ret i32* %P
; CHECK: @test13()
; CHECK-NEXT: malloc
; CHECK-NEXT: bitcast
; CHECK-NEXT: call void
}
define i32 addrspace(1)* @test13_addrspacecast() {
%p = tail call i8* @malloc(i32 4)
%p.bc = bitcast i8* %p to i32*
%P = addrspacecast i32* %p.bc to i32 addrspace(1)*
%DEAD = load i32, i32 addrspace(1)* %P
%DEAD2 = add i32 %DEAD, 1
store i32 %DEAD2, i32 addrspace(1)* %P
call void @test13f( )
store i32 0, i32 addrspace(1)* %P
ret i32 addrspace(1)* %P
; CHECK: @test13_addrspacecast()
; CHECK-NEXT: malloc
; CHECK-NEXT: bitcast
; CHECK-NEXT: addrspacecast
; CHECK-NEXT: call void
}
declare noalias i8* @malloc(i32)
declare noalias i8* @calloc(i32, i32)
define void @test14(i32* %Q) {
%P = alloca i32
%DEAD = load i32, i32* %Q
store i32 %DEAD, i32* %P
ret void
; CHECK-LABEL: @test14(
; CHECK-NEXT: ret void
}
; PR8701
;; Fully dead overwrite of memcpy.
define void @test15(i8* %P, i8* %Q) nounwind ssp {
tail call void @llvm.memcpy.p0i8.p0i8.i64(i8* %P, i8* %Q, i64 12, i32 1, i1 false)
tail call void @llvm.memcpy.p0i8.p0i8.i64(i8* %P, i8* %Q, i64 12, i32 1, i1 false)
ret void
; CHECK-LABEL: @test15(
; CHECK-NEXT: call void @llvm.memcpy
; CHECK-NEXT: ret
}
;; Full overwrite of smaller memcpy.
define void @test16(i8* %P, i8* %Q) nounwind ssp {
tail call void @llvm.memcpy.p0i8.p0i8.i64(i8* %P, i8* %Q, i64 8, i32 1, i1 false)
tail call void @llvm.memcpy.p0i8.p0i8.i64(i8* %P, i8* %Q, i64 12, i32 1, i1 false)
ret void
; CHECK-LABEL: @test16(
; CHECK-NEXT: call void @llvm.memcpy
; CHECK-NEXT: ret
}
;; Overwrite of memset by memcpy.
define void @test17(i8* %P, i8* noalias %Q) nounwind ssp {
tail call void @llvm.memset.p0i8.i64(i8* %P, i8 42, i64 8, i32 1, i1 false)
tail call void @llvm.memcpy.p0i8.p0i8.i64(i8* %P, i8* %Q, i64 12, i32 1, i1 false)
ret void
; CHECK-LABEL: @test17(
; CHECK-NEXT: call void @llvm.memcpy
; CHECK-NEXT: ret
}
; Should not delete the volatile memset.
define void @test17v(i8* %P, i8* %Q) nounwind ssp {
tail call void @llvm.memset.p0i8.i64(i8* %P, i8 42, i64 8, i32 1, i1 true)
tail call void @llvm.memcpy.p0i8.p0i8.i64(i8* %P, i8* %Q, i64 12, i32 1, i1 false)
ret void
; CHECK-LABEL: @test17v(
; CHECK-NEXT: call void @llvm.memset
; CHECK-NEXT: call void @llvm.memcpy
; CHECK-NEXT: ret
}
; PR8728
; Do not delete instruction where possible situation is:
; A = B
; A = A
define void @test18(i8* %P, i8* %Q, i8* %R) nounwind ssp {
tail call void @llvm.memcpy.p0i8.p0i8.i64(i8* %P, i8* %Q, i64 12, i32 1, i1 false)
tail call void @llvm.memcpy.p0i8.p0i8.i64(i8* %P, i8* %R, i64 12, i32 1, i1 false)
ret void
; CHECK-LABEL: @test18(
; CHECK-NEXT: call void @llvm.memcpy
; CHECK-NEXT: call void @llvm.memcpy
; CHECK-NEXT: ret
}
; The store here is not dead because the byval call reads it.
