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llvm-mirror/test/Transforms/DeadStoreElimination/PartialStore.ll
Sanjay Patel 13ff833337 [DSE] Merge stores when the later store only writes to memory locations the early store also wrote to (2nd try)
This is a 2nd attempt at:
https://reviews.llvm.org/rL310055
...which was reverted at rL310123 because of PR34074:
https://bugs.llvm.org/show_bug.cgi?id=34074

In this version, we break out of the inner loop after we successfully merge and kill a pair of stores. In the
earlier rev, we were continuing instead, which meant we could process the invalid info from a now dead store.

Original commit message (authored by Filipe Cabecinhas):

This fixes PR31777.

If both stores' values are ConstantInt, we merge the two stores
(shifting the smaller store appropriately) and replace the earlier (and
larger) store with an updated constant.

In the future we should also support vectors of integers. And maybe
float/double if we can.  

Differential Revision: https://reviews.llvm.org/D30703

llvm-svn: 314206
2017-09-26 13:54:28 +00:00

88 lines
2.3 KiB
LLVM

; RUN: opt < %s -basicaa -dse -enable-dse-partial-store-merging=false -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"
; Ensure that the dead store is deleted in this case. It is wholely
; overwritten by the second store.
define void @test1(i32 *%V) {
%V2 = bitcast i32* %V to i8* ; <i8*> [#uses=1]
store i8 0, i8* %V2
store i32 1234567, i32* %V
ret void
; CHECK-LABEL: @test1(
; CHECK-NEXT: store i32 1234567
}
; Note that we could do better by merging the two stores into one.
define void @test2(i32* %P) {
; CHECK-LABEL: @test2(
store i32 0, i32* %P
; CHECK: store i32
%Q = bitcast i32* %P to i16*
store i16 1, i16* %Q
; CHECK: store i16
ret void
}
define i32 @test3(double %__x) {
; CHECK-LABEL: @test3(
; CHECK: store double
%__u = alloca { [3 x i32] }
%tmp.1 = bitcast { [3 x i32] }* %__u to double*
store double %__x, double* %tmp.1
%tmp.4 = getelementptr { [3 x i32] }, { [3 x i32] }* %__u, i32 0, i32 0, i32 1
%tmp.5 = load i32, i32* %tmp.4
%tmp.6 = icmp slt i32 %tmp.5, 0
%tmp.7 = zext i1 %tmp.6 to i32
ret i32 %tmp.7
}
; PR6043
define void @test4(i8* %P) {
; CHECK-LABEL: @test4(
; CHECK-NEXT: bitcast
; CHECK-NEXT: store double
store i8 19, i8* %P ;; dead
%A = getelementptr i8, i8* %P, i32 3
store i8 42, i8* %A ;; dead
%Q = bitcast i8* %P to double*
store double 0.0, double* %Q
ret void
}
; PR8657
declare void @test5a(i32*)
define void @test5(i32 %i) nounwind ssp {
%A = alloca i32
%B = bitcast i32* %A to i8*
%C = getelementptr i8, i8* %B, i32 %i
store i8 10, i8* %C ;; Dead store to variable index.
store i32 20, i32* %A
call void @test5a(i32* %A)
ret void
; CHECK-LABEL: @test5(
; CHECK-NEXT: alloca
; CHECK-NEXT: store i32 20
; CHECK-NEXT: call void @test5a
}
declare void @test5a_as1(i32*)
define void @test5_addrspacecast(i32 %i) nounwind ssp {
%A = alloca i32
%B = addrspacecast i32* %A to i8 addrspace(1)*
%C = getelementptr i8, i8 addrspace(1)* %B, i32 %i
store i8 10, i8 addrspace(1)* %C ;; Dead store to variable index.
store i32 20, i32* %A
call void @test5a(i32* %A)
ret void
; CHECK-LABEL: @test5_addrspacecast(
; CHECK-NEXT: alloca
; CHECK-NEXT: store i32 20
; CHECK-NEXT: call void @test5a
}