mirror of
https://github.com/RPCS3/llvm.git
synced 2025-03-06 09:39:28 +00:00
12b807e83a
Pass MemCpyOpt doesn't check if a store instruction is nontemporal.
As a consequence, adjacent nontemporal stores are always merged into a
memset call.
Example:
;;;
define void @foo(<4 x float>* nocapture %p) {
entry:
store <4 x float> zeroinitializer, <4 x float>* %p, align 16, !nontemporal !0
%p1 = getelementptr inbounds <4 x float>, <4 x float>* %dst, i64 1
store <4 x float> zeroinitializer, <4 x float>* %p1, align 16, !nontemporal !0
ret void
}
!0 = !{i32 1}
;;;
In this example, the two nontemporal stores are combined to a memset of zero
which does not preserve the nontemporal hint. Later on the backend (tested on a
x86-64 corei7) expands that memset call into a sequence of two normal 16-byte
aligned vector stores.
opt -memcpyopt example.ll -S -o - | llc -mcpu=corei7 -o -
Before:
xorps %xmm0, %xmm0
movaps %xmm0, 16(%rdi)
movaps %xmm0, (%rdi)
With this patch, we no longer merge nontemporal stores into calls to memset.
In this example, llc correctly expands the two stores into two movntps:
xorps %xmm0, %xmm0
movntps %xmm0, 16(%rdi)
movntps %xmm0, (%rdi)
In theory, we could extend the usage of !nontemporal metadata to memcpy/memset
calls. However a change like that would only have the effect of forcing the
backend to expand !nontemporal memsets back to sequences of store instructions.
A memset library call would not have exactly the same semantic of a builtin
!nontemporal memset call. So, SelectionDAG will have to conservatively expand
it back to a sequence of !nontemporal stores (effectively undoing the merging).
Differential Revision: http://reviews.llvm.org/D13519
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@249820 91177308-0d34-0410-b5e6-96231b3b80d8
50 lines
2.7 KiB
LLVM
50 lines
2.7 KiB
LLVM
; RUN: opt < %s -memcpyopt -S | FileCheck %s
|
|
|
|
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
|
|
|
|
; Verify that we don't combine nontemporal stores into memset calls.
|
|
|
|
define void @nontemporal_stores_1(<4 x float>* nocapture %dst) {
|
|
; CHECK-LABEL: @nontemporal_stores_1
|
|
; CHECK: store <4 x float> zeroinitializer, <4 x float>* %dst, align 16, !nontemporal !0
|
|
; CHECK: store <4 x float> zeroinitializer, <4 x float>* %ptr1, align 16, !nontemporal !0
|
|
; CHECK: store <4 x float> zeroinitializer, <4 x float>* %ptr2, align 16, !nontemporal !0
|
|
; CHECK: store <4 x float> zeroinitializer, <4 x float>* %ptr3, align 16, !nontemporal !0
|
|
; CHECK: store <4 x float> zeroinitializer, <4 x float>* %ptr4, align 16, !nontemporal !0
|
|
; CHECK: store <4 x float> zeroinitializer, <4 x float>* %ptr5, align 16, !nontemporal !0
|
|
; CHECK: store <4 x float> zeroinitializer, <4 x float>* %ptr6, align 16, !nontemporal !0
|
|
; CHECK: store <4 x float> zeroinitializer, <4 x float>* %ptr7, align 16, !nontemporal !0
|
|
; CHECK-NEXT: ret void
|
|
entry:
|
|
store <4 x float> zeroinitializer, <4 x float>* %dst, align 16, !nontemporal !0
|
|
%ptr1 = getelementptr inbounds <4 x float>, <4 x float>* %dst, i64 1
|
|
store <4 x float> zeroinitializer, <4 x float>* %ptr1, align 16, !nontemporal !0
|
|
%ptr2 = getelementptr inbounds <4 x float>, <4 x float>* %dst, i64 2
|
|
store <4 x float> zeroinitializer, <4 x float>* %ptr2, align 16, !nontemporal !0
|
|
%ptr3 = getelementptr inbounds <4 x float>, <4 x float>* %dst, i64 3
|
|
store <4 x float> zeroinitializer, <4 x float>* %ptr3, align 16, !nontemporal !0
|
|
%ptr4 = getelementptr inbounds <4 x float>, <4 x float>* %dst, i64 4
|
|
store <4 x float> zeroinitializer, <4 x float>* %ptr4, align 16, !nontemporal !0
|
|
%ptr5 = getelementptr inbounds <4 x float>, <4 x float>* %dst, i64 5
|
|
store <4 x float> zeroinitializer, <4 x float>* %ptr5, align 16, !nontemporal !0
|
|
%ptr6 = getelementptr inbounds <4 x float>, <4 x float>* %dst, i64 6
|
|
store <4 x float> zeroinitializer, <4 x float>* %ptr6, align 16, !nontemporal !0
|
|
%ptr7 = getelementptr inbounds <4 x float>, <4 x float>* %dst, i64 7
|
|
store <4 x float> zeroinitializer, <4 x float>* %ptr7, align 16, !nontemporal !0
|
|
ret void
|
|
}
|
|
|
|
define void @nontemporal_stores_2(<4 x float>* nocapture %dst) {
|
|
; CHECK-LABEL: @nontemporal_stores_2
|
|
; CHECK: store <4 x float> zeroinitializer, <4 x float>* %dst, align 16, !nontemporal !0
|
|
; CHECK: store <4 x float> zeroinitializer, <4 x float>* %ptr1, align 16, !nontemporal !0
|
|
; CHECK-NEXT: ret void
|
|
entry:
|
|
store <4 x float> zeroinitializer, <4 x float>* %dst, align 16, !nontemporal !0
|
|
%ptr1 = getelementptr inbounds <4 x float>, <4 x float>* %dst, i64 1
|
|
store <4 x float> zeroinitializer, <4 x float>* %ptr1, align 16, !nontemporal !0
|
|
ret void
|
|
}
|
|
|
|
!0 = !{i32 1}
|