declare void @test19f({i32}* byval align 4 %P)
define void @test19({i32} * nocapture byval align 4 %arg5) nounwind ssp {
bb:
%tmp7 = getelementptr inbounds {i32}, {i32}* %arg5, i32 0, i32 0
store i32 912, i32* %tmp7
call void @test19f({i32}* byval align 4 %arg5)
ret void
; CHECK-LABEL: @test19(
; CHECK: store i32 912
; CHECK: call void @test19f
}
define void @test20() {
%m = call i8* @malloc(i32 24)
store i8 0, i8* %m
ret void
}
; CHECK-LABEL: @test20(
; CHECK-NEXT: ret void
; CHECK-LABEL: @test21(
define void @test21() {
%m = call i8* @calloc(i32 9, i32 7)
store i8 0, i8* %m
; CHECK-NEXT: ret void
ret void
}
; CHECK-LABEL: @test22(
define void @test22(i1 %i, i32 %k, i32 %m) nounwind {
%k.addr = alloca i32
%m.addr = alloca i32
%k.addr.m.addr = select i1 %i, i32* %k.addr, i32* %m.addr
store i32 0, i32* %k.addr.m.addr, align 4
; CHECK-NEXT: ret void
ret void
}
; PR13547
; CHECK-LABEL: @test23(
; CHECK: store i8 97
; CHECK: store i8 0
declare noalias i8* @strdup(i8* nocapture) nounwind
define noalias i8* @test23() nounwind uwtable ssp {
%x = alloca [2 x i8], align 1
%arrayidx = getelementptr inbounds [2 x i8], [2 x i8]* %x, i64 0, i64 0
store i8 97, i8* %arrayidx, align 1
%arrayidx1 = getelementptr inbounds [2 x i8], [2 x i8]* %x, i64 0, i64 1
store i8 0, i8* %arrayidx1, align 1
%call = call i8* @strdup(i8* %arrayidx) nounwind
ret i8* %call
}
; Make sure same sized store to later element is deleted
; CHECK-LABEL: @test24(
; CHECK-NOT: store i32 0
; CHECK-NOT: store i32 0
; CHECK: store i32 %b
; CHECK: store i32 %c
; CHECK: ret void
define void @test24([2 x i32]* %a, i32 %b, i32 %c) nounwind {
%1 = getelementptr inbounds [2 x i32], [2 x i32]* %a, i64 0, i64 0
store i32 0, i32* %1, align 4
%2 = getelementptr inbounds [2 x i32], [2 x i32]* %a, i64 0, i64 1
store i32 0, i32* %2, align 4
%3 = getelementptr inbounds [2 x i32], [2 x i32]* %a, i64 0, i64 0
store i32 %b, i32* %3, align 4
%4 = getelementptr inbounds [2 x i32], [2 x i32]* %a, i64 0, i64 1
store i32 %c, i32* %4, align 4
ret void
}
; Check another case like PR13547 where strdup is not like malloc.
; CHECK-LABEL: @test25(
; CHECK: load i8
; CHECK: store i8 0
; CHECK: store i8 %tmp
define i8* @test25(i8* %p) nounwind {
%p.4 = getelementptr i8, i8* %p, i64 4
%tmp = load i8, i8* %p.4, align 1
store i8 0, i8* %p.4, align 1
%q = call i8* @strdup(i8* %p) nounwind optsize
store i8 %tmp, i8* %p.4, align 1
ret i8* %q
}
; Remove redundant store if loaded value is in another block.
; CHECK-LABEL: @test26(
; CHECK-NOT: store
; CHECK: ret
define i32 @test26(i1 %c, i32* %p) {
entry:
%v = load i32, i32* %p, align 4
br i1 %c, label %bb1, label %bb2
bb1:
br label %bb3
bb2:
store i32 %v, i32* %p, align 4
br label %bb3
bb3:
ret i32 0
}
; Remove redundant store if loaded value is in another block.
; CHECK-LABEL: @test27(
; CHECK-NOT: store
; CHECK: ret
define i32 @test27(i1 %c, i32* %p) {
entry:
%v = load i32, i32* %p, align 4
br i1 %c, label %bb1, label %bb2
bb1:
br label %bb3
bb2:
br label %bb3
bb3:
store i32 %v, i32* %p, align 4
ret i32 0
}
; Don't remove redundant store because of may-aliased store.
; CHECK-LABEL: @test28(
; CHECK: bb3:
; CHECK-NEXT: store i32 %v
define i32 @test28(i1 %c, i32* %p, i32* %p2, i32 %i) {
entry:
%v = load i32, i32* %p, align 4
; Might overwrite value at %p
store i32 %i, i32* %p2, align 4
br i1 %c, label %bb1, label %bb2
bb1:
br label %bb3
bb2:
br label %bb3
bb3:
store i32 %v, i32* %p, align 4
ret i32 0
}
; Don't remove redundant store because of may-aliased store.
; CHECK-LABEL: @test29(
; CHECK: bb3:
; CHECK-NEXT: store i32 %v
define i32 @test29(i1 %c, i32* %p, i32* %p2, i32 %i) {
entry:
%v = load i32, i32* %p, align 4
br i1 %c, label %bb1, label %bb2
bb1:
br label %bb3
bb2:
; Might overwrite value at %p
store i32 %i, i32* %p2, align 4
br label %bb3
bb3:
store i32 %v, i32* %p, align 4
ret i32 0
}
declare void @unknown_func()
; Don't remove redundant store because of unknown call.
; CHECK-LABEL: @test30(
; CHECK: bb3:
; CHECK-NEXT: store i32 %v
define i32 @test30(i1 %c, i32* %p, i32 %i) {
entry:
%v = load i32, i32* %p, align 4
br i1 %c, label %bb1, label %bb2
bb1:
br label %bb3
bb2:
; Might overwrite value at %p
call void @unknown_func()
br label %bb3
bb3:
store i32 %v, i32* %p, align 4
ret i32 0
}
; Remove redundant store if loaded value is in another block inside a loop.
; CHECK-LABEL: @test31(
; CHECK-NOT: store
; CHECK: ret
define i32 @test31(i1 %c, i32* %p, i32 %i) {
entry:
%v = load i32, i32* %p, align 4
br label %bb1
bb1:
store i32 %v, i32* %p, align 4
br i1 undef, label %bb1, label %bb2
bb2:
ret i32 0
}
; Don't remove redundant store in a loop with a may-alias store.
; CHECK-LABEL: @test32(
; CHECK: bb1:
; CHECK-NEXT: store i32 %v
; CHECK-NEXT: call void @unknown_func
define i32 @test32(i1 %c, i32* %p, i32 %i) {
entry:
%v = load i32, i32* %p, align 4
br label %bb1
bb1:
store i32 %v, i32* %p, align 4
; Might read and overwrite value at %p
call void @unknown_func()
br i1 undef, label %bb1, label %bb2
bb2:
ret i32 0
}
; Remove redundant store, which is in the lame loop as the load.
; CHECK-LABEL: @test33(
; CHECK-NOT: store
; CHECK: ret
define i32 @test33(i1 %c, i32* %p, i32 %i) {
entry:
br label %bb1
bb1:
%v = load i32, i32* %p, align 4
br label %bb2
bb2:
store i32 %v, i32* %p, align 4
; Might read and overwrite value at %p, but doesn't matter.
call void @unknown_func()
br i1 undef, label %bb1, label %bb3
bb3:
ret i32 0
}
